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iii ~ ampor II 11 ~ W W

1111118

11111125 1111114 1111116 11I1112~ 1111114 1111116

MICROCOPY RESOLUTION TEST CHART MICROCOPY RESOLUTION TEST CHART

NATIONAL BUREAU Of STANDARDS-1963-A NATIONAL BUREAU or STANDARDS-1963-A

on the Viability of Rice

0 (f

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(tgt rgt ~bull ~

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h ~Jl -gt( -3 gt-

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~-Jen A Report of lt-

~ - Research and a ~ ~ Literature Survey

TECHNICAL BULLETIN NO 1129 U S DEPARTMENT OF AGRICULTURE WASHINGTON D C DECEMBER 1955

CONTENTS

Introduction Southern pramiddotti( ill rice conditionin~ Reyiew of literature E~rimetal matcrial and proee(illlls

Natwe of experimcnls Determination of moiilurc contnl Determination of ricl temperature during IwaL treatment Water haths Detel~llin1 tion of pnssun~ in toPIIlred 1I11w bull GennmH tlon Ie t~

Heat-treatment experiments ill 1950 Temperature and 1lI0iture-contellt triablei Temperatllre and time ntriabk

Heat-treatment experinl(nl in 1951 bull Temperatlll( and lIIoisturc-eonLCllt ariahlmiddot Temperature and tillie variables Tcmperature 1II0istllJ(-(ontent alld )Illlrit~ ulriahies

Hcal-treatmfn l expcrill1en ts in 1952 Tempcr~ 1111( and lIIoisturt-(olltellt ria hi Telllperltllre and tillle middotariahli _ _

The gcrmina tinn test _ _ _ Seetling almoJllIaliLi Dry secd _ ExcessiYely Wet s(fdhed Resistanec to fungi Improved germina tioll

General discussion _ _ Seed heat-trca tmen t 1II(middotthods ald Lhlmiddotir appliea t ion

Dirc(l (olltact il hot wahmiddotr Direct eonta(l lit) Iuatfd air _ Closed (olltaineni _ _ Dircet eOll tHet wi th liq lIid 0 tlwl Llta II I a itl New methods and modificatiOlls

SunnnalY _ _ _ Litclmiddotatll~e (ittd _ _

Page

1 2 3 8 I)

10 10 11 11 12 12 15 15 16 17 21 26 28 bull 28 33 36 36 36 37 37 37 38 42 43 43 44 44 4-5 4middot5 47

Jor 5alo hy thl SlP(llntel~lIt of lOllIn1lIIIS t S (iorrnllIcuL Printing Ollico

3Sllin~tQn 21 O C PIcc 2() ccnt$

A Report of Research and a literature Survey I

B VERSOS H [(FARrSF nllftfriolrHjiNt T()~lPH T HO(rS (nflnshydegiNtl engi11fet and TXyenLOR ~- ~[cLn[ORE engil1(fling aid Southern Ctiliiiltioll FtXfIII(z 1Jrll1(middot1 _lfri(olt1tllfl [NI fl(z fliee ~

INTRODECTION

bull

The e frects () f heat on lOuh or paddy lmiddotiee laquo() fyZfl sati lel) have tlssumed greatEl IlllpOrrlt1nee in the l-nited States ~il1ee the introducshytion of combine hanEtil1 and the nsnciated ulld fnr artificial dryshying or conditionillg lmproEment in the method of clrying including eqnipment and operation an lil1lited by the danger of heat injury to the rice Pnutical ricl-c1rying proclclllle have been cleshyvelopedlargely as H result of experimentltion in eomnHrein1 plants Fortuitollsly plocldme that haP favorpd high milling yillds haY( Et1Enllly fiHorNl high sltc1 viability Xlnlthei(ss tIlt presEnt sizlble risk if we consider for ExHmple that in 1952 on~r 48 million Icut al () f inmiddot PIP pmdllced in _ rlm11as LOlliiantl Tpxas MiEsisshy~ippi nnd (nlifomin Uin 3 bull ~r()~t of tlIi I(P ] (()1l11)ill~d It moisshyture (ontEnts aboe H percent and required artificial drying before milling or storHaE

Vel littlp i bHnnl abol1t the E1lpds of hElt aloLH 011 thedability of artIficiallY tlliplt1 rOllh rice on thE activity of its enznnes on tlie nutritioual nnilnbilir or dEtrilction of it proteini aild Itamins or on itg othEl eharactEriri(s In(l (olltitllEnt~ J[nch of the knowlshyedae now appliEltl in the heat treatment of Jollh rice is based on the Hmlfllptioll that it bphnsi~ll will lip lImlootl to that observed for other EN] that haeuro been suntlnllv heurout-trlated

To adnuHe ollr kllowlNle of tlie ptrft of hPllt OTI lmiddotice n series of investigation PI(- ltlldrtakp11 11111ill thE lluyetina SEaSOllS of U150 ID51 tnt Ifj)l nlVlPs(lItarip lXllerillllntE are lepolted in this uulletin Their (ope is limitEd prinHlrily to demonstrating certain tlmperatllJ time and IllOitnlE-tollltllt lEIlrioultips of treatlllent to the ittuilitv of rOlla11 rie

The ilutlion deciCled to invetiate the effects of the different vllrishyabIes on viability ratbEl than on other physical chEmi~al or biological

LRlllmittptl fllr Inllll(ntOll pril ls H) ThE n Ilthorl In itHlphttl til W n TIa rt dirptnr (rfti rlfll of till Lonisiana

AfPipllltntullxp(rinwttt ~tltin to n T HnlT IIPH(1 (lr till _gri(nltlllti EngishynCtrillg jp)pa 111 f)(plltrulnt Ind ro [ K allI uperint(lHlenr an L O C)()lltmiddotoltl f01lllPrly usistallt 1Tinlflllal PI1inPIr of rill Rit EX[lrillllnt Stashytion rOtmiddot tllP lllhi1p~e 01 (OII(IIltin tllP hltt-tlpatIllPnt pqwriments at the Rice EXlIerillllllt Krntioll (Imiddotuwlmiddotmiddot L1

Halit numhNs III llIUlntltlp r(f(r 10 Literainn lit(d V 47

1

AGRICUlTURE

charactermiddotstics There were practical reasons for this decision Themiddot smnples of heat-treated rough rice ere too small for sa6sfuctory millin~valuation tests To obtai ~- ~~xles would have necesshysitated decreasing the number of variables investigated Skilled techniCtl assistants were not lwnilable to perform complicated bioshychemical tests On the other hnnd tacilities Y(le adequate for making germination tests middotMoreover these tests reflect the biological conditions of seeds within limitations They IHlve the arlc1ecl a(lYanshytage of being uniYelsally used and understood Hence they provide data interpreta ble by mn ny workers other than seed analysts uch as seedsmen and fanners commercial grain-drier operators and millers p1nnt physiologi-t and pathologist and hio(lpnlists

Although three major yaliables-temperature of treatment time (duration) of treatmrnt and 11loitllLc content of the rice-ale CCll1shysiderecl the greatest ell1phasi~ is placed on the temperature of treatshyment or tIle llllt 1lli is beelusl altilit-iaily hpated til is nsP(l ill til(gt commercial drying 01 conditioning of rough rice and becHnse it has been useful in plpvp~ting deterioratiol1 of rice durillg stmiddotolage

Experiments Wlc planned fo nccolllplish se(lal objPcti-ps (llier among tllem (IP to detPllllil1e (1) the pl)pet of tpJ1lperatule oj heatshyill~ on iability (~) the effpct of time (dulation) of heating Oll

viability (3) thC rp1ntionship bCtweC11 till J1OistlllP eontCl1t of the rongh rice and the teJlJpemtulC crt hpHtinl and its etleet 011 viability and (4) the eltect of prolonged storage 011 the viability of heatshytreateel rice

SOUTHERN PRACTICES IN RICE CONDITIONING

Chanfres in the methods of l111IVptin~ and storing nrC lespol1Slible for the prescntintCIpst in the ellpets of hpnt 011 Iice pploximat(ly DO percent oJ thp ~outh~s 11l1l1l1nl1i(e cJopi no comhilll(1 a(Conling to Jones et al (P) Smith and Jonps ((J) found that the best tinle to halv(Ht Ii(p is wl1(11 til( ll1oi-t UI( (Ollt(llt of tltl ~tHII(IjIW rice ranges flol11 aboutmiddot 23 to 28 I(eIIL ~[lX(H (5)) and folenso et al C(8) ill I((pnl studips Ippolt(d that Ii(p SliOlll(l bp cOlllbinpcl when its JlJOiSIIIJ( lollilnt is within till lIi- to W-PPI((nt lanle i e if the fielcl]oss(S intludil1 hpl]iII and bJPtlkal ill thl (olllbilil alt to be reduced to a JIlininilllll flndif J1JaXillllJJ11 i(lds of [oll[ilanci helld rice H 1( to Ill obta inNl Fleh hmiddot (oJlJbi IWeI Iollrrh [iep will cleteriolatC rapid1middot 1IIIIp prolllpily dried Ol COIHlitionell

AltiliCiully II(gtutpd ail is lIllt1 ill lOIlli1lP llill1 dclirtllalioll op(rHtions to lP(uee the nJOistlln (ontpllt or tlw f[pshly COilibilIPd Iourrli ric( to 1J perccllt butmiddot tlie uttainlllllIt or this l11oiIIIIP 1((gt] i llO ~IHlIalltee that the rice wil] klPP indplinitplv IIndlI all conditions of stOlltIP ( I Cl) [I I l I tsorenson et (I to IP 1ta()1 JS t HI lIg I tpJl1]lllahIIPs nnd humidities Inail in til( soutillrn Ii(p-glowing HICns-Lolliialla Texas Arkansas al1d Mississippi (fpnkills J) andKInJl1pr j() Sirrshynilicant (oMriillltiollS hJp I)(pn 111[(1( to til( knohltlp of Iie( ltllyil~ OJ conditiolling- as it i lHncti(ell ill the (middotnittd Staft (~lIlifh ( rB 71 7~ 5 (( Bodlt I jJ BuCr 11 It 11 EJllel a l(l ~r(X(gta I J1 ~rcl~eal [if] )7 )8 (jO ]c1I((] alld KruIHr j -1 KlHlller 164748 4fJ

bull

bull

- Kramer and ~Iclnd )1 --ilwlHr and ~lllilins 10 1 Sorenson ct at

E~FE1CTS OF HEAT TREAl1IENT ON THE VIABILITY OF RICE 3

J7 lJ8 the Lonisiana Agricultmal Experiment Stntion 54 Cruz and Lltforteza ~() Bond 14 am1 Autrey ct at 8)

Bin aeration and (1rying techniques are being c1eYe1oped to remove the excesS l1l0isiUle from rough rice that has been stored at too high It moisture content that has absorbed moisture since storage or that is heating Ambient air is commonly used dUling the warm daylight houls when the relntiye humidity is lo-w Altifieially 11eated air is used if the nepd for the ltpiLilClllonLl of moistllle is apparent Seyera1 yorkers h1Ye contlibuttd a1ti](s on the (ItelopnlPnt of bin Htration and drying tpclllliqncs Illong thtlll mt ~tiln i nan ft fl Cl 9) Todd (8J) Ball a ntl (oon1O(l (12) 1 (oomotl (16) SOllnson et al (78) and ~Iol1isoll rt al (6J (in and the Lou isinna Aglicult-uml Experishyment StHtion (J5)

Rice fol sCtcl is O-[tCll c1lipd in commercial ltlryin units in the same llumllCl ns tIlt bulk t-hnt is dlitc1 to a 11l0istl1lp c(mtent suitable for millillg 01 StOlUlt TIlt COlllllHlcial u11its alP of course (leaned and inspected bpfc)le being loadell with Iiee to be (hiNl 101 s(ed purposes 111tir nse is l~nely one of conwnipnce Gp1lllination tests and farmshy(10]gt obsP]at-iom Sllpport thp prn(tice but (lata mp not 1lTailab1e to pya11latr jllpSPllt (Ollllll(1cia I tl1yi ng pIo(pd Il1PF folll the standpoint of Illlp1O-jng sp((l quality

UEVIEW OF LITERATURE

bull Although hpat has probnll1y lwen app1ipd in tl1( t1lllhnrnt of rough rice 101 clntlllies thpp mp lmt ipy publishpd l(eOllllts-nt ]Plst those readily iwnilable to occic1pntnl teac1EI3--that (kseribpits eJiect on the abilit) of ricp to gplminnte On til( other hall(11 lllunbpl of publicashytions a few of which h1e npPPH1ed in 1p(pnt yelrs plespnt data on the ptleuroct of hpat- trpItnlPnt- Oil gllmination capacity but mostly rot otltpl kin(ls of sPPlt1 than liel

1)n Fano (21) inyp~igltp(l the influpn(( of timp amI tpll1perature ofhpnJing Oil (uiptips of 1ICP and corn Loh of pIeh variety of rice e1p exposp(l to amlliPllt tplll]Jllatuts and to 100-DllO C at 10deg jntershynils iOI L~ and 1 hous 1foistme eontpntF of the sampllS appeared fo 111p 1gtp(n lithin n 1- to lgt-pp1cpnt 1lngp plio to tTpatnwllt except two alllbiPllt-nil-(l1i((l controls whieh P1P UUi2 anlt1 212 percent lespectinlr ftpl t tpatlllPllt the llloisfulp (OlltplltS ntnf(tl from 43 to l~n~ PPITllli l111d thp moittuc Imps ilOlll 1Ui to nll percent (rprmillation t(FiR WPlP 1111lt1( illllllNtiattlv aftpl tT(lilllent Vialone n(lo and (llillPRe Iice uiPlils ltlPlllOniTat(d maximum ability to gellUi11ntp aftpl ]llafing at 30 0 fot~ hOll]s tIlt Hanhino nl1iety (l1tel hNlting at _10deg 101 2 hOll]8 ~JillilllUlll pllllinntin abi1itips wele cOllstailtly ohtaillPltl by hputillf at HOdeg 101 )houls allt1 the seed gelshyJnillat j ng Ia llg-((l lHtml1l IS nn( 2~ PP j(pll t 11 t hp Yllieties lost thei l gelminating- PO(J cOllpl(t(ly hpil lllni((1 nt PO fol 1 hOlll The inshyvpstignto] did not lil1lt1 t-Ill nwxillllllll gtllllinating POWl to (OIlPspond to the maximulll ppl(pniage of ntPl (ontained in the S(N[S put to gpIminate Sill cli(tfilld how(p1 that heat t1pnhlHllts withill lUV01shy

nble lime nnd tllll]p]ntlllp lang(F implopc thp gtlminfltioll capacity 01 the tle1I(( mp thnt of Ih( llmilipnt--nil-lt1lipll]ill sIlt nlso 1tCOI2shynizp( till pORsibl( signili(HIHP of tht IHetlcatnwllt his(OlT of the seed

~

in dTecting til( (XIWlillllJltal I(sults

TEC~LCAL BULLETIN U S DEPT OF AGRICULTURE

Nagn i (65) exposed air-dried and desiccated grn ins of rice for 2 hoUls at 97deg-)SO C He found that the germinative power of the bull grain especially if desiccated was only slightly affected

Jones (39) exposed Colusa ami Caloro rice seed on saturated paper toweling in pttri dishes for 1 2 and 3 hours respectively at constant temperatures of 50deg 544deg Rnd (Hi7deg C Exposure for 1 to 2 hours at liOdeg and 544deg had no appreciable effect on ennination capacity but exposure at (j(L7deg for 1 hoUlmiddot materially reduced the percentage germination of both yar~eties and exposure for 3 hours entirely deshystroyecl the power of germination

In another series of expCgtliments Tones exposed air-dlmiddotjed seed of the same hvo nUieties in ((gtUl (II pehi dishes for 1 hom at 50deg 54-4deg (Q0 (i5n 0 70 0 bull 7(i70 bull H7S o bull n(i 0 and 100deg C Treatment at 70deg or Huckr apparently did not t(gtlt1nce the gennination of either variety The 7fi7deg treatment slightly reduced th( germination ctshypacity of the (t1oto yariety n H7S0 treatment greatly reduced the germination cn ptlti tieR of bol-h n1lipti0 tlHlt of the Cnloro to a gr(nter pxtent than that of thp Colma Treatl1l(llts nt f)(U deg and IO()O for I hour ki]ecl a11 sppd of both ytri(ties JOllPS statc(l that these experishymcnts show (-]wt air-dli(( s((d ill stand n I11l1ch higher tel11]gtC]aturc than wet seed and its germination will not b( afJect(d

Further intcl]gtretn[ion or thp data 111lt1 olserqtions of Da Fano Nagai and Jones is Ilot attempted because pteh failld to describe

C1Cilrly and (ollJpl(t(ly tlH pxp(gtrillltntal (oIHlitiol1s employCc1 In Da Fanos (xp(rinllnts the Imiddotice lost 1l10isttll( (Juring heat trrahn(gtnt III Tones eXl)(Iil11Cnts the moist ri(p prolJa hly ( id not lose an appreshy bull ciable al1l0unt On t11( nth(l ha n(l Jones d ill not gie the moisture contents of his loh of Ii(p pilllcIwiorp 01 aftcr tr(~ltnl(nt

Smith et al (71) in thlir siwl of Ihe (f1cet of dat(gt of httlTest on yield and milling quality of Ii(( ~(gtI( tlw first to remark on thp cflect of germination of tht artifi(ial tlrying of riel in nn (xp(gtIiJllrnlal and in a comm(lcial driPI UP Ill I ina Iion I-esl-s wcrp mt(lp on sa III pl(s of Bltle Hosp 1i(( (iJi(d in Ill( lahorlllOIY nlldN normal lttil (onditions nl1c1 in the (xp(rinH-nhll dri(r at DcIyltl IIL with thc nil at +U3deg 4-SDo 5Lmiddot~o nn(J (iOO C Heinlt of silllilnr Ugts ma(( on l111pl(gts of Enrly ProlifiC ForhllJa allcl Blu( Hop Iic( lt1Ii(d ill th( (xplgtriJ1Jpntal drier at XOI11( Tlx ga( 110inlt1i(alioll of injury le~LJltillg flonl rtltishyfieial dlyil1 nt the t(llJpelatlll(s u((l Additional lefits made in a greenhollse on SOIll( 01 tll( HampleH of riel ~a( 110 clpnl eidence of any difr(lcneC in th( s(((llillps hom Hll sHmpl(s dri((l at dill(IPllt t(lilpemtUJps Sal1lplps (1( ohlnin(d I10III a 101- of sP(d Iice c1liEc1 with a comJ1wJcia 1 dli(l wil11 the ail at apploximatcly middotIBno ~tncl no indicatioJl wm f(uJl(l of injlll) to gelmillalioll lefiulting flOIlI the dlying opeJation

SOI(JlIOIl d al (77) (11i(gt(1 Sl(ks cOJltaining approximafrly a barrel ench of lOIl~dl Ii(( in a tllllnplI)IH sack (hitI al ail tpl1Ilwratul(s of 461deg517deg (H)G 7lAmiddoto nnd ni1~3deg C Ilsppdiply tmiddoto dfI-(Imine the

efreet of the drying nil f(llljlPIahll( and th( initial 1ll0ishne (Cllltent of the grain 011 tb( Illilling C(1Itlity and the gClmination Sacks of lic(~ 01 21-perccllt of 2(J- 10 21-prreeni alld of 17-])(I(enl moiHtnle bull cont(nt welc dlirc1 Ht (ach tPlllpPIntllre (KCCpt- the last was not dried at 033deg Dlyillg t-imes CIP longrl at the ]0(1 telllp(latUles The temperature of the nirill the riec durillg drying alld the moisture

5

EFFECTS OF HFAT TREATMENT ON THE VIABILITY OF RICE

content of the rice on completion of drying were generally lOYeI in the center or the sack tlttlll at the top and boltom Inlet) injun to germination capacity occurred it was greater In the top aml bottom layers than in the center of the sack Too high an air temp(~latllle lul(l a detrimelltitl effect on both the germination and the milling quaJity of rice A temperature of 656 0 had no detrimental effect on germination for rice with 1i-H percent of l110istl1le These workers lIdvisecl that the nil tlmperature hoe(I hon1c1 not (gtx(ppd 5170

to 3+10 for ri(l with ~-11llr(pnt or ]))oi8tuI( The telllplraturl or the rice yjth pither moisture content Wit (onsi(10r1bl 10(1 thnn the ellYshying air tpl11jlel1tllle oyiJ1g to the cooling etlpct of PYapolntion

bull

~[cXpnl (8) in HHmiddotJ 1H3 and tnmiddotHi (ondllde(l 11 sPlie of sturlies on the lrtifkial dryillg of combined II(e to obtnin information on the relation of su(h fudols lS tinll~ dried ail tlmpemtllle reltti(~ hushymiditv and cniJl time to millillg llsults In(l elmiddotminatioll Riee yarieii~s (Zelliih ]allllos( Jap-trpl FIJ1tulla Xira nnd PI(11J(le) Wle halTPtPlI at 1 moistlll( coMlnt of W-H pplc(nt alld stoled and t0111 p(lNI (j to l~ homs in balTll pliOl to d lyi ng TWthe-pOllnd sa11lplps of each telll]lPlpd alilty W(le dlied ill pqJPIill1ll1tal lt11IPI5 Olle two tll(P all(l onl(till1PS fOlll dni]]g (1( uspd to leduce the moi-t11ll content- of tllP riel floll1 field ((indilioll to Imiddot~ pelCpnt rile telll ppli I1g plriod betY((11 slH(lpdi ng dIyi ngs Y Oenllt1ly 24 houls Dlyillg tpm ppla t111P ra ngl(l in i lIttlYals of ii)O C from riHJ to -T)O hut not all riel llietips (lP dliP(1 Ht (H(ll tempplature Extremes ill total (1nill timps Iallge(l 110111 li lllillU(I nt ~TKO to 2~() minutes at Tiideg Total dnill tlllHgt llsuall d(cmiddotlpapc1 as the l1U111-b(I of dl~i ngs as i11(I(14((1 11 i m pr)]ta nl (middot(mllusion of tlip stud ies ns fllal lllllinatioll is ledUl0rl ylHlllice i (11jeltl at nil t-Plll])pratllles alloY( j_k~lo -OllW of the data jllcli(atrd thM tllllP llliu-ht he nllirtal (lil1el(11(es in Il4ist1llCp to 11(( 11(1 t1wt af tIl( hig-hpmiddot t(11lpelatllres intelmittlnt drying might hE ipss destlllctin of WlI11illation (apacity tltnn (0l1tillI1011 (bTin

_ldIPcl HnrlKIalI(l ()) lt111(1 1](111P] (f)) dliprl llllpllS 011( glnin thide of (dOlO pnith Bhllh(ll111(t[agnolin ami Htxolo at 11Tlshyp(]atule f]om l~~O to HlI e ( _ los in gPllllinntioll llsually ocshy(I 11 ]r (1 at tp11lpPIattl1PS ahot -ltF C amI fa~t ltrS of drying diel not appel] to lp(ll1(( geI11linatioll

La te] Idlpltl 11](1 K lil 11](1 (n made n twl to ohtai 11 C0111shypnlatin milli1g 11lt1 Opl11linatioll lPclllts on tl1(a11l(lot of 1i(1 c1]i((l si1l111Itnmollsh- ill nnJ i(iPlltic11 Bl]ico (hitI with nil ltInillg (cl11c1ishytio) Iw1d (oilstallt CX(Pllt drying ail PllIjlllntlllmiddotl Ti]( iet was pxpold fol I) ll1illlltp to all aYlntgl ail tlllll)lrnt1](~ oi middotHLl 01 iilJdeg C am] to an ail (JJllllli of Ibol -)(11) (llhil fpCt ]gtll 1I1illl1l( 1)(1 htulPl Additionn (llying Wl( olllptillHS llP((SSH1Y DliNl samples 1(1e SelSrllll11 for m da- hPlOl1 11lillil1 ips nIHl (ill 1lity hefore Plll1ination Ipst Xo si~1Iili(tl1lt dit1PIPl1(C as llotpd in th( 111illin Clllalitlls of tlip 11(( (llit1t Ht ttt two 1 (111]gt(11111 I(S -suall) an jll~ e)Pt1Fl in gll1ll il1ll i01 llltl]t(( l n t till higlllI t (11)1)(1 t 11p

bull In thl l)](gt((gt(ling sturlils (-mith d Ii -Ol(llS()1 rf a JrcSenL nml

AI(h((] l11(1 K[1Il(l) tllP riel waS lXP0-ll to clit1pl(llt tl11lpllnhllCs of tlltifiCinlly htntpd ail ~lth()lUh tlw llll1ttd ail llll hl maintained at a (()1Istanl te1llpl[lflll( 101 dplillitp p(Iioltl 110 lt1](lt1 11( antilable ns to the maximulll tellllwratlll( 1middotlaclwd by tlw grains of lice 01 as to

BULLE~IN DEPTo OF AGRICULTURE

the timethey are mailltained Itt this temperatureo The (lilta supplied by these workers do 110t define the tolernlw( of rice to tl given temperashyture in itselfo NeTertheless they do IHnllit lin (stllllntioll of the eJiect on germination capacity when riel is eXl-ecl to a gien tem perature during drying in present-clay commercial dehydration equipment

In contrast to the preceding illvestigatiollsin which 111(1eis doubt about the tenlperutures reached by the rice Adair and Cralley (1) presoaked rice seld for 12 hours and then illllllClS(c it ill hot water ntmiddot 50deg-52deg Co for 15 lIIinuiCso This trCatment efrectiely cOlltTo1J(d wll1te tip in 19 vtlrietips oJ rice and although not intli(ah~1 apparently did not haY( an addegCo( efrect on nIP gcrminatioll capacity of thl se((l

Tisdale (83) 101111(1 that oaking- LOllisiana TTonc1l1rtls rice in yatetO at 54deg Co for Ji) minlltcs after lHolsoHkillg it 101 IG hOllri killed the internal llIn~)i and (tUll( llparest to ~oiying as rood grrlllinntioll as thl untreated eontTolso T[OPoltgtl in lill(t ionlly tel~T PXIWlillwIlt with presoaked ricl tilt permillation was ~Iiphlly IOWPl tll1I thatmiddot of Ih(lunholtgtahd (OOlltT01-o

Tisdalltgt (litlllot ~ri( lilp ini(ialllloiillll (olltplli of []l( Iiel bllt itmiddot is inttlcsting tOIlO( ill Olll of hi~ (Xl)(lilloJ(IlI 1hal IIII till lil1l( alld temperlltllrt of tIlt llOt-wallloildeglail1wnt- nlllHillPcl (()n~tant the gllomishynation capacity wus IOIll tIll IOIl)2degll til( Illloiod of Ih( plpsoak This observation slIpptsl- that tllP ltlillpIPIl(o( ill til( g(IOlllinntioll eapneitirs of the difl(J(nt batdlls of ITPatptl ((lt1 plolJilbly rlllet dilllrellc(s in the degree of lPsituwl to ll(at n- 10platmiddotP(] to ltl i I]Plop11 ((S in pl(soaking til1lPs and 1lI0i~tllloP (011 1lt11 f ul thp hlllp of (XPOSIIIPo

As tJw PlpcOpclin ldeg(-i(o il1di[atp- tIl( lil(lnll1lop COJl(PIOnp(l ith thl efrect of tlmpllontllloP Oil degpll1lil1atill ability of Ii(p (ol1-isls 101 111( most part 01 a IWiprogPlH()lIS (olIPdioll of stnelieo Thl mOIl systllllshyatie stnelies hal hlPIl (OllcPlllecl with (OOITPintillt limil((l lilo-lt1rril1 t(mpelntnrp air-dlying (illll and S(prl-IIIOitllloP 1llationships it~ milling qllnlit-y and germinatiol1 (Hll1l(ifyo EYPll (iI(s( kaye llIU(ll to be desired bceHIIgtp thpy were Jillli(pd ill s(ope and the temperatu)cs of the lots of s~~((l ))(il1)1 (l1i(lt1 (IP 1I0t (lctp1I11ill((1 Xo olle has )cport(d investigations ill which lo[~ of loi(( of eli fllI(llt ll)()isftl1p (ollt(nts hut ofthE salll( Yillip nnd FIolll tlIP Hlllp lipId plnl linn iJPPIl (xposlltl to clillclpnt PIllIHloal11 ldegr- fcwditlplpnt pllio(b of ti))I(

Yaggolwl (87) is J))obahly IlIl fildeg til Ian -Illdild 0 0 0 in s(ri(s the llsistalHP of till ~allll killd 01 sP((]s (middotolllaillill lPfinit( 1n(l kllOWIl quantiti(s of watIOat til( lill1( of hpa(illo TIp llas tnblllni((] gplllIishynation dntaol 1adi-iI sp(ltI- hayillU illitial 1)(IO(Opllt IllOis(1I1deg( (olltpllls omiddote 4 D 1middot1middot IS ~ ~() ~o middot11 iO 1ll)(1 71 l1Ilt1hi(h hac bern cxpos(c1 for 30 milllltps in indC In PISill slIi))lIlIdegeltl FIOIo(I](( flasks atotPIlI peraturES frolll i() tl) lOO Co Ht iiilllltiTalso Otlwl dahl nre also given 1or radish ((gtlt1s of JcnYl1 IIlOitlllP (ollt(nis f(l)O hig-IIP) Il1I1JWIHshytl1l(soflHntillmiddot (10 12jC)oolld fOldilllloPllt 11llthodsofhCafillgo lIis conclusions 1I11icoh 11( paJficolllnly llOPOlothro 110( IS foil degs

111( IPiiIlIJ((gt I s ds I iIfliIlIlH 1i01 Wllilll Lo lX]lIlp(1 10 lriJ1r h1ll1)(IrshyOtm ( iH innl1llr PIOOPdeg1i Ollnl 10 llil iJlillr1 lItlI 00lllllIt o IIll p(ds rt til(timp of 11fatilll0

AI fPIIIJHIrtlllls hlllt PllClllJh [II 1)( illjl11i Illp IinlJililo of nldil) IP(ls 01 n ginlI il1itial 0r1(1 (0111 d(I(ls(s rs lit 11111111111111( 10 wllil-It llic) nlP0nrhjl(Ipl is 1 ilcl

111( fWI1(I11 10jIIIWo0 o Ioil-Ipo Jlml( NPlllHl Yillllldeg nml (Isl11 l)olo(il1gIadish seeds lXPIlS(t til hiJh 111111)(111(111( i1 PIOY -illlillIo

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CONTENTS

Introduction Southern pramiddotti( ill rice conditionin~ Reyiew of literature E~rimetal matcrial and proee(illlls

Natwe of experimcnls Determination of moiilurc contnl Determination of ricl temperature during IwaL treatment Water haths Detel~llin1 tion of pnssun~ in toPIIlred 1I11w bull GennmH tlon Ie t~

Heat-treatment experiments ill 1950 Temperature and 1lI0iture-contellt triablei Temperatllre and time ntriabk

Heat-treatment experinl(nl in 1951 bull Temperatlll( and lIIoisturc-eonLCllt ariahlmiddot Temperature and tillie variables Tcmperature 1II0istllJ(-(ontent alld )Illlrit~ ulriahies

Hcal-treatmfn l expcrill1en ts in 1952 Tempcr~ 1111( and lIIoisturt-(olltellt ria hi Telllperltllre and tillle middotariahli _ _

The gcrmina tinn test _ _ _ Seetling almoJllIaliLi Dry secd _ ExcessiYely Wet s(fdhed Resistanec to fungi Improved germina tioll

General discussion _ _ Seed heat-trca tmen t 1II(middotthods ald Lhlmiddotir appliea t ion

Dirc(l (olltact il hot wahmiddotr Direct eonta(l lit) Iuatfd air _ Closed (olltaineni _ _ Dircet eOll tHet wi th liq lIid 0 tlwl Llta II I a itl New methods and modificatiOlls

SunnnalY _ _ _ Litclmiddotatll~e (ittd _ _

Page

1 2 3 8 I)

10 10 11 11 12 12 15 15 16 17 21 26 28 bull 28 33 36 36 36 37 37 37 38 42 43 43 44 44 4-5 4middot5 47

Jor 5alo hy thl SlP(llntel~lIt of lOllIn1lIIIS t S (iorrnllIcuL Printing Ollico

3Sllin~tQn 21 O C PIcc 2() ccnt$

A Report of Research and a literature Survey I

B VERSOS H [(FARrSF nllftfriolrHjiNt T()~lPH T HO(rS (nflnshydegiNtl engi11fet and TXyenLOR ~- ~[cLn[ORE engil1(fling aid Southern Ctiliiiltioll FtXfIII(z 1Jrll1(middot1 _lfri(olt1tllfl [NI fl(z fliee ~

INTRODECTION

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The e frects () f heat on lOuh or paddy lmiddotiee laquo() fyZfl sati lel) have tlssumed greatEl IlllpOrrlt1nee in the l-nited States ~il1ee the introducshytion of combine hanEtil1 and the nsnciated ulld fnr artificial dryshying or conditionillg lmproEment in the method of clrying including eqnipment and operation an lil1lited by the danger of heat injury to the rice Pnutical ricl-c1rying proclclllle have been cleshyvelopedlargely as H result of experimentltion in eomnHrein1 plants Fortuitollsly plocldme that haP favorpd high milling yillds haY( Et1Enllly fiHorNl high sltc1 viability Xlnlthei(ss tIlt presEnt sizlble risk if we consider for ExHmple that in 1952 on~r 48 million Icut al () f inmiddot PIP pmdllced in _ rlm11as LOlliiantl Tpxas MiEsisshy~ippi nnd (nlifomin Uin 3 bull ~r()~t of tlIi I(P ] (()1l11)ill~d It moisshyture (ontEnts aboe H percent and required artificial drying before milling or storHaE

Vel littlp i bHnnl abol1t the E1lpds of hElt aloLH 011 thedability of artIficiallY tlliplt1 rOllh rice on thE activity of its enznnes on tlie nutritioual nnilnbilir or dEtrilction of it proteini aild Itamins or on itg othEl eharactEriri(s In(l (olltitllEnt~ J[nch of the knowlshyedae now appliEltl in the heat treatment of Jollh rice is based on the Hmlfllptioll that it bphnsi~ll will lip lImlootl to that observed for other EN] that haeuro been suntlnllv heurout-trlated

To adnuHe ollr kllowlNle of tlie ptrft of hPllt OTI lmiddotice n series of investigation PI(- ltlldrtakp11 11111ill thE lluyetina SEaSOllS of U150 ID51 tnt Ifj)l nlVlPs(lItarip lXllerillllntE are lepolted in this uulletin Their (ope is limitEd prinHlrily to demonstrating certain tlmperatllJ time and IllOitnlE-tollltllt lEIlrioultips of treatlllent to the ittuilitv of rOlla11 rie

The ilutlion deciCled to invetiate the effects of the different vllrishyabIes on viability ratbEl than on other physical chEmi~al or biological

LRlllmittptl fllr Inllll(ntOll pril ls H) ThE n Ilthorl In itHlphttl til W n TIa rt dirptnr (rfti rlfll of till Lonisiana

AfPipllltntullxp(rinwttt ~tltin to n T HnlT IIPH(1 (lr till _gri(nltlllti EngishynCtrillg jp)pa 111 f)(plltrulnt Ind ro [ K allI uperint(lHlenr an L O C)()lltmiddotoltl f01lllPrly usistallt 1Tinlflllal PI1inPIr of rill Rit EX[lrillllnt Stashytion rOtmiddot tllP lllhi1p~e 01 (OII(IIltin tllP hltt-tlpatIllPnt pqwriments at the Rice EXlIerillllllt Krntioll (Imiddotuwlmiddotmiddot L1

Halit numhNs III llIUlntltlp r(f(r 10 Literainn lit(d V 47

1

AGRICUlTURE

charactermiddotstics There were practical reasons for this decision Themiddot smnples of heat-treated rough rice ere too small for sa6sfuctory millin~valuation tests To obtai ~- ~~xles would have necesshysitated decreasing the number of variables investigated Skilled techniCtl assistants were not lwnilable to perform complicated bioshychemical tests On the other hnnd tacilities Y(le adequate for making germination tests middotMoreover these tests reflect the biological conditions of seeds within limitations They IHlve the arlc1ecl a(lYanshytage of being uniYelsally used and understood Hence they provide data interpreta ble by mn ny workers other than seed analysts uch as seedsmen and fanners commercial grain-drier operators and millers p1nnt physiologi-t and pathologist and hio(lpnlists

Although three major yaliables-temperature of treatment time (duration) of treatmrnt and 11loitllLc content of the rice-ale CCll1shysiderecl the greatest ell1phasi~ is placed on the temperature of treatshyment or tIle llllt 1lli is beelusl altilit-iaily hpated til is nsP(l ill til(gt commercial drying 01 conditioning of rough rice and becHnse it has been useful in plpvp~ting deterioratiol1 of rice durillg stmiddotolage

Experiments Wlc planned fo nccolllplish se(lal objPcti-ps (llier among tllem (IP to detPllllil1e (1) the pl)pet of tpJ1lperatule oj heatshyill~ on iability (~) the effpct of time (dulation) of heating Oll

viability (3) thC rp1ntionship bCtweC11 till J1OistlllP eontCl1t of the rongh rice and the teJlJpemtulC crt hpHtinl and its etleet 011 viability and (4) the eltect of prolonged storage 011 the viability of heatshytreateel rice

SOUTHERN PRACTICES IN RICE CONDITIONING

Chanfres in the methods of l111IVptin~ and storing nrC lespol1Slible for the prescntintCIpst in the ellpets of hpnt 011 Iice pploximat(ly DO percent oJ thp ~outh~s 11l1l1l1nl1i(e cJopi no comhilll(1 a(Conling to Jones et al (P) Smith and Jonps ((J) found that the best tinle to halv(Ht Ii(p is wl1(11 til( ll1oi-t UI( (Ollt(llt of tltl ~tHII(IjIW rice ranges flol11 aboutmiddot 23 to 28 I(eIIL ~[lX(H (5)) and folenso et al C(8) ill I((pnl studips Ippolt(d that Ii(p SliOlll(l bp cOlllbinpcl when its JlJOiSIIIJ( lollilnt is within till lIi- to W-PPI((nt lanle i e if the fielcl]oss(S intludil1 hpl]iII and bJPtlkal ill thl (olllbilil alt to be reduced to a JIlininilllll flndif J1JaXillllJJ11 i(lds of [oll[ilanci helld rice H 1( to Ill obta inNl Fleh hmiddot (oJlJbi IWeI Iollrrh [iep will cleteriolatC rapid1middot 1IIIIp prolllpily dried Ol COIHlitionell

AltiliCiully II(gtutpd ail is lIllt1 ill lOIlli1lP llill1 dclirtllalioll op(rHtions to lP(uee the nJOistlln (ontpllt or tlw f[pshly COilibilIPd Iourrli ric( to 1J perccllt butmiddot tlie uttainlllllIt or this l11oiIIIIP 1((gt] i llO ~IHlIalltee that the rice wil] klPP indplinitplv IIndlI all conditions of stOlltIP ( I Cl) [I I l I tsorenson et (I to IP 1ta()1 JS t HI lIg I tpJl1]lllahIIPs nnd humidities Inail in til( soutillrn Ii(p-glowing HICns-Lolliialla Texas Arkansas al1d Mississippi (fpnkills J) andKInJl1pr j() Sirrshynilicant (oMriillltiollS hJp I)(pn 111[(1( to til( knohltlp of Iie( ltllyil~ OJ conditiolling- as it i lHncti(ell ill the (middotnittd Staft (~lIlifh ( rB 71 7~ 5 (( Bodlt I jJ BuCr 11 It 11 EJllel a l(l ~r(X(gta I J1 ~rcl~eal [if] )7 )8 (jO ]c1I((] alld KruIHr j -1 KlHlller 164748 4fJ

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- Kramer and ~Iclnd )1 --ilwlHr and ~lllilins 10 1 Sorenson ct at

E~FE1CTS OF HEAT TREAl1IENT ON THE VIABILITY OF RICE 3

J7 lJ8 the Lonisiana Agricultmal Experiment Stntion 54 Cruz and Lltforteza ~() Bond 14 am1 Autrey ct at 8)

Bin aeration and (1rying techniques are being c1eYe1oped to remove the excesS l1l0isiUle from rough rice that has been stored at too high It moisture content that has absorbed moisture since storage or that is heating Ambient air is commonly used dUling the warm daylight houls when the relntiye humidity is lo-w Altifieially 11eated air is used if the nepd for the ltpiLilClllonLl of moistllle is apparent Seyera1 yorkers h1Ye contlibuttd a1ti](s on the (ItelopnlPnt of bin Htration and drying tpclllliqncs Illong thtlll mt ~tiln i nan ft fl Cl 9) Todd (8J) Ball a ntl (oon1O(l (12) 1 (oomotl (16) SOllnson et al (78) and ~Iol1isoll rt al (6J (in and the Lou isinna Aglicult-uml Experishyment StHtion (J5)

Rice fol sCtcl is O-[tCll c1lipd in commercial ltlryin units in the same llumllCl ns tIlt bulk t-hnt is dlitc1 to a 11l0istl1lp c(mtent suitable for millillg 01 StOlUlt TIlt COlllllHlcial u11its alP of course (leaned and inspected bpfc)le being loadell with Iiee to be (hiNl 101 s(ed purposes 111tir nse is l~nely one of conwnipnce Gp1lllination tests and farmshy(10]gt obsP]at-iom Sllpport thp prn(tice but (lata mp not 1lTailab1e to pya11latr jllpSPllt (Ollllll(1cia I tl1yi ng pIo(pd Il1PF folll the standpoint of Illlp1O-jng sp((l quality

UEVIEW OF LITERATURE

bull Although hpat has probnll1y lwen app1ipd in tl1( t1lllhnrnt of rough rice 101 clntlllies thpp mp lmt ipy publishpd l(eOllllts-nt ]Plst those readily iwnilable to occic1pntnl teac1EI3--that (kseribpits eJiect on the abilit) of ricp to gplminnte On til( other hall(11 lllunbpl of publicashytions a few of which h1e npPPH1ed in 1p(pnt yelrs plespnt data on the ptleuroct of hpat- trpItnlPnt- Oil gllmination capacity but mostly rot otltpl kin(ls of sPPlt1 than liel

1)n Fano (21) inyp~igltp(l the influpn(( of timp amI tpll1perature ofhpnJing Oil (uiptips of 1ICP and corn Loh of pIeh variety of rice e1p exposp(l to amlliPllt tplll]Jllatuts and to 100-DllO C at 10deg jntershynils iOI L~ and 1 hous 1foistme eontpntF of the sampllS appeared fo 111p 1gtp(n lithin n 1- to lgt-pp1cpnt 1lngp plio to tTpatnwllt except two alllbiPllt-nil-(l1i((l controls whieh P1P UUi2 anlt1 212 percent lespectinlr ftpl t tpatlllPllt the llloisfulp (OlltplltS ntnf(tl from 43 to l~n~ PPITllli l111d thp moittuc Imps ilOlll 1Ui to nll percent (rprmillation t(FiR WPlP 1111lt1( illllllNtiattlv aftpl tT(lilllent Vialone n(lo and (llillPRe Iice uiPlils ltlPlllOniTat(d maximum ability to gellUi11ntp aftpl ]llafing at 30 0 fot~ hOll]s tIlt Hanhino nl1iety (l1tel hNlting at _10deg 101 2 hOll]8 ~JillilllUlll pllllinntin abi1itips wele cOllstailtly ohtaillPltl by hputillf at HOdeg 101 )houls allt1 the seed gelshyJnillat j ng Ia llg-((l lHtml1l IS nn( 2~ PP j(pll t 11 t hp Yllieties lost thei l gelminating- PO(J cOllpl(t(ly hpil lllni((1 nt PO fol 1 hOlll The inshyvpstignto] did not lil1lt1 t-Ill nwxillllllll gtllllinating POWl to (OIlPspond to the maximulll ppl(pniage of ntPl (ontained in the S(N[S put to gpIminate Sill cli(tfilld how(p1 that heat t1pnhlHllts withill lUV01shy

nble lime nnd tllll]p]ntlllp lang(F implopc thp gtlminfltioll capacity 01 the tle1I(( mp thnt of Ih( llmilipnt--nil-lt1lipll]ill sIlt nlso 1tCOI2shynizp( till pORsibl( signili(HIHP of tht IHetlcatnwllt his(OlT of the seed

~

in dTecting til( (XIWlillllJltal I(sults

TEC~LCAL BULLETIN U S DEPT OF AGRICULTURE

Nagn i (65) exposed air-dried and desiccated grn ins of rice for 2 hoUls at 97deg-)SO C He found that the germinative power of the bull grain especially if desiccated was only slightly affected

Jones (39) exposed Colusa ami Caloro rice seed on saturated paper toweling in pttri dishes for 1 2 and 3 hours respectively at constant temperatures of 50deg 544deg Rnd (Hi7deg C Exposure for 1 to 2 hours at liOdeg and 544deg had no appreciable effect on ennination capacity but exposure at (j(L7deg for 1 hoUlmiddot materially reduced the percentage germination of both yar~eties and exposure for 3 hours entirely deshystroyecl the power of germination

In another series of expCgtliments Tones exposed air-dlmiddotjed seed of the same hvo nUieties in ((gtUl (II pehi dishes for 1 hom at 50deg 54-4deg (Q0 (i5n 0 70 0 bull 7(i70 bull H7S o bull n(i 0 and 100deg C Treatment at 70deg or Huckr apparently did not t(gtlt1nce the gennination of either variety The 7fi7deg treatment slightly reduced th( germination ctshypacity of the (t1oto yariety n H7S0 treatment greatly reduced the germination cn ptlti tieR of bol-h n1lipti0 tlHlt of the Cnloro to a gr(nter pxtent than that of thp Colma Treatl1l(llts nt f)(U deg and IO()O for I hour ki]ecl a11 sppd of both ytri(ties JOllPS statc(l that these experishymcnts show (-]wt air-dli(( s((d ill stand n I11l1ch higher tel11]gtC]aturc than wet seed and its germination will not b( afJect(d

Further intcl]gtretn[ion or thp data 111lt1 olserqtions of Da Fano Nagai and Jones is Ilot attempted because pteh failld to describe

C1Cilrly and (ollJpl(t(ly tlH pxp(gtrillltntal (oIHlitiol1s employCc1 In Da Fanos (xp(rinllnts the Imiddotice lost 1l10isttll( (Juring heat trrahn(gtnt III Tones eXl)(Iil11Cnts the moist ri(p prolJa hly ( id not lose an appreshy bull ciable al1l0unt On t11( nth(l ha n(l Jones d ill not gie the moisture contents of his loh of Ii(p pilllcIwiorp 01 aftcr tr(~ltnl(nt

Smith et al (71) in thlir siwl of Ihe (f1cet of dat(gt of httlTest on yield and milling quality of Ii(( ~(gtI( tlw first to remark on thp cflect of germination of tht artifi(ial tlrying of riel in nn (xp(gtIiJllrnlal and in a comm(lcial driPI UP Ill I ina Iion I-esl-s wcrp mt(lp on sa III pl(s of Bltle Hosp 1i(( (iJi(d in Ill( lahorlllOIY nlldN normal lttil (onditions nl1c1 in the (xp(rinH-nhll dri(r at DcIyltl IIL with thc nil at +U3deg 4-SDo 5Lmiddot~o nn(J (iOO C Heinlt of silllilnr Ugts ma(( on l111pl(gts of Enrly ProlifiC ForhllJa allcl Blu( Hop Iic( lt1Ii(d ill th( (xplgtriJ1Jpntal drier at XOI11( Tlx ga( 110inlt1i(alioll of injury le~LJltillg flonl rtltishyfieial dlyil1 nt the t(llJpelatlll(s u((l Additional lefits made in a greenhollse on SOIll( 01 tll( HampleH of riel ~a( 110 clpnl eidence of any difr(lcneC in th( s(((llillps hom Hll sHmpl(s dri((l at dill(IPllt t(lilpemtUJps Sal1lplps (1( ohlnin(d I10III a 101- of sP(d Iice c1liEc1 with a comJ1wJcia 1 dli(l wil11 the ail at apploximatcly middotIBno ~tncl no indicatioJl wm f(uJl(l of injlll) to gelmillalioll lefiulting flOIlI the dlying opeJation

SOI(JlIOIl d al (77) (11i(gt(1 Sl(ks cOJltaining approximafrly a barrel ench of lOIl~dl Ii(( in a tllllnplI)IH sack (hitI al ail tpl1Ilwratul(s of 461deg517deg (H)G 7lAmiddoto nnd ni1~3deg C Ilsppdiply tmiddoto dfI-(Imine the

efreet of the drying nil f(llljlPIahll( and th( initial 1ll0ishne (Cllltent of the grain 011 tb( Illilling C(1Itlity and the gClmination Sacks of lic(~ 01 21-perccllt of 2(J- 10 21-prreeni alld of 17-])(I(enl moiHtnle bull cont(nt welc dlirc1 Ht (ach tPlllpPIntllre (KCCpt- the last was not dried at 033deg Dlyillg t-imes CIP longrl at the ]0(1 telllp(latUles The temperature of the nirill the riec durillg drying alld the moisture

5

EFFECTS OF HFAT TREATMENT ON THE VIABILITY OF RICE

content of the rice on completion of drying were generally lOYeI in the center or the sack tlttlll at the top and boltom Inlet) injun to germination capacity occurred it was greater In the top aml bottom layers than in the center of the sack Too high an air temp(~latllle lul(l a detrimelltitl effect on both the germination and the milling quaJity of rice A temperature of 656 0 had no detrimental effect on germination for rice with 1i-H percent of l110istl1le These workers lIdvisecl that the nil tlmperature hoe(I hon1c1 not (gtx(ppd 5170

to 3+10 for ri(l with ~-11llr(pnt or ]))oi8tuI( The telllplraturl or the rice yjth pither moisture content Wit (onsi(10r1bl 10(1 thnn the ellYshying air tpl11jlel1tllle oyiJ1g to the cooling etlpct of PYapolntion

bull

~[cXpnl (8) in HHmiddotJ 1H3 and tnmiddotHi (ondllde(l 11 sPlie of sturlies on the lrtifkial dryillg of combined II(e to obtnin information on the relation of su(h fudols lS tinll~ dried ail tlmpemtllle reltti(~ hushymiditv and cniJl time to millillg llsults In(l elmiddotminatioll Riee yarieii~s (Zelliih ]allllos( Jap-trpl FIJ1tulla Xira nnd PI(11J(le) Wle halTPtPlI at 1 moistlll( coMlnt of W-H pplc(nt alld stoled and t0111 p(lNI (j to l~ homs in balTll pliOl to d lyi ng TWthe-pOllnd sa11lplps of each telll]lPlpd alilty W(le dlied ill pqJPIill1ll1tal lt11IPI5 Olle two tll(P all(l onl(till1PS fOlll dni]]g (1( uspd to leduce the moi-t11ll content- of tllP riel floll1 field ((indilioll to Imiddot~ pelCpnt rile telll ppli I1g plriod betY((11 slH(lpdi ng dIyi ngs Y Oenllt1ly 24 houls Dlyillg tpm ppla t111P ra ngl(l in i lIttlYals of ii)O C from riHJ to -T)O hut not all riel llietips (lP dliP(1 Ht (H(ll tempplature Extremes ill total (1nill timps Iallge(l 110111 li lllillU(I nt ~TKO to 2~() minutes at Tiideg Total dnill tlllHgt llsuall d(cmiddotlpapc1 as the l1U111-b(I of dl~i ngs as i11(I(14((1 11 i m pr)]ta nl (middot(mllusion of tlip stud ies ns fllal lllllinatioll is ledUl0rl ylHlllice i (11jeltl at nil t-Plll])pratllles alloY( j_k~lo -OllW of the data jllcli(atrd thM tllllP llliu-ht he nllirtal (lil1el(11(es in Il4ist1llCp to 11(( 11(1 t1wt af tIl( hig-hpmiddot t(11lpelatllres intelmittlnt drying might hE ipss destlllctin of WlI11illation (apacity tltnn (0l1tillI1011 (bTin

_ldIPcl HnrlKIalI(l ()) lt111(1 1](111P] (f)) dliprl llllpllS 011( glnin thide of (dOlO pnith Bhllh(ll111(t[agnolin ami Htxolo at 11Tlshyp(]atule f]om l~~O to HlI e ( _ los in gPllllinntioll llsually ocshy(I 11 ]r (1 at tp11lpPIattl1PS ahot -ltF C amI fa~t ltrS of drying diel not appel] to lp(ll1(( geI11linatioll

La te] Idlpltl 11](1 K lil 11](1 (n made n twl to ohtai 11 C0111shypnlatin milli1g 11lt1 Opl11linatioll lPclllts on tl1(a11l(lot of 1i(1 c1]i((l si1l111Itnmollsh- ill nnJ i(iPlltic11 Bl]ico (hitI with nil ltInillg (cl11c1ishytio) Iw1d (oilstallt CX(Pllt drying ail PllIjlllntlllmiddotl Ti]( iet was pxpold fol I) ll1illlltp to all aYlntgl ail tlllll)lrnt1](~ oi middotHLl 01 iilJdeg C am] to an ail (JJllllli of Ibol -)(11) (llhil fpCt ]gtll 1I1illl1l( 1)(1 htulPl Additionn (llying Wl( olllptillHS llP((SSH1Y DliNl samples 1(1e SelSrllll11 for m da- hPlOl1 11lillil1 ips nIHl (ill 1lity hefore Plll1ination Ipst Xo si~1Iili(tl1lt dit1PIPl1(C as llotpd in th( 111illin Clllalitlls of tlip 11(( (llit1t Ht ttt two 1 (111]gt(11111 I(S -suall) an jll~ e)Pt1Fl in gll1ll il1ll i01 llltl]t(( l n t till higlllI t (11)1)(1 t 11p

bull In thl l)](gt((gt(ling sturlils (-mith d Ii -Ol(llS()1 rf a JrcSenL nml

AI(h((] l11(1 K[1Il(l) tllP riel waS lXP0-ll to clit1pl(llt tl11lpllnhllCs of tlltifiCinlly htntpd ail ~lth()lUh tlw llll1ttd ail llll hl maintained at a (()1Istanl te1llpl[lflll( 101 dplillitp p(Iioltl 110 lt1](lt1 11( antilable ns to the maximulll tellllwratlll( 1middotlaclwd by tlw grains of lice 01 as to

BULLE~IN DEPTo OF AGRICULTURE

the timethey are mailltained Itt this temperatureo The (lilta supplied by these workers do 110t define the tolernlw( of rice to tl given temperashyture in itselfo NeTertheless they do IHnllit lin (stllllntioll of the eJiect on germination capacity when riel is eXl-ecl to a gien tem perature during drying in present-clay commercial dehydration equipment

In contrast to the preceding illvestigatiollsin which 111(1eis doubt about the tenlperutures reached by the rice Adair and Cralley (1) presoaked rice seld for 12 hours and then illllllClS(c it ill hot water ntmiddot 50deg-52deg Co for 15 lIIinuiCso This trCatment efrectiely cOlltTo1J(d wll1te tip in 19 vtlrietips oJ rice and although not intli(ah~1 apparently did not haY( an addegCo( efrect on nIP gcrminatioll capacity of thl se((l

Tisdale (83) 101111(1 that oaking- LOllisiana TTonc1l1rtls rice in yatetO at 54deg Co for Ji) minlltcs after lHolsoHkillg it 101 IG hOllri killed the internal llIn~)i and (tUll( llparest to ~oiying as rood grrlllinntioll as thl untreated eontTolso T[OPoltgtl in lill(t ionlly tel~T PXIWlillwIlt with presoaked ricl tilt permillation was ~Iiphlly IOWPl tll1I thatmiddot of Ih(lunholtgtahd (OOlltT01-o

Tisdalltgt (litlllot ~ri( lilp ini(ialllloiillll (olltplli of []l( Iiel bllt itmiddot is inttlcsting tOIlO( ill Olll of hi~ (Xl)(lilloJ(IlI 1hal IIII till lil1l( alld temperlltllrt of tIlt llOt-wallloildeglail1wnt- nlllHillPcl (()n~tant the gllomishynation capacity wus IOIll tIll IOIl)2degll til( Illloiod of Ih( plpsoak This observation slIpptsl- that tllP ltlillpIPIl(o( ill til( g(IOlllinntioll eapneitirs of the difl(J(nt batdlls of ITPatptl ((lt1 plolJilbly rlllet dilllrellc(s in the degree of lPsituwl to ll(at n- 10platmiddotP(] to ltl i I]Plop11 ((S in pl(soaking til1lPs and 1lI0i~tllloP (011 1lt11 f ul thp hlllp of (XPOSIIIPo

As tJw PlpcOpclin ldeg(-i(o il1di[atp- tIl( lil(lnll1lop COJl(PIOnp(l ith thl efrect of tlmpllontllloP Oil degpll1lil1atill ability of Ii(p (ol1-isls 101 111( most part 01 a IWiprogPlH()lIS (olIPdioll of stnelieo Thl mOIl systllllshyatie stnelies hal hlPIl (OllcPlllecl with (OOITPintillt limil((l lilo-lt1rril1 t(mpelntnrp air-dlying (illll and S(prl-IIIOitllloP 1llationships it~ milling qllnlit-y and germinatiol1 (Hll1l(ifyo EYPll (iI(s( kaye llIU(ll to be desired bceHIIgtp thpy were Jillli(pd ill s(ope and the temperatu)cs of the lots of s~~((l ))(il1)1 (l1i(lt1 (IP 1I0t (lctp1I11ill((1 Xo olle has )cport(d investigations ill which lo[~ of loi(( of eli fllI(llt ll)()isftl1p (ollt(nts hut ofthE salll( Yillip nnd FIolll tlIP Hlllp lipId plnl linn iJPPIl (xposlltl to clillclpnt PIllIHloal11 ldegr- fcwditlplpnt pllio(b of ti))I(

Yaggolwl (87) is J))obahly IlIl fildeg til Ian -Illdild 0 0 0 in s(ri(s the llsistalHP of till ~allll killd 01 sP((]s (middotolllaillill lPfinit( 1n(l kllOWIl quantiti(s of watIOat til( lill1( of hpa(illo TIp llas tnblllni((] gplllIishynation dntaol 1adi-iI sp(ltI- hayillU illitial 1)(IO(Opllt IllOis(1I1deg( (olltpllls omiddote 4 D 1middot1middot IS ~ ~() ~o middot11 iO 1ll)(1 71 l1Ilt1hi(h hac bern cxpos(c1 for 30 milllltps in indC In PISill slIi))lIlIdegeltl FIOIo(I](( flasks atotPIlI peraturES frolll i() tl) lOO Co Ht iiilllltiTalso Otlwl dahl nre also given 1or radish ((gtlt1s of JcnYl1 IIlOitlllP (ollt(nis f(l)O hig-IIP) Il1I1JWIHshytl1l(soflHntillmiddot (10 12jC)oolld fOldilllloPllt 11llthodsofhCafillgo lIis conclusions 1I11icoh 11( paJficolllnly llOPOlothro 110( IS foil degs

111( IPiiIlIJ((gt I s ds I iIfliIlIlH 1i01 Wllilll Lo lX]lIlp(1 10 lriJ1r h1ll1)(IrshyOtm ( iH innl1llr PIOOPdeg1i Ollnl 10 llil iJlillr1 lItlI 00lllllIt o IIll p(ds rt til(timp of 11fatilll0

AI fPIIIJHIrtlllls hlllt PllClllJh [II 1)( illjl11i Illp IinlJililo of nldil) IP(ls 01 n ginlI il1itial 0r1(1 (0111 d(I(ls(s rs lit 11111111111111( 10 wllil-It llic) nlP0nrhjl(Ipl is 1 ilcl

111( fWI1(I11 10jIIIWo0 o Ioil-Ipo Jlml( NPlllHl Yillllldeg nml (Isl11 l)olo(il1gIadish seeds lXPIlS(t til hiJh 111111)(111(111( i1 PIOY -illlillIo

bull

bull

bull

A Report of Research and a literature Survey I

B VERSOS H [(FARrSF nllftfriolrHjiNt T()~lPH T HO(rS (nflnshydegiNtl engi11fet and TXyenLOR ~- ~[cLn[ORE engil1(fling aid Southern Ctiliiiltioll FtXfIII(z 1Jrll1(middot1 _lfri(olt1tllfl [NI fl(z fliee ~

INTRODECTION

bull

The e frects () f heat on lOuh or paddy lmiddotiee laquo() fyZfl sati lel) have tlssumed greatEl IlllpOrrlt1nee in the l-nited States ~il1ee the introducshytion of combine hanEtil1 and the nsnciated ulld fnr artificial dryshying or conditionillg lmproEment in the method of clrying including eqnipment and operation an lil1lited by the danger of heat injury to the rice Pnutical ricl-c1rying proclclllle have been cleshyvelopedlargely as H result of experimentltion in eomnHrein1 plants Fortuitollsly plocldme that haP favorpd high milling yillds haY( Et1Enllly fiHorNl high sltc1 viability Xlnlthei(ss tIlt presEnt sizlble risk if we consider for ExHmple that in 1952 on~r 48 million Icut al () f inmiddot PIP pmdllced in _ rlm11as LOlliiantl Tpxas MiEsisshy~ippi nnd (nlifomin Uin 3 bull ~r()~t of tlIi I(P ] (()1l11)ill~d It moisshyture (ontEnts aboe H percent and required artificial drying before milling or storHaE

Vel littlp i bHnnl abol1t the E1lpds of hElt aloLH 011 thedability of artIficiallY tlliplt1 rOllh rice on thE activity of its enznnes on tlie nutritioual nnilnbilir or dEtrilction of it proteini aild Itamins or on itg othEl eharactEriri(s In(l (olltitllEnt~ J[nch of the knowlshyedae now appliEltl in the heat treatment of Jollh rice is based on the Hmlfllptioll that it bphnsi~ll will lip lImlootl to that observed for other EN] that haeuro been suntlnllv heurout-trlated

To adnuHe ollr kllowlNle of tlie ptrft of hPllt OTI lmiddotice n series of investigation PI(- ltlldrtakp11 11111ill thE lluyetina SEaSOllS of U150 ID51 tnt Ifj)l nlVlPs(lItarip lXllerillllntE are lepolted in this uulletin Their (ope is limitEd prinHlrily to demonstrating certain tlmperatllJ time and IllOitnlE-tollltllt lEIlrioultips of treatlllent to the ittuilitv of rOlla11 rie

The ilutlion deciCled to invetiate the effects of the different vllrishyabIes on viability ratbEl than on other physical chEmi~al or biological

LRlllmittptl fllr Inllll(ntOll pril ls H) ThE n Ilthorl In itHlphttl til W n TIa rt dirptnr (rfti rlfll of till Lonisiana

AfPipllltntullxp(rinwttt ~tltin to n T HnlT IIPH(1 (lr till _gri(nltlllti EngishynCtrillg jp)pa 111 f)(plltrulnt Ind ro [ K allI uperint(lHlenr an L O C)()lltmiddotoltl f01lllPrly usistallt 1Tinlflllal PI1inPIr of rill Rit EX[lrillllnt Stashytion rOtmiddot tllP lllhi1p~e 01 (OII(IIltin tllP hltt-tlpatIllPnt pqwriments at the Rice EXlIerillllllt Krntioll (Imiddotuwlmiddotmiddot L1

Halit numhNs III llIUlntltlp r(f(r 10 Literainn lit(d V 47

1

AGRICUlTURE

charactermiddotstics There were practical reasons for this decision Themiddot smnples of heat-treated rough rice ere too small for sa6sfuctory millin~valuation tests To obtai ~- ~~xles would have necesshysitated decreasing the number of variables investigated Skilled techniCtl assistants were not lwnilable to perform complicated bioshychemical tests On the other hnnd tacilities Y(le adequate for making germination tests middotMoreover these tests reflect the biological conditions of seeds within limitations They IHlve the arlc1ecl a(lYanshytage of being uniYelsally used and understood Hence they provide data interpreta ble by mn ny workers other than seed analysts uch as seedsmen and fanners commercial grain-drier operators and millers p1nnt physiologi-t and pathologist and hio(lpnlists

Although three major yaliables-temperature of treatment time (duration) of treatmrnt and 11loitllLc content of the rice-ale CCll1shysiderecl the greatest ell1phasi~ is placed on the temperature of treatshyment or tIle llllt 1lli is beelusl altilit-iaily hpated til is nsP(l ill til(gt commercial drying 01 conditioning of rough rice and becHnse it has been useful in plpvp~ting deterioratiol1 of rice durillg stmiddotolage

Experiments Wlc planned fo nccolllplish se(lal objPcti-ps (llier among tllem (IP to detPllllil1e (1) the pl)pet of tpJ1lperatule oj heatshyill~ on iability (~) the effpct of time (dulation) of heating Oll

viability (3) thC rp1ntionship bCtweC11 till J1OistlllP eontCl1t of the rongh rice and the teJlJpemtulC crt hpHtinl and its etleet 011 viability and (4) the eltect of prolonged storage 011 the viability of heatshytreateel rice

SOUTHERN PRACTICES IN RICE CONDITIONING

Chanfres in the methods of l111IVptin~ and storing nrC lespol1Slible for the prescntintCIpst in the ellpets of hpnt 011 Iice pploximat(ly DO percent oJ thp ~outh~s 11l1l1l1nl1i(e cJopi no comhilll(1 a(Conling to Jones et al (P) Smith and Jonps ((J) found that the best tinle to halv(Ht Ii(p is wl1(11 til( ll1oi-t UI( (Ollt(llt of tltl ~tHII(IjIW rice ranges flol11 aboutmiddot 23 to 28 I(eIIL ~[lX(H (5)) and folenso et al C(8) ill I((pnl studips Ippolt(d that Ii(p SliOlll(l bp cOlllbinpcl when its JlJOiSIIIJ( lollilnt is within till lIi- to W-PPI((nt lanle i e if the fielcl]oss(S intludil1 hpl]iII and bJPtlkal ill thl (olllbilil alt to be reduced to a JIlininilllll flndif J1JaXillllJJ11 i(lds of [oll[ilanci helld rice H 1( to Ill obta inNl Fleh hmiddot (oJlJbi IWeI Iollrrh [iep will cleteriolatC rapid1middot 1IIIIp prolllpily dried Ol COIHlitionell

AltiliCiully II(gtutpd ail is lIllt1 ill lOIlli1lP llill1 dclirtllalioll op(rHtions to lP(uee the nJOistlln (ontpllt or tlw f[pshly COilibilIPd Iourrli ric( to 1J perccllt butmiddot tlie uttainlllllIt or this l11oiIIIIP 1((gt] i llO ~IHlIalltee that the rice wil] klPP indplinitplv IIndlI all conditions of stOlltIP ( I Cl) [I I l I tsorenson et (I to IP 1ta()1 JS t HI lIg I tpJl1]lllahIIPs nnd humidities Inail in til( soutillrn Ii(p-glowing HICns-Lolliialla Texas Arkansas al1d Mississippi (fpnkills J) andKInJl1pr j() Sirrshynilicant (oMriillltiollS hJp I)(pn 111[(1( to til( knohltlp of Iie( ltllyil~ OJ conditiolling- as it i lHncti(ell ill the (middotnittd Staft (~lIlifh ( rB 71 7~ 5 (( Bodlt I jJ BuCr 11 It 11 EJllel a l(l ~r(X(gta I J1 ~rcl~eal [if] )7 )8 (jO ]c1I((] alld KruIHr j -1 KlHlller 164748 4fJ

bull

bull

- Kramer and ~Iclnd )1 --ilwlHr and ~lllilins 10 1 Sorenson ct at

E~FE1CTS OF HEAT TREAl1IENT ON THE VIABILITY OF RICE 3

J7 lJ8 the Lonisiana Agricultmal Experiment Stntion 54 Cruz and Lltforteza ~() Bond 14 am1 Autrey ct at 8)

Bin aeration and (1rying techniques are being c1eYe1oped to remove the excesS l1l0isiUle from rough rice that has been stored at too high It moisture content that has absorbed moisture since storage or that is heating Ambient air is commonly used dUling the warm daylight houls when the relntiye humidity is lo-w Altifieially 11eated air is used if the nepd for the ltpiLilClllonLl of moistllle is apparent Seyera1 yorkers h1Ye contlibuttd a1ti](s on the (ItelopnlPnt of bin Htration and drying tpclllliqncs Illong thtlll mt ~tiln i nan ft fl Cl 9) Todd (8J) Ball a ntl (oon1O(l (12) 1 (oomotl (16) SOllnson et al (78) and ~Iol1isoll rt al (6J (in and the Lou isinna Aglicult-uml Experishyment StHtion (J5)

Rice fol sCtcl is O-[tCll c1lipd in commercial ltlryin units in the same llumllCl ns tIlt bulk t-hnt is dlitc1 to a 11l0istl1lp c(mtent suitable for millillg 01 StOlUlt TIlt COlllllHlcial u11its alP of course (leaned and inspected bpfc)le being loadell with Iiee to be (hiNl 101 s(ed purposes 111tir nse is l~nely one of conwnipnce Gp1lllination tests and farmshy(10]gt obsP]at-iom Sllpport thp prn(tice but (lata mp not 1lTailab1e to pya11latr jllpSPllt (Ollllll(1cia I tl1yi ng pIo(pd Il1PF folll the standpoint of Illlp1O-jng sp((l quality

UEVIEW OF LITERATURE

bull Although hpat has probnll1y lwen app1ipd in tl1( t1lllhnrnt of rough rice 101 clntlllies thpp mp lmt ipy publishpd l(eOllllts-nt ]Plst those readily iwnilable to occic1pntnl teac1EI3--that (kseribpits eJiect on the abilit) of ricp to gplminnte On til( other hall(11 lllunbpl of publicashytions a few of which h1e npPPH1ed in 1p(pnt yelrs plespnt data on the ptleuroct of hpat- trpItnlPnt- Oil gllmination capacity but mostly rot otltpl kin(ls of sPPlt1 than liel

1)n Fano (21) inyp~igltp(l the influpn(( of timp amI tpll1perature ofhpnJing Oil (uiptips of 1ICP and corn Loh of pIeh variety of rice e1p exposp(l to amlliPllt tplll]Jllatuts and to 100-DllO C at 10deg jntershynils iOI L~ and 1 hous 1foistme eontpntF of the sampllS appeared fo 111p 1gtp(n lithin n 1- to lgt-pp1cpnt 1lngp plio to tTpatnwllt except two alllbiPllt-nil-(l1i((l controls whieh P1P UUi2 anlt1 212 percent lespectinlr ftpl t tpatlllPllt the llloisfulp (OlltplltS ntnf(tl from 43 to l~n~ PPITllli l111d thp moittuc Imps ilOlll 1Ui to nll percent (rprmillation t(FiR WPlP 1111lt1( illllllNtiattlv aftpl tT(lilllent Vialone n(lo and (llillPRe Iice uiPlils ltlPlllOniTat(d maximum ability to gellUi11ntp aftpl ]llafing at 30 0 fot~ hOll]s tIlt Hanhino nl1iety (l1tel hNlting at _10deg 101 2 hOll]8 ~JillilllUlll pllllinntin abi1itips wele cOllstailtly ohtaillPltl by hputillf at HOdeg 101 )houls allt1 the seed gelshyJnillat j ng Ia llg-((l lHtml1l IS nn( 2~ PP j(pll t 11 t hp Yllieties lost thei l gelminating- PO(J cOllpl(t(ly hpil lllni((1 nt PO fol 1 hOlll The inshyvpstignto] did not lil1lt1 t-Ill nwxillllllll gtllllinating POWl to (OIlPspond to the maximulll ppl(pniage of ntPl (ontained in the S(N[S put to gpIminate Sill cli(tfilld how(p1 that heat t1pnhlHllts withill lUV01shy

nble lime nnd tllll]p]ntlllp lang(F implopc thp gtlminfltioll capacity 01 the tle1I(( mp thnt of Ih( llmilipnt--nil-lt1lipll]ill sIlt nlso 1tCOI2shynizp( till pORsibl( signili(HIHP of tht IHetlcatnwllt his(OlT of the seed

~

in dTecting til( (XIWlillllJltal I(sults

TEC~LCAL BULLETIN U S DEPT OF AGRICULTURE

Nagn i (65) exposed air-dried and desiccated grn ins of rice for 2 hoUls at 97deg-)SO C He found that the germinative power of the bull grain especially if desiccated was only slightly affected

Jones (39) exposed Colusa ami Caloro rice seed on saturated paper toweling in pttri dishes for 1 2 and 3 hours respectively at constant temperatures of 50deg 544deg Rnd (Hi7deg C Exposure for 1 to 2 hours at liOdeg and 544deg had no appreciable effect on ennination capacity but exposure at (j(L7deg for 1 hoUlmiddot materially reduced the percentage germination of both yar~eties and exposure for 3 hours entirely deshystroyecl the power of germination

In another series of expCgtliments Tones exposed air-dlmiddotjed seed of the same hvo nUieties in ((gtUl (II pehi dishes for 1 hom at 50deg 54-4deg (Q0 (i5n 0 70 0 bull 7(i70 bull H7S o bull n(i 0 and 100deg C Treatment at 70deg or Huckr apparently did not t(gtlt1nce the gennination of either variety The 7fi7deg treatment slightly reduced th( germination ctshypacity of the (t1oto yariety n H7S0 treatment greatly reduced the germination cn ptlti tieR of bol-h n1lipti0 tlHlt of the Cnloro to a gr(nter pxtent than that of thp Colma Treatl1l(llts nt f)(U deg and IO()O for I hour ki]ecl a11 sppd of both ytri(ties JOllPS statc(l that these experishymcnts show (-]wt air-dli(( s((d ill stand n I11l1ch higher tel11]gtC]aturc than wet seed and its germination will not b( afJect(d

Further intcl]gtretn[ion or thp data 111lt1 olserqtions of Da Fano Nagai and Jones is Ilot attempted because pteh failld to describe

C1Cilrly and (ollJpl(t(ly tlH pxp(gtrillltntal (oIHlitiol1s employCc1 In Da Fanos (xp(rinllnts the Imiddotice lost 1l10isttll( (Juring heat trrahn(gtnt III Tones eXl)(Iil11Cnts the moist ri(p prolJa hly ( id not lose an appreshy bull ciable al1l0unt On t11( nth(l ha n(l Jones d ill not gie the moisture contents of his loh of Ii(p pilllcIwiorp 01 aftcr tr(~ltnl(nt

Smith et al (71) in thlir siwl of Ihe (f1cet of dat(gt of httlTest on yield and milling quality of Ii(( ~(gtI( tlw first to remark on thp cflect of germination of tht artifi(ial tlrying of riel in nn (xp(gtIiJllrnlal and in a comm(lcial driPI UP Ill I ina Iion I-esl-s wcrp mt(lp on sa III pl(s of Bltle Hosp 1i(( (iJi(d in Ill( lahorlllOIY nlldN normal lttil (onditions nl1c1 in the (xp(rinH-nhll dri(r at DcIyltl IIL with thc nil at +U3deg 4-SDo 5Lmiddot~o nn(J (iOO C Heinlt of silllilnr Ugts ma(( on l111pl(gts of Enrly ProlifiC ForhllJa allcl Blu( Hop Iic( lt1Ii(d ill th( (xplgtriJ1Jpntal drier at XOI11( Tlx ga( 110inlt1i(alioll of injury le~LJltillg flonl rtltishyfieial dlyil1 nt the t(llJpelatlll(s u((l Additional lefits made in a greenhollse on SOIll( 01 tll( HampleH of riel ~a( 110 clpnl eidence of any difr(lcneC in th( s(((llillps hom Hll sHmpl(s dri((l at dill(IPllt t(lilpemtUJps Sal1lplps (1( ohlnin(d I10III a 101- of sP(d Iice c1liEc1 with a comJ1wJcia 1 dli(l wil11 the ail at apploximatcly middotIBno ~tncl no indicatioJl wm f(uJl(l of injlll) to gelmillalioll lefiulting flOIlI the dlying opeJation

SOI(JlIOIl d al (77) (11i(gt(1 Sl(ks cOJltaining approximafrly a barrel ench of lOIl~dl Ii(( in a tllllnplI)IH sack (hitI al ail tpl1Ilwratul(s of 461deg517deg (H)G 7lAmiddoto nnd ni1~3deg C Ilsppdiply tmiddoto dfI-(Imine the

efreet of the drying nil f(llljlPIahll( and th( initial 1ll0ishne (Cllltent of the grain 011 tb( Illilling C(1Itlity and the gClmination Sacks of lic(~ 01 21-perccllt of 2(J- 10 21-prreeni alld of 17-])(I(enl moiHtnle bull cont(nt welc dlirc1 Ht (ach tPlllpPIntllre (KCCpt- the last was not dried at 033deg Dlyillg t-imes CIP longrl at the ]0(1 telllp(latUles The temperature of the nirill the riec durillg drying alld the moisture

5

EFFECTS OF HFAT TREATMENT ON THE VIABILITY OF RICE

content of the rice on completion of drying were generally lOYeI in the center or the sack tlttlll at the top and boltom Inlet) injun to germination capacity occurred it was greater In the top aml bottom layers than in the center of the sack Too high an air temp(~latllle lul(l a detrimelltitl effect on both the germination and the milling quaJity of rice A temperature of 656 0 had no detrimental effect on germination for rice with 1i-H percent of l110istl1le These workers lIdvisecl that the nil tlmperature hoe(I hon1c1 not (gtx(ppd 5170

to 3+10 for ri(l with ~-11llr(pnt or ]))oi8tuI( The telllplraturl or the rice yjth pither moisture content Wit (onsi(10r1bl 10(1 thnn the ellYshying air tpl11jlel1tllle oyiJ1g to the cooling etlpct of PYapolntion

bull

~[cXpnl (8) in HHmiddotJ 1H3 and tnmiddotHi (ondllde(l 11 sPlie of sturlies on the lrtifkial dryillg of combined II(e to obtnin information on the relation of su(h fudols lS tinll~ dried ail tlmpemtllle reltti(~ hushymiditv and cniJl time to millillg llsults In(l elmiddotminatioll Riee yarieii~s (Zelliih ]allllos( Jap-trpl FIJ1tulla Xira nnd PI(11J(le) Wle halTPtPlI at 1 moistlll( coMlnt of W-H pplc(nt alld stoled and t0111 p(lNI (j to l~ homs in balTll pliOl to d lyi ng TWthe-pOllnd sa11lplps of each telll]lPlpd alilty W(le dlied ill pqJPIill1ll1tal lt11IPI5 Olle two tll(P all(l onl(till1PS fOlll dni]]g (1( uspd to leduce the moi-t11ll content- of tllP riel floll1 field ((indilioll to Imiddot~ pelCpnt rile telll ppli I1g plriod betY((11 slH(lpdi ng dIyi ngs Y Oenllt1ly 24 houls Dlyillg tpm ppla t111P ra ngl(l in i lIttlYals of ii)O C from riHJ to -T)O hut not all riel llietips (lP dliP(1 Ht (H(ll tempplature Extremes ill total (1nill timps Iallge(l 110111 li lllillU(I nt ~TKO to 2~() minutes at Tiideg Total dnill tlllHgt llsuall d(cmiddotlpapc1 as the l1U111-b(I of dl~i ngs as i11(I(14((1 11 i m pr)]ta nl (middot(mllusion of tlip stud ies ns fllal lllllinatioll is ledUl0rl ylHlllice i (11jeltl at nil t-Plll])pratllles alloY( j_k~lo -OllW of the data jllcli(atrd thM tllllP llliu-ht he nllirtal (lil1el(11(es in Il4ist1llCp to 11(( 11(1 t1wt af tIl( hig-hpmiddot t(11lpelatllres intelmittlnt drying might hE ipss destlllctin of WlI11illation (apacity tltnn (0l1tillI1011 (bTin

_ldIPcl HnrlKIalI(l ()) lt111(1 1](111P] (f)) dliprl llllpllS 011( glnin thide of (dOlO pnith Bhllh(ll111(t[agnolin ami Htxolo at 11Tlshyp(]atule f]om l~~O to HlI e ( _ los in gPllllinntioll llsually ocshy(I 11 ]r (1 at tp11lpPIattl1PS ahot -ltF C amI fa~t ltrS of drying diel not appel] to lp(ll1(( geI11linatioll

La te] Idlpltl 11](1 K lil 11](1 (n made n twl to ohtai 11 C0111shypnlatin milli1g 11lt1 Opl11linatioll lPclllts on tl1(a11l(lot of 1i(1 c1]i((l si1l111Itnmollsh- ill nnJ i(iPlltic11 Bl]ico (hitI with nil ltInillg (cl11c1ishytio) Iw1d (oilstallt CX(Pllt drying ail PllIjlllntlllmiddotl Ti]( iet was pxpold fol I) ll1illlltp to all aYlntgl ail tlllll)lrnt1](~ oi middotHLl 01 iilJdeg C am] to an ail (JJllllli of Ibol -)(11) (llhil fpCt ]gtll 1I1illl1l( 1)(1 htulPl Additionn (llying Wl( olllptillHS llP((SSH1Y DliNl samples 1(1e SelSrllll11 for m da- hPlOl1 11lillil1 ips nIHl (ill 1lity hefore Plll1ination Ipst Xo si~1Iili(tl1lt dit1PIPl1(C as llotpd in th( 111illin Clllalitlls of tlip 11(( (llit1t Ht ttt two 1 (111]gt(11111 I(S -suall) an jll~ e)Pt1Fl in gll1ll il1ll i01 llltl]t(( l n t till higlllI t (11)1)(1 t 11p

bull In thl l)](gt((gt(ling sturlils (-mith d Ii -Ol(llS()1 rf a JrcSenL nml

AI(h((] l11(1 K[1Il(l) tllP riel waS lXP0-ll to clit1pl(llt tl11lpllnhllCs of tlltifiCinlly htntpd ail ~lth()lUh tlw llll1ttd ail llll hl maintained at a (()1Istanl te1llpl[lflll( 101 dplillitp p(Iioltl 110 lt1](lt1 11( antilable ns to the maximulll tellllwratlll( 1middotlaclwd by tlw grains of lice 01 as to

BULLE~IN DEPTo OF AGRICULTURE

the timethey are mailltained Itt this temperatureo The (lilta supplied by these workers do 110t define the tolernlw( of rice to tl given temperashyture in itselfo NeTertheless they do IHnllit lin (stllllntioll of the eJiect on germination capacity when riel is eXl-ecl to a gien tem perature during drying in present-clay commercial dehydration equipment

In contrast to the preceding illvestigatiollsin which 111(1eis doubt about the tenlperutures reached by the rice Adair and Cralley (1) presoaked rice seld for 12 hours and then illllllClS(c it ill hot water ntmiddot 50deg-52deg Co for 15 lIIinuiCso This trCatment efrectiely cOlltTo1J(d wll1te tip in 19 vtlrietips oJ rice and although not intli(ah~1 apparently did not haY( an addegCo( efrect on nIP gcrminatioll capacity of thl se((l

Tisdale (83) 101111(1 that oaking- LOllisiana TTonc1l1rtls rice in yatetO at 54deg Co for Ji) minlltcs after lHolsoHkillg it 101 IG hOllri killed the internal llIn~)i and (tUll( llparest to ~oiying as rood grrlllinntioll as thl untreated eontTolso T[OPoltgtl in lill(t ionlly tel~T PXIWlillwIlt with presoaked ricl tilt permillation was ~Iiphlly IOWPl tll1I thatmiddot of Ih(lunholtgtahd (OOlltT01-o

Tisdalltgt (litlllot ~ri( lilp ini(ialllloiillll (olltplli of []l( Iiel bllt itmiddot is inttlcsting tOIlO( ill Olll of hi~ (Xl)(lilloJ(IlI 1hal IIII till lil1l( alld temperlltllrt of tIlt llOt-wallloildeglail1wnt- nlllHillPcl (()n~tant the gllomishynation capacity wus IOIll tIll IOIl)2degll til( Illloiod of Ih( plpsoak This observation slIpptsl- that tllP ltlillpIPIl(o( ill til( g(IOlllinntioll eapneitirs of the difl(J(nt batdlls of ITPatptl ((lt1 plolJilbly rlllet dilllrellc(s in the degree of lPsituwl to ll(at n- 10platmiddotP(] to ltl i I]Plop11 ((S in pl(soaking til1lPs and 1lI0i~tllloP (011 1lt11 f ul thp hlllp of (XPOSIIIPo

As tJw PlpcOpclin ldeg(-i(o il1di[atp- tIl( lil(lnll1lop COJl(PIOnp(l ith thl efrect of tlmpllontllloP Oil degpll1lil1atill ability of Ii(p (ol1-isls 101 111( most part 01 a IWiprogPlH()lIS (olIPdioll of stnelieo Thl mOIl systllllshyatie stnelies hal hlPIl (OllcPlllecl with (OOITPintillt limil((l lilo-lt1rril1 t(mpelntnrp air-dlying (illll and S(prl-IIIOitllloP 1llationships it~ milling qllnlit-y and germinatiol1 (Hll1l(ifyo EYPll (iI(s( kaye llIU(ll to be desired bceHIIgtp thpy were Jillli(pd ill s(ope and the temperatu)cs of the lots of s~~((l ))(il1)1 (l1i(lt1 (IP 1I0t (lctp1I11ill((1 Xo olle has )cport(d investigations ill which lo[~ of loi(( of eli fllI(llt ll)()isftl1p (ollt(nts hut ofthE salll( Yillip nnd FIolll tlIP Hlllp lipId plnl linn iJPPIl (xposlltl to clillclpnt PIllIHloal11 ldegr- fcwditlplpnt pllio(b of ti))I(

Yaggolwl (87) is J))obahly IlIl fildeg til Ian -Illdild 0 0 0 in s(ri(s the llsistalHP of till ~allll killd 01 sP((]s (middotolllaillill lPfinit( 1n(l kllOWIl quantiti(s of watIOat til( lill1( of hpa(illo TIp llas tnblllni((] gplllIishynation dntaol 1adi-iI sp(ltI- hayillU illitial 1)(IO(Opllt IllOis(1I1deg( (olltpllls omiddote 4 D 1middot1middot IS ~ ~() ~o middot11 iO 1ll)(1 71 l1Ilt1hi(h hac bern cxpos(c1 for 30 milllltps in indC In PISill slIi))lIlIdegeltl FIOIo(I](( flasks atotPIlI peraturES frolll i() tl) lOO Co Ht iiilllltiTalso Otlwl dahl nre also given 1or radish ((gtlt1s of JcnYl1 IIlOitlllP (ollt(nis f(l)O hig-IIP) Il1I1JWIHshytl1l(soflHntillmiddot (10 12jC)oolld fOldilllloPllt 11llthodsofhCafillgo lIis conclusions 1I11icoh 11( paJficolllnly llOPOlothro 110( IS foil degs

111( IPiiIlIJ((gt I s ds I iIfliIlIlH 1i01 Wllilll Lo lX]lIlp(1 10 lriJ1r h1ll1)(IrshyOtm ( iH innl1llr PIOOPdeg1i Ollnl 10 llil iJlillr1 lItlI 00lllllIt o IIll p(ds rt til(timp of 11fatilll0

AI fPIIIJHIrtlllls hlllt PllClllJh [II 1)( illjl11i Illp IinlJililo of nldil) IP(ls 01 n ginlI il1itial 0r1(1 (0111 d(I(ls(s rs lit 11111111111111( 10 wllil-It llic) nlP0nrhjl(Ipl is 1 ilcl

111( fWI1(I11 10jIIIWo0 o Ioil-Ipo Jlml( NPlllHl Yillllldeg nml (Isl11 l)olo(il1gIadish seeds lXPIlS(t til hiJh 111111)(111(111( i1 PIOY -illlillIo

bull

bull

bull

AGRICUlTURE

charactermiddotstics There were practical reasons for this decision Themiddot smnples of heat-treated rough rice ere too small for sa6sfuctory millin~valuation tests To obtai ~- ~~xles would have necesshysitated decreasing the number of variables investigated Skilled techniCtl assistants were not lwnilable to perform complicated bioshychemical tests On the other hnnd tacilities Y(le adequate for making germination tests middotMoreover these tests reflect the biological conditions of seeds within limitations They IHlve the arlc1ecl a(lYanshytage of being uniYelsally used and understood Hence they provide data interpreta ble by mn ny workers other than seed analysts uch as seedsmen and fanners commercial grain-drier operators and millers p1nnt physiologi-t and pathologist and hio(lpnlists

Although three major yaliables-temperature of treatment time (duration) of treatmrnt and 11loitllLc content of the rice-ale CCll1shysiderecl the greatest ell1phasi~ is placed on the temperature of treatshyment or tIle llllt 1lli is beelusl altilit-iaily hpated til is nsP(l ill til(gt commercial drying 01 conditioning of rough rice and becHnse it has been useful in plpvp~ting deterioratiol1 of rice durillg stmiddotolage

Experiments Wlc planned fo nccolllplish se(lal objPcti-ps (llier among tllem (IP to detPllllil1e (1) the pl)pet of tpJ1lperatule oj heatshyill~ on iability (~) the effpct of time (dulation) of heating Oll

viability (3) thC rp1ntionship bCtweC11 till J1OistlllP eontCl1t of the rongh rice and the teJlJpemtulC crt hpHtinl and its etleet 011 viability and (4) the eltect of prolonged storage 011 the viability of heatshytreateel rice

SOUTHERN PRACTICES IN RICE CONDITIONING

Chanfres in the methods of l111IVptin~ and storing nrC lespol1Slible for the prescntintCIpst in the ellpets of hpnt 011 Iice pploximat(ly DO percent oJ thp ~outh~s 11l1l1l1nl1i(e cJopi no comhilll(1 a(Conling to Jones et al (P) Smith and Jonps ((J) found that the best tinle to halv(Ht Ii(p is wl1(11 til( ll1oi-t UI( (Ollt(llt of tltl ~tHII(IjIW rice ranges flol11 aboutmiddot 23 to 28 I(eIIL ~[lX(H (5)) and folenso et al C(8) ill I((pnl studips Ippolt(d that Ii(p SliOlll(l bp cOlllbinpcl when its JlJOiSIIIJ( lollilnt is within till lIi- to W-PPI((nt lanle i e if the fielcl]oss(S intludil1 hpl]iII and bJPtlkal ill thl (olllbilil alt to be reduced to a JIlininilllll flndif J1JaXillllJJ11 i(lds of [oll[ilanci helld rice H 1( to Ill obta inNl Fleh hmiddot (oJlJbi IWeI Iollrrh [iep will cleteriolatC rapid1middot 1IIIIp prolllpily dried Ol COIHlitionell

AltiliCiully II(gtutpd ail is lIllt1 ill lOIlli1lP llill1 dclirtllalioll op(rHtions to lP(uee the nJOistlln (ontpllt or tlw f[pshly COilibilIPd Iourrli ric( to 1J perccllt butmiddot tlie uttainlllllIt or this l11oiIIIIP 1((gt] i llO ~IHlIalltee that the rice wil] klPP indplinitplv IIndlI all conditions of stOlltIP ( I Cl) [I I l I tsorenson et (I to IP 1ta()1 JS t HI lIg I tpJl1]lllahIIPs nnd humidities Inail in til( soutillrn Ii(p-glowing HICns-Lolliialla Texas Arkansas al1d Mississippi (fpnkills J) andKInJl1pr j() Sirrshynilicant (oMriillltiollS hJp I)(pn 111[(1( to til( knohltlp of Iie( ltllyil~ OJ conditiolling- as it i lHncti(ell ill the (middotnittd Staft (~lIlifh ( rB 71 7~ 5 (( Bodlt I jJ BuCr 11 It 11 EJllel a l(l ~r(X(gta I J1 ~rcl~eal [if] )7 )8 (jO ]c1I((] alld KruIHr j -1 KlHlller 164748 4fJ

bull

bull

- Kramer and ~Iclnd )1 --ilwlHr and ~lllilins 10 1 Sorenson ct at

E~FE1CTS OF HEAT TREAl1IENT ON THE VIABILITY OF RICE 3

J7 lJ8 the Lonisiana Agricultmal Experiment Stntion 54 Cruz and Lltforteza ~() Bond 14 am1 Autrey ct at 8)

Bin aeration and (1rying techniques are being c1eYe1oped to remove the excesS l1l0isiUle from rough rice that has been stored at too high It moisture content that has absorbed moisture since storage or that is heating Ambient air is commonly used dUling the warm daylight houls when the relntiye humidity is lo-w Altifieially 11eated air is used if the nepd for the ltpiLilClllonLl of moistllle is apparent Seyera1 yorkers h1Ye contlibuttd a1ti](s on the (ItelopnlPnt of bin Htration and drying tpclllliqncs Illong thtlll mt ~tiln i nan ft fl Cl 9) Todd (8J) Ball a ntl (oon1O(l (12) 1 (oomotl (16) SOllnson et al (78) and ~Iol1isoll rt al (6J (in and the Lou isinna Aglicult-uml Experishyment StHtion (J5)

Rice fol sCtcl is O-[tCll c1lipd in commercial ltlryin units in the same llumllCl ns tIlt bulk t-hnt is dlitc1 to a 11l0istl1lp c(mtent suitable for millillg 01 StOlUlt TIlt COlllllHlcial u11its alP of course (leaned and inspected bpfc)le being loadell with Iiee to be (hiNl 101 s(ed purposes 111tir nse is l~nely one of conwnipnce Gp1lllination tests and farmshy(10]gt obsP]at-iom Sllpport thp prn(tice but (lata mp not 1lTailab1e to pya11latr jllpSPllt (Ollllll(1cia I tl1yi ng pIo(pd Il1PF folll the standpoint of Illlp1O-jng sp((l quality

UEVIEW OF LITERATURE

bull Although hpat has probnll1y lwen app1ipd in tl1( t1lllhnrnt of rough rice 101 clntlllies thpp mp lmt ipy publishpd l(eOllllts-nt ]Plst those readily iwnilable to occic1pntnl teac1EI3--that (kseribpits eJiect on the abilit) of ricp to gplminnte On til( other hall(11 lllunbpl of publicashytions a few of which h1e npPPH1ed in 1p(pnt yelrs plespnt data on the ptleuroct of hpat- trpItnlPnt- Oil gllmination capacity but mostly rot otltpl kin(ls of sPPlt1 than liel

1)n Fano (21) inyp~igltp(l the influpn(( of timp amI tpll1perature ofhpnJing Oil (uiptips of 1ICP and corn Loh of pIeh variety of rice e1p exposp(l to amlliPllt tplll]Jllatuts and to 100-DllO C at 10deg jntershynils iOI L~ and 1 hous 1foistme eontpntF of the sampllS appeared fo 111p 1gtp(n lithin n 1- to lgt-pp1cpnt 1lngp plio to tTpatnwllt except two alllbiPllt-nil-(l1i((l controls whieh P1P UUi2 anlt1 212 percent lespectinlr ftpl t tpatlllPllt the llloisfulp (OlltplltS ntnf(tl from 43 to l~n~ PPITllli l111d thp moittuc Imps ilOlll 1Ui to nll percent (rprmillation t(FiR WPlP 1111lt1( illllllNtiattlv aftpl tT(lilllent Vialone n(lo and (llillPRe Iice uiPlils ltlPlllOniTat(d maximum ability to gellUi11ntp aftpl ]llafing at 30 0 fot~ hOll]s tIlt Hanhino nl1iety (l1tel hNlting at _10deg 101 2 hOll]8 ~JillilllUlll pllllinntin abi1itips wele cOllstailtly ohtaillPltl by hputillf at HOdeg 101 )houls allt1 the seed gelshyJnillat j ng Ia llg-((l lHtml1l IS nn( 2~ PP j(pll t 11 t hp Yllieties lost thei l gelminating- PO(J cOllpl(t(ly hpil lllni((1 nt PO fol 1 hOlll The inshyvpstignto] did not lil1lt1 t-Ill nwxillllllll gtllllinating POWl to (OIlPspond to the maximulll ppl(pniage of ntPl (ontained in the S(N[S put to gpIminate Sill cli(tfilld how(p1 that heat t1pnhlHllts withill lUV01shy

nble lime nnd tllll]p]ntlllp lang(F implopc thp gtlminfltioll capacity 01 the tle1I(( mp thnt of Ih( llmilipnt--nil-lt1lipll]ill sIlt nlso 1tCOI2shynizp( till pORsibl( signili(HIHP of tht IHetlcatnwllt his(OlT of the seed

~

in dTecting til( (XIWlillllJltal I(sults

TEC~LCAL BULLETIN U S DEPT OF AGRICULTURE

Nagn i (65) exposed air-dried and desiccated grn ins of rice for 2 hoUls at 97deg-)SO C He found that the germinative power of the bull grain especially if desiccated was only slightly affected

Jones (39) exposed Colusa ami Caloro rice seed on saturated paper toweling in pttri dishes for 1 2 and 3 hours respectively at constant temperatures of 50deg 544deg Rnd (Hi7deg C Exposure for 1 to 2 hours at liOdeg and 544deg had no appreciable effect on ennination capacity but exposure at (j(L7deg for 1 hoUlmiddot materially reduced the percentage germination of both yar~eties and exposure for 3 hours entirely deshystroyecl the power of germination

In another series of expCgtliments Tones exposed air-dlmiddotjed seed of the same hvo nUieties in ((gtUl (II pehi dishes for 1 hom at 50deg 54-4deg (Q0 (i5n 0 70 0 bull 7(i70 bull H7S o bull n(i 0 and 100deg C Treatment at 70deg or Huckr apparently did not t(gtlt1nce the gennination of either variety The 7fi7deg treatment slightly reduced th( germination ctshypacity of the (t1oto yariety n H7S0 treatment greatly reduced the germination cn ptlti tieR of bol-h n1lipti0 tlHlt of the Cnloro to a gr(nter pxtent than that of thp Colma Treatl1l(llts nt f)(U deg and IO()O for I hour ki]ecl a11 sppd of both ytri(ties JOllPS statc(l that these experishymcnts show (-]wt air-dli(( s((d ill stand n I11l1ch higher tel11]gtC]aturc than wet seed and its germination will not b( afJect(d

Further intcl]gtretn[ion or thp data 111lt1 olserqtions of Da Fano Nagai and Jones is Ilot attempted because pteh failld to describe

C1Cilrly and (ollJpl(t(ly tlH pxp(gtrillltntal (oIHlitiol1s employCc1 In Da Fanos (xp(rinllnts the Imiddotice lost 1l10isttll( (Juring heat trrahn(gtnt III Tones eXl)(Iil11Cnts the moist ri(p prolJa hly ( id not lose an appreshy bull ciable al1l0unt On t11( nth(l ha n(l Jones d ill not gie the moisture contents of his loh of Ii(p pilllcIwiorp 01 aftcr tr(~ltnl(nt

Smith et al (71) in thlir siwl of Ihe (f1cet of dat(gt of httlTest on yield and milling quality of Ii(( ~(gtI( tlw first to remark on thp cflect of germination of tht artifi(ial tlrying of riel in nn (xp(gtIiJllrnlal and in a comm(lcial driPI UP Ill I ina Iion I-esl-s wcrp mt(lp on sa III pl(s of Bltle Hosp 1i(( (iJi(d in Ill( lahorlllOIY nlldN normal lttil (onditions nl1c1 in the (xp(rinH-nhll dri(r at DcIyltl IIL with thc nil at +U3deg 4-SDo 5Lmiddot~o nn(J (iOO C Heinlt of silllilnr Ugts ma(( on l111pl(gts of Enrly ProlifiC ForhllJa allcl Blu( Hop Iic( lt1Ii(d ill th( (xplgtriJ1Jpntal drier at XOI11( Tlx ga( 110inlt1i(alioll of injury le~LJltillg flonl rtltishyfieial dlyil1 nt the t(llJpelatlll(s u((l Additional lefits made in a greenhollse on SOIll( 01 tll( HampleH of riel ~a( 110 clpnl eidence of any difr(lcneC in th( s(((llillps hom Hll sHmpl(s dri((l at dill(IPllt t(lilpemtUJps Sal1lplps (1( ohlnin(d I10III a 101- of sP(d Iice c1liEc1 with a comJ1wJcia 1 dli(l wil11 the ail at apploximatcly middotIBno ~tncl no indicatioJl wm f(uJl(l of injlll) to gelmillalioll lefiulting flOIlI the dlying opeJation

SOI(JlIOIl d al (77) (11i(gt(1 Sl(ks cOJltaining approximafrly a barrel ench of lOIl~dl Ii(( in a tllllnplI)IH sack (hitI al ail tpl1Ilwratul(s of 461deg517deg (H)G 7lAmiddoto nnd ni1~3deg C Ilsppdiply tmiddoto dfI-(Imine the

efreet of the drying nil f(llljlPIahll( and th( initial 1ll0ishne (Cllltent of the grain 011 tb( Illilling C(1Itlity and the gClmination Sacks of lic(~ 01 21-perccllt of 2(J- 10 21-prreeni alld of 17-])(I(enl moiHtnle bull cont(nt welc dlirc1 Ht (ach tPlllpPIntllre (KCCpt- the last was not dried at 033deg Dlyillg t-imes CIP longrl at the ]0(1 telllp(latUles The temperature of the nirill the riec durillg drying alld the moisture

5

EFFECTS OF HFAT TREATMENT ON THE VIABILITY OF RICE

content of the rice on completion of drying were generally lOYeI in the center or the sack tlttlll at the top and boltom Inlet) injun to germination capacity occurred it was greater In the top aml bottom layers than in the center of the sack Too high an air temp(~latllle lul(l a detrimelltitl effect on both the germination and the milling quaJity of rice A temperature of 656 0 had no detrimental effect on germination for rice with 1i-H percent of l110istl1le These workers lIdvisecl that the nil tlmperature hoe(I hon1c1 not (gtx(ppd 5170

to 3+10 for ri(l with ~-11llr(pnt or ]))oi8tuI( The telllplraturl or the rice yjth pither moisture content Wit (onsi(10r1bl 10(1 thnn the ellYshying air tpl11jlel1tllle oyiJ1g to the cooling etlpct of PYapolntion

bull

~[cXpnl (8) in HHmiddotJ 1H3 and tnmiddotHi (ondllde(l 11 sPlie of sturlies on the lrtifkial dryillg of combined II(e to obtnin information on the relation of su(h fudols lS tinll~ dried ail tlmpemtllle reltti(~ hushymiditv and cniJl time to millillg llsults In(l elmiddotminatioll Riee yarieii~s (Zelliih ]allllos( Jap-trpl FIJ1tulla Xira nnd PI(11J(le) Wle halTPtPlI at 1 moistlll( coMlnt of W-H pplc(nt alld stoled and t0111 p(lNI (j to l~ homs in balTll pliOl to d lyi ng TWthe-pOllnd sa11lplps of each telll]lPlpd alilty W(le dlied ill pqJPIill1ll1tal lt11IPI5 Olle two tll(P all(l onl(till1PS fOlll dni]]g (1( uspd to leduce the moi-t11ll content- of tllP riel floll1 field ((indilioll to Imiddot~ pelCpnt rile telll ppli I1g plriod betY((11 slH(lpdi ng dIyi ngs Y Oenllt1ly 24 houls Dlyillg tpm ppla t111P ra ngl(l in i lIttlYals of ii)O C from riHJ to -T)O hut not all riel llietips (lP dliP(1 Ht (H(ll tempplature Extremes ill total (1nill timps Iallge(l 110111 li lllillU(I nt ~TKO to 2~() minutes at Tiideg Total dnill tlllHgt llsuall d(cmiddotlpapc1 as the l1U111-b(I of dl~i ngs as i11(I(14((1 11 i m pr)]ta nl (middot(mllusion of tlip stud ies ns fllal lllllinatioll is ledUl0rl ylHlllice i (11jeltl at nil t-Plll])pratllles alloY( j_k~lo -OllW of the data jllcli(atrd thM tllllP llliu-ht he nllirtal (lil1el(11(es in Il4ist1llCp to 11(( 11(1 t1wt af tIl( hig-hpmiddot t(11lpelatllres intelmittlnt drying might hE ipss destlllctin of WlI11illation (apacity tltnn (0l1tillI1011 (bTin

_ldIPcl HnrlKIalI(l ()) lt111(1 1](111P] (f)) dliprl llllpllS 011( glnin thide of (dOlO pnith Bhllh(ll111(t[agnolin ami Htxolo at 11Tlshyp(]atule f]om l~~O to HlI e ( _ los in gPllllinntioll llsually ocshy(I 11 ]r (1 at tp11lpPIattl1PS ahot -ltF C amI fa~t ltrS of drying diel not appel] to lp(ll1(( geI11linatioll

La te] Idlpltl 11](1 K lil 11](1 (n made n twl to ohtai 11 C0111shypnlatin milli1g 11lt1 Opl11linatioll lPclllts on tl1(a11l(lot of 1i(1 c1]i((l si1l111Itnmollsh- ill nnJ i(iPlltic11 Bl]ico (hitI with nil ltInillg (cl11c1ishytio) Iw1d (oilstallt CX(Pllt drying ail PllIjlllntlllmiddotl Ti]( iet was pxpold fol I) ll1illlltp to all aYlntgl ail tlllll)lrnt1](~ oi middotHLl 01 iilJdeg C am] to an ail (JJllllli of Ibol -)(11) (llhil fpCt ]gtll 1I1illl1l( 1)(1 htulPl Additionn (llying Wl( olllptillHS llP((SSH1Y DliNl samples 1(1e SelSrllll11 for m da- hPlOl1 11lillil1 ips nIHl (ill 1lity hefore Plll1ination Ipst Xo si~1Iili(tl1lt dit1PIPl1(C as llotpd in th( 111illin Clllalitlls of tlip 11(( (llit1t Ht ttt two 1 (111]gt(11111 I(S -suall) an jll~ e)Pt1Fl in gll1ll il1ll i01 llltl]t(( l n t till higlllI t (11)1)(1 t 11p

bull In thl l)](gt((gt(ling sturlils (-mith d Ii -Ol(llS()1 rf a JrcSenL nml

AI(h((] l11(1 K[1Il(l) tllP riel waS lXP0-ll to clit1pl(llt tl11lpllnhllCs of tlltifiCinlly htntpd ail ~lth()lUh tlw llll1ttd ail llll hl maintained at a (()1Istanl te1llpl[lflll( 101 dplillitp p(Iioltl 110 lt1](lt1 11( antilable ns to the maximulll tellllwratlll( 1middotlaclwd by tlw grains of lice 01 as to

BULLE~IN DEPTo OF AGRICULTURE

the timethey are mailltained Itt this temperatureo The (lilta supplied by these workers do 110t define the tolernlw( of rice to tl given temperashyture in itselfo NeTertheless they do IHnllit lin (stllllntioll of the eJiect on germination capacity when riel is eXl-ecl to a gien tem perature during drying in present-clay commercial dehydration equipment

In contrast to the preceding illvestigatiollsin which 111(1eis doubt about the tenlperutures reached by the rice Adair and Cralley (1) presoaked rice seld for 12 hours and then illllllClS(c it ill hot water ntmiddot 50deg-52deg Co for 15 lIIinuiCso This trCatment efrectiely cOlltTo1J(d wll1te tip in 19 vtlrietips oJ rice and although not intli(ah~1 apparently did not haY( an addegCo( efrect on nIP gcrminatioll capacity of thl se((l

Tisdale (83) 101111(1 that oaking- LOllisiana TTonc1l1rtls rice in yatetO at 54deg Co for Ji) minlltcs after lHolsoHkillg it 101 IG hOllri killed the internal llIn~)i and (tUll( llparest to ~oiying as rood grrlllinntioll as thl untreated eontTolso T[OPoltgtl in lill(t ionlly tel~T PXIWlillwIlt with presoaked ricl tilt permillation was ~Iiphlly IOWPl tll1I thatmiddot of Ih(lunholtgtahd (OOlltT01-o

Tisdalltgt (litlllot ~ri( lilp ini(ialllloiillll (olltplli of []l( Iiel bllt itmiddot is inttlcsting tOIlO( ill Olll of hi~ (Xl)(lilloJ(IlI 1hal IIII till lil1l( alld temperlltllrt of tIlt llOt-wallloildeglail1wnt- nlllHillPcl (()n~tant the gllomishynation capacity wus IOIll tIll IOIl)2degll til( Illloiod of Ih( plpsoak This observation slIpptsl- that tllP ltlillpIPIl(o( ill til( g(IOlllinntioll eapneitirs of the difl(J(nt batdlls of ITPatptl ((lt1 plolJilbly rlllet dilllrellc(s in the degree of lPsituwl to ll(at n- 10platmiddotP(] to ltl i I]Plop11 ((S in pl(soaking til1lPs and 1lI0i~tllloP (011 1lt11 f ul thp hlllp of (XPOSIIIPo

As tJw PlpcOpclin ldeg(-i(o il1di[atp- tIl( lil(lnll1lop COJl(PIOnp(l ith thl efrect of tlmpllontllloP Oil degpll1lil1atill ability of Ii(p (ol1-isls 101 111( most part 01 a IWiprogPlH()lIS (olIPdioll of stnelieo Thl mOIl systllllshyatie stnelies hal hlPIl (OllcPlllecl with (OOITPintillt limil((l lilo-lt1rril1 t(mpelntnrp air-dlying (illll and S(prl-IIIOitllloP 1llationships it~ milling qllnlit-y and germinatiol1 (Hll1l(ifyo EYPll (iI(s( kaye llIU(ll to be desired bceHIIgtp thpy were Jillli(pd ill s(ope and the temperatu)cs of the lots of s~~((l ))(il1)1 (l1i(lt1 (IP 1I0t (lctp1I11ill((1 Xo olle has )cport(d investigations ill which lo[~ of loi(( of eli fllI(llt ll)()isftl1p (ollt(nts hut ofthE salll( Yillip nnd FIolll tlIP Hlllp lipId plnl linn iJPPIl (xposlltl to clillclpnt PIllIHloal11 ldegr- fcwditlplpnt pllio(b of ti))I(

Yaggolwl (87) is J))obahly IlIl fildeg til Ian -Illdild 0 0 0 in s(ri(s the llsistalHP of till ~allll killd 01 sP((]s (middotolllaillill lPfinit( 1n(l kllOWIl quantiti(s of watIOat til( lill1( of hpa(illo TIp llas tnblllni((] gplllIishynation dntaol 1adi-iI sp(ltI- hayillU illitial 1)(IO(Opllt IllOis(1I1deg( (olltpllls omiddote 4 D 1middot1middot IS ~ ~() ~o middot11 iO 1ll)(1 71 l1Ilt1hi(h hac bern cxpos(c1 for 30 milllltps in indC In PISill slIi))lIlIdegeltl FIOIo(I](( flasks atotPIlI peraturES frolll i() tl) lOO Co Ht iiilllltiTalso Otlwl dahl nre also given 1or radish ((gtlt1s of JcnYl1 IIlOitlllP (ollt(nis f(l)O hig-IIP) Il1I1JWIHshytl1l(soflHntillmiddot (10 12jC)oolld fOldilllloPllt 11llthodsofhCafillgo lIis conclusions 1I11icoh 11( paJficolllnly llOPOlothro 110( IS foil degs

111( IPiiIlIJ((gt I s ds I iIfliIlIlH 1i01 Wllilll Lo lX]lIlp(1 10 lriJ1r h1ll1)(IrshyOtm ( iH innl1llr PIOOPdeg1i Ollnl 10 llil iJlillr1 lItlI 00lllllIt o IIll p(ds rt til(timp of 11fatilll0

AI fPIIIJHIrtlllls hlllt PllClllJh [II 1)( illjl11i Illp IinlJililo of nldil) IP(ls 01 n ginlI il1itial 0r1(1 (0111 d(I(ls(s rs lit 11111111111111( 10 wllil-It llic) nlP0nrhjl(Ipl is 1 ilcl

111( fWI1(I11 10jIIIWo0 o Ioil-Ipo Jlml( NPlllHl Yillllldeg nml (Isl11 l)olo(il1gIadish seeds lXPIlS(t til hiJh 111111)(111(111( i1 PIOY -illlillIo

bull

bull

bull

E~FE1CTS OF HEAT TREAl1IENT ON THE VIABILITY OF RICE 3

J7 lJ8 the Lonisiana Agricultmal Experiment Stntion 54 Cruz and Lltforteza ~() Bond 14 am1 Autrey ct at 8)

Bin aeration and (1rying techniques are being c1eYe1oped to remove the excesS l1l0isiUle from rough rice that has been stored at too high It moisture content that has absorbed moisture since storage or that is heating Ambient air is commonly used dUling the warm daylight houls when the relntiye humidity is lo-w Altifieially 11eated air is used if the nepd for the ltpiLilClllonLl of moistllle is apparent Seyera1 yorkers h1Ye contlibuttd a1ti](s on the (ItelopnlPnt of bin Htration and drying tpclllliqncs Illong thtlll mt ~tiln i nan ft fl Cl 9) Todd (8J) Ball a ntl (oon1O(l (12) 1 (oomotl (16) SOllnson et al (78) and ~Iol1isoll rt al (6J (in and the Lou isinna Aglicult-uml Experishyment StHtion (J5)

Rice fol sCtcl is O-[tCll c1lipd in commercial ltlryin units in the same llumllCl ns tIlt bulk t-hnt is dlitc1 to a 11l0istl1lp c(mtent suitable for millillg 01 StOlUlt TIlt COlllllHlcial u11its alP of course (leaned and inspected bpfc)le being loadell with Iiee to be (hiNl 101 s(ed purposes 111tir nse is l~nely one of conwnipnce Gp1lllination tests and farmshy(10]gt obsP]at-iom Sllpport thp prn(tice but (lata mp not 1lTailab1e to pya11latr jllpSPllt (Ollllll(1cia I tl1yi ng pIo(pd Il1PF folll the standpoint of Illlp1O-jng sp((l quality

UEVIEW OF LITERATURE

bull Although hpat has probnll1y lwen app1ipd in tl1( t1lllhnrnt of rough rice 101 clntlllies thpp mp lmt ipy publishpd l(eOllllts-nt ]Plst those readily iwnilable to occic1pntnl teac1EI3--that (kseribpits eJiect on the abilit) of ricp to gplminnte On til( other hall(11 lllunbpl of publicashytions a few of which h1e npPPH1ed in 1p(pnt yelrs plespnt data on the ptleuroct of hpat- trpItnlPnt- Oil gllmination capacity but mostly rot otltpl kin(ls of sPPlt1 than liel

1)n Fano (21) inyp~igltp(l the influpn(( of timp amI tpll1perature ofhpnJing Oil (uiptips of 1ICP and corn Loh of pIeh variety of rice e1p exposp(l to amlliPllt tplll]Jllatuts and to 100-DllO C at 10deg jntershynils iOI L~ and 1 hous 1foistme eontpntF of the sampllS appeared fo 111p 1gtp(n lithin n 1- to lgt-pp1cpnt 1lngp plio to tTpatnwllt except two alllbiPllt-nil-(l1i((l controls whieh P1P UUi2 anlt1 212 percent lespectinlr ftpl t tpatlllPllt the llloisfulp (OlltplltS ntnf(tl from 43 to l~n~ PPITllli l111d thp moittuc Imps ilOlll 1Ui to nll percent (rprmillation t(FiR WPlP 1111lt1( illllllNtiattlv aftpl tT(lilllent Vialone n(lo and (llillPRe Iice uiPlils ltlPlllOniTat(d maximum ability to gellUi11ntp aftpl ]llafing at 30 0 fot~ hOll]s tIlt Hanhino nl1iety (l1tel hNlting at _10deg 101 2 hOll]8 ~JillilllUlll pllllinntin abi1itips wele cOllstailtly ohtaillPltl by hputillf at HOdeg 101 )houls allt1 the seed gelshyJnillat j ng Ia llg-((l lHtml1l IS nn( 2~ PP j(pll t 11 t hp Yllieties lost thei l gelminating- PO(J cOllpl(t(ly hpil lllni((1 nt PO fol 1 hOlll The inshyvpstignto] did not lil1lt1 t-Ill nwxillllllll gtllllinating POWl to (OIlPspond to the maximulll ppl(pniage of ntPl (ontained in the S(N[S put to gpIminate Sill cli(tfilld how(p1 that heat t1pnhlHllts withill lUV01shy

nble lime nnd tllll]p]ntlllp lang(F implopc thp gtlminfltioll capacity 01 the tle1I(( mp thnt of Ih( llmilipnt--nil-lt1lipll]ill sIlt nlso 1tCOI2shynizp( till pORsibl( signili(HIHP of tht IHetlcatnwllt his(OlT of the seed

~

in dTecting til( (XIWlillllJltal I(sults

TEC~LCAL BULLETIN U S DEPT OF AGRICULTURE

Nagn i (65) exposed air-dried and desiccated grn ins of rice for 2 hoUls at 97deg-)SO C He found that the germinative power of the bull grain especially if desiccated was only slightly affected

Jones (39) exposed Colusa ami Caloro rice seed on saturated paper toweling in pttri dishes for 1 2 and 3 hours respectively at constant temperatures of 50deg 544deg Rnd (Hi7deg C Exposure for 1 to 2 hours at liOdeg and 544deg had no appreciable effect on ennination capacity but exposure at (j(L7deg for 1 hoUlmiddot materially reduced the percentage germination of both yar~eties and exposure for 3 hours entirely deshystroyecl the power of germination

In another series of expCgtliments Tones exposed air-dlmiddotjed seed of the same hvo nUieties in ((gtUl (II pehi dishes for 1 hom at 50deg 54-4deg (Q0 (i5n 0 70 0 bull 7(i70 bull H7S o bull n(i 0 and 100deg C Treatment at 70deg or Huckr apparently did not t(gtlt1nce the gennination of either variety The 7fi7deg treatment slightly reduced th( germination ctshypacity of the (t1oto yariety n H7S0 treatment greatly reduced the germination cn ptlti tieR of bol-h n1lipti0 tlHlt of the Cnloro to a gr(nter pxtent than that of thp Colma Treatl1l(llts nt f)(U deg and IO()O for I hour ki]ecl a11 sppd of both ytri(ties JOllPS statc(l that these experishymcnts show (-]wt air-dli(( s((d ill stand n I11l1ch higher tel11]gtC]aturc than wet seed and its germination will not b( afJect(d

Further intcl]gtretn[ion or thp data 111lt1 olserqtions of Da Fano Nagai and Jones is Ilot attempted because pteh failld to describe

C1Cilrly and (ollJpl(t(ly tlH pxp(gtrillltntal (oIHlitiol1s employCc1 In Da Fanos (xp(rinllnts the Imiddotice lost 1l10isttll( (Juring heat trrahn(gtnt III Tones eXl)(Iil11Cnts the moist ri(p prolJa hly ( id not lose an appreshy bull ciable al1l0unt On t11( nth(l ha n(l Jones d ill not gie the moisture contents of his loh of Ii(p pilllcIwiorp 01 aftcr tr(~ltnl(nt

Smith et al (71) in thlir siwl of Ihe (f1cet of dat(gt of httlTest on yield and milling quality of Ii(( ~(gtI( tlw first to remark on thp cflect of germination of tht artifi(ial tlrying of riel in nn (xp(gtIiJllrnlal and in a comm(lcial driPI UP Ill I ina Iion I-esl-s wcrp mt(lp on sa III pl(s of Bltle Hosp 1i(( (iJi(d in Ill( lahorlllOIY nlldN normal lttil (onditions nl1c1 in the (xp(rinH-nhll dri(r at DcIyltl IIL with thc nil at +U3deg 4-SDo 5Lmiddot~o nn(J (iOO C Heinlt of silllilnr Ugts ma(( on l111pl(gts of Enrly ProlifiC ForhllJa allcl Blu( Hop Iic( lt1Ii(d ill th( (xplgtriJ1Jpntal drier at XOI11( Tlx ga( 110inlt1i(alioll of injury le~LJltillg flonl rtltishyfieial dlyil1 nt the t(llJpelatlll(s u((l Additional lefits made in a greenhollse on SOIll( 01 tll( HampleH of riel ~a( 110 clpnl eidence of any difr(lcneC in th( s(((llillps hom Hll sHmpl(s dri((l at dill(IPllt t(lilpemtUJps Sal1lplps (1( ohlnin(d I10III a 101- of sP(d Iice c1liEc1 with a comJ1wJcia 1 dli(l wil11 the ail at apploximatcly middotIBno ~tncl no indicatioJl wm f(uJl(l of injlll) to gelmillalioll lefiulting flOIlI the dlying opeJation

SOI(JlIOIl d al (77) (11i(gt(1 Sl(ks cOJltaining approximafrly a barrel ench of lOIl~dl Ii(( in a tllllnplI)IH sack (hitI al ail tpl1Ilwratul(s of 461deg517deg (H)G 7lAmiddoto nnd ni1~3deg C Ilsppdiply tmiddoto dfI-(Imine the

efreet of the drying nil f(llljlPIahll( and th( initial 1ll0ishne (Cllltent of the grain 011 tb( Illilling C(1Itlity and the gClmination Sacks of lic(~ 01 21-perccllt of 2(J- 10 21-prreeni alld of 17-])(I(enl moiHtnle bull cont(nt welc dlirc1 Ht (ach tPlllpPIntllre (KCCpt- the last was not dried at 033deg Dlyillg t-imes CIP longrl at the ]0(1 telllp(latUles The temperature of the nirill the riec durillg drying alld the moisture

5

EFFECTS OF HFAT TREATMENT ON THE VIABILITY OF RICE

content of the rice on completion of drying were generally lOYeI in the center or the sack tlttlll at the top and boltom Inlet) injun to germination capacity occurred it was greater In the top aml bottom layers than in the center of the sack Too high an air temp(~latllle lul(l a detrimelltitl effect on both the germination and the milling quaJity of rice A temperature of 656 0 had no detrimental effect on germination for rice with 1i-H percent of l110istl1le These workers lIdvisecl that the nil tlmperature hoe(I hon1c1 not (gtx(ppd 5170

to 3+10 for ri(l with ~-11llr(pnt or ]))oi8tuI( The telllplraturl or the rice yjth pither moisture content Wit (onsi(10r1bl 10(1 thnn the ellYshying air tpl11jlel1tllle oyiJ1g to the cooling etlpct of PYapolntion

bull

~[cXpnl (8) in HHmiddotJ 1H3 and tnmiddotHi (ondllde(l 11 sPlie of sturlies on the lrtifkial dryillg of combined II(e to obtnin information on the relation of su(h fudols lS tinll~ dried ail tlmpemtllle reltti(~ hushymiditv and cniJl time to millillg llsults In(l elmiddotminatioll Riee yarieii~s (Zelliih ]allllos( Jap-trpl FIJ1tulla Xira nnd PI(11J(le) Wle halTPtPlI at 1 moistlll( coMlnt of W-H pplc(nt alld stoled and t0111 p(lNI (j to l~ homs in balTll pliOl to d lyi ng TWthe-pOllnd sa11lplps of each telll]lPlpd alilty W(le dlied ill pqJPIill1ll1tal lt11IPI5 Olle two tll(P all(l onl(till1PS fOlll dni]]g (1( uspd to leduce the moi-t11ll content- of tllP riel floll1 field ((indilioll to Imiddot~ pelCpnt rile telll ppli I1g plriod betY((11 slH(lpdi ng dIyi ngs Y Oenllt1ly 24 houls Dlyillg tpm ppla t111P ra ngl(l in i lIttlYals of ii)O C from riHJ to -T)O hut not all riel llietips (lP dliP(1 Ht (H(ll tempplature Extremes ill total (1nill timps Iallge(l 110111 li lllillU(I nt ~TKO to 2~() minutes at Tiideg Total dnill tlllHgt llsuall d(cmiddotlpapc1 as the l1U111-b(I of dl~i ngs as i11(I(14((1 11 i m pr)]ta nl (middot(mllusion of tlip stud ies ns fllal lllllinatioll is ledUl0rl ylHlllice i (11jeltl at nil t-Plll])pratllles alloY( j_k~lo -OllW of the data jllcli(atrd thM tllllP llliu-ht he nllirtal (lil1el(11(es in Il4ist1llCp to 11(( 11(1 t1wt af tIl( hig-hpmiddot t(11lpelatllres intelmittlnt drying might hE ipss destlllctin of WlI11illation (apacity tltnn (0l1tillI1011 (bTin

_ldIPcl HnrlKIalI(l ()) lt111(1 1](111P] (f)) dliprl llllpllS 011( glnin thide of (dOlO pnith Bhllh(ll111(t[agnolin ami Htxolo at 11Tlshyp(]atule f]om l~~O to HlI e ( _ los in gPllllinntioll llsually ocshy(I 11 ]r (1 at tp11lpPIattl1PS ahot -ltF C amI fa~t ltrS of drying diel not appel] to lp(ll1(( geI11linatioll

La te] Idlpltl 11](1 K lil 11](1 (n made n twl to ohtai 11 C0111shypnlatin milli1g 11lt1 Opl11linatioll lPclllts on tl1(a11l(lot of 1i(1 c1]i((l si1l111Itnmollsh- ill nnJ i(iPlltic11 Bl]ico (hitI with nil ltInillg (cl11c1ishytio) Iw1d (oilstallt CX(Pllt drying ail PllIjlllntlllmiddotl Ti]( iet was pxpold fol I) ll1illlltp to all aYlntgl ail tlllll)lrnt1](~ oi middotHLl 01 iilJdeg C am] to an ail (JJllllli of Ibol -)(11) (llhil fpCt ]gtll 1I1illl1l( 1)(1 htulPl Additionn (llying Wl( olllptillHS llP((SSH1Y DliNl samples 1(1e SelSrllll11 for m da- hPlOl1 11lillil1 ips nIHl (ill 1lity hefore Plll1ination Ipst Xo si~1Iili(tl1lt dit1PIPl1(C as llotpd in th( 111illin Clllalitlls of tlip 11(( (llit1t Ht ttt two 1 (111]gt(11111 I(S -suall) an jll~ e)Pt1Fl in gll1ll il1ll i01 llltl]t(( l n t till higlllI t (11)1)(1 t 11p

bull In thl l)](gt((gt(ling sturlils (-mith d Ii -Ol(llS()1 rf a JrcSenL nml

AI(h((] l11(1 K[1Il(l) tllP riel waS lXP0-ll to clit1pl(llt tl11lpllnhllCs of tlltifiCinlly htntpd ail ~lth()lUh tlw llll1ttd ail llll hl maintained at a (()1Istanl te1llpl[lflll( 101 dplillitp p(Iioltl 110 lt1](lt1 11( antilable ns to the maximulll tellllwratlll( 1middotlaclwd by tlw grains of lice 01 as to

BULLE~IN DEPTo OF AGRICULTURE

the timethey are mailltained Itt this temperatureo The (lilta supplied by these workers do 110t define the tolernlw( of rice to tl given temperashyture in itselfo NeTertheless they do IHnllit lin (stllllntioll of the eJiect on germination capacity when riel is eXl-ecl to a gien tem perature during drying in present-clay commercial dehydration equipment

In contrast to the preceding illvestigatiollsin which 111(1eis doubt about the tenlperutures reached by the rice Adair and Cralley (1) presoaked rice seld for 12 hours and then illllllClS(c it ill hot water ntmiddot 50deg-52deg Co for 15 lIIinuiCso This trCatment efrectiely cOlltTo1J(d wll1te tip in 19 vtlrietips oJ rice and although not intli(ah~1 apparently did not haY( an addegCo( efrect on nIP gcrminatioll capacity of thl se((l

Tisdale (83) 101111(1 that oaking- LOllisiana TTonc1l1rtls rice in yatetO at 54deg Co for Ji) minlltcs after lHolsoHkillg it 101 IG hOllri killed the internal llIn~)i and (tUll( llparest to ~oiying as rood grrlllinntioll as thl untreated eontTolso T[OPoltgtl in lill(t ionlly tel~T PXIWlillwIlt with presoaked ricl tilt permillation was ~Iiphlly IOWPl tll1I thatmiddot of Ih(lunholtgtahd (OOlltT01-o

Tisdalltgt (litlllot ~ri( lilp ini(ialllloiillll (olltplli of []l( Iiel bllt itmiddot is inttlcsting tOIlO( ill Olll of hi~ (Xl)(lilloJ(IlI 1hal IIII till lil1l( alld temperlltllrt of tIlt llOt-wallloildeglail1wnt- nlllHillPcl (()n~tant the gllomishynation capacity wus IOIll tIll IOIl)2degll til( Illloiod of Ih( plpsoak This observation slIpptsl- that tllP ltlillpIPIl(o( ill til( g(IOlllinntioll eapneitirs of the difl(J(nt batdlls of ITPatptl ((lt1 plolJilbly rlllet dilllrellc(s in the degree of lPsituwl to ll(at n- 10platmiddotP(] to ltl i I]Plop11 ((S in pl(soaking til1lPs and 1lI0i~tllloP (011 1lt11 f ul thp hlllp of (XPOSIIIPo

As tJw PlpcOpclin ldeg(-i(o il1di[atp- tIl( lil(lnll1lop COJl(PIOnp(l ith thl efrect of tlmpllontllloP Oil degpll1lil1atill ability of Ii(p (ol1-isls 101 111( most part 01 a IWiprogPlH()lIS (olIPdioll of stnelieo Thl mOIl systllllshyatie stnelies hal hlPIl (OllcPlllecl with (OOITPintillt limil((l lilo-lt1rril1 t(mpelntnrp air-dlying (illll and S(prl-IIIOitllloP 1llationships it~ milling qllnlit-y and germinatiol1 (Hll1l(ifyo EYPll (iI(s( kaye llIU(ll to be desired bceHIIgtp thpy were Jillli(pd ill s(ope and the temperatu)cs of the lots of s~~((l ))(il1)1 (l1i(lt1 (IP 1I0t (lctp1I11ill((1 Xo olle has )cport(d investigations ill which lo[~ of loi(( of eli fllI(llt ll)()isftl1p (ollt(nts hut ofthE salll( Yillip nnd FIolll tlIP Hlllp lipId plnl linn iJPPIl (xposlltl to clillclpnt PIllIHloal11 ldegr- fcwditlplpnt pllio(b of ti))I(

Yaggolwl (87) is J))obahly IlIl fildeg til Ian -Illdild 0 0 0 in s(ri(s the llsistalHP of till ~allll killd 01 sP((]s (middotolllaillill lPfinit( 1n(l kllOWIl quantiti(s of watIOat til( lill1( of hpa(illo TIp llas tnblllni((] gplllIishynation dntaol 1adi-iI sp(ltI- hayillU illitial 1)(IO(Opllt IllOis(1I1deg( (olltpllls omiddote 4 D 1middot1middot IS ~ ~() ~o middot11 iO 1ll)(1 71 l1Ilt1hi(h hac bern cxpos(c1 for 30 milllltps in indC In PISill slIi))lIlIdegeltl FIOIo(I](( flasks atotPIlI peraturES frolll i() tl) lOO Co Ht iiilllltiTalso Otlwl dahl nre also given 1or radish ((gtlt1s of JcnYl1 IIlOitlllP (ollt(nis f(l)O hig-IIP) Il1I1JWIHshytl1l(soflHntillmiddot (10 12jC)oolld fOldilllloPllt 11llthodsofhCafillgo lIis conclusions 1I11icoh 11( paJficolllnly llOPOlothro 110( IS foil degs

111( IPiiIlIJ((gt I s ds I iIfliIlIlH 1i01 Wllilll Lo lX]lIlp(1 10 lriJ1r h1ll1)(IrshyOtm ( iH innl1llr PIOOPdeg1i Ollnl 10 llil iJlillr1 lItlI 00lllllIt o IIll p(ds rt til(timp of 11fatilll0

AI fPIIIJHIrtlllls hlllt PllClllJh [II 1)( illjl11i Illp IinlJililo of nldil) IP(ls 01 n ginlI il1itial 0r1(1 (0111 d(I(ls(s rs lit 11111111111111( 10 wllil-It llic) nlP0nrhjl(Ipl is 1 ilcl

111( fWI1(I11 10jIIIWo0 o Ioil-Ipo Jlml( NPlllHl Yillllldeg nml (Isl11 l)olo(il1gIadish seeds lXPIlS(t til hiJh 111111)(111(111( i1 PIOY -illlillIo

bull

bull

bull

TEC~LCAL BULLETIN U S DEPT OF AGRICULTURE

Nagn i (65) exposed air-dried and desiccated grn ins of rice for 2 hoUls at 97deg-)SO C He found that the germinative power of the bull grain especially if desiccated was only slightly affected

Jones (39) exposed Colusa ami Caloro rice seed on saturated paper toweling in pttri dishes for 1 2 and 3 hours respectively at constant temperatures of 50deg 544deg Rnd (Hi7deg C Exposure for 1 to 2 hours at liOdeg and 544deg had no appreciable effect on ennination capacity but exposure at (j(L7deg for 1 hoUlmiddot materially reduced the percentage germination of both yar~eties and exposure for 3 hours entirely deshystroyecl the power of germination

In another series of expCgtliments Tones exposed air-dlmiddotjed seed of the same hvo nUieties in ((gtUl (II pehi dishes for 1 hom at 50deg 54-4deg (Q0 (i5n 0 70 0 bull 7(i70 bull H7S o bull n(i 0 and 100deg C Treatment at 70deg or Huckr apparently did not t(gtlt1nce the gennination of either variety The 7fi7deg treatment slightly reduced th( germination ctshypacity of the (t1oto yariety n H7S0 treatment greatly reduced the germination cn ptlti tieR of bol-h n1lipti0 tlHlt of the Cnloro to a gr(nter pxtent than that of thp Colma Treatl1l(llts nt f)(U deg and IO()O for I hour ki]ecl a11 sppd of both ytri(ties JOllPS statc(l that these experishymcnts show (-]wt air-dli(( s((d ill stand n I11l1ch higher tel11]gtC]aturc than wet seed and its germination will not b( afJect(d

Further intcl]gtretn[ion or thp data 111lt1 olserqtions of Da Fano Nagai and Jones is Ilot attempted because pteh failld to describe

C1Cilrly and (ollJpl(t(ly tlH pxp(gtrillltntal (oIHlitiol1s employCc1 In Da Fanos (xp(rinllnts the Imiddotice lost 1l10isttll( (Juring heat trrahn(gtnt III Tones eXl)(Iil11Cnts the moist ri(p prolJa hly ( id not lose an appreshy bull ciable al1l0unt On t11( nth(l ha n(l Jones d ill not gie the moisture contents of his loh of Ii(p pilllcIwiorp 01 aftcr tr(~ltnl(nt

Smith et al (71) in thlir siwl of Ihe (f1cet of dat(gt of httlTest on yield and milling quality of Ii(( ~(gtI( tlw first to remark on thp cflect of germination of tht artifi(ial tlrying of riel in nn (xp(gtIiJllrnlal and in a comm(lcial driPI UP Ill I ina Iion I-esl-s wcrp mt(lp on sa III pl(s of Bltle Hosp 1i(( (iJi(d in Ill( lahorlllOIY nlldN normal lttil (onditions nl1c1 in the (xp(rinH-nhll dri(r at DcIyltl IIL with thc nil at +U3deg 4-SDo 5Lmiddot~o nn(J (iOO C Heinlt of silllilnr Ugts ma(( on l111pl(gts of Enrly ProlifiC ForhllJa allcl Blu( Hop Iic( lt1Ii(d ill th( (xplgtriJ1Jpntal drier at XOI11( Tlx ga( 110inlt1i(alioll of injury le~LJltillg flonl rtltishyfieial dlyil1 nt the t(llJpelatlll(s u((l Additional lefits made in a greenhollse on SOIll( 01 tll( HampleH of riel ~a( 110 clpnl eidence of any difr(lcneC in th( s(((llillps hom Hll sHmpl(s dri((l at dill(IPllt t(lilpemtUJps Sal1lplps (1( ohlnin(d I10III a 101- of sP(d Iice c1liEc1 with a comJ1wJcia 1 dli(l wil11 the ail at apploximatcly middotIBno ~tncl no indicatioJl wm f(uJl(l of injlll) to gelmillalioll lefiulting flOIlI the dlying opeJation

SOI(JlIOIl d al (77) (11i(gt(1 Sl(ks cOJltaining approximafrly a barrel ench of lOIl~dl Ii(( in a tllllnplI)IH sack (hitI al ail tpl1Ilwratul(s of 461deg517deg (H)G 7lAmiddoto nnd ni1~3deg C Ilsppdiply tmiddoto dfI-(Imine the

efreet of the drying nil f(llljlPIahll( and th( initial 1ll0ishne (Cllltent of the grain 011 tb( Illilling C(1Itlity and the gClmination Sacks of lic(~ 01 21-perccllt of 2(J- 10 21-prreeni alld of 17-])(I(enl moiHtnle bull cont(nt welc dlirc1 Ht (ach tPlllpPIntllre (KCCpt- the last was not dried at 033deg Dlyillg t-imes CIP longrl at the ]0(1 telllp(latUles The temperature of the nirill the riec durillg drying alld the moisture

5

EFFECTS OF HFAT TREATMENT ON THE VIABILITY OF RICE

content of the rice on completion of drying were generally lOYeI in the center or the sack tlttlll at the top and boltom Inlet) injun to germination capacity occurred it was greater In the top aml bottom layers than in the center of the sack Too high an air temp(~latllle lul(l a detrimelltitl effect on both the germination and the milling quaJity of rice A temperature of 656 0 had no detrimental effect on germination for rice with 1i-H percent of l110istl1le These workers lIdvisecl that the nil tlmperature hoe(I hon1c1 not (gtx(ppd 5170

to 3+10 for ri(l with ~-11llr(pnt or ]))oi8tuI( The telllplraturl or the rice yjth pither moisture content Wit (onsi(10r1bl 10(1 thnn the ellYshying air tpl11jlel1tllle oyiJ1g to the cooling etlpct of PYapolntion

bull

~[cXpnl (8) in HHmiddotJ 1H3 and tnmiddotHi (ondllde(l 11 sPlie of sturlies on the lrtifkial dryillg of combined II(e to obtnin information on the relation of su(h fudols lS tinll~ dried ail tlmpemtllle reltti(~ hushymiditv and cniJl time to millillg llsults In(l elmiddotminatioll Riee yarieii~s (Zelliih ]allllos( Jap-trpl FIJ1tulla Xira nnd PI(11J(le) Wle halTPtPlI at 1 moistlll( coMlnt of W-H pplc(nt alld stoled and t0111 p(lNI (j to l~ homs in balTll pliOl to d lyi ng TWthe-pOllnd sa11lplps of each telll]lPlpd alilty W(le dlied ill pqJPIill1ll1tal lt11IPI5 Olle two tll(P all(l onl(till1PS fOlll dni]]g (1( uspd to leduce the moi-t11ll content- of tllP riel floll1 field ((indilioll to Imiddot~ pelCpnt rile telll ppli I1g plriod betY((11 slH(lpdi ng dIyi ngs Y Oenllt1ly 24 houls Dlyillg tpm ppla t111P ra ngl(l in i lIttlYals of ii)O C from riHJ to -T)O hut not all riel llietips (lP dliP(1 Ht (H(ll tempplature Extremes ill total (1nill timps Iallge(l 110111 li lllillU(I nt ~TKO to 2~() minutes at Tiideg Total dnill tlllHgt llsuall d(cmiddotlpapc1 as the l1U111-b(I of dl~i ngs as i11(I(14((1 11 i m pr)]ta nl (middot(mllusion of tlip stud ies ns fllal lllllinatioll is ledUl0rl ylHlllice i (11jeltl at nil t-Plll])pratllles alloY( j_k~lo -OllW of the data jllcli(atrd thM tllllP llliu-ht he nllirtal (lil1el(11(es in Il4ist1llCp to 11(( 11(1 t1wt af tIl( hig-hpmiddot t(11lpelatllres intelmittlnt drying might hE ipss destlllctin of WlI11illation (apacity tltnn (0l1tillI1011 (bTin

_ldIPcl HnrlKIalI(l ()) lt111(1 1](111P] (f)) dliprl llllpllS 011( glnin thide of (dOlO pnith Bhllh(ll111(t[agnolin ami Htxolo at 11Tlshyp(]atule f]om l~~O to HlI e ( _ los in gPllllinntioll llsually ocshy(I 11 ]r (1 at tp11lpPIattl1PS ahot -ltF C amI fa~t ltrS of drying diel not appel] to lp(ll1(( geI11linatioll

La te] Idlpltl 11](1 K lil 11](1 (n made n twl to ohtai 11 C0111shypnlatin milli1g 11lt1 Opl11linatioll lPclllts on tl1(a11l(lot of 1i(1 c1]i((l si1l111Itnmollsh- ill nnJ i(iPlltic11 Bl]ico (hitI with nil ltInillg (cl11c1ishytio) Iw1d (oilstallt CX(Pllt drying ail PllIjlllntlllmiddotl Ti]( iet was pxpold fol I) ll1illlltp to all aYlntgl ail tlllll)lrnt1](~ oi middotHLl 01 iilJdeg C am] to an ail (JJllllli of Ibol -)(11) (llhil fpCt ]gtll 1I1illl1l( 1)(1 htulPl Additionn (llying Wl( olllptillHS llP((SSH1Y DliNl samples 1(1e SelSrllll11 for m da- hPlOl1 11lillil1 ips nIHl (ill 1lity hefore Plll1ination Ipst Xo si~1Iili(tl1lt dit1PIPl1(C as llotpd in th( 111illin Clllalitlls of tlip 11(( (llit1t Ht ttt two 1 (111]gt(11111 I(S -suall) an jll~ e)Pt1Fl in gll1ll il1ll i01 llltl]t(( l n t till higlllI t (11)1)(1 t 11p

bull In thl l)](gt((gt(ling sturlils (-mith d Ii -Ol(llS()1 rf a JrcSenL nml

AI(h((] l11(1 K[1Il(l) tllP riel waS lXP0-ll to clit1pl(llt tl11lpllnhllCs of tlltifiCinlly htntpd ail ~lth()lUh tlw llll1ttd ail llll hl maintained at a (()1Istanl te1llpl[lflll( 101 dplillitp p(Iioltl 110 lt1](lt1 11( antilable ns to the maximulll tellllwratlll( 1middotlaclwd by tlw grains of lice 01 as to

BULLE~IN DEPTo OF AGRICULTURE

the timethey are mailltained Itt this temperatureo The (lilta supplied by these workers do 110t define the tolernlw( of rice to tl given temperashyture in itselfo NeTertheless they do IHnllit lin (stllllntioll of the eJiect on germination capacity when riel is eXl-ecl to a gien tem perature during drying in present-clay commercial dehydration equipment

In contrast to the preceding illvestigatiollsin which 111(1eis doubt about the tenlperutures reached by the rice Adair and Cralley (1) presoaked rice seld for 12 hours and then illllllClS(c it ill hot water ntmiddot 50deg-52deg Co for 15 lIIinuiCso This trCatment efrectiely cOlltTo1J(d wll1te tip in 19 vtlrietips oJ rice and although not intli(ah~1 apparently did not haY( an addegCo( efrect on nIP gcrminatioll capacity of thl se((l

Tisdale (83) 101111(1 that oaking- LOllisiana TTonc1l1rtls rice in yatetO at 54deg Co for Ji) minlltcs after lHolsoHkillg it 101 IG hOllri killed the internal llIn~)i and (tUll( llparest to ~oiying as rood grrlllinntioll as thl untreated eontTolso T[OPoltgtl in lill(t ionlly tel~T PXIWlillwIlt with presoaked ricl tilt permillation was ~Iiphlly IOWPl tll1I thatmiddot of Ih(lunholtgtahd (OOlltT01-o

Tisdalltgt (litlllot ~ri( lilp ini(ialllloiillll (olltplli of []l( Iiel bllt itmiddot is inttlcsting tOIlO( ill Olll of hi~ (Xl)(lilloJ(IlI 1hal IIII till lil1l( alld temperlltllrt of tIlt llOt-wallloildeglail1wnt- nlllHillPcl (()n~tant the gllomishynation capacity wus IOIll tIll IOIl)2degll til( Illloiod of Ih( plpsoak This observation slIpptsl- that tllP ltlillpIPIl(o( ill til( g(IOlllinntioll eapneitirs of the difl(J(nt batdlls of ITPatptl ((lt1 plolJilbly rlllet dilllrellc(s in the degree of lPsituwl to ll(at n- 10platmiddotP(] to ltl i I]Plop11 ((S in pl(soaking til1lPs and 1lI0i~tllloP (011 1lt11 f ul thp hlllp of (XPOSIIIPo

As tJw PlpcOpclin ldeg(-i(o il1di[atp- tIl( lil(lnll1lop COJl(PIOnp(l ith thl efrect of tlmpllontllloP Oil degpll1lil1atill ability of Ii(p (ol1-isls 101 111( most part 01 a IWiprogPlH()lIS (olIPdioll of stnelieo Thl mOIl systllllshyatie stnelies hal hlPIl (OllcPlllecl with (OOITPintillt limil((l lilo-lt1rril1 t(mpelntnrp air-dlying (illll and S(prl-IIIOitllloP 1llationships it~ milling qllnlit-y and germinatiol1 (Hll1l(ifyo EYPll (iI(s( kaye llIU(ll to be desired bceHIIgtp thpy were Jillli(pd ill s(ope and the temperatu)cs of the lots of s~~((l ))(il1)1 (l1i(lt1 (IP 1I0t (lctp1I11ill((1 Xo olle has )cport(d investigations ill which lo[~ of loi(( of eli fllI(llt ll)()isftl1p (ollt(nts hut ofthE salll( Yillip nnd FIolll tlIP Hlllp lipId plnl linn iJPPIl (xposlltl to clillclpnt PIllIHloal11 ldegr- fcwditlplpnt pllio(b of ti))I(

Yaggolwl (87) is J))obahly IlIl fildeg til Ian -Illdild 0 0 0 in s(ri(s the llsistalHP of till ~allll killd 01 sP((]s (middotolllaillill lPfinit( 1n(l kllOWIl quantiti(s of watIOat til( lill1( of hpa(illo TIp llas tnblllni((] gplllIishynation dntaol 1adi-iI sp(ltI- hayillU illitial 1)(IO(Opllt IllOis(1I1deg( (olltpllls omiddote 4 D 1middot1middot IS ~ ~() ~o middot11 iO 1ll)(1 71 l1Ilt1hi(h hac bern cxpos(c1 for 30 milllltps in indC In PISill slIi))lIlIdegeltl FIOIo(I](( flasks atotPIlI peraturES frolll i() tl) lOO Co Ht iiilllltiTalso Otlwl dahl nre also given 1or radish ((gtlt1s of JcnYl1 IIlOitlllP (ollt(nis f(l)O hig-IIP) Il1I1JWIHshytl1l(soflHntillmiddot (10 12jC)oolld fOldilllloPllt 11llthodsofhCafillgo lIis conclusions 1I11icoh 11( paJficolllnly llOPOlothro 110( IS foil degs

111( IPiiIlIJ((gt I s ds I iIfliIlIlH 1i01 Wllilll Lo lX]lIlp(1 10 lriJ1r h1ll1)(IrshyOtm ( iH innl1llr PIOOPdeg1i Ollnl 10 llil iJlillr1 lItlI 00lllllIt o IIll p(ds rt til(timp of 11fatilll0

AI fPIIIJHIrtlllls hlllt PllClllJh [II 1)( illjl11i Illp IinlJililo of nldil) IP(ls 01 n ginlI il1itial 0r1(1 (0111 d(I(ls(s rs lit 11111111111111( 10 wllil-It llic) nlP0nrhjl(Ipl is 1 ilcl

111( fWI1(I11 10jIIIWo0 o Ioil-Ipo Jlml( NPlllHl Yillllldeg nml (Isl11 l)olo(il1gIadish seeds lXPIlS(t til hiJh 111111)(111(111( i1 PIOY -illlillIo

bull

bull

bull

5

EFFECTS OF HFAT TREATMENT ON THE VIABILITY OF RICE

content of the rice on completion of drying were generally lOYeI in the center or the sack tlttlll at the top and boltom Inlet) injun to germination capacity occurred it was greater In the top aml bottom layers than in the center of the sack Too high an air temp(~latllle lul(l a detrimelltitl effect on both the germination and the milling quaJity of rice A temperature of 656 0 had no detrimental effect on germination for rice with 1i-H percent of l110istl1le These workers lIdvisecl that the nil tlmperature hoe(I hon1c1 not (gtx(ppd 5170

to 3+10 for ri(l with ~-11llr(pnt or ]))oi8tuI( The telllplraturl or the rice yjth pither moisture content Wit (onsi(10r1bl 10(1 thnn the ellYshying air tpl11jlel1tllle oyiJ1g to the cooling etlpct of PYapolntion

bull

~[cXpnl (8) in HHmiddotJ 1H3 and tnmiddotHi (ondllde(l 11 sPlie of sturlies on the lrtifkial dryillg of combined II(e to obtnin information on the relation of su(h fudols lS tinll~ dried ail tlmpemtllle reltti(~ hushymiditv and cniJl time to millillg llsults In(l elmiddotminatioll Riee yarieii~s (Zelliih ]allllos( Jap-trpl FIJ1tulla Xira nnd PI(11J(le) Wle halTPtPlI at 1 moistlll( coMlnt of W-H pplc(nt alld stoled and t0111 p(lNI (j to l~ homs in balTll pliOl to d lyi ng TWthe-pOllnd sa11lplps of each telll]lPlpd alilty W(le dlied ill pqJPIill1ll1tal lt11IPI5 Olle two tll(P all(l onl(till1PS fOlll dni]]g (1( uspd to leduce the moi-t11ll content- of tllP riel floll1 field ((indilioll to Imiddot~ pelCpnt rile telll ppli I1g plriod betY((11 slH(lpdi ng dIyi ngs Y Oenllt1ly 24 houls Dlyillg tpm ppla t111P ra ngl(l in i lIttlYals of ii)O C from riHJ to -T)O hut not all riel llietips (lP dliP(1 Ht (H(ll tempplature Extremes ill total (1nill timps Iallge(l 110111 li lllillU(I nt ~TKO to 2~() minutes at Tiideg Total dnill tlllHgt llsuall d(cmiddotlpapc1 as the l1U111-b(I of dl~i ngs as i11(I(14((1 11 i m pr)]ta nl (middot(mllusion of tlip stud ies ns fllal lllllinatioll is ledUl0rl ylHlllice i (11jeltl at nil t-Plll])pratllles alloY( j_k~lo -OllW of the data jllcli(atrd thM tllllP llliu-ht he nllirtal (lil1el(11(es in Il4ist1llCp to 11(( 11(1 t1wt af tIl( hig-hpmiddot t(11lpelatllres intelmittlnt drying might hE ipss destlllctin of WlI11illation (apacity tltnn (0l1tillI1011 (bTin

_ldIPcl HnrlKIalI(l ()) lt111(1 1](111P] (f)) dliprl llllpllS 011( glnin thide of (dOlO pnith Bhllh(ll111(t[agnolin ami Htxolo at 11Tlshyp(]atule f]om l~~O to HlI e ( _ los in gPllllinntioll llsually ocshy(I 11 ]r (1 at tp11lpPIattl1PS ahot -ltF C amI fa~t ltrS of drying diel not appel] to lp(ll1(( geI11linatioll

La te] Idlpltl 11](1 K lil 11](1 (n made n twl to ohtai 11 C0111shypnlatin milli1g 11lt1 Opl11linatioll lPclllts on tl1(a11l(lot of 1i(1 c1]i((l si1l111Itnmollsh- ill nnJ i(iPlltic11 Bl]ico (hitI with nil ltInillg (cl11c1ishytio) Iw1d (oilstallt CX(Pllt drying ail PllIjlllntlllmiddotl Ti]( iet was pxpold fol I) ll1illlltp to all aYlntgl ail tlllll)lrnt1](~ oi middotHLl 01 iilJdeg C am] to an ail (JJllllli of Ibol -)(11) (llhil fpCt ]gtll 1I1illl1l( 1)(1 htulPl Additionn (llying Wl( olllptillHS llP((SSH1Y DliNl samples 1(1e SelSrllll11 for m da- hPlOl1 11lillil1 ips nIHl (ill 1lity hefore Plll1ination Ipst Xo si~1Iili(tl1lt dit1PIPl1(C as llotpd in th( 111illin Clllalitlls of tlip 11(( (llit1t Ht ttt two 1 (111]gt(11111 I(S -suall) an jll~ e)Pt1Fl in gll1ll il1ll i01 llltl]t(( l n t till higlllI t (11)1)(1 t 11p

bull In thl l)](gt((gt(ling sturlils (-mith d Ii -Ol(llS()1 rf a JrcSenL nml

AI(h((] l11(1 K[1Il(l) tllP riel waS lXP0-ll to clit1pl(llt tl11lpllnhllCs of tlltifiCinlly htntpd ail ~lth()lUh tlw llll1ttd ail llll hl maintained at a (()1Istanl te1llpl[lflll( 101 dplillitp p(Iioltl 110 lt1](lt1 11( antilable ns to the maximulll tellllwratlll( 1middotlaclwd by tlw grains of lice 01 as to

BULLE~IN DEPTo OF AGRICULTURE

the timethey are mailltained Itt this temperatureo The (lilta supplied by these workers do 110t define the tolernlw( of rice to tl given temperashyture in itselfo NeTertheless they do IHnllit lin (stllllntioll of the eJiect on germination capacity when riel is eXl-ecl to a gien tem perature during drying in present-clay commercial dehydration equipment

In contrast to the preceding illvestigatiollsin which 111(1eis doubt about the tenlperutures reached by the rice Adair and Cralley (1) presoaked rice seld for 12 hours and then illllllClS(c it ill hot water ntmiddot 50deg-52deg Co for 15 lIIinuiCso This trCatment efrectiely cOlltTo1J(d wll1te tip in 19 vtlrietips oJ rice and although not intli(ah~1 apparently did not haY( an addegCo( efrect on nIP gcrminatioll capacity of thl se((l

Tisdale (83) 101111(1 that oaking- LOllisiana TTonc1l1rtls rice in yatetO at 54deg Co for Ji) minlltcs after lHolsoHkillg it 101 IG hOllri killed the internal llIn~)i and (tUll( llparest to ~oiying as rood grrlllinntioll as thl untreated eontTolso T[OPoltgtl in lill(t ionlly tel~T PXIWlillwIlt with presoaked ricl tilt permillation was ~Iiphlly IOWPl tll1I thatmiddot of Ih(lunholtgtahd (OOlltT01-o

Tisdalltgt (litlllot ~ri( lilp ini(ialllloiillll (olltplli of []l( Iiel bllt itmiddot is inttlcsting tOIlO( ill Olll of hi~ (Xl)(lilloJ(IlI 1hal IIII till lil1l( alld temperlltllrt of tIlt llOt-wallloildeglail1wnt- nlllHillPcl (()n~tant the gllomishynation capacity wus IOIll tIll IOIl)2degll til( Illloiod of Ih( plpsoak This observation slIpptsl- that tllP ltlillpIPIl(o( ill til( g(IOlllinntioll eapneitirs of the difl(J(nt batdlls of ITPatptl ((lt1 plolJilbly rlllet dilllrellc(s in the degree of lPsituwl to ll(at n- 10platmiddotP(] to ltl i I]Plop11 ((S in pl(soaking til1lPs and 1lI0i~tllloP (011 1lt11 f ul thp hlllp of (XPOSIIIPo

As tJw PlpcOpclin ldeg(-i(o il1di[atp- tIl( lil(lnll1lop COJl(PIOnp(l ith thl efrect of tlmpllontllloP Oil degpll1lil1atill ability of Ii(p (ol1-isls 101 111( most part 01 a IWiprogPlH()lIS (olIPdioll of stnelieo Thl mOIl systllllshyatie stnelies hal hlPIl (OllcPlllecl with (OOITPintillt limil((l lilo-lt1rril1 t(mpelntnrp air-dlying (illll and S(prl-IIIOitllloP 1llationships it~ milling qllnlit-y and germinatiol1 (Hll1l(ifyo EYPll (iI(s( kaye llIU(ll to be desired bceHIIgtp thpy were Jillli(pd ill s(ope and the temperatu)cs of the lots of s~~((l ))(il1)1 (l1i(lt1 (IP 1I0t (lctp1I11ill((1 Xo olle has )cport(d investigations ill which lo[~ of loi(( of eli fllI(llt ll)()isftl1p (ollt(nts hut ofthE salll( Yillip nnd FIolll tlIP Hlllp lipId plnl linn iJPPIl (xposlltl to clillclpnt PIllIHloal11 ldegr- fcwditlplpnt pllio(b of ti))I(

Yaggolwl (87) is J))obahly IlIl fildeg til Ian -Illdild 0 0 0 in s(ri(s the llsistalHP of till ~allll killd 01 sP((]s (middotolllaillill lPfinit( 1n(l kllOWIl quantiti(s of watIOat til( lill1( of hpa(illo TIp llas tnblllni((] gplllIishynation dntaol 1adi-iI sp(ltI- hayillU illitial 1)(IO(Opllt IllOis(1I1deg( (olltpllls omiddote 4 D 1middot1middot IS ~ ~() ~o middot11 iO 1ll)(1 71 l1Ilt1hi(h hac bern cxpos(c1 for 30 milllltps in indC In PISill slIi))lIlIdegeltl FIOIo(I](( flasks atotPIlI peraturES frolll i() tl) lOO Co Ht iiilllltiTalso Otlwl dahl nre also given 1or radish ((gtlt1s of JcnYl1 IIlOitlllP (ollt(nis f(l)O hig-IIP) Il1I1JWIHshytl1l(soflHntillmiddot (10 12jC)oolld fOldilllloPllt 11llthodsofhCafillgo lIis conclusions 1I11icoh 11( paJficolllnly llOPOlothro 110( IS foil degs

111( IPiiIlIJ((gt I s ds I iIfliIlIlH 1i01 Wllilll Lo lX]lIlp(1 10 lriJ1r h1ll1)(IrshyOtm ( iH innl1llr PIOOPdeg1i Ollnl 10 llil iJlillr1 lItlI 00lllllIt o IIll p(ds rt til(timp of 11fatilll0

AI fPIIIJHIrtlllls hlllt PllClllJh [II 1)( illjl11i Illp IinlJililo of nldil) IP(ls 01 n ginlI il1itial 0r1(1 (0111 d(I(ls(s rs lit 11111111111111( 10 wllil-It llic) nlP0nrhjl(Ipl is 1 ilcl

111( fWI1(I11 10jIIIWo0 o Ioil-Ipo Jlml( NPlllHl Yillllldeg nml (Isl11 l)olo(il1gIadish seeds lXPIlS(t til hiJh 111111)(111(111( i1 PIOY -illlillIo

bull

bull

bull

BULLE~IN DEPTo OF AGRICULTURE

the timethey are mailltained Itt this temperatureo The (lilta supplied by these workers do 110t define the tolernlw( of rice to tl given temperashyture in itselfo NeTertheless they do IHnllit lin (stllllntioll of the eJiect on germination capacity when riel is eXl-ecl to a gien tem perature during drying in present-clay commercial dehydration equipment

In contrast to the preceding illvestigatiollsin which 111(1eis doubt about the tenlperutures reached by the rice Adair and Cralley (1) presoaked rice seld for 12 hours and then illllllClS(c it ill hot water ntmiddot 50deg-52deg Co for 15 lIIinuiCso This trCatment efrectiely cOlltTo1J(d wll1te tip in 19 vtlrietips oJ rice and although not intli(ah~1 apparently did not haY( an addegCo( efrect on nIP gcrminatioll capacity of thl se((l

Tisdale (83) 101111(1 that oaking- LOllisiana TTonc1l1rtls rice in yatetO at 54deg Co for Ji) minlltcs after lHolsoHkillg it 101 IG hOllri killed the internal llIn~)i and (tUll( llparest to ~oiying as rood grrlllinntioll as thl untreated eontTolso T[OPoltgtl in lill(t ionlly tel~T PXIWlillwIlt with presoaked ricl tilt permillation was ~Iiphlly IOWPl tll1I thatmiddot of Ih(lunholtgtahd (OOlltT01-o

Tisdalltgt (litlllot ~ri( lilp ini(ialllloiillll (olltplli of []l( Iiel bllt itmiddot is inttlcsting tOIlO( ill Olll of hi~ (Xl)(lilloJ(IlI 1hal IIII till lil1l( alld temperlltllrt of tIlt llOt-wallloildeglail1wnt- nlllHillPcl (()n~tant the gllomishynation capacity wus IOIll tIll IOIl)2degll til( Illloiod of Ih( plpsoak This observation slIpptsl- that tllP ltlillpIPIl(o( ill til( g(IOlllinntioll eapneitirs of the difl(J(nt batdlls of ITPatptl ((lt1 plolJilbly rlllet dilllrellc(s in the degree of lPsituwl to ll(at n- 10platmiddotP(] to ltl i I]Plop11 ((S in pl(soaking til1lPs and 1lI0i~tllloP (011 1lt11 f ul thp hlllp of (XPOSIIIPo

As tJw PlpcOpclin ldeg(-i(o il1di[atp- tIl( lil(lnll1lop COJl(PIOnp(l ith thl efrect of tlmpllontllloP Oil degpll1lil1atill ability of Ii(p (ol1-isls 101 111( most part 01 a IWiprogPlH()lIS (olIPdioll of stnelieo Thl mOIl systllllshyatie stnelies hal hlPIl (OllcPlllecl with (OOITPintillt limil((l lilo-lt1rril1 t(mpelntnrp air-dlying (illll and S(prl-IIIOitllloP 1llationships it~ milling qllnlit-y and germinatiol1 (Hll1l(ifyo EYPll (iI(s( kaye llIU(ll to be desired bceHIIgtp thpy were Jillli(pd ill s(ope and the temperatu)cs of the lots of s~~((l ))(il1)1 (l1i(lt1 (IP 1I0t (lctp1I11ill((1 Xo olle has )cport(d investigations ill which lo[~ of loi(( of eli fllI(llt ll)()isftl1p (ollt(nts hut ofthE salll( Yillip nnd FIolll tlIP Hlllp lipId plnl linn iJPPIl (xposlltl to clillclpnt PIllIHloal11 ldegr- fcwditlplpnt pllio(b of ti))I(

Yaggolwl (87) is J))obahly IlIl fildeg til Ian -Illdild 0 0 0 in s(ri(s the llsistalHP of till ~allll killd 01 sP((]s (middotolllaillill lPfinit( 1n(l kllOWIl quantiti(s of watIOat til( lill1( of hpa(illo TIp llas tnblllni((] gplllIishynation dntaol 1adi-iI sp(ltI- hayillU illitial 1)(IO(Opllt IllOis(1I1deg( (olltpllls omiddote 4 D 1middot1middot IS ~ ~() ~o middot11 iO 1ll)(1 71 l1Ilt1hi(h hac bern cxpos(c1 for 30 milllltps in indC In PISill slIi))lIlIdegeltl FIOIo(I](( flasks atotPIlI peraturES frolll i() tl) lOO Co Ht iiilllltiTalso Otlwl dahl nre also given 1or radish ((gtlt1s of JcnYl1 IIlOitlllP (ollt(nis f(l)O hig-IIP) Il1I1JWIHshytl1l(soflHntillmiddot (10 12jC)oolld fOldilllloPllt 11llthodsofhCafillgo lIis conclusions 1I11icoh 11( paJficolllnly llOPOlothro 110( IS foil degs

111( IPiiIlIJ((gt I s ds I iIfliIlIlH 1i01 Wllilll Lo lX]lIlp(1 10 lriJ1r h1ll1)(IrshyOtm ( iH innl1llr PIOOPdeg1i Ollnl 10 llil iJlillr1 lItlI 00lllllIt o IIll p(ds rt til(timp of 11fatilll0

AI fPIIIJHIrtlllls hlllt PllClllJh [II 1)( illjl11i Illp IinlJililo of nldil) IP(ls 01 n ginlI il1itial 0r1(1 (0111 d(I(ls(s rs lit 11111111111111( 10 wllil-It llic) nlP0nrhjl(Ipl is 1 ilcl

111( fWI1(I11 10jIIIWo0 o Ioil-Ipo Jlml( NPlllHl Yillllldeg nml (Isl11 l)olo(il1gIadish seeds lXPIlS(t til hiJh 111111)(111(111( i1 PIOY -illlillIo

bull

bull

bull

7 EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

Radish seeds injnred by high water (ontpnt and high tpll1velntnrps Ilrt retarded in their gerIU inution Thl$ retanlltioll )elunH~ mon limrkLll s tIll temperashyture or water content or both is increasl(1

Radish Seeds of the same initial water content show r(Ir gr(at ltlifferpnees ill resistunce when heatNl at the same temp(latll[C hulbY diffp[Cnt Ill(thod~ nal1lel~ ill wuter in dry orkerl flnsks or in oD(gt]1 lIi]](gt in OY(I11

The nmount of wate aJsor)(d or ginll off hy Indi~h fll1f Iurilll trelttmellt i~ the chief fnctor dehlInining the r(ilIIII(( ut the Plc] ]HltP(] at the same telilperatnre Il~ the ditt(J(nt nlttho(]

Wh(tn radifh gtl(( nrl jl(lte(] dil((ll ill Ialpr rh( lInPI I Irnllllal loss of dl~ nhiitlnee lhis los bel()Jllr Irllt(1 H llll tell)lJ(~rn tn IP of till it ttr is imr(asNl

Hutchinsons expeliJllPlfs (JJ) ex(eut(d 2R years later with wheat of tlle Square lIeacls )Jatel Yariet) possess refinements OYer those of IYaggonel Samples of yhent yith moisture contents 1llnging from iJ2 to 35 percent were heated for inlenals of 122middot1 3G 48 GO anc1120 minutes at templIntllres Lnnging from 41 0 to IHlO C The standard lleating period for the nHHe fxtpllsiw work as (jO minutes In tlentshyll)(nt li5-mm c1i(lmetcl tulles of glnss 01 brass were packed one-third tull closed nmI SUblllllgt1 in a bath of the (Ipsirtcl PJ11pernture for a speeilipd ppliocl of time Glll1linatioll tesiSHIP normally made on the tlelt(cl sepd aftp) it lta(111ac1 n 2~-ltolll rest ]gt(liod Some of the llighlight- of lTlItchillSOllS filldill~s alp

1 Excp-in itllt-i 11 IIIIPlit i plwrllti (Ii(lt1 b ((f) ltIva tit in follir of til( gllIilf

bull (II) tho lot kilipl IIOIYiug nllyilll (]pIHY ill glIllIillJlioll I (0111]11(lt1 witlt the contlol Thi glI1lIinltiol1 Ing- whidl I Ylt l)IlIlJt 1)( plilllillntp(] IlIllHt be COllshysicillr( 1I t ig-n of c1JIllIg(

~ 111( lll[ two tnll or datlln dill to IIPa Ii II (u) 111( til In i ltlIIall bill (]pfinil( illtllnilll nlpi(lIy with tll1l]1prlIIlI Iud II) IiPI IiiI lag- i gleat und (Ill Iig-htlt il1(nJ~l in Ih tlIII]1Iltllll (()lI]1llIPly d(ITO gpllIlillatioll ca I))(i IS bull

1H1l thp tpl1ll)(lattup at 11 ich thlp fin) tHgPS 0((11111lt1 were plotted by Hutchinson 10) tIl( l11oistlllp ((Jlltellt of (Heh of fhe 32- to 1ii-per(lnt llloisture sanlplrs) 11l obtajned tWO ClllTes

Thl UPIW (Urn lit (1111 tillll intpII11 fhOn thl 1111l1l11ll111 1l1Il]ll)nlnlli nt Inlll llloiIln (011 ((n I fol whilll rh llmillntinll (n]la(il~ nttll ITnllIllut i nil whil1 tit 10(1 (lIITP how tit t(IIl]lIttl1ll~ ai lti(11 rill Ii 1( tage of dl1l1ngp (WIIlI i l 111( 111111 i t It fillill dlllY ill gtrIiJilllllioll nlfllOugh (lIl1illl(ioll (f]la(il I [wit j (1[((1 ilT(I(lL Fol Ill ginlI ]JIIiod or IlllI-lnl111111I1 Ih l1I 1gt(111((11 fill Iwo (IIITl ltll Ill I~alltd nil 1011( or IWnt lnlllaj

bull bull ~ 1 bullbull ill IIH 1I11Ig- of 11111 i1111( ((11111111 -) 10 lV I ltc lIP]ll nllil Il)wll lJuunishy

alip of 01 dJ ilIa (jIlP (ould hI dpIIfd ill Iltl fOlm III 1itl two (fllIl I i()n~ 11[1]1(1 I ( nil CllIlinltinn 0=1)0- log I -11s IOI III 1()(I i ( stnrt of (lallllg O=middotlO- 0middot4 1~ 1-middotSgtltO[J lII hlll 0 i) I Ill tpllIl)Llnl1ll in DC I i iltl timp of pxpoUIP ill TIlillllf( (OIIP((P(] to dlo fOI thr tillll ilkpli to IPIlch Uti (illll(gtrltlllP) 11 i~ flIP i IllOitlllP (Ollhill 01 Iltt IYhpnL Their (Ofjl11Iionl lll]I to tltt r111( lIIil1l1t( to ]J(j lIlilllllo- filHl ll( iWJl lWeHUip 11ll IJ11Y]loKlibll he or ntllJ( ill (Ollll(xinll with th (ollllitiOIl ill (Olllllwnial illTlI

bull t TTrat (gt(I(ld if dlfllldin action on t1H germillation capa(ity

of wh(gta( of 1 ginlI lI11i(lllP (011 t(gt11 f- on t 1(lafin1ly shot tempelshyatll JC rlllgl This In IIge fol (he GO ll illUfl hpat-tTPa hnent curves cxtend ill flolll -bllf of d lllllagp (0 II iJ gPII11 inn tion 1(1111 inecl abollt (11( Ram( in llHlgllitucl( (H) fo J~O) bill difT(l(d in its position on the fPllIpPlnhlle seale 101 wheat of pl(ll IlJOist 111( (ontNIL lTtIfchins611

8middot TECJ-lNICAL BULLr~TIN 1129 U S mpl OF AGRlCULlURE

referred to this nnlTO critical temperature range as being about 9deg C (Hutchinson etaZ 34)

Although the excellent researches of Vnggoner and of Hutchinson have not been concerned yith rice they haTe been cited for the followshying reasons (1) They illustrate the kind of research that needed to be undertaken with rice (2) thcy have selYed as patterns in planning the rice research described in this bulletin and (3) the~ haye resulted in the acclunulatioll of extensiw data on the pllects of hctt treatmcnt 011 the germination capacitic of radish and helt sped which arc likely to have mllch in (ommon with 010se l(clIJ11u1ttec1 fOl ricc in spite of the chemical structuml and physiological lt1ilYercnccsin the kinds of seeds and in spite of cliffcIenccs ill the experimental procedllres

EXPERIliENTAL lIATERIALS AND PROCEDURES

~ll tmiddothe riel LlsCc1 in the H)50 1J51 and lJi~ lXlwjilllCnts was glown in the vici1lity of Crowlpy Ln Ynrieti0s gmin types) (1ttes of harvest alld other information alp giwn in table 1

TBLllt l~Dat( on 1(lidil8 of rOllf1i jrr 18Nl in h((t~tJwdluJt (middotlllilll(nts Ifj)()-i

- - -q----~-- ~

----~-- - - --- --~- ---Dnlp comhilwel and loistII rC i Lot

pur and aripty ( rnill tyJ)P ]Hat ( r(ntl1lllt (onlltllt of dpsipnntion Iartfd ricp I (SRBLl 2

[90

H(I (iJmiddotmiddot2fi 12 IlpX(lr(L bull

[PriiIlIlL LOllP

~pp 2R 0(( 2

~ - ----shyPacllzi

- I_J

2middot1 3 31 BR2 In

Zenilh R(gtx()fo _ bull _ bull _ bullbull _

[pdiIlIlL_ LOllpbullbullbull _

0(1 - - -~ shyO(t lfi _________

21 21 9

Z2 H3

91

BhlPIH)llllL __ bull Do

Hpl 0[- 2) 12_

LOllg rio

1 (ltIilln

Hpt 7 -~ -- -

Ort 2 -__--------Or R

-~--------

2) 2 179 ID R

BBl HIli 34 B H23

19)

BIIIlJonllPi _ _ CNltllry )2 ____

Iollp -~ - - - ~

-shy do_______ (3) Nppt an -_

21 (j 11 2

BIlIO C2

~ ----~-

1 At tilllP til(gt lirt lt1l111plps WI talPH for Jral trpatlllllt lIgtltuallr 11(1 hOIlls Ir01l1 tilll of omili Ili liP 111 IJrllil

SmHIH11l Rpdollal H(Ilaleh Lalioratol 3C()llIiJill((i -ept 9 hlH t ()( tnlen Is sl H11 ((1 -(pL 11

To nSSUle ]gtloxinlity to a supply of frp111y (olllbinrd rOllgh rice (paddy) of known hi~toly 11pat-tlpntn1Pnt appnlHhlS wn~ spt up (tleh season in OIW of til( llllildinps of tllC niee J~xpllinlCnt Shtfion in ClOylty FSlIally it was possiblp to obtnill a ballpl 01 fo of liee ilom the hoppPI of II Iie( en lt wif It i n 1 (0 lltollrf of (om hi n i ll~ [ore attcntioll was ~inn hJ splpcting n lot of liel 01 the hi~llPstll1oistllre

bull

bull

bull content unillblt Illnn to (hooing it lot of it SlH(middotifi( raliclT (tlOSS

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 9

debris such as eticks strnw grasshoppers and weed seed was removed by hanel Ko meclHlnical cleaning of the rough rice was attenlpted in 1950 and IV1 but one lot was mechanically cleaned in IV52 As soon as a sufficient quantity of a given Jot of rice had been cleaned 100 to 150 heat-resistant glass test tubes 1G by 150 mm were tightly packed with rie-e by jarring the butts agaillst tIle pt1m of the hand These filled and stoppered test tubes were promptly snbjeeted to heat treatment

Yhile the tect tubps were being filled moisture determinations were bein made on 11e yell-mixed portions of tIle bulk lot omiddotf cleaned rice Their tlverae moistll1e content was recorded as that of the rice being tubed On cOlllpletioll of the dispPllsing the remainder of the rice was spretld in layers to air-dry It wa frequently 111ixP(l fwd (heeked for moisture (ontent Ea(h time tIll moisture content of the lot dropped about 2 pereent a number of test tubes were filled with this lice tllld heat-trented This procedure pelmittpd t1 serips of exshyperiments to be run with batches of rice of successively lower nntllrtll-llIoistUlp contents oriinntill rom the same combined lot

bull

Then the weather was ntrll and dry a 2-peLcent drop in moistnre (ontent sOlllPlillles (leclIlTed in 2 Oi B hours whereas during hmuicl wpathpr it miIIllw (kltwrl sPHral dnrs or nnlil tlwlP was a decrease in the 1elaJi~ humidity Vitll Ih(1 olmel (ol1(lil-iol1 it was sometimes necessflry to hoM a bateh of Iiee in a closed (ontainel until it (ould be treatpd Holding 1)(liolt1 Hre usually sholt 1 to 3 hours and very rarely ex(eec1ed 2+ houls lInl(~s the ri(( was dry t1mt is 14-pershycent m(ji~tu[( tcnhlll OJ lowll ~Joishllp eOl1t(llt omiddotf 0 percent and lower ere obtained by (llil1 Ii(( of llJ- to ll-]JPIlent moistme conshytent in (lesi((tl tor 0(1 (laquolei Hill (h lOli(i( am1or phosphorus pelitshyoxide The control snmplp IPPI(~llltnti-p of eneh loL was always airshydried

NATURE OF EXPERIMENTS

Two kinds oj eXl)tIillllllts WPIP llIH]pdnk(ll pnell Y(nl Tn OIH till tll1lltnLtlllP of 11Plring and till 11loistuIP eOllt(nt c)r the rough rice P10 thp 11ltljOJ Ytliables and the tillle (duldioll) of h(atlllpnt was Illld COllstant TlI Ihp OlhPI t lIP tclI1lern tlllP nIlcl li nl( of tleatnwnt were the major -u-iabhs alld the Illoisture coutent of the Iice -as held (oustant

bull

In theexpplilllents with (PIIlPPIaiUIP nnd moistlllP coutent as varishyables lmtchps of lollh riel flom thp ~an1P (ol1lhinp(11ot lnd- of clillelshyenr Jl1()i~tull (IIJlfllllS -ere epamhly dispPIlHe(l and 10 to 14 test tubls of (aell WPI( SlIIJIlIPI(d alld IIpa[-llpafp(( 101 ao ll1illlltpS atlel tlIP Ii(( 1(I(I1(d Ihe (Ill])(ratlllp 01 tll( balh A BO-millute heatin ]l(liolt1 was BplrtNI 101 1liOSt of tmiddoth( exp(llinllllf be(llIse it a pproalhpd Ilw (illle lollgh rice is expmpd 10 hih tClllpelnllllps ill eOIl1I11Pleial dli(ls ~(ff of 10 to 14 (pst fubes 01 lOllgh ri(c of the lII1P moisture (OlltPllt and flOIll the salllP initial batchof Iic( were eaeh hcatedat eli flprPllt jPlllpplatII J(S

111 lin expllilllllIS with t(1I11lPldlllP nlld finlP Hi nriahl(s basklis of IilINI stoPP(lIPlt tN tlllps cOlltaillillg Iil( 01 t hl sa III( moisture eOIlshytent alld 110111 tll( sHill( illitinl balt-h of Imiddotj(t (1( SlIbllllltd ill1 watmiddotpl oath at a gi-PII IPIIIgtPla( 1I11 flpl tll( (OIIllllls of t lIP Ipsf IIillS htHl

1129 U S DEPT OF AGRICULTURE

reached the temperilture of the bath 3 to 10 test tubes were withdrtwm every 10 minutcs for periods of 60 to 120 minutes This procedllre was repeated for each of 4 temperatures spaced at 50 intervals in 1950 and 1951 and for each of 7 temperatules spaced at 3 0 intervals in 1952

In all experiments -whenever a set of completely submerged test tubes was removed from a giyen bath the surfaces of the test tubes were quickly dried llld the contents -were composited in a small abshysorbent paper tray consisting of four thicknesses of paper toweling Rice from leakv test tubes and from te~t tubes filted with thermoshycouples vas discarded A moisture determinaUon yas made when the composited sample yeighed 75 gm or more (contcnts of 8 to 14 test tubes) It WfiS made ythin 2 1-0 5 minutes of emptying the test tubes depending upon the number of test tnbes lind the loeaHon of j-he moisshyture tester Immediatelv after tlle moisture determination was made the rice was sprenc1 in tile tray and plncecl in 1 sheltered location to

-air-dry at the ]1reyailing atmospheric temperature Yhen dly-14shypercent moisture contcn1- or lower-the rice yas emptied from the tray into a small coded paper hag

At the conclusion of the lilhl work each season these bags of treated samples and controls ere fonmlc1ed to the Southern Regional Reshysearch Laborfitory llW Orleans La tmel storrcl at 2~0_2(jO 0 Gershymination tests Yele l1I11 on eneh Sflmp 1r S IG 2middotk and 32 weeks after the clate of treatment

DETERMINATION OF lHOISTU1U~ CONTENT

The moisture (onteni of the lough rice in Ill( range of 10 to gO percent was c1etellnined itll n S1einli1r Jroi~tuJ( T(~1-PJJ This i11shystrumentwns conwnient to use in the fi(gt1ltl and was (alihrntecl ench season aga inst the ortecl-clrn ft oYen mltll)(l 101 (Hplm ining thr moisture conielltin the higher rnnge Samplcs helirYlrl to contain less thnn 10 pClcrnt of moisture Pre srnlpd in 1pst t11bes and returned to the Soutlwrn Regional Hp~e[r(h LnbolutolY here their respecshytive Illoistlne toMents Wle determined by a forcrcl-cllaft ocn method In this mdhoc1lhe samples er(gt hra1((i at 101 0 C ot Hi homs in tl

forced-chaft oen reYrighecl ancl tl]( loss ill weight WlIS ca1clllated ns moisture content on nlr pt bnsi~ Snmplr~ 01 10- toI2-ppltent moisture content yen sometimes similarly checked Allm01sturB contents ere lrpolteel on a wpi basis and 011 cCnn((l 8(((1

DETERMINATION OF IUCE TEMPERATURE DUIUNG HEAT TREATMENT

The temperntlll( of tlll rough Iicl in flIt eloslltl (si jubCs nncllhl thne tlken for it to lPHch the rlllplratlln of the bath (IP cl(terlllilled by means of thcII1l0C0uples 111 ctell of two tpst tubrs 1)(1 batll an jlOI1-constmtnn thermocouple was pushed ((n1Tall) in1o the packed rICe for 1 to 112 il1cll(s Each fllCI11l0lollplc lead extllll1rd above the water through a long glnss tube which was Jilted into tt rubber stopshy

bull rll( mention of 111[1(gt )Ioc1l1ds 01 (olllJ1f1ni(gts [lops not illlply that they nrc (11(101(d hy nIl p ~ TlP]JIIItllHlIt oj lIi(lIlllln 01(gt1 illlilnl ]llo(lll(l or eOIll shy

bull

bull

bull]Hll1itH not 111(gt111 iOlltl1

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 11

per Leads from the test tubes in the different baths were connected to a mUltiple switch and tIlls in turn to a potentiometer Potentiometer readings yere cOllverted to temperature readings by Ineans of a chart

WATER BATHS

AU the water batlls were of homemade constrllcHon Nine plain cylindrical heat-reRistant jars 12 by 12 inches yere each insulated sides and bottom 1ilh one-fonrth-iuch sheet asbestos They were placed on one-half-inell insulation bO1ld on n specially constructed combination platforl1J and rack Accessory equipment compactly turanged at the back of each bath consisted of t relay mounting bracket two f1exible immersion heaters a bimetn11ic thermoregulator a thell110metel and a stirrer yith pulley mounted at the top of its shaft Stirrer pulleys connected in series to a speed-redncer pulley and elliv-en by an electric motor permitted uniform and 00ntinuous agitation of the ~-atel in all brlths A set of six water baths is shown in Iigure 1

bull F1GLnE I-A StriC3 of the 1111 hath uord in the heat II(all1lent or rough rice

Test tubcs of ]1((gt tn 1Jl sllb11lcrg-ec1 wcre plaled in lest-tube baskets oJ nOllc()lI)~ingt ile each of whilh was ploYided with an elongated hook for nthtdlll1Cnt to the edge of thp bath Each balh was almost coYced dUlmiddotjllg OPC1htion by a olw-middotfol1lth-inch complcssed-bonrd eove1

DETERMINATION OF PRESSURES IN STOPPERED TUBES

bull Simultaneonsly witl1 each heat-treatment experiment in 1052 manoshy

metric measlIremelltmiddots wee made of the tohtl prcssUles clenloped in a test tube 01 rough 11(( in cach bath The llessllrC-l11eHsllling device (onsisjed of Hll 0pllI-end I1IHllOllletel on( end of h ieh wus Iitted into a rice-filled t(st hlhe b 111(111 of a lllbber stoppel Eneh mlnometel was equipped with t1 nllleurj le~elT(jir and a leveling tube which perm itted 1 constant yolulIIC 10 be mn intninecl during 1 heating expel jille n t

A typical experiment consisted in filling the test tube carefully tightJy packing the rice fitting the lnanometm in the test tube by

12 T]~CfLJCAL BULLETiN 1129 U S- DEPT OF AGHICULTUHE

means of the rubber stopper and then submerging the test tube in bull the water bath J usi prior to submergence of the test tube howeyel the mercury leveling tube was adjusted to bring the enclosed system to constant volume and the initial pressure was recorded Dudng the courSe of an experiment in which 8 minutes were allowed fol the test lube and contellt to attain the tempprature of the Im(-h and 10 minutes fol the actioll of heat of a given temperatme the nlallOlneter

- WflS open to the rice at all tilllPS and was adjusted so as to maintain a constant volume in the enclosed system The tobJ pressures reshysulting f1om the expansion of free ail and the vnpor wele recorded every 5 minutes of the 30-minute period in terms of centimeters of Inercury

GERMINATION TESTS

81ed glllJ1inatioll hS(H welp cOl1l1i1etelt1 by fhe nwtho(ll)lpsnibecl by (he FeltlelHl ~eed (t (Y 85) FOllr hlllltlrld HeE-ds from ladl sample were germinated in replicahs of 100 behHl1I byers of moist paper toelillg They -ere glrminattltl 1+ clays in the dark ill a watershycudnin type gell11inator that as automatictlly and thermoshystatjcnlly controlled It was spt to opelllte at alternating temperashytures of 20deg C for 8 hOllrs and 3()0 for lCi hOllrs Counts ere made on each sample on the 5th 7th lOth and1+th days A germinating seed was counted only if it had both a root and a shoot and only if one of these stluctl1les was at least olle-fourth inch long Germinated shyseeds wpre disCal(lld at the time of cOllnting

The terl1ls gelmination capacity and ftelminntion vigor lle used throllplwllt the IHlllr-in to n~f(gtr to total germination ana rntc of germination llspeetilly

HEATmiddotTUEATlVIENT EXPEIUlIENTS IN 1950

The investigafiolls in l)iO wer( stalec1 withollt l priori knowlpclge of the efreds of heat Oil the iabilitv of Iollgh Ii(( h(11 hpa- itS applied according to the expelimenttil cOllditl(lIIs ltINclibed HenCc in the experiments in which temperature and moisture content were the majol variables all samples were heat-treatec1 in 5deg steps alhishyharily selected over a range of 15deg to 75deg C Similarly in the expelishyInents in which temperatllre and time of hpatillg were the Imljor variables tempelature~ of 10deg el5deg GOdeg and 55deg were also arbitrn1ily selected

Three arieies of ice wen lIsCd ill chI expclill1ents-Sel (if~2fi-H Hexol() alld Zellith (htbll 1) Sel GI-ni-B i a lrip(y declopec1 at (he 11ice ExpelinH~lIt ~tatioll Crowley La (Joc1on and De La HOllssaye B8)

Dnta from representative experimen(-s ale given in (-ables 2-fl 1he PCICllItagps of s(l(I gCllIlillating IIC given only for Sfllllplcs tested 32 weeks from the dal-c of heat hpahnellt Onc reason Ol this plltill presentatjon oJ c1ntn is (-hnt no appreciable di Ilerences ere observe in the germinatioll capacities or seed between the 8- and 32-c peri ods of sto mge (2+deg-26 deg 0)

EFFECTS OF HEAT lREArMJ~NT ON THE VIABILITY OF RICE 13

PltABLE 2-Gelmiddotmination of 1ougk rice altel lwat tJcatment at ditfeent i bullbull-

~ tempelatUIC8 1950

SEL 6T-25-12

MoiRlurfmiddot IDUlution co I 1-0 I ~oo I ~~o noo contint of hput n- ~ I J I )~

(pPle(nt) tlatlll(nt trol c ( I C c -----middot--i-------middot--

Per- Per- Pr- IPershycelli cent Icelli Ctll

o 0 0 0

8g 1 ~ ____ ~_i _____ ~ ---S7T---g- g g

8i 1 0 0 1)0 82 1 0 90 77 0 0 89 86 70 0 89 87 39 0 )2 88 83 0 90 88 71 0 85 87 87 90 85 87 87 I 8-10 85 81 88 85i

86 S7 87 88

HEXOHO 1

I8shy1 79 62 02J3_______ 30 J I 86 I I

090 t60 88 88 8G 57 0 0

186_______ 80 89 92 89 87 8(i 0 ~ 85 IGO 89 88 89 81 73 0

J32 _______ ] 30 89 88 90 91 89 0 GO 85 89 87 87 Sri I 88 7G 0 0

J] L ______i 30 87 87 88 l 88 t 60 91 90 ---~~-l 88 l---~~-l 0 I I -=-~l 80

ZEXITH

~

2 I5 ___ ~___ 30

90 92 92 92 85 33 0 0

lG3_______ 30 92 I 85 1)3 1)1 91 92 36 0 shy106 _______ 30 j 93 91 92 92 02 I 84 78 0

~

--_

j

gt~lIJot IU

bull -~-

~

J

~

14 TECHNIcAl i3lJLLETIN 1129 1 S DEPT OF AGRICULTURE

TABLE 3-jJloislt7e contents of 8el OI-f35-1B rough 1icp S to 5 minutes aitel heat treatment at different te1np(J~ature8 1950 bull

TAllL -L-Ol )1 illatioll of 1(1010 I 0 Il[h Ufl IIh hlrd 1)Nt1I1fn t fol ditt(fent periorlN of time 1950

--- -~~- -~ ~- ------- ~- -------_ -~----~-

Tcmp~ratlllp bullof COIl- 10 20 30 40 50 Go 90 l20 treatmcut trol III ill Illin mi 11 min llIin min mi Il min(0 C)

PC1- p( r- fJu- P- ( r- Icl- Igtrr- Per- PIr-c(I C( III cot CUll CI1I1 CIII celli c(lIl cent

40__ bull_______ 05 Oi (1) )middot1 nmiddot1 f)middot1 93 93 n845 ___________ 50___________ nij n2 JmiddotI 9middot1 )(j 03 91 ))

JmiddotI J-I 02 0middot[ 93 08 n) nmiddot1 S-(55______ __~ -- 0middot1 08 JI no J2 n8 ss 85__--_ -- -ILot Ra

TABLE G-Ellert of t illll (dllmtioJl) oj h((t t reament at iF) O on the flel11illatioll of Nldoro 1 ough icc aIc) 5 7 lO and J~ days1950

-~~---- ------- - -~~-- - -~~-

Duration of IHnt trcatnwnt ij daYllt 7 day I () dly~ 1middot1 cbtYllt Total(miuute)

-------------~

1gt11(( nl p( 111 (((1I1 1(1111 PelllIII ControL~ III 1 ()gt HJ 10~ 75 16 2 I BJ 20~ oX 21 middot1 0 )830__ (jmiddot1 ItI Ii 2 UIWbull _ H3 23 3 I no50 16 an J I l2 bull60bull i)1 ]i 5 2 03no_ 40 7 10 88120__ 87 an 10 2 85 --lt---~

IIot R3

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

8middot TECJ-lNICAL BULLr~TIN 1129 U S mpl OF AGRlCULlURE

referred to this nnlTO critical temperature range as being about 9deg C (Hutchinson etaZ 34)

Although the excellent researches of Vnggoner and of Hutchinson have not been concerned yith rice they haTe been cited for the followshying reasons (1) They illustrate the kind of research that needed to be undertaken with rice (2) thcy have selYed as patterns in planning the rice research described in this bulletin and (3) the~ haye resulted in the acclunulatioll of extensiw data on the pllects of hctt treatmcnt 011 the germination capacitic of radish and helt sped which arc likely to have mllch in (ommon with 010se l(clIJ11u1ttec1 fOl ricc in spite of the chemical structuml and physiological lt1ilYercnccsin the kinds of seeds and in spite of cliffcIenccs ill the experimental procedllres

EXPERIliENTAL lIATERIALS AND PROCEDURES

~ll tmiddothe riel LlsCc1 in the H)50 1J51 and lJi~ lXlwjilllCnts was glown in the vici1lity of Crowlpy Ln Ynrieti0s gmin types) (1ttes of harvest alld other information alp giwn in table 1

TBLllt l~Dat( on 1(lidil8 of rOllf1i jrr 18Nl in h((t~tJwdluJt (middotlllilll(nts Ifj)()-i

- - -q----~-- ~

----~-- - - --- --~- ---Dnlp comhilwel and loistII rC i Lot

pur and aripty ( rnill tyJ)P ]Hat ( r(ntl1lllt (onlltllt of dpsipnntion Iartfd ricp I (SRBLl 2

[90

H(I (iJmiddotmiddot2fi 12 IlpX(lr(L bull

[PriiIlIlL LOllP

~pp 2R 0(( 2

~ - ----shyPacllzi

- I_J

2middot1 3 31 BR2 In

Zenilh R(gtx()fo _ bull _ bull _ bullbull _

[pdiIlIlL_ LOllpbullbullbull _

0(1 - - -~ shyO(t lfi _________

21 21 9

Z2 H3

91

BhlPIH)llllL __ bull Do

Hpl 0[- 2) 12_

LOllg rio

1 (ltIilln

Hpt 7 -~ -- -

Ort 2 -__--------Or R

-~--------

2) 2 179 ID R

BBl HIli 34 B H23

19)

BIIIlJonllPi _ _ CNltllry )2 ____

Iollp -~ - - - ~

-shy do_______ (3) Nppt an -_

21 (j 11 2

BIlIO C2

~ ----~-

1 At tilllP til(gt lirt lt1l111plps WI talPH for Jral trpatlllllt lIgtltuallr 11(1 hOIlls Ir01l1 tilll of omili Ili liP 111 IJrllil

SmHIH11l Rpdollal H(Ilaleh Lalioratol 3C()llIiJill((i -ept 9 hlH t ()( tnlen Is sl H11 ((1 -(pL 11

To nSSUle ]gtloxinlity to a supply of frp111y (olllbinrd rOllgh rice (paddy) of known hi~toly 11pat-tlpntn1Pnt appnlHhlS wn~ spt up (tleh season in OIW of til( llllildinps of tllC niee J~xpllinlCnt Shtfion in ClOylty FSlIally it was possiblp to obtnill a ballpl 01 fo of liee ilom the hoppPI of II Iie( en lt wif It i n 1 (0 lltollrf of (om hi n i ll~ [ore attcntioll was ~inn hJ splpcting n lot of liel 01 the hi~llPstll1oistllre

bull

bull

bull content unillblt Illnn to (hooing it lot of it SlH(middotifi( raliclT (tlOSS

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 9

debris such as eticks strnw grasshoppers and weed seed was removed by hanel Ko meclHlnical cleaning of the rough rice was attenlpted in 1950 and IV1 but one lot was mechanically cleaned in IV52 As soon as a sufficient quantity of a given Jot of rice had been cleaned 100 to 150 heat-resistant glass test tubes 1G by 150 mm were tightly packed with rie-e by jarring the butts agaillst tIle pt1m of the hand These filled and stoppered test tubes were promptly snbjeeted to heat treatment

Yhile the tect tubps were being filled moisture determinations were bein made on 11e yell-mixed portions of tIle bulk lot omiddotf cleaned rice Their tlverae moistll1e content was recorded as that of the rice being tubed On cOlllpletioll of the dispPllsing the remainder of the rice was spretld in layers to air-dry It wa frequently 111ixP(l fwd (heeked for moisture (ontent Ea(h time tIll moisture content of the lot dropped about 2 pereent a number of test tubes were filled with this lice tllld heat-trented This procedure pelmittpd t1 serips of exshyperiments to be run with batches of rice of successively lower nntllrtll-llIoistUlp contents oriinntill rom the same combined lot

bull

Then the weather was ntrll and dry a 2-peLcent drop in moistnre (ontent sOlllPlillles (leclIlTed in 2 Oi B hours whereas during hmuicl wpathpr it miIIllw (kltwrl sPHral dnrs or nnlil tlwlP was a decrease in the 1elaJi~ humidity Vitll Ih(1 olmel (ol1(lil-iol1 it was sometimes necessflry to hoM a bateh of Iiee in a closed (ontainel until it (ould be treatpd Holding 1)(liolt1 Hre usually sholt 1 to 3 hours and very rarely ex(eec1ed 2+ houls lInl(~s the ri(( was dry t1mt is 14-pershycent m(ji~tu[( tcnhlll OJ lowll ~Joishllp eOl1t(llt omiddotf 0 percent and lower ere obtained by (llil1 Ii(( of llJ- to ll-]JPIlent moistme conshytent in (lesi((tl tor 0(1 (laquolei Hill (h lOli(i( am1or phosphorus pelitshyoxide The control snmplp IPPI(~llltnti-p of eneh loL was always airshydried

NATURE OF EXPERIMENTS

Two kinds oj eXl)tIillllllts WPIP llIH]pdnk(ll pnell Y(nl Tn OIH till tll1lltnLtlllP of 11Plring and till 11loistuIP eOllt(nt c)r the rough rice P10 thp 11ltljOJ Ytliables and the tillle (duldioll) of h(atlllpnt was Illld COllstant TlI Ihp OlhPI t lIP tclI1lern tlllP nIlcl li nl( of tleatnwnt were the major -u-iabhs alld the Illoisture coutent of the Iice -as held (oustant

bull

In theexpplilllents with (PIIlPPIaiUIP nnd moistlllP coutent as varishyables lmtchps of lollh riel flom thp ~an1P (ol1lhinp(11ot lnd- of clillelshyenr Jl1()i~tull (IIJlfllllS -ere epamhly dispPIlHe(l and 10 to 14 test tubls of (aell WPI( SlIIJIlIPI(d alld IIpa[-llpafp(( 101 ao ll1illlltpS atlel tlIP Ii(( 1(I(I1(d Ihe (Ill])(ratlllp 01 tll( balh A BO-millute heatin ]l(liolt1 was BplrtNI 101 1liOSt of tmiddoth( exp(llinllllf be(llIse it a pproalhpd Ilw (illle lollgh rice is expmpd 10 hih tClllpelnllllps ill eOIl1I11Pleial dli(ls ~(ff of 10 to 14 (pst fubes 01 lOllgh ri(c of the lII1P moisture (OlltPllt and flOIll the salllP initial batchof Iic( were eaeh hcatedat eli flprPllt jPlllpplatII J(S

111 lin expllilllllIS with t(1I11lPldlllP nlld finlP Hi nriahl(s basklis of IilINI stoPP(lIPlt tN tlllps cOlltaillillg Iil( 01 t hl sa III( moisture eOIlshytent alld 110111 tll( sHill( illitinl balt-h of Imiddotj(t (1( SlIbllllltd ill1 watmiddotpl oath at a gi-PII IPIIIgtPla( 1I11 flpl tll( (OIIllllls of t lIP Ipsf IIillS htHl

1129 U S DEPT OF AGRICULTURE

reached the temperilture of the bath 3 to 10 test tubes were withdrtwm every 10 minutcs for periods of 60 to 120 minutes This procedllre was repeated for each of 4 temperatures spaced at 50 intervals in 1950 and 1951 and for each of 7 temperatules spaced at 3 0 intervals in 1952

In all experiments -whenever a set of completely submerged test tubes was removed from a giyen bath the surfaces of the test tubes were quickly dried llld the contents -were composited in a small abshysorbent paper tray consisting of four thicknesses of paper toweling Rice from leakv test tubes and from te~t tubes filted with thermoshycouples vas discarded A moisture determinaUon yas made when the composited sample yeighed 75 gm or more (contcnts of 8 to 14 test tubes) It WfiS made ythin 2 1-0 5 minutes of emptying the test tubes depending upon the number of test tnbes lind the loeaHon of j-he moisshyture tester Immediatelv after tlle moisture determination was made the rice was sprenc1 in tile tray and plncecl in 1 sheltered location to

-air-dry at the ]1reyailing atmospheric temperature Yhen dly-14shypercent moisture contcn1- or lower-the rice yas emptied from the tray into a small coded paper hag

At the conclusion of the lilhl work each season these bags of treated samples and controls ere fonmlc1ed to the Southern Regional Reshysearch Laborfitory llW Orleans La tmel storrcl at 2~0_2(jO 0 Gershymination tests Yele l1I11 on eneh Sflmp 1r S IG 2middotk and 32 weeks after the clate of treatment

DETERMINATION OF lHOISTU1U~ CONTENT

The moisture (onteni of the lough rice in Ill( range of 10 to gO percent was c1etellnined itll n S1einli1r Jroi~tuJ( T(~1-PJJ This i11shystrumentwns conwnient to use in the fi(gt1ltl and was (alihrntecl ench season aga inst the ortecl-clrn ft oYen mltll)(l 101 (Hplm ining thr moisture conielltin the higher rnnge Samplcs helirYlrl to contain less thnn 10 pClcrnt of moisture Pre srnlpd in 1pst t11bes and returned to the Soutlwrn Regional Hp~e[r(h LnbolutolY here their respecshytive Illoistlne toMents Wle determined by a forcrcl-cllaft ocn method In this mdhoc1lhe samples er(gt hra1((i at 101 0 C ot Hi homs in tl

forced-chaft oen reYrighecl ancl tl]( loss ill weight WlIS ca1clllated ns moisture content on nlr pt bnsi~ Snmplr~ 01 10- toI2-ppltent moisture content yen sometimes similarly checked Allm01sturB contents ere lrpolteel on a wpi basis and 011 cCnn((l 8(((1

DETERMINATION OF IUCE TEMPERATURE DUIUNG HEAT TREATMENT

The temperntlll( of tlll rough Iicl in flIt eloslltl (si jubCs nncllhl thne tlken for it to lPHch the rlllplratlln of the bath (IP cl(terlllilled by means of thcII1l0C0uples 111 ctell of two tpst tubrs 1)(1 batll an jlOI1-constmtnn thermocouple was pushed ((n1Tall) in1o the packed rICe for 1 to 112 il1cll(s Each fllCI11l0lollplc lead extllll1rd above the water through a long glnss tube which was Jilted into tt rubber stopshy

bull rll( mention of 111[1(gt )Ioc1l1ds 01 (olllJ1f1ni(gts [lops not illlply that they nrc (11(101(d hy nIl p ~ TlP]JIIItllHlIt oj lIi(lIlllln 01(gt1 illlilnl ]llo(lll(l or eOIll shy

bull

bull

bull]Hll1itH not 111(gt111 iOlltl1

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 11

per Leads from the test tubes in the different baths were connected to a mUltiple switch and tIlls in turn to a potentiometer Potentiometer readings yere cOllverted to temperature readings by Ineans of a chart

WATER BATHS

AU the water batlls were of homemade constrllcHon Nine plain cylindrical heat-reRistant jars 12 by 12 inches yere each insulated sides and bottom 1ilh one-fonrth-iuch sheet asbestos They were placed on one-half-inell insulation bO1ld on n specially constructed combination platforl1J and rack Accessory equipment compactly turanged at the back of each bath consisted of t relay mounting bracket two f1exible immersion heaters a bimetn11ic thermoregulator a thell110metel and a stirrer yith pulley mounted at the top of its shaft Stirrer pulleys connected in series to a speed-redncer pulley and elliv-en by an electric motor permitted uniform and 00ntinuous agitation of the ~-atel in all brlths A set of six water baths is shown in Iigure 1

bull F1GLnE I-A StriC3 of the 1111 hath uord in the heat II(all1lent or rough rice

Test tubcs of ]1((gt tn 1Jl sllb11lcrg-ec1 wcre plaled in lest-tube baskets oJ nOllc()lI)~ingt ile each of whilh was ploYided with an elongated hook for nthtdlll1Cnt to the edge of thp bath Each balh was almost coYced dUlmiddotjllg OPC1htion by a olw-middotfol1lth-inch complcssed-bonrd eove1

DETERMINATION OF PRESSURES IN STOPPERED TUBES

bull Simultaneonsly witl1 each heat-treatment experiment in 1052 manoshy

metric measlIremelltmiddots wee made of the tohtl prcssUles clenloped in a test tube 01 rough 11(( in cach bath The llessllrC-l11eHsllling device (onsisjed of Hll 0pllI-end I1IHllOllletel on( end of h ieh wus Iitted into a rice-filled t(st hlhe b 111(111 of a lllbber stoppel Eneh mlnometel was equipped with t1 nllleurj le~elT(jir and a leveling tube which perm itted 1 constant yolulIIC 10 be mn intninecl during 1 heating expel jille n t

A typical experiment consisted in filling the test tube carefully tightJy packing the rice fitting the lnanometm in the test tube by

12 T]~CfLJCAL BULLETiN 1129 U S- DEPT OF AGHICULTUHE

means of the rubber stopper and then submerging the test tube in bull the water bath J usi prior to submergence of the test tube howeyel the mercury leveling tube was adjusted to bring the enclosed system to constant volume and the initial pressure was recorded Dudng the courSe of an experiment in which 8 minutes were allowed fol the test lube and contellt to attain the tempprature of the Im(-h and 10 minutes fol the actioll of heat of a given temperatme the nlallOlneter

- WflS open to the rice at all tilllPS and was adjusted so as to maintain a constant volume in the enclosed system The tobJ pressures reshysulting f1om the expansion of free ail and the vnpor wele recorded every 5 minutes of the 30-minute period in terms of centimeters of Inercury

GERMINATION TESTS

81ed glllJ1inatioll hS(H welp cOl1l1i1etelt1 by fhe nwtho(ll)lpsnibecl by (he FeltlelHl ~eed (t (Y 85) FOllr hlllltlrld HeE-ds from ladl sample were germinated in replicahs of 100 behHl1I byers of moist paper toelillg They -ere glrminattltl 1+ clays in the dark ill a watershycudnin type gell11inator that as automatictlly and thermoshystatjcnlly controlled It was spt to opelllte at alternating temperashytures of 20deg C for 8 hOllrs and 3()0 for lCi hOllrs Counts ere made on each sample on the 5th 7th lOth and1+th days A germinating seed was counted only if it had both a root and a shoot and only if one of these stluctl1les was at least olle-fourth inch long Germinated shyseeds wpre disCal(lld at the time of cOllnting

The terl1ls gelmination capacity and ftelminntion vigor lle used throllplwllt the IHlllr-in to n~f(gtr to total germination ana rntc of germination llspeetilly

HEATmiddotTUEATlVIENT EXPEIUlIENTS IN 1950

The investigafiolls in l)iO wer( stalec1 withollt l priori knowlpclge of the efreds of heat Oil the iabilitv of Iollgh Ii(( h(11 hpa- itS applied according to the expelimenttil cOllditl(lIIs ltINclibed HenCc in the experiments in which temperature and moisture content were the majol variables all samples were heat-treatec1 in 5deg steps alhishyharily selected over a range of 15deg to 75deg C Similarly in the expelishyInents in which temperatllre and time of hpatillg were the Imljor variables tempelature~ of 10deg el5deg GOdeg and 55deg were also arbitrn1ily selected

Three arieies of ice wen lIsCd ill chI expclill1ents-Sel (if~2fi-H Hexol() alld Zellith (htbll 1) Sel GI-ni-B i a lrip(y declopec1 at (he 11ice ExpelinH~lIt ~tatioll Crowley La (Joc1on and De La HOllssaye B8)

Dnta from representative experimen(-s ale given in (-ables 2-fl 1he PCICllItagps of s(l(I gCllIlillating IIC given only for Sfllllplcs tested 32 weeks from the dal-c of heat hpahnellt Onc reason Ol this plltill presentatjon oJ c1ntn is (-hnt no appreciable di Ilerences ere observe in the germinatioll capacities or seed between the 8- and 32-c peri ods of sto mge (2+deg-26 deg 0)

EFFECTS OF HEAT lREArMJ~NT ON THE VIABILITY OF RICE 13

PltABLE 2-Gelmiddotmination of 1ougk rice altel lwat tJcatment at ditfeent i bullbull-

~ tempelatUIC8 1950

SEL 6T-25-12

MoiRlurfmiddot IDUlution co I 1-0 I ~oo I ~~o noo contint of hput n- ~ I J I )~

(pPle(nt) tlatlll(nt trol c ( I C c -----middot--i-------middot--

Per- Per- Pr- IPershycelli cent Icelli Ctll

o 0 0 0

8g 1 ~ ____ ~_i _____ ~ ---S7T---g- g g

8i 1 0 0 1)0 82 1 0 90 77 0 0 89 86 70 0 89 87 39 0 )2 88 83 0 90 88 71 0 85 87 87 90 85 87 87 I 8-10 85 81 88 85i

86 S7 87 88

HEXOHO 1

I8shy1 79 62 02J3_______ 30 J I 86 I I

090 t60 88 88 8G 57 0 0

186_______ 80 89 92 89 87 8(i 0 ~ 85 IGO 89 88 89 81 73 0

J32 _______ ] 30 89 88 90 91 89 0 GO 85 89 87 87 Sri I 88 7G 0 0

J] L ______i 30 87 87 88 l 88 t 60 91 90 ---~~-l 88 l---~~-l 0 I I -=-~l 80

ZEXITH

~

2 I5 ___ ~___ 30

90 92 92 92 85 33 0 0

lG3_______ 30 92 I 85 1)3 1)1 91 92 36 0 shy106 _______ 30 j 93 91 92 92 02 I 84 78 0

~

--_

j

gt~lIJot IU

bull -~-

~

J

~

14 TECHNIcAl i3lJLLETIN 1129 1 S DEPT OF AGRICULTURE

TABLE 3-jJloislt7e contents of 8el OI-f35-1B rough 1icp S to 5 minutes aitel heat treatment at different te1np(J~ature8 1950 bull

TAllL -L-Ol )1 illatioll of 1(1010 I 0 Il[h Ufl IIh hlrd 1)Nt1I1fn t fol ditt(fent periorlN of time 1950

--- -~~- -~ ~- ------- ~- -------_ -~----~-

Tcmp~ratlllp bullof COIl- 10 20 30 40 50 Go 90 l20 treatmcut trol III ill Illin mi 11 min llIin min mi Il min(0 C)

PC1- p( r- fJu- P- ( r- Icl- Igtrr- Per- PIr-c(I C( III cot CUll CI1I1 CIII celli c(lIl cent

40__ bull_______ 05 Oi (1) )middot1 nmiddot1 f)middot1 93 93 n845 ___________ 50___________ nij n2 JmiddotI 9middot1 )(j 03 91 ))

JmiddotI J-I 02 0middot[ 93 08 n) nmiddot1 S-(55______ __~ -- 0middot1 08 JI no J2 n8 ss 85__--_ -- -ILot Ra

TABLE G-Ellert of t illll (dllmtioJl) oj h((t t reament at iF) O on the flel11illatioll of Nldoro 1 ough icc aIc) 5 7 lO and J~ days1950

-~~---- ------- - -~~-- - -~~-

Duration of IHnt trcatnwnt ij daYllt 7 day I () dly~ 1middot1 cbtYllt Total(miuute)

-------------~

1gt11(( nl p( 111 (((1I1 1(1111 PelllIII ControL~ III 1 ()gt HJ 10~ 75 16 2 I BJ 20~ oX 21 middot1 0 )830__ (jmiddot1 ItI Ii 2 UIWbull _ H3 23 3 I no50 16 an J I l2 bull60bull i)1 ]i 5 2 03no_ 40 7 10 88120__ 87 an 10 2 85 --lt---~

IIot R3

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 9

debris such as eticks strnw grasshoppers and weed seed was removed by hanel Ko meclHlnical cleaning of the rough rice was attenlpted in 1950 and IV1 but one lot was mechanically cleaned in IV52 As soon as a sufficient quantity of a given Jot of rice had been cleaned 100 to 150 heat-resistant glass test tubes 1G by 150 mm were tightly packed with rie-e by jarring the butts agaillst tIle pt1m of the hand These filled and stoppered test tubes were promptly snbjeeted to heat treatment

Yhile the tect tubps were being filled moisture determinations were bein made on 11e yell-mixed portions of tIle bulk lot omiddotf cleaned rice Their tlverae moistll1e content was recorded as that of the rice being tubed On cOlllpletioll of the dispPllsing the remainder of the rice was spretld in layers to air-dry It wa frequently 111ixP(l fwd (heeked for moisture (ontent Ea(h time tIll moisture content of the lot dropped about 2 pereent a number of test tubes were filled with this lice tllld heat-trented This procedure pelmittpd t1 serips of exshyperiments to be run with batches of rice of successively lower nntllrtll-llIoistUlp contents oriinntill rom the same combined lot

bull

Then the weather was ntrll and dry a 2-peLcent drop in moistnre (ontent sOlllPlillles (leclIlTed in 2 Oi B hours whereas during hmuicl wpathpr it miIIllw (kltwrl sPHral dnrs or nnlil tlwlP was a decrease in the 1elaJi~ humidity Vitll Ih(1 olmel (ol1(lil-iol1 it was sometimes necessflry to hoM a bateh of Iiee in a closed (ontainel until it (ould be treatpd Holding 1)(liolt1 Hre usually sholt 1 to 3 hours and very rarely ex(eec1ed 2+ houls lInl(~s the ri(( was dry t1mt is 14-pershycent m(ji~tu[( tcnhlll OJ lowll ~Joishllp eOl1t(llt omiddotf 0 percent and lower ere obtained by (llil1 Ii(( of llJ- to ll-]JPIlent moistme conshytent in (lesi((tl tor 0(1 (laquolei Hill (h lOli(i( am1or phosphorus pelitshyoxide The control snmplp IPPI(~llltnti-p of eneh loL was always airshydried

NATURE OF EXPERIMENTS

Two kinds oj eXl)tIillllllts WPIP llIH]pdnk(ll pnell Y(nl Tn OIH till tll1lltnLtlllP of 11Plring and till 11loistuIP eOllt(nt c)r the rough rice P10 thp 11ltljOJ Ytliables and the tillle (duldioll) of h(atlllpnt was Illld COllstant TlI Ihp OlhPI t lIP tclI1lern tlllP nIlcl li nl( of tleatnwnt were the major -u-iabhs alld the Illoisture coutent of the Iice -as held (oustant

bull

In theexpplilllents with (PIIlPPIaiUIP nnd moistlllP coutent as varishyables lmtchps of lollh riel flom thp ~an1P (ol1lhinp(11ot lnd- of clillelshyenr Jl1()i~tull (IIJlfllllS -ere epamhly dispPIlHe(l and 10 to 14 test tubls of (aell WPI( SlIIJIlIPI(d alld IIpa[-llpafp(( 101 ao ll1illlltpS atlel tlIP Ii(( 1(I(I1(d Ihe (Ill])(ratlllp 01 tll( balh A BO-millute heatin ]l(liolt1 was BplrtNI 101 1liOSt of tmiddoth( exp(llinllllf be(llIse it a pproalhpd Ilw (illle lollgh rice is expmpd 10 hih tClllpelnllllps ill eOIl1I11Pleial dli(ls ~(ff of 10 to 14 (pst fubes 01 lOllgh ri(c of the lII1P moisture (OlltPllt and flOIll the salllP initial batchof Iic( were eaeh hcatedat eli flprPllt jPlllpplatII J(S

111 lin expllilllllIS with t(1I11lPldlllP nlld finlP Hi nriahl(s basklis of IilINI stoPP(lIPlt tN tlllps cOlltaillillg Iil( 01 t hl sa III( moisture eOIlshytent alld 110111 tll( sHill( illitinl balt-h of Imiddotj(t (1( SlIbllllltd ill1 watmiddotpl oath at a gi-PII IPIIIgtPla( 1I11 flpl tll( (OIIllllls of t lIP Ipsf IIillS htHl

1129 U S DEPT OF AGRICULTURE

reached the temperilture of the bath 3 to 10 test tubes were withdrtwm every 10 minutcs for periods of 60 to 120 minutes This procedllre was repeated for each of 4 temperatures spaced at 50 intervals in 1950 and 1951 and for each of 7 temperatules spaced at 3 0 intervals in 1952

In all experiments -whenever a set of completely submerged test tubes was removed from a giyen bath the surfaces of the test tubes were quickly dried llld the contents -were composited in a small abshysorbent paper tray consisting of four thicknesses of paper toweling Rice from leakv test tubes and from te~t tubes filted with thermoshycouples vas discarded A moisture determinaUon yas made when the composited sample yeighed 75 gm or more (contcnts of 8 to 14 test tubes) It WfiS made ythin 2 1-0 5 minutes of emptying the test tubes depending upon the number of test tnbes lind the loeaHon of j-he moisshyture tester Immediatelv after tlle moisture determination was made the rice was sprenc1 in tile tray and plncecl in 1 sheltered location to

-air-dry at the ]1reyailing atmospheric temperature Yhen dly-14shypercent moisture contcn1- or lower-the rice yas emptied from the tray into a small coded paper hag

At the conclusion of the lilhl work each season these bags of treated samples and controls ere fonmlc1ed to the Southern Regional Reshysearch Laborfitory llW Orleans La tmel storrcl at 2~0_2(jO 0 Gershymination tests Yele l1I11 on eneh Sflmp 1r S IG 2middotk and 32 weeks after the clate of treatment

DETERMINATION OF lHOISTU1U~ CONTENT

The moisture (onteni of the lough rice in Ill( range of 10 to gO percent was c1etellnined itll n S1einli1r Jroi~tuJ( T(~1-PJJ This i11shystrumentwns conwnient to use in the fi(gt1ltl and was (alihrntecl ench season aga inst the ortecl-clrn ft oYen mltll)(l 101 (Hplm ining thr moisture conielltin the higher rnnge Samplcs helirYlrl to contain less thnn 10 pClcrnt of moisture Pre srnlpd in 1pst t11bes and returned to the Soutlwrn Regional Hp~e[r(h LnbolutolY here their respecshytive Illoistlne toMents Wle determined by a forcrcl-cllaft ocn method In this mdhoc1lhe samples er(gt hra1((i at 101 0 C ot Hi homs in tl

forced-chaft oen reYrighecl ancl tl]( loss ill weight WlIS ca1clllated ns moisture content on nlr pt bnsi~ Snmplr~ 01 10- toI2-ppltent moisture content yen sometimes similarly checked Allm01sturB contents ere lrpolteel on a wpi basis and 011 cCnn((l 8(((1

DETERMINATION OF IUCE TEMPERATURE DUIUNG HEAT TREATMENT

The temperntlll( of tlll rough Iicl in flIt eloslltl (si jubCs nncllhl thne tlken for it to lPHch the rlllplratlln of the bath (IP cl(terlllilled by means of thcII1l0C0uples 111 ctell of two tpst tubrs 1)(1 batll an jlOI1-constmtnn thermocouple was pushed ((n1Tall) in1o the packed rICe for 1 to 112 il1cll(s Each fllCI11l0lollplc lead extllll1rd above the water through a long glnss tube which was Jilted into tt rubber stopshy

bull rll( mention of 111[1(gt )Ioc1l1ds 01 (olllJ1f1ni(gts [lops not illlply that they nrc (11(101(d hy nIl p ~ TlP]JIIItllHlIt oj lIi(lIlllln 01(gt1 illlilnl ]llo(lll(l or eOIll shy

bull

bull

bull]Hll1itH not 111(gt111 iOlltl1

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 11

per Leads from the test tubes in the different baths were connected to a mUltiple switch and tIlls in turn to a potentiometer Potentiometer readings yere cOllverted to temperature readings by Ineans of a chart

WATER BATHS

AU the water batlls were of homemade constrllcHon Nine plain cylindrical heat-reRistant jars 12 by 12 inches yere each insulated sides and bottom 1ilh one-fonrth-iuch sheet asbestos They were placed on one-half-inell insulation bO1ld on n specially constructed combination platforl1J and rack Accessory equipment compactly turanged at the back of each bath consisted of t relay mounting bracket two f1exible immersion heaters a bimetn11ic thermoregulator a thell110metel and a stirrer yith pulley mounted at the top of its shaft Stirrer pulleys connected in series to a speed-redncer pulley and elliv-en by an electric motor permitted uniform and 00ntinuous agitation of the ~-atel in all brlths A set of six water baths is shown in Iigure 1

bull F1GLnE I-A StriC3 of the 1111 hath uord in the heat II(all1lent or rough rice

Test tubcs of ]1((gt tn 1Jl sllb11lcrg-ec1 wcre plaled in lest-tube baskets oJ nOllc()lI)~ingt ile each of whilh was ploYided with an elongated hook for nthtdlll1Cnt to the edge of thp bath Each balh was almost coYced dUlmiddotjllg OPC1htion by a olw-middotfol1lth-inch complcssed-bonrd eove1

DETERMINATION OF PRESSURES IN STOPPERED TUBES

bull Simultaneonsly witl1 each heat-treatment experiment in 1052 manoshy

metric measlIremelltmiddots wee made of the tohtl prcssUles clenloped in a test tube 01 rough 11(( in cach bath The llessllrC-l11eHsllling device (onsisjed of Hll 0pllI-end I1IHllOllletel on( end of h ieh wus Iitted into a rice-filled t(st hlhe b 111(111 of a lllbber stoppel Eneh mlnometel was equipped with t1 nllleurj le~elT(jir and a leveling tube which perm itted 1 constant yolulIIC 10 be mn intninecl during 1 heating expel jille n t

A typical experiment consisted in filling the test tube carefully tightJy packing the rice fitting the lnanometm in the test tube by

12 T]~CfLJCAL BULLETiN 1129 U S- DEPT OF AGHICULTUHE

means of the rubber stopper and then submerging the test tube in bull the water bath J usi prior to submergence of the test tube howeyel the mercury leveling tube was adjusted to bring the enclosed system to constant volume and the initial pressure was recorded Dudng the courSe of an experiment in which 8 minutes were allowed fol the test lube and contellt to attain the tempprature of the Im(-h and 10 minutes fol the actioll of heat of a given temperatme the nlallOlneter

- WflS open to the rice at all tilllPS and was adjusted so as to maintain a constant volume in the enclosed system The tobJ pressures reshysulting f1om the expansion of free ail and the vnpor wele recorded every 5 minutes of the 30-minute period in terms of centimeters of Inercury

GERMINATION TESTS

81ed glllJ1inatioll hS(H welp cOl1l1i1etelt1 by fhe nwtho(ll)lpsnibecl by (he FeltlelHl ~eed (t (Y 85) FOllr hlllltlrld HeE-ds from ladl sample were germinated in replicahs of 100 behHl1I byers of moist paper toelillg They -ere glrminattltl 1+ clays in the dark ill a watershycudnin type gell11inator that as automatictlly and thermoshystatjcnlly controlled It was spt to opelllte at alternating temperashytures of 20deg C for 8 hOllrs and 3()0 for lCi hOllrs Counts ere made on each sample on the 5th 7th lOth and1+th days A germinating seed was counted only if it had both a root and a shoot and only if one of these stluctl1les was at least olle-fourth inch long Germinated shyseeds wpre disCal(lld at the time of cOllnting

The terl1ls gelmination capacity and ftelminntion vigor lle used throllplwllt the IHlllr-in to n~f(gtr to total germination ana rntc of germination llspeetilly

HEATmiddotTUEATlVIENT EXPEIUlIENTS IN 1950

The investigafiolls in l)iO wer( stalec1 withollt l priori knowlpclge of the efreds of heat Oil the iabilitv of Iollgh Ii(( h(11 hpa- itS applied according to the expelimenttil cOllditl(lIIs ltINclibed HenCc in the experiments in which temperature and moisture content were the majol variables all samples were heat-treatec1 in 5deg steps alhishyharily selected over a range of 15deg to 75deg C Similarly in the expelishyInents in which temperatllre and time of hpatillg were the Imljor variables tempelature~ of 10deg el5deg GOdeg and 55deg were also arbitrn1ily selected

Three arieies of ice wen lIsCd ill chI expclill1ents-Sel (if~2fi-H Hexol() alld Zellith (htbll 1) Sel GI-ni-B i a lrip(y declopec1 at (he 11ice ExpelinH~lIt ~tatioll Crowley La (Joc1on and De La HOllssaye B8)

Dnta from representative experimen(-s ale given in (-ables 2-fl 1he PCICllItagps of s(l(I gCllIlillating IIC given only for Sfllllplcs tested 32 weeks from the dal-c of heat hpahnellt Onc reason Ol this plltill presentatjon oJ c1ntn is (-hnt no appreciable di Ilerences ere observe in the germinatioll capacities or seed between the 8- and 32-c peri ods of sto mge (2+deg-26 deg 0)

EFFECTS OF HEAT lREArMJ~NT ON THE VIABILITY OF RICE 13

PltABLE 2-Gelmiddotmination of 1ougk rice altel lwat tJcatment at ditfeent i bullbull-

~ tempelatUIC8 1950

SEL 6T-25-12

MoiRlurfmiddot IDUlution co I 1-0 I ~oo I ~~o noo contint of hput n- ~ I J I )~

(pPle(nt) tlatlll(nt trol c ( I C c -----middot--i-------middot--

Per- Per- Pr- IPershycelli cent Icelli Ctll

o 0 0 0

8g 1 ~ ____ ~_i _____ ~ ---S7T---g- g g

8i 1 0 0 1)0 82 1 0 90 77 0 0 89 86 70 0 89 87 39 0 )2 88 83 0 90 88 71 0 85 87 87 90 85 87 87 I 8-10 85 81 88 85i

86 S7 87 88

HEXOHO 1

I8shy1 79 62 02J3_______ 30 J I 86 I I

090 t60 88 88 8G 57 0 0

186_______ 80 89 92 89 87 8(i 0 ~ 85 IGO 89 88 89 81 73 0

J32 _______ ] 30 89 88 90 91 89 0 GO 85 89 87 87 Sri I 88 7G 0 0

J] L ______i 30 87 87 88 l 88 t 60 91 90 ---~~-l 88 l---~~-l 0 I I -=-~l 80

ZEXITH

~

2 I5 ___ ~___ 30

90 92 92 92 85 33 0 0

lG3_______ 30 92 I 85 1)3 1)1 91 92 36 0 shy106 _______ 30 j 93 91 92 92 02 I 84 78 0

~

--_

j

gt~lIJot IU

bull -~-

~

J

~

14 TECHNIcAl i3lJLLETIN 1129 1 S DEPT OF AGRICULTURE

TABLE 3-jJloislt7e contents of 8el OI-f35-1B rough 1icp S to 5 minutes aitel heat treatment at different te1np(J~ature8 1950 bull

TAllL -L-Ol )1 illatioll of 1(1010 I 0 Il[h Ufl IIh hlrd 1)Nt1I1fn t fol ditt(fent periorlN of time 1950

--- -~~- -~ ~- ------- ~- -------_ -~----~-

Tcmp~ratlllp bullof COIl- 10 20 30 40 50 Go 90 l20 treatmcut trol III ill Illin mi 11 min llIin min mi Il min(0 C)

PC1- p( r- fJu- P- ( r- Icl- Igtrr- Per- PIr-c(I C( III cot CUll CI1I1 CIII celli c(lIl cent

40__ bull_______ 05 Oi (1) )middot1 nmiddot1 f)middot1 93 93 n845 ___________ 50___________ nij n2 JmiddotI 9middot1 )(j 03 91 ))

JmiddotI J-I 02 0middot[ 93 08 n) nmiddot1 S-(55______ __~ -- 0middot1 08 JI no J2 n8 ss 85__--_ -- -ILot Ra

TABLE G-Ellert of t illll (dllmtioJl) oj h((t t reament at iF) O on the flel11illatioll of Nldoro 1 ough icc aIc) 5 7 lO and J~ days1950

-~~---- ------- - -~~-- - -~~-

Duration of IHnt trcatnwnt ij daYllt 7 day I () dly~ 1middot1 cbtYllt Total(miuute)

-------------~

1gt11(( nl p( 111 (((1I1 1(1111 PelllIII ControL~ III 1 ()gt HJ 10~ 75 16 2 I BJ 20~ oX 21 middot1 0 )830__ (jmiddot1 ItI Ii 2 UIWbull _ H3 23 3 I no50 16 an J I l2 bull60bull i)1 ]i 5 2 03no_ 40 7 10 88120__ 87 an 10 2 85 --lt---~

IIot R3

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

1129 U S DEPT OF AGRICULTURE

reached the temperilture of the bath 3 to 10 test tubes were withdrtwm every 10 minutcs for periods of 60 to 120 minutes This procedllre was repeated for each of 4 temperatures spaced at 50 intervals in 1950 and 1951 and for each of 7 temperatules spaced at 3 0 intervals in 1952

In all experiments -whenever a set of completely submerged test tubes was removed from a giyen bath the surfaces of the test tubes were quickly dried llld the contents -were composited in a small abshysorbent paper tray consisting of four thicknesses of paper toweling Rice from leakv test tubes and from te~t tubes filted with thermoshycouples vas discarded A moisture determinaUon yas made when the composited sample yeighed 75 gm or more (contcnts of 8 to 14 test tubes) It WfiS made ythin 2 1-0 5 minutes of emptying the test tubes depending upon the number of test tnbes lind the loeaHon of j-he moisshyture tester Immediatelv after tlle moisture determination was made the rice was sprenc1 in tile tray and plncecl in 1 sheltered location to

-air-dry at the ]1reyailing atmospheric temperature Yhen dly-14shypercent moisture contcn1- or lower-the rice yas emptied from the tray into a small coded paper hag

At the conclusion of the lilhl work each season these bags of treated samples and controls ere fonmlc1ed to the Southern Regional Reshysearch Laborfitory llW Orleans La tmel storrcl at 2~0_2(jO 0 Gershymination tests Yele l1I11 on eneh Sflmp 1r S IG 2middotk and 32 weeks after the clate of treatment

DETERMINATION OF lHOISTU1U~ CONTENT

The moisture (onteni of the lough rice in Ill( range of 10 to gO percent was c1etellnined itll n S1einli1r Jroi~tuJ( T(~1-PJJ This i11shystrumentwns conwnient to use in the fi(gt1ltl and was (alihrntecl ench season aga inst the ortecl-clrn ft oYen mltll)(l 101 (Hplm ining thr moisture conielltin the higher rnnge Samplcs helirYlrl to contain less thnn 10 pClcrnt of moisture Pre srnlpd in 1pst t11bes and returned to the Soutlwrn Regional Hp~e[r(h LnbolutolY here their respecshytive Illoistlne toMents Wle determined by a forcrcl-cllaft ocn method In this mdhoc1lhe samples er(gt hra1((i at 101 0 C ot Hi homs in tl

forced-chaft oen reYrighecl ancl tl]( loss ill weight WlIS ca1clllated ns moisture content on nlr pt bnsi~ Snmplr~ 01 10- toI2-ppltent moisture content yen sometimes similarly checked Allm01sturB contents ere lrpolteel on a wpi basis and 011 cCnn((l 8(((1

DETERMINATION OF IUCE TEMPERATURE DUIUNG HEAT TREATMENT

The temperntlll( of tlll rough Iicl in flIt eloslltl (si jubCs nncllhl thne tlken for it to lPHch the rlllplratlln of the bath (IP cl(terlllilled by means of thcII1l0C0uples 111 ctell of two tpst tubrs 1)(1 batll an jlOI1-constmtnn thermocouple was pushed ((n1Tall) in1o the packed rICe for 1 to 112 il1cll(s Each fllCI11l0lollplc lead extllll1rd above the water through a long glnss tube which was Jilted into tt rubber stopshy

bull rll( mention of 111[1(gt )Ioc1l1ds 01 (olllJ1f1ni(gts [lops not illlply that they nrc (11(101(d hy nIl p ~ TlP]JIIItllHlIt oj lIi(lIlllln 01(gt1 illlilnl ]llo(lll(l or eOIll shy

bull

bull

bull]Hll1itH not 111(gt111 iOlltl1

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 11

per Leads from the test tubes in the different baths were connected to a mUltiple switch and tIlls in turn to a potentiometer Potentiometer readings yere cOllverted to temperature readings by Ineans of a chart

WATER BATHS

AU the water batlls were of homemade constrllcHon Nine plain cylindrical heat-reRistant jars 12 by 12 inches yere each insulated sides and bottom 1ilh one-fonrth-iuch sheet asbestos They were placed on one-half-inell insulation bO1ld on n specially constructed combination platforl1J and rack Accessory equipment compactly turanged at the back of each bath consisted of t relay mounting bracket two f1exible immersion heaters a bimetn11ic thermoregulator a thell110metel and a stirrer yith pulley mounted at the top of its shaft Stirrer pulleys connected in series to a speed-redncer pulley and elliv-en by an electric motor permitted uniform and 00ntinuous agitation of the ~-atel in all brlths A set of six water baths is shown in Iigure 1

bull F1GLnE I-A StriC3 of the 1111 hath uord in the heat II(all1lent or rough rice

Test tubcs of ]1((gt tn 1Jl sllb11lcrg-ec1 wcre plaled in lest-tube baskets oJ nOllc()lI)~ingt ile each of whilh was ploYided with an elongated hook for nthtdlll1Cnt to the edge of thp bath Each balh was almost coYced dUlmiddotjllg OPC1htion by a olw-middotfol1lth-inch complcssed-bonrd eove1

DETERMINATION OF PRESSURES IN STOPPERED TUBES

bull Simultaneonsly witl1 each heat-treatment experiment in 1052 manoshy

metric measlIremelltmiddots wee made of the tohtl prcssUles clenloped in a test tube 01 rough 11(( in cach bath The llessllrC-l11eHsllling device (onsisjed of Hll 0pllI-end I1IHllOllletel on( end of h ieh wus Iitted into a rice-filled t(st hlhe b 111(111 of a lllbber stoppel Eneh mlnometel was equipped with t1 nllleurj le~elT(jir and a leveling tube which perm itted 1 constant yolulIIC 10 be mn intninecl during 1 heating expel jille n t

A typical experiment consisted in filling the test tube carefully tightJy packing the rice fitting the lnanometm in the test tube by

12 T]~CfLJCAL BULLETiN 1129 U S- DEPT OF AGHICULTUHE

means of the rubber stopper and then submerging the test tube in bull the water bath J usi prior to submergence of the test tube howeyel the mercury leveling tube was adjusted to bring the enclosed system to constant volume and the initial pressure was recorded Dudng the courSe of an experiment in which 8 minutes were allowed fol the test lube and contellt to attain the tempprature of the Im(-h and 10 minutes fol the actioll of heat of a given temperatme the nlallOlneter

- WflS open to the rice at all tilllPS and was adjusted so as to maintain a constant volume in the enclosed system The tobJ pressures reshysulting f1om the expansion of free ail and the vnpor wele recorded every 5 minutes of the 30-minute period in terms of centimeters of Inercury

GERMINATION TESTS

81ed glllJ1inatioll hS(H welp cOl1l1i1etelt1 by fhe nwtho(ll)lpsnibecl by (he FeltlelHl ~eed (t (Y 85) FOllr hlllltlrld HeE-ds from ladl sample were germinated in replicahs of 100 behHl1I byers of moist paper toelillg They -ere glrminattltl 1+ clays in the dark ill a watershycudnin type gell11inator that as automatictlly and thermoshystatjcnlly controlled It was spt to opelllte at alternating temperashytures of 20deg C for 8 hOllrs and 3()0 for lCi hOllrs Counts ere made on each sample on the 5th 7th lOth and1+th days A germinating seed was counted only if it had both a root and a shoot and only if one of these stluctl1les was at least olle-fourth inch long Germinated shyseeds wpre disCal(lld at the time of cOllnting

The terl1ls gelmination capacity and ftelminntion vigor lle used throllplwllt the IHlllr-in to n~f(gtr to total germination ana rntc of germination llspeetilly

HEATmiddotTUEATlVIENT EXPEIUlIENTS IN 1950

The investigafiolls in l)iO wer( stalec1 withollt l priori knowlpclge of the efreds of heat Oil the iabilitv of Iollgh Ii(( h(11 hpa- itS applied according to the expelimenttil cOllditl(lIIs ltINclibed HenCc in the experiments in which temperature and moisture content were the majol variables all samples were heat-treatec1 in 5deg steps alhishyharily selected over a range of 15deg to 75deg C Similarly in the expelishyInents in which temperatllre and time of hpatillg were the Imljor variables tempelature~ of 10deg el5deg GOdeg and 55deg were also arbitrn1ily selected

Three arieies of ice wen lIsCd ill chI expclill1ents-Sel (if~2fi-H Hexol() alld Zellith (htbll 1) Sel GI-ni-B i a lrip(y declopec1 at (he 11ice ExpelinH~lIt ~tatioll Crowley La (Joc1on and De La HOllssaye B8)

Dnta from representative experimen(-s ale given in (-ables 2-fl 1he PCICllItagps of s(l(I gCllIlillating IIC given only for Sfllllplcs tested 32 weeks from the dal-c of heat hpahnellt Onc reason Ol this plltill presentatjon oJ c1ntn is (-hnt no appreciable di Ilerences ere observe in the germinatioll capacities or seed between the 8- and 32-c peri ods of sto mge (2+deg-26 deg 0)

EFFECTS OF HEAT lREArMJ~NT ON THE VIABILITY OF RICE 13

PltABLE 2-Gelmiddotmination of 1ougk rice altel lwat tJcatment at ditfeent i bullbull-

~ tempelatUIC8 1950

SEL 6T-25-12

MoiRlurfmiddot IDUlution co I 1-0 I ~oo I ~~o noo contint of hput n- ~ I J I )~

(pPle(nt) tlatlll(nt trol c ( I C c -----middot--i-------middot--

Per- Per- Pr- IPershycelli cent Icelli Ctll

o 0 0 0

8g 1 ~ ____ ~_i _____ ~ ---S7T---g- g g

8i 1 0 0 1)0 82 1 0 90 77 0 0 89 86 70 0 89 87 39 0 )2 88 83 0 90 88 71 0 85 87 87 90 85 87 87 I 8-10 85 81 88 85i

86 S7 87 88

HEXOHO 1

I8shy1 79 62 02J3_______ 30 J I 86 I I

090 t60 88 88 8G 57 0 0

186_______ 80 89 92 89 87 8(i 0 ~ 85 IGO 89 88 89 81 73 0

J32 _______ ] 30 89 88 90 91 89 0 GO 85 89 87 87 Sri I 88 7G 0 0

J] L ______i 30 87 87 88 l 88 t 60 91 90 ---~~-l 88 l---~~-l 0 I I -=-~l 80

ZEXITH

~

2 I5 ___ ~___ 30

90 92 92 92 85 33 0 0

lG3_______ 30 92 I 85 1)3 1)1 91 92 36 0 shy106 _______ 30 j 93 91 92 92 02 I 84 78 0

~

--_

j

gt~lIJot IU

bull -~-

~

J

~

14 TECHNIcAl i3lJLLETIN 1129 1 S DEPT OF AGRICULTURE

TABLE 3-jJloislt7e contents of 8el OI-f35-1B rough 1icp S to 5 minutes aitel heat treatment at different te1np(J~ature8 1950 bull

TAllL -L-Ol )1 illatioll of 1(1010 I 0 Il[h Ufl IIh hlrd 1)Nt1I1fn t fol ditt(fent periorlN of time 1950

--- -~~- -~ ~- ------- ~- -------_ -~----~-

Tcmp~ratlllp bullof COIl- 10 20 30 40 50 Go 90 l20 treatmcut trol III ill Illin mi 11 min llIin min mi Il min(0 C)

PC1- p( r- fJu- P- ( r- Icl- Igtrr- Per- PIr-c(I C( III cot CUll CI1I1 CIII celli c(lIl cent

40__ bull_______ 05 Oi (1) )middot1 nmiddot1 f)middot1 93 93 n845 ___________ 50___________ nij n2 JmiddotI 9middot1 )(j 03 91 ))

JmiddotI J-I 02 0middot[ 93 08 n) nmiddot1 S-(55______ __~ -- 0middot1 08 JI no J2 n8 ss 85__--_ -- -ILot Ra

TABLE G-Ellert of t illll (dllmtioJl) oj h((t t reament at iF) O on the flel11illatioll of Nldoro 1 ough icc aIc) 5 7 lO and J~ days1950

-~~---- ------- - -~~-- - -~~-

Duration of IHnt trcatnwnt ij daYllt 7 day I () dly~ 1middot1 cbtYllt Total(miuute)

-------------~

1gt11(( nl p( 111 (((1I1 1(1111 PelllIII ControL~ III 1 ()gt HJ 10~ 75 16 2 I BJ 20~ oX 21 middot1 0 )830__ (jmiddot1 ItI Ii 2 UIWbull _ H3 23 3 I no50 16 an J I l2 bull60bull i)1 ]i 5 2 03no_ 40 7 10 88120__ 87 an 10 2 85 --lt---~

IIot R3

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 11

per Leads from the test tubes in the different baths were connected to a mUltiple switch and tIlls in turn to a potentiometer Potentiometer readings yere cOllverted to temperature readings by Ineans of a chart

WATER BATHS

AU the water batlls were of homemade constrllcHon Nine plain cylindrical heat-reRistant jars 12 by 12 inches yere each insulated sides and bottom 1ilh one-fonrth-iuch sheet asbestos They were placed on one-half-inell insulation bO1ld on n specially constructed combination platforl1J and rack Accessory equipment compactly turanged at the back of each bath consisted of t relay mounting bracket two f1exible immersion heaters a bimetn11ic thermoregulator a thell110metel and a stirrer yith pulley mounted at the top of its shaft Stirrer pulleys connected in series to a speed-redncer pulley and elliv-en by an electric motor permitted uniform and 00ntinuous agitation of the ~-atel in all brlths A set of six water baths is shown in Iigure 1

bull F1GLnE I-A StriC3 of the 1111 hath uord in the heat II(all1lent or rough rice

Test tubcs of ]1((gt tn 1Jl sllb11lcrg-ec1 wcre plaled in lest-tube baskets oJ nOllc()lI)~ingt ile each of whilh was ploYided with an elongated hook for nthtdlll1Cnt to the edge of thp bath Each balh was almost coYced dUlmiddotjllg OPC1htion by a olw-middotfol1lth-inch complcssed-bonrd eove1

DETERMINATION OF PRESSURES IN STOPPERED TUBES

bull Simultaneonsly witl1 each heat-treatment experiment in 1052 manoshy

metric measlIremelltmiddots wee made of the tohtl prcssUles clenloped in a test tube 01 rough 11(( in cach bath The llessllrC-l11eHsllling device (onsisjed of Hll 0pllI-end I1IHllOllletel on( end of h ieh wus Iitted into a rice-filled t(st hlhe b 111(111 of a lllbber stoppel Eneh mlnometel was equipped with t1 nllleurj le~elT(jir and a leveling tube which perm itted 1 constant yolulIIC 10 be mn intninecl during 1 heating expel jille n t

A typical experiment consisted in filling the test tube carefully tightJy packing the rice fitting the lnanometm in the test tube by

12 T]~CfLJCAL BULLETiN 1129 U S- DEPT OF AGHICULTUHE

means of the rubber stopper and then submerging the test tube in bull the water bath J usi prior to submergence of the test tube howeyel the mercury leveling tube was adjusted to bring the enclosed system to constant volume and the initial pressure was recorded Dudng the courSe of an experiment in which 8 minutes were allowed fol the test lube and contellt to attain the tempprature of the Im(-h and 10 minutes fol the actioll of heat of a given temperatme the nlallOlneter

- WflS open to the rice at all tilllPS and was adjusted so as to maintain a constant volume in the enclosed system The tobJ pressures reshysulting f1om the expansion of free ail and the vnpor wele recorded every 5 minutes of the 30-minute period in terms of centimeters of Inercury

GERMINATION TESTS

81ed glllJ1inatioll hS(H welp cOl1l1i1etelt1 by fhe nwtho(ll)lpsnibecl by (he FeltlelHl ~eed (t (Y 85) FOllr hlllltlrld HeE-ds from ladl sample were germinated in replicahs of 100 behHl1I byers of moist paper toelillg They -ere glrminattltl 1+ clays in the dark ill a watershycudnin type gell11inator that as automatictlly and thermoshystatjcnlly controlled It was spt to opelllte at alternating temperashytures of 20deg C for 8 hOllrs and 3()0 for lCi hOllrs Counts ere made on each sample on the 5th 7th lOth and1+th days A germinating seed was counted only if it had both a root and a shoot and only if one of these stluctl1les was at least olle-fourth inch long Germinated shyseeds wpre disCal(lld at the time of cOllnting

The terl1ls gelmination capacity and ftelminntion vigor lle used throllplwllt the IHlllr-in to n~f(gtr to total germination ana rntc of germination llspeetilly

HEATmiddotTUEATlVIENT EXPEIUlIENTS IN 1950

The investigafiolls in l)iO wer( stalec1 withollt l priori knowlpclge of the efreds of heat Oil the iabilitv of Iollgh Ii(( h(11 hpa- itS applied according to the expelimenttil cOllditl(lIIs ltINclibed HenCc in the experiments in which temperature and moisture content were the majol variables all samples were heat-treatec1 in 5deg steps alhishyharily selected over a range of 15deg to 75deg C Similarly in the expelishyInents in which temperatllre and time of hpatillg were the Imljor variables tempelature~ of 10deg el5deg GOdeg and 55deg were also arbitrn1ily selected

Three arieies of ice wen lIsCd ill chI expclill1ents-Sel (if~2fi-H Hexol() alld Zellith (htbll 1) Sel GI-ni-B i a lrip(y declopec1 at (he 11ice ExpelinH~lIt ~tatioll Crowley La (Joc1on and De La HOllssaye B8)

Dnta from representative experimen(-s ale given in (-ables 2-fl 1he PCICllItagps of s(l(I gCllIlillating IIC given only for Sfllllplcs tested 32 weeks from the dal-c of heat hpahnellt Onc reason Ol this plltill presentatjon oJ c1ntn is (-hnt no appreciable di Ilerences ere observe in the germinatioll capacities or seed between the 8- and 32-c peri ods of sto mge (2+deg-26 deg 0)

EFFECTS OF HEAT lREArMJ~NT ON THE VIABILITY OF RICE 13

PltABLE 2-Gelmiddotmination of 1ougk rice altel lwat tJcatment at ditfeent i bullbull-

~ tempelatUIC8 1950

SEL 6T-25-12

MoiRlurfmiddot IDUlution co I 1-0 I ~oo I ~~o noo contint of hput n- ~ I J I )~

(pPle(nt) tlatlll(nt trol c ( I C c -----middot--i-------middot--

Per- Per- Pr- IPershycelli cent Icelli Ctll

o 0 0 0

8g 1 ~ ____ ~_i _____ ~ ---S7T---g- g g

8i 1 0 0 1)0 82 1 0 90 77 0 0 89 86 70 0 89 87 39 0 )2 88 83 0 90 88 71 0 85 87 87 90 85 87 87 I 8-10 85 81 88 85i

86 S7 87 88

HEXOHO 1

I8shy1 79 62 02J3_______ 30 J I 86 I I

090 t60 88 88 8G 57 0 0

186_______ 80 89 92 89 87 8(i 0 ~ 85 IGO 89 88 89 81 73 0

J32 _______ ] 30 89 88 90 91 89 0 GO 85 89 87 87 Sri I 88 7G 0 0

J] L ______i 30 87 87 88 l 88 t 60 91 90 ---~~-l 88 l---~~-l 0 I I -=-~l 80

ZEXITH

~

2 I5 ___ ~___ 30

90 92 92 92 85 33 0 0

lG3_______ 30 92 I 85 1)3 1)1 91 92 36 0 shy106 _______ 30 j 93 91 92 92 02 I 84 78 0

~

--_

j

gt~lIJot IU

bull -~-

~

J

~

14 TECHNIcAl i3lJLLETIN 1129 1 S DEPT OF AGRICULTURE

TABLE 3-jJloislt7e contents of 8el OI-f35-1B rough 1icp S to 5 minutes aitel heat treatment at different te1np(J~ature8 1950 bull

TAllL -L-Ol )1 illatioll of 1(1010 I 0 Il[h Ufl IIh hlrd 1)Nt1I1fn t fol ditt(fent periorlN of time 1950

--- -~~- -~ ~- ------- ~- -------_ -~----~-

Tcmp~ratlllp bullof COIl- 10 20 30 40 50 Go 90 l20 treatmcut trol III ill Illin mi 11 min llIin min mi Il min(0 C)

PC1- p( r- fJu- P- ( r- Icl- Igtrr- Per- PIr-c(I C( III cot CUll CI1I1 CIII celli c(lIl cent

40__ bull_______ 05 Oi (1) )middot1 nmiddot1 f)middot1 93 93 n845 ___________ 50___________ nij n2 JmiddotI 9middot1 )(j 03 91 ))

JmiddotI J-I 02 0middot[ 93 08 n) nmiddot1 S-(55______ __~ -- 0middot1 08 JI no J2 n8 ss 85__--_ -- -ILot Ra

TABLE G-Ellert of t illll (dllmtioJl) oj h((t t reament at iF) O on the flel11illatioll of Nldoro 1 ough icc aIc) 5 7 lO and J~ days1950

-~~---- ------- - -~~-- - -~~-

Duration of IHnt trcatnwnt ij daYllt 7 day I () dly~ 1middot1 cbtYllt Total(miuute)

-------------~

1gt11(( nl p( 111 (((1I1 1(1111 PelllIII ControL~ III 1 ()gt HJ 10~ 75 16 2 I BJ 20~ oX 21 middot1 0 )830__ (jmiddot1 ItI Ii 2 UIWbull _ H3 23 3 I no50 16 an J I l2 bull60bull i)1 ]i 5 2 03no_ 40 7 10 88120__ 87 an 10 2 85 --lt---~

IIot R3

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

12 T]~CfLJCAL BULLETiN 1129 U S- DEPT OF AGHICULTUHE

means of the rubber stopper and then submerging the test tube in bull the water bath J usi prior to submergence of the test tube howeyel the mercury leveling tube was adjusted to bring the enclosed system to constant volume and the initial pressure was recorded Dudng the courSe of an experiment in which 8 minutes were allowed fol the test lube and contellt to attain the tempprature of the Im(-h and 10 minutes fol the actioll of heat of a given temperatme the nlallOlneter

- WflS open to the rice at all tilllPS and was adjusted so as to maintain a constant volume in the enclosed system The tobJ pressures reshysulting f1om the expansion of free ail and the vnpor wele recorded every 5 minutes of the 30-minute period in terms of centimeters of Inercury

GERMINATION TESTS

81ed glllJ1inatioll hS(H welp cOl1l1i1etelt1 by fhe nwtho(ll)lpsnibecl by (he FeltlelHl ~eed (t (Y 85) FOllr hlllltlrld HeE-ds from ladl sample were germinated in replicahs of 100 behHl1I byers of moist paper toelillg They -ere glrminattltl 1+ clays in the dark ill a watershycudnin type gell11inator that as automatictlly and thermoshystatjcnlly controlled It was spt to opelllte at alternating temperashytures of 20deg C for 8 hOllrs and 3()0 for lCi hOllrs Counts ere made on each sample on the 5th 7th lOth and1+th days A germinating seed was counted only if it had both a root and a shoot and only if one of these stluctl1les was at least olle-fourth inch long Germinated shyseeds wpre disCal(lld at the time of cOllnting

The terl1ls gelmination capacity and ftelminntion vigor lle used throllplwllt the IHlllr-in to n~f(gtr to total germination ana rntc of germination llspeetilly

HEATmiddotTUEATlVIENT EXPEIUlIENTS IN 1950

The investigafiolls in l)iO wer( stalec1 withollt l priori knowlpclge of the efreds of heat Oil the iabilitv of Iollgh Ii(( h(11 hpa- itS applied according to the expelimenttil cOllditl(lIIs ltINclibed HenCc in the experiments in which temperature and moisture content were the majol variables all samples were heat-treatec1 in 5deg steps alhishyharily selected over a range of 15deg to 75deg C Similarly in the expelishyInents in which temperatllre and time of hpatillg were the Imljor variables tempelature~ of 10deg el5deg GOdeg and 55deg were also arbitrn1ily selected

Three arieies of ice wen lIsCd ill chI expclill1ents-Sel (if~2fi-H Hexol() alld Zellith (htbll 1) Sel GI-ni-B i a lrip(y declopec1 at (he 11ice ExpelinH~lIt ~tatioll Crowley La (Joc1on and De La HOllssaye B8)

Dnta from representative experimen(-s ale given in (-ables 2-fl 1he PCICllItagps of s(l(I gCllIlillating IIC given only for Sfllllplcs tested 32 weeks from the dal-c of heat hpahnellt Onc reason Ol this plltill presentatjon oJ c1ntn is (-hnt no appreciable di Ilerences ere observe in the germinatioll capacities or seed between the 8- and 32-c peri ods of sto mge (2+deg-26 deg 0)

EFFECTS OF HEAT lREArMJ~NT ON THE VIABILITY OF RICE 13

PltABLE 2-Gelmiddotmination of 1ougk rice altel lwat tJcatment at ditfeent i bullbull-

~ tempelatUIC8 1950

SEL 6T-25-12

MoiRlurfmiddot IDUlution co I 1-0 I ~oo I ~~o noo contint of hput n- ~ I J I )~

(pPle(nt) tlatlll(nt trol c ( I C c -----middot--i-------middot--

Per- Per- Pr- IPershycelli cent Icelli Ctll

o 0 0 0

8g 1 ~ ____ ~_i _____ ~ ---S7T---g- g g

8i 1 0 0 1)0 82 1 0 90 77 0 0 89 86 70 0 89 87 39 0 )2 88 83 0 90 88 71 0 85 87 87 90 85 87 87 I 8-10 85 81 88 85i

86 S7 87 88

HEXOHO 1

I8shy1 79 62 02J3_______ 30 J I 86 I I

090 t60 88 88 8G 57 0 0

186_______ 80 89 92 89 87 8(i 0 ~ 85 IGO 89 88 89 81 73 0

J32 _______ ] 30 89 88 90 91 89 0 GO 85 89 87 87 Sri I 88 7G 0 0

J] L ______i 30 87 87 88 l 88 t 60 91 90 ---~~-l 88 l---~~-l 0 I I -=-~l 80

ZEXITH

~

2 I5 ___ ~___ 30

90 92 92 92 85 33 0 0

lG3_______ 30 92 I 85 1)3 1)1 91 92 36 0 shy106 _______ 30 j 93 91 92 92 02 I 84 78 0

~

--_

j

gt~lIJot IU

bull -~-

~

J

~

14 TECHNIcAl i3lJLLETIN 1129 1 S DEPT OF AGRICULTURE

TABLE 3-jJloislt7e contents of 8el OI-f35-1B rough 1icp S to 5 minutes aitel heat treatment at different te1np(J~ature8 1950 bull

TAllL -L-Ol )1 illatioll of 1(1010 I 0 Il[h Ufl IIh hlrd 1)Nt1I1fn t fol ditt(fent periorlN of time 1950

--- -~~- -~ ~- ------- ~- -------_ -~----~-

Tcmp~ratlllp bullof COIl- 10 20 30 40 50 Go 90 l20 treatmcut trol III ill Illin mi 11 min llIin min mi Il min(0 C)

PC1- p( r- fJu- P- ( r- Icl- Igtrr- Per- PIr-c(I C( III cot CUll CI1I1 CIII celli c(lIl cent

40__ bull_______ 05 Oi (1) )middot1 nmiddot1 f)middot1 93 93 n845 ___________ 50___________ nij n2 JmiddotI 9middot1 )(j 03 91 ))

JmiddotI J-I 02 0middot[ 93 08 n) nmiddot1 S-(55______ __~ -- 0middot1 08 JI no J2 n8 ss 85__--_ -- -ILot Ra

TABLE G-Ellert of t illll (dllmtioJl) oj h((t t reament at iF) O on the flel11illatioll of Nldoro 1 ough icc aIc) 5 7 lO and J~ days1950

-~~---- ------- - -~~-- - -~~-

Duration of IHnt trcatnwnt ij daYllt 7 day I () dly~ 1middot1 cbtYllt Total(miuute)

-------------~

1gt11(( nl p( 111 (((1I1 1(1111 PelllIII ControL~ III 1 ()gt HJ 10~ 75 16 2 I BJ 20~ oX 21 middot1 0 )830__ (jmiddot1 ItI Ii 2 UIWbull _ H3 23 3 I no50 16 an J I l2 bull60bull i)1 ]i 5 2 03no_ 40 7 10 88120__ 87 an 10 2 85 --lt---~

IIot R3

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

EFFECTS OF HEAT lREArMJ~NT ON THE VIABILITY OF RICE 13

PltABLE 2-Gelmiddotmination of 1ougk rice altel lwat tJcatment at ditfeent i bullbull-

~ tempelatUIC8 1950

SEL 6T-25-12

MoiRlurfmiddot IDUlution co I 1-0 I ~oo I ~~o noo contint of hput n- ~ I J I )~

(pPle(nt) tlatlll(nt trol c ( I C c -----middot--i-------middot--

Per- Per- Pr- IPershycelli cent Icelli Ctll

o 0 0 0

8g 1 ~ ____ ~_i _____ ~ ---S7T---g- g g

8i 1 0 0 1)0 82 1 0 90 77 0 0 89 86 70 0 89 87 39 0 )2 88 83 0 90 88 71 0 85 87 87 90 85 87 87 I 8-10 85 81 88 85i

86 S7 87 88

HEXOHO 1

I8shy1 79 62 02J3_______ 30 J I 86 I I

090 t60 88 88 8G 57 0 0

186_______ 80 89 92 89 87 8(i 0 ~ 85 IGO 89 88 89 81 73 0

J32 _______ ] 30 89 88 90 91 89 0 GO 85 89 87 87 Sri I 88 7G 0 0

J] L ______i 30 87 87 88 l 88 t 60 91 90 ---~~-l 88 l---~~-l 0 I I -=-~l 80

ZEXITH

~

2 I5 ___ ~___ 30

90 92 92 92 85 33 0 0

lG3_______ 30 92 I 85 1)3 1)1 91 92 36 0 shy106 _______ 30 j 93 91 92 92 02 I 84 78 0

~

--_

j

gt~lIJot IU

bull -~-

~

J

~

14 TECHNIcAl i3lJLLETIN 1129 1 S DEPT OF AGRICULTURE

TABLE 3-jJloislt7e contents of 8el OI-f35-1B rough 1icp S to 5 minutes aitel heat treatment at different te1np(J~ature8 1950 bull

TAllL -L-Ol )1 illatioll of 1(1010 I 0 Il[h Ufl IIh hlrd 1)Nt1I1fn t fol ditt(fent periorlN of time 1950

--- -~~- -~ ~- ------- ~- -------_ -~----~-

Tcmp~ratlllp bullof COIl- 10 20 30 40 50 Go 90 l20 treatmcut trol III ill Illin mi 11 min llIin min mi Il min(0 C)

PC1- p( r- fJu- P- ( r- Icl- Igtrr- Per- PIr-c(I C( III cot CUll CI1I1 CIII celli c(lIl cent

40__ bull_______ 05 Oi (1) )middot1 nmiddot1 f)middot1 93 93 n845 ___________ 50___________ nij n2 JmiddotI 9middot1 )(j 03 91 ))

JmiddotI J-I 02 0middot[ 93 08 n) nmiddot1 S-(55______ __~ -- 0middot1 08 JI no J2 n8 ss 85__--_ -- -ILot Ra

TABLE G-Ellert of t illll (dllmtioJl) oj h((t t reament at iF) O on the flel11illatioll of Nldoro 1 ough icc aIc) 5 7 lO and J~ days1950

-~~---- ------- - -~~-- - -~~-

Duration of IHnt trcatnwnt ij daYllt 7 day I () dly~ 1middot1 cbtYllt Total(miuute)

-------------~

1gt11(( nl p( 111 (((1I1 1(1111 PelllIII ControL~ III 1 ()gt HJ 10~ 75 16 2 I BJ 20~ oX 21 middot1 0 )830__ (jmiddot1 ItI Ii 2 UIWbull _ H3 23 3 I no50 16 an J I l2 bull60bull i)1 ]i 5 2 03no_ 40 7 10 88120__ 87 an 10 2 85 --lt---~

IIot R3

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

14 TECHNIcAl i3lJLLETIN 1129 1 S DEPT OF AGRICULTURE

TABLE 3-jJloislt7e contents of 8el OI-f35-1B rough 1icp S to 5 minutes aitel heat treatment at different te1np(J~ature8 1950 bull

TAllL -L-Ol )1 illatioll of 1(1010 I 0 Il[h Ufl IIh hlrd 1)Nt1I1fn t fol ditt(fent periorlN of time 1950

--- -~~- -~ ~- ------- ~- -------_ -~----~-

Tcmp~ratlllp bullof COIl- 10 20 30 40 50 Go 90 l20 treatmcut trol III ill Illin mi 11 min llIin min mi Il min(0 C)

PC1- p( r- fJu- P- ( r- Icl- Igtrr- Per- PIr-c(I C( III cot CUll CI1I1 CIII celli c(lIl cent

40__ bull_______ 05 Oi (1) )middot1 nmiddot1 f)middot1 93 93 n845 ___________ 50___________ nij n2 JmiddotI 9middot1 )(j 03 91 ))

JmiddotI J-I 02 0middot[ 93 08 n) nmiddot1 S-(55______ __~ -- 0middot1 08 JI no J2 n8 ss 85__--_ -- -ILot Ra

TABLE G-Ellert of t illll (dllmtioJl) oj h((t t reament at iF) O on the flel11illatioll of Nldoro 1 ough icc aIc) 5 7 lO and J~ days1950

-~~---- ------- - -~~-- - -~~-

Duration of IHnt trcatnwnt ij daYllt 7 day I () dly~ 1middot1 cbtYllt Total(miuute)

-------------~

1gt11(( nl p( 111 (((1I1 1(1111 PelllIII ControL~ III 1 ()gt HJ 10~ 75 16 2 I BJ 20~ oX 21 middot1 0 )830__ (jmiddot1 ItI Ii 2 UIWbull _ H3 23 3 I no50 16 an J I l2 bull60bull i)1 ]i 5 2 03no_ 40 7 10 88120__ 87 an 10 2 85 --lt---~

IIot R3

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

EFFECTS OF HEAT iiltEAT1vIENr ON THE VIABlLITY OF RICE 15

TElIPERATURE AND MOISTUREmiddotCONTENT VARIABLES

TabJe 2 shows that as the moisture content in rice decreases its reshysistance- to the dpstllIctiw action of heat increases In rough rice of 25- to 2G-percent moistnre content viability was completely destToyed in 30 minutes at (lOdeg C ~t ~5- to 7A-penent moistllre content there -as no indieation that gcgtlmination Cilpacity (totalg-elmillation) had been signifieantlv alreefed een uttil (jO minutes at7ideg

Saml)les with Ui- to U-peJcent moistlllmiddot(gt contellt lxhibited slightly Jess gell1Iillatioll igor (rate of cnnination I thnHIgllOU the stndThis~loss in ig01 a not obicHls hom the total (mInts made on tlie Jifth day of tIl(gt (llllination test blltit was in(Li(ated by shorter roots and shools than tJ)()s(gt possessed IJy tll(gt contlOl Also at I-his stage tlll mots were frequelltly 1I10lC de-elopecl than the shoots

TaLle2 flllilwl sIlO tll)t tlw range onI hi(h 11(gt1- exelts its deshysbudin ndion on Ii(e of a giclJ moistlllC cOlltent- dmillg exposllrcs of () Hl1(l GI) lllinutes is a nano one-about )_12deg C This range reshymains aboll the SHII1P iJul its position tlillels 011 the tempelatulcscale

bull

for Ii(( of (neh Illoistme content SeI GI-i-l U(XOlo and Zenith Ot (olTlspouclinl moistllre (onshy

tents d ispllycd a bout thl sa nl(gt dtgrlt of IPsistn Il(e to heat They may ltIi fl(l in their llsistalHe to hpat but lhlsC lxl)(gtrilllelJis Ire not cOllsiclshy(red adrql1ale to estaltljmiddoth this valmiddotitble ~[OIlO(gtI soil and other shy(lwilOnlJlental nUinblps well lJot pstablislteltl Th( wed of each -

Ya riety was I acki II sl igl t h ill un i 101111 it as shown br the elllIi nation testsen illdiidlltl sll11ples of the nir-cili(gtcl (ontlois A number of t(st were Jlwlt1l on the ail-illierL contlols at int(l-als of H Hi 2-1- and 52 weeks Thp middotinbility eOllnt- (pel((gtntages) 101 HeI fiI-2i-12 tor these intelnls aemgetl ~87 HRH ~iLi and HUa 1ls)petively foJ TIlXOIO 8~H Kii-l til I lllld Si7 nnd fOl Z(l1ith DO D26 927 and

bull

fJ Hi StoPIWIing- tl1(gt t(st tuhes o-f rice JlClut(gt(l ll1oishll(gt lossls dUJing the

period of henting foistlllP contCnl-s of (PIll samples of Sel ([-2i-12 (hrPI1l1illC(1 hOlth II ftPllIPal I lpaflll(llt tl( iYen in tnble =3-Thp data aI( typ i(a I () r hm lhhl iIWrl th l(lugiloll I I h s(middotnson Gna test lossps (W(Urlpel flf)lIl Ihos( 1alllpl(s that oligin 11 llad Ihpoundgt highpstshyIIlOi-fIIlP ((JlltPllt nud also FIOIll Ihmil thnt hnd I)((n lXPO(middotc] to tile h ighpsi t Pill pPImiddotafuIPs TIll gl tpst Ins unclolllJt pelly O((IIlllc1 when till wn11ll rlcC WI lxp()s([l to 11I dnl()pIHmiddotI lsHall =j toi millutes Clapwd dUling tilp (Illptying luixing PIghill and 1ll0ittlll mete I Ipadillg of a SHlllpll Illi_~lrt ill (xjJ((jed -nnlplps initinlly (ontainshying from aii to ~~ 1gt(1((gtlIt of ll1ois[III( IOit IY littl i I ally moisture dlllmiddotjng this pClmiddotiod The llloishlle-(onlCnt -alllts rpcoldld aftel heat trea t-ment SeIT( Oil I to illo th t t lrelC (mild not ha rc b(pn m ueh chnngt in moisture olltpnt of the rice ill the t(sf tllbCs dllling heat tl(gtntlllenL TIHY do nol- 1((]pC1 tllP 11] 0 i-I II 1( p(Jllilibliull1 conditiolls wi I hill tlw elo(gt(l Ipst IIII IPS t hI it Iill t i OilS ill PI(SIII( anet -Hlch eha ngls as t-iH reditrihution of til(gt llloist Ull within tI uiwlI sped and behrePII seNls in rhp lIlass

TEJUPEHATURE AND TlME VARIABLES

VIIPII sarnpts of Hpoundgtxolo of Hlmiddotperc(llt Illoist 111( NJllt(1If (gtIe heatshy -

tlcatPd TOtmiddot p(gtIiod~ of LO to 120 nlinllttR trcy all (xl1ibit(( niJont the

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

16 lECfulICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

same germination capacity except the two samples beat-treated for 120 minutes at 50deg aml 55deg C respectively Tab]e 4 indicate(J that 10 to bull 120 minutes of heating at 40deg 45deg 50deg and 55deg with the exceptions J10ted did not affect the germination cnpacity of the rice

However on the basis of germination vigor hent damage waS moro extensive thnn is shon in table 4 A11 snmpies hent-treated at 55deg C were retarded in their rnte of germination (table 5) One sample of the Jot heat-treated for 120 minutes at 50deg also exhibited a germination 1a

Data similar to those riven in tnb1es 4 and 5 were nlso obtained with Zenith (lot Z3) and Hexoro (lot H5) nt moisture contents of 16 and 21H percent respectively The highest temper1ltllre 5deg C used in Ill( U)im time-temperat1lre stlHlies bl01Ight abollt some impairnwnt of til( germination vigor (table 5) particularly in the samples exposed for )O nncl120 minllteR In general thp tteiltN1 samples on testing did not satisfactorily illustrate a proglpssive dlcrlasein germination capacity withincrensing temperature and time of tteatment (table 4) They did illustTajp thnt ri(l of 1 iplI nloillIrp (onl(nt (ould withshystand prolonged heating (to 12h minlltes) at some temperahues withOllt Joss in germination capacily and even without loss in germishynation vigor filey 111111)(1 illuRITatcd that los of gennination igor is t more sensilive IIwasure of hpnt damal n11n loss of ermination capacity In othpl words decreasps in germination YigOl may be detected a l lowel fPnll)lratlIres Ihan c1eereaRpR i n ~ellll ina I ion ea pa( i I)

Additional partin1 cOllfirmntion of the ime-telllperahlrc clata are contained in middottable 2 In Ihis table it is eiden tllnt a GO-minute bull heat-treatment period diel not exed any greatel cefTimpnhtl aetimiddotity on germination capiHity than a O-nlinute period excppt when the expoSllre was al a llllIpelltllre Ihat fpII within Ihe IlUIO rallgc c1nmagin~ to rice of n gi(~n moistllre content

HEATmiddotTREATMENT EXPEIUMENTS IN 1951

SineI Yerifieatioll of thp 1Il findings wa c1(Rired the expelin)(nhl in ID5l middotwen simi1u 10 tllOe of Ihe 1)J((eclillg year Two major experiments en planMd ill glpatcr (Ittail Ill c1(monITatl the (fleelR of lelllpelahI ll of Iwaling on the viability of riel of difler(nt moistllp contents and of time of hlatinr 011 Ii(( of a ~inn moiRtllle eontent In addition a third experimentnls plalllHltl t() how t11p enects of heat tleatment on the viability of rice of c1ifieJ(nt maturities

Minor ehnn~es Y(l(nlnc1p in thp J)50 1)lOcpdull Theintenals betmiddotwpen tpmpertIur(s of tlpntment (1( decllasltl flOnt 5deg to 8deg O Nine sampleR of eltleh bnteh of rough rice of a g-ien moishlle con 1(11 I were treated inslend of SpPII as in tltp plwCdillg yea (table 2) The overall temperlllllC ange waS seleetCt on Ill( basis of Ihp l1Ioi8tlll( content of the Ii(( and fcll Hlost blllehes PXltpt tll( driest ltllllollnled to 25deg The1dor( the low the I1loisture lonfpnl 01 Ihp rice the

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE

higher its temperatures (25deg range) of treatment As nn illustration Bluebonnet (lot BB1) with a moisture content of 252 percent was heat-treated at temperatures of 46deg-70deg with 176 percentat 55deg-790 and with 107 percent at 61 deg_85deg

An endeavor was made to select temperatures of treatment for rice of each moisture content so that the lower temperatures would 110t have any effect on viability whereas the higher ones would bril1g about its destruction These changes to a sliding temperature scale nnd 3deg infelvals of treatUlPllt wele made in the hope that the results wOllld permit a closeI approximation of the tempemtures at which destruction of germination (viability) just started and at which it was just complete

An test tubps of lOIIh rice were llloed 8 minutes to reaeh the temperature of the bad It was ohselYed in following the potenshytiometer readings in the previons seasons ex peri ments that the time for the rice in the fest tubes to reach the temperiltures of their respecshytive baths did not 1) greatlY for the di fleltnt temperatnresinvestishygated MOreOVlL the germination t-est data in tables 2 and 4 indicated that 2 01 3 minutes Imdel 01 in exeess of the true time would probably ]10t have any appre(iable (freet on gelminability

bull Bluebonllet and Se1 6I-J5-12 WlIe IIsed in the 11)31 experiments

(table 1) The Bluebonnet is 011e of the early releases of the RiceshyPasturc Expelintent Stat~oll Beaumont Tex alldis referred to locally as the olel style~ Table 1 does not list the smnlllots of rough riee lisel1 in the mntulitr study They (1( hand-h~rvested frol11 September lSmiddotthlough Odober n Two large bUlldlts of gra in were Cllt from the same field plot each day befwPCn 7 Hi and H 15 a m Six to eight pounds of rice were promptly stripped from the panicles SlIrfa(p moistllrt wheli preslllt wns rpmoved by (a poration The rough rice was spread in shallow layels in trays with wire-screen botshytOI11 and illlowpd to ail-(lr -iih flequPllt- tlllnillg As soon as the surface 1ll0iStlll(gt had disappeared and the riee WlS flee flowing it was tubed and heat-tleated The bllndles of Iice (lit on Sepfember 18-28 PIt hom a flooltl(gt] field Draillllp started the 28th bllt the seledNI plot rpmained lllu(hly t-o slightly nlllddy through Odober 2 On O(Ilt)bcl 3-() fhp soil was still damp bllt filln

~[Oistlf (ontellts of til( diflelnt tlllples 01 lOlll-dl rice tintPS and hIl1IgtPIaitIlp of hpat tlent n1Pnt and g(rlllination test data for the 11)51 pxpcrinlcnts alC gi-en in tables (i-II

TEMPERATUItE AND MOISTURE-CONTENT VARIABLES

The 1gtpICenhlges of Blllebonnet rough Iiec Wlmillating 8 16 24 and a2 ((ks ait(I heat tT(atmpnt a 1( giV(1l ill talJIl G Dahl are not le(OI(]((I 101 all flIP 1I111]gtlps illntpcl nt tIle higlll1 tplllpllntllJes tlmt- showpd ZPJO PIlllillttioll Till nlliatiol1s ill tll( leslIlt-s follow thc tlends obtaill(dill Ilil() fOl similII f1xl)(rirnPllts

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

bull bull

TABLE 6-Germination of Bl~lebonllet 1 1ough ice 8 16 e4 and 32 tlec1s afte heat treatment for 30 mimttes ai different tcmpcmcwJcs 1951

~ 8 WggKS ()

[oiMurc ~ ()contcnt ControlL60 01400 o 52deg C15~0 c1580 C ~IO C 64deg C 07deg C170deg CI73deg c176deg C1700 C182deg 0185deg 0188deg C

(pCr(cnO I I ~ ~- ~- ---)-------I--- ---1---------j--- ~ Permiddot Jgtrrshy Pashy PIr- Irr- PN- Prr- Prr- Pcr- Per- I Per- Pcr- I Per- Pcr- Per- ~Perrent rrnl cent (cnl III ((~ ((III (rn I r(nl (rnl rent I crnt cent I cent cent cent ll252 ______ bull __ 81 uo Smiddotl 75 7middot middot1 lt I 0 ~i I I

23middot1 __ 81 Sl 71 71 1- I I - I ~~J -7 1 11 () I I

203 __ _ R8 i 87 7S 72 73 18 () I 17tL ___ ~ -87 80 S8 75 liS (i8 0 0 I 1(i-l __ bull 88 Sli S8 77 70 ]5 0 tgtgt 13( so 87 8S ~ 70 0 o o 1IL __ _ 8n SO 88 85 6 8 o o

~107 ____ ~ __ 8middot1 I ~ -~ S8 SI 71 3U 0 o o nn __ _ 87 84 SO 8 I 72 57 o o -middotan------0 J1 ~~

03 _____ ~ 80 87 83 84 83 85 80 I 67 t1i ll d

IG I~KS ~

252 ____ 1 57 ill88 III JO )0 8G 0 0 --~---~ -~ -----f--middot---I------ ----- 234 __ S6 80 SS SI 80 72 13 0 --- -~ -shy ~ 203 __ bull 88 JO 80 77 70 15 o ~ _ _ ~ =~ = T= == CT 170 ___ 87 nl 85 87 77 71 0 0 ~-- -- -I -- --I------ ~

() ~ _ _1 ______ 1_____ _IG4 ___ ~_ SO 87 no 8G 80 8 0 C1

13G __ _ 8middot1 00 87 88 i 72 0 o i t 115 __ bull __ bull _ 87 85 84 77 58 4 o ~o~ ===)==1====107 _bull __ __ _ o ____ _ _____ bull__ _88 83 74 53 o o Un_ __ _ 8middot1 88 S) 7H 6n 58 i o ll

87

7~ 1-- ~ 69 -I 26-l-- ---0 ~

G3 __ 87 81lt -

83 84 80 76

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

bull bull 24 WEEKS

252 ___ ~ ao 88 DO 00 87 50 I o o - --- - ----L- -- _1 __ ---- -- -1----- -----shy234 - 8a 01 88 S7 SO 74 11 o 203 _ bull sa S5 S(i w (8 8gt 13 17(1_ bull 86 l0 no 8G S3 -~-middotmiddotmiddot-==b= - - - -~- = ===i~==~=i=-=t====16-L _ 85 DO 85 S5 78 8 0 136 _ fiS no 8G 85 I G5 0 iJ ~ ~ = == = I====1 = === 115 __ 8fi 83 83 78middot 50 (i 107 _ bullbull 87 82 S2 (in 3n 0 g ~==========Jn _ 87 87 85 81 70 03 o 0 _ --gt -- __ i_____ _03 ___

yen _ i _ __85 --- -j S5 I 8(j Sol 83 j 85 80 05 27 I 0 ~--~

32 WIIKS

------ ~-----------------------------

252 __ 85 )0 I00 01 80 middottS o deg ---~-----~ -- --__- -----J-----shy23A bullbull 87 00 SO Sl5 85 R7 11 o203 _bull 85 86 S7 81 fiS 15 l76 _ 87 sn S3 fig- -~ -=o==~= -~~~ ~======== ===~==8n 8DW-L ___ ~ 80 80 88 87 81 fi 0 __ bullbull ----J---- _____ bull__ 13(i bull _ 8Ci JO 8J SS (iJ 0 0 - - - - - - -1 __________ _115 __ bull 1~5 ~ 8fi 83 70 (H SObullbullbull -----i ---- _____ _ tl107 bullbullbullbull SCi 85 7J 73 middotlS 0 0 - - - ____ j______ _____ _ (UL bullbull 83 83 82 G3 __ 84 8~ ~~ ~6 j ~~ )~ 7g-- 5riT--20-i-----oI - bull ~ shy

-- ----~~-------~------ILotBBl

~

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

20 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Because more samples of rice of each mOlsture content were heatshytreated in 1951 than in 1950 and at intervals of 3deg instead of 5deg C bull germination data are available for 1 01 2 additional samples of rice of each moisture content which have been heat-treated for HO minutes within the damaging temperntllle range The additional data pellnit closer approximations of thc temperatures at hich chHnage to viashyhility just fltalts and itt middothich it is just eompletl They also present a clearcr picture of the eftect ofhent within these temperatllle limitashytions

____~~----------A X

80 D

60 B

bull40

8- WEEK TESTS II

16- WEEK TESTS 0

24- WEEK TESTS c 20 32- WEEK TESTS X

AVERAGE OF TESTS bull

o~----~------~----~~----~50 60 70

oTEMPERATURE OF RICE C

FIGUII~ 2-Glrmination of Bluebonllet rice (lot UBl taille 6) afr(r heat Ireutment al different IcmpntlllrlS for 30 minules A Airmiddotdritmiddotd ronlro nol hlal-lrtUle 13 rile lontaining 203 pNClnl of moislure al tht lilll( of hN11 InulnHlIl Valll~ an averages of germination tesls made afler 8 16 24 und 32 weeks of storage at 2~o_26deg C

These obsenat-iollfi al( il1ustTu(-(d in figtlll 2 for Hllllbonnet rice bullof 203-percent moistllle colttent A sigmoid or S-typc CLUTe is obshy

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

bull

bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABfLITY OF RICE 21

tahlecl when the percentage of rice germinating is plotted against the (fmperatllle of treatment The shmp drop in the slope of the curye for the higher temperatures of treatment within the damaging range proves theIr greateilethtll action Hutchinson (33) has published tt similar type CIllTe depiciing the germination capacity of wheat of 14-pr1cent l1l0istl1le content afttr 3( minutes~ heat trenhnent at (O_ jO C

As bl f)fiOit was frequcntly ob~enec1 thai- defTeases in germination igor lolllltllw detected at lower tell1perattlles than could decreases in glIlllinai-ioll capacity This finding is illustrated by flle data in table 7 The heat treatment of samples of Bluebonnet of 2i2-pereent moisshyture content for W minutes at temperatures of 4-0 0 and 52 0 C reshyspectively did not (a use a decrease in germinatioll capacity Howshyee1 it did cause it decrease in germination igor for the sample iTeated at the higller temperahlle lso til( greatest IORs in genninashyIion vigor occurred in those samples 11tning the highest moisture (on tents Of course the tempemtmc hacl to bc within the range damaging for the samples

Tlu 7-fjf(r8 of rmp(wtflllf of liNd tlratJII(l1t PO minut(8) and olIIoiltIlIP Nmtent 011 t1lp germil1atioll of lJluebrml1(middott 1 lOlgIL 1ire atelb 710 ((lid 11 days If (JJrI-IImiddot(er germination data)

_____vnriabl~_____ 5 ~ay~~~ ~la=-i~~~lay I Total

(ol1trol 2 pcr(lr~41 Perrl~ IPrrrrl1 Per((g Perce~7 Pl1lI)(n1tUJt 0 Cj 3

Hi s5 middot1 I 0 90) sl ~ ()-) 0 91Q- 2 90G5 ~I ~ 55 Iii -I (j J 80filL I Ii I~ 20 4801 0 () ()0 01()i~tllJ( (pPJ(PJII ~fl2_ _ 15 12 20 middot1823middot1 __ 2 21 18 G I~03 __ _ G7nR 11 I 84shy170 __ _

s-( 2 0 8Hdeg1 Lotmiddot Hin 2 nIagp of ~(lImiddotlllillntinlJ IP-r- ~I()it IJJ( (OlJlpllt ~ 11(1(111 IIrll I-UplIIcl at 1 (

Data -il11ilnr to fllllP 101 BlupiJOllllet in tnllll n are 1)Jesentcd for Sel 6J-25-El in table H

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

bull bull

TABU 8~Gelmiwtion Of Sel Cf-5-m ough pice 810 34 and 82wee7~ aite) eat teat7nent to 30 minutes at ditfelent tempelatll7(J8 1951

8 WmiddotglKS

~~---------------- --bull--

Moisture I I conte III Oontrol I 40deg C t 152deg C 55deg C 58deg O 61 deg O 64deg C 67deg O 70deg O 73deg 01760 C I 79deg C

(percent) I f I I--------- ------------------------1----middot--------------------

P(ICII~ Parent II Parenl i Prwl~ PIlernl P(1l(~lt PClr(l I Percent Percenl Percenl I Percent Percent 10S__ ______ bullbull IH I 84 SO I 7w 70 64 ob 5 0 0________ ------- shyIS2 __ __ bull _ 81 __ I 81 bull 77 80 75 71 I 10 0 0 -------- ------- shy J5IL _bull _ 85 _I i 87 80 81 76 70 1 0 i 0 ____ bullbull__ 1-10 80 78 78 75 I 73 52 0 0 ------- shy ~ltr)I --j 12middot1 81 middotmiddot_middot--middot1 middot 80 78 I~ i 64 36 I ltI 0 0IOL 81 ______ __ __ j__ 78 10 I 71 30 lt1 0 0 ~ 71- _ 85 ----1-------- ___ bull -__ _ 77 i 80 75 52 lt1 0 rIiI I ---------____ -- ~- --------~--------- Ij

t=i U WIBKS d

-3 I 1 o1J8 __ _________ 1 80 I 8~ 85 i 70 72 I 64 60 i 0 o i_~ ____I________o _______________ _]82_ _ ___ _ 81 I 70 7J 71 73 (i5 Hl O

82 8) 1 o 0 _______ _ ~

J56__ -------1 70 ~ I 7) 78 GO 1 i fj]40 ________ _1 77 80 I 81 78 73 56 I124 ____ bull ______ 83 j85 73 61J o I 0 ___ bull ___ _101 _ _ _ _ _ __ SOl 82 82 74 g g1=======~~ I I77 ____ _ _j 82 S3 82 77 55 i lt1 0

--- shytj

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

1 T~~

24 VJ~EKS

bull bull 0

~~

shy~

It ~~ ~ J98 _____________ tgtl - ~ 182bull ___________ 74 64 5 lt1 ~g j-----~~- ~~-- ~g I ~l -------- _------ _------ ~ 81 77 1 71 22 0~1 I 156_ -------- 83 - - - - - - - - - __ bull _ _ 87 i lt1

0------- J------ -------- t c 140 _o _ _______ 84 ___ _ ___ bull _ _ __ bull _ bullbull _ 85 82 83 67 o I 0 -------- 3 c I) 4 82 80 78 72 45 o i 0 ______ ~- flI - - --- - 80

~- ---- ~-- ---- 84 83 76 o 0 ______ ~-~ 0101 __ bull ____ bull __ o 65 2880 -- -- ~-- -- ~ --- --- --- 80 70 69 28It- 77 __ bullbullbull __ 82 77middot__ middotmiddotmiddot------1-------- --------1----middot middot 83 72 58 I lt~ -------0 ~ i _ I

~ 12 WI~EKS

198___________ -- 77 78 82 o middot-7s~I-middot-middot 71 65 - 56 o 1________ _______ _182_ o __________ 77 _______ S3 81 70 70 i156 __________ 1 73 o _____ ___ _ __2~ I 8 140_ _________ 1 83 - - - -- - - - i - - -- -- - - 82 J 83 S I 82 (j8 1 o 0 1_______ _

80 -------------- ___ bullbull 81 81 81 72 f 52 o 0 ______ _ 124bull __ bull ____ _ 81 ______ __________ __ 1 78 74 78 o 0 _______ _ 101 _____ __ _ 28 8] -------- --- _____ - bullbull ---i------- SO 72 63 I 177 ____ bull __ bull ___ 76

71 i 29 lt1 0 078 ____________ -- _ ____ 1_ - bullbull - - shy 76 I 74 54 0 0 ---~-- - _- 8o-o- _____ _ __---__---__

~ ltgttJj ~ ~

~

_ --f _~ )~ bullbull ~

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

24 TECIThICAt BULLETIN 1129 U S DEPT OF AGRICULTURE

TEMPERATURE AND TIME VARIABLES

In contrast to the ID50 experiments more extensive experimental evidence was obtained to show that the destruction of the germination capacity of rice with a given moisture content increases as the treatshyment time increases Again this relationship was more evident hen the temperature of treatment was within the range damaging to rice of a particular moisture content

The percentages of Bluebonnet rough rice of I7V-percent moisture content germinating 8 16 24 and 32 weeks after being heat-treated for periods of 10 to 120 minutes are given in table D The elata like those in blbles 6 and 8 SllOW that the ditlerences in the germination percentages for the four periods aTe sligllt They are also sufficiently inconsistent to suggest snmplinl elTorS aIHl general experimental limitations

TABLE fJ-GellIIillatioJ of Rluebollnet 1 jOllgll jire 8 lG iB4 and 32 1lecJo~ ajtpl heat treatlllent fo cliffeclit jJCIiod8 of ti1ne 195l

8 rJEKS

Temperature j

i 40 I ~()-I-------I--lO~aoof treat ment I min min min l1Iin min min(0 C)

I-- shy -- shy~-- -------1---------Pr1shy Prrshy 1(1shy P(r- P(- Pr- Per- P(- Per-

5L __ 50 _ ~ _ _ _ ~

cenl 15 )4

((nl I H3

rrfll 05 II

((nlnmiddot 83

(rnl HO 78

((nt )2 88

((111

no HI

renl )3 03

cent 02 02

G5_ 70 __ ~

14 02

78 15

73 0

80 0

7J 0

81 i 0

70 0

G5 0

53 0

------~- ~---~---

55_ bullbull 88 01 no 12 13 I 88 88 80 GO_ l l2 H) JI 8il 84 83 83 G5_ J2 )3 88 8i 8n 51 3370 __ lO 22 () o o o o

24 wrmKf

55 ~ J I 80 88 81l 8J I 871 87~~ i sn

GO_ J4 88 H) 8l 8il li) ~ 85 81 80 G5_ )4 88 88 DO 83 Sl 77 GO 5270 __ ____ )1 o 0 () o 01middot1 0 o

I

55 _ __ 111 (ll lmiddot1 () I 03 88 ll no i no 60_ _ __ _ _ _ _ [ nI )3 JI J2 J I ) li)O no I 8l

5_5-_-_-_-__-_-_-_~__~l~I~__8~83_L_~85_1__8_8~~1f__~)_0211__~8~2_lmiddot__7~08~1middot 5(~raquo I 402

70___________ 01 () 0 0 _ _ ILot UBri

bull

bull

bull TClllpClahllcs of Ji 0 and (jOO C applipr -Im s long as JW lllilllltlS

did not ailed the gcrmination capacity In contrast II tempcrature of

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

bull

bull

bull

gt EFFECTS f)F HEAT TREATMENT ON THE VIABILITY OF RICE 25(

65deg reduced the percentage of germinable seeds about one-half in 120 minutes The evidence is not conclusive for the 65deg heat treatments but it indicates a gradual reduction in the percentage of germinahle seeds starting with the lO-minute period Vhen the temperature of treatment was raised to 70deg the percentages of germinable seeds were reduced to 13-22 in ] 0111 inutes and to 0 in 20 minutes

A temperature of 5[)0 C Ippliecl for as long as 120 minutes did not have any effect on the germination vigor of Bluebonnet with 179shypercent moisture content At GOdeg however hetlt treatments for 50 minutes lind longer did bring about a slight decrease in germination yigor as indicated in table 10 Only the 32-week data are included beclluse those -for the other storage periods differed only in minor reshyspects AJI samples heat-treated at ()5deg except possibly the one exposed for only 10 minutes pxhibited a loss in germination vigor The loss yas greater at this temperature the longer the period of treatshyment Also the PlogllssiYe loss of germination vigor was more apshyparent than that of germination capacity At 70 0 the viability of most of the seeds as destroyed in 10 minutes and completely destroyed i

in 20

TIlLI O-Etmiddotr 0 till( (dumtion) olleat tlMtment at difle1gtent telljJelllIIIS (III lite fj(llIIil(tioll oj IJhlfbol1llet I rough lice after 5r 10 and Ji ra8 IDl1 (middotJ2d-I(ek rIllJIillatioJl data)

- I

1---gt----

Dllrfltion of heat trcatmcnt 7 cla 10 day I 14 davs Total(minlllrs) bullbull J I

------------------- ------ ----------- shy bull - 1

P(f((l1i Pcr((nt Pertenl 11Jercent IPercentConfroL __ _ 88 2 I I deg 91

I 1

10_ 20___

l2 01

30_ SO i 40_ SO I

50_ 60 ___ no ___ _120_______ _

87 8f 87 84

I

t

gt

3 183 2 o 88 I) 17J 2 o S5

(7 IG I 4 1 S8 no 20 I 8 2 no 57 15 1 Sf 2 S2 48 10 8 3 781

14 18 i 13 7 52 G 15 i 13 8 42

Ar 7nc c

10 _______________ _ 20_-- ______________________ _

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

26 TECHNICAL BULLETIN 1129 U S DEPT OF AGlUCULTURE

TEMPERATURE MOISTUREmiddotCONTENT AND MATURITY VARIABLES bull

Germination test data are gien in table 11 for lots of rice handshyIUlrvested and heat-treated from 2 to 20 days before the Held was ready for combining

Eleven lots with moisture contents from 313 to 324 percent were harvested Oil SeptembeJ 18-28 Samples of each ere heat-treated 101 30 minutes at 40deg-64deg C in 3deg intelYals The earlier samples with high moistnre (ontents shoed greater losses in germinatioll capacity at the higher temperatures than the later samples The control and the heat-treated samples with 32 percent of moisture of September 18 were slower to germinate i e they exllibitecl a lower genninatioll vigor than the more lllatllle samples with lowel moist11re (on tents from lhe lot comhine-llHnestecl on Ocl-obel 8 The ail-clripd control had slightly less gelmination vigor than the snmples exposed to 40deg 41deg and 4()0 but morc than those exposed to higher temperatnrcs The samples of SepLcmuer 19 also pxllibited a Iar ill gerlllillaj-ing but to a less degree in the control and also in the samples exposed to 40deg 43deg ancl46deg

Samples of the remainingnine lots September 20-2R did not exh ibil any marked decrcase ill germination igor opr thaj- of tl1(ir respecshytive controls except at 52deg C and higher TIH air-dried controls for all lots including the olle o-f Octobel 8 exhibited some germination lag-more than was enconntercd in j-hp same Yllrilgtj-y of rice in ] )50 llld in Blllebonnet in 1051 Thc effeds of heat on the viability of rice bull samples from lots halYes(-e(l from Scptember 20 through O(tober 8 vere similar to those desCrib((l -for othpr cxperiments (1nbles 2 G and 8) in which moishllp content of the rice aml temperattllc of trentmcnI have been the major variables

Vhen the maltllity study was ini(-iated on Sppfel1lber 1R 11I0sj- of the kernels of ReI GI-25-12 (rp firm but green pigl1Hnt prcdorninatp(] in most of thc hlills Hy SlptlllIiler 2H till kClIlPls PIP firlllCl awl (hp hulls predominantly yellow Ko objP(fiw ea11lI1-iol of tliP cllnllgNi in mnJurity from clay to (lay tlS llttpll1ptNl V(~afhel (onditions were C101lCly Ill in and (n(rall V Illrfa olable 101 loss of Illoishlle 110111 til( ginin Nohvij-hitnnding file faiI1lr( to explOle fhe lllnllllity fadors the experiment clemonshates j-hat in a study of the effect of heat Oil ri(( via hi Iity moisture (ontellt is of morc pradiCal sign i ficance than matnrify

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

bullbull -

rlHu ll-Germination 01Se7 l-fj-ll rough dee of different matwitics 32 weeks aftel lLeat treatment for 30 mhwtes at diff(Ield tem pel(dwes1 )51

Till( - ------ bull ---- I I I natlmiddot of hcat I)rfol( OIiitulr Control 10deg C I J3deg C 40deg C i 49deg C 52deg C 55deg C] 58deg C I 01deg C 64deg C 67deg C trpntlllcllt hnnpst eOlltcllt I

------__------ -~----I ---

I ITCI II I 1(re(lIl Percent Pcrc(nt Percent PacellI PClcenl P(lcflti Percent IPTc(n ipercent Percent Sppt Js 1 Days 320 (if) 72 08 60 55 18 1 0 bullbullbull __ __ ___ 1___ - bullbull11)_ ------- 20 322 (ii 03 GI) 72 I 70 30 l 2 0 1 ____ _1 ___ __ 1______ _20 ----middotmiddot-middot----1 JI) )) ) -7 ~ SO -7 7~ i 7 0 I21----------~-1 18 0_ ~ - () c ( ) -- bullbullbull -- bull ------r---shy----------I J7 32middot1 71 7middot1 i 72 7S 71 67 10 0 _ ___ J __ ___ ___

31 8 70 74 78 71 78 H 20 0 _bull __ __1_ bull __23---------- IG 31 8 7l SO 71) SO 81 72 2f) 0 ____ bull __ ______ +_____ 31 (l 72 70 75 7j HI 7G 46 0 bullbullbullbullbullbullbull _ __ _bullbullbullbullbullbullbull~ci===~=======-i ~1 31 I) 73 73 SO SI 77 77 middot17 0 ---bullbullbull - bullbull--1---26 --------- 13 I 3 I 3 middot0 -8 81 81 -8 _ 13 0 I27 - ----- 12 ( ( bull ~ bull - ( (J ____ ______ n 81 71) 77 8178 7(1 44 0__ ___ ____ _ ___ _ 28-=--------1 II 31 (l (i) 7middot1 77 78 77 72 -II 1 0 _bull __ __ __ ___ bull_20 middot--middot-----1 10 22middot1 80 ___ _______ _______ 85 7( 73 50 48 8 030- -------1 9 21 7 7G ______ __________ bull 71 73 71 71 4n 13 0 ~

Ort 1------------1 8 230 74 ________________ __ _ 81 81 73 5f) 25 0 02--------- 7I

28 2 77 8j 83 83 8G 73 35 lt1 0 0 ~ 2li 2 S3 i _____ bull _____ bull _ 80 8ii 8-1 75 43 0 0 0 Id 237 70 _________ __ bull 77 I 81 80 75 oa 5 0 0

r===========l ~ 20 I) 8middot1 11------ bull ______ _______ 1 83 8-1 80 73 62 8 0 ~ S------------ I ________ __ 5 ]) 8 ~7 _~~---bullt-----+------ 82 71 i 05 17 ~ 78 78 56

1 ~

fAt 70 0 C tolll O-llcrcPllt g~llJIillatioli d d tl

~

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

28 TEC~ICAL BULLETIN 1129) U S DEPT OF AGRICULTURE

HEATTREATMENT EXPERIMENTS IN 1952

Although more detailed and confirmatory information concerning bullthe effects of heat on the germination capacity and germination vigor of rough rice of different moisture contents was obtained in 1951 than in 1950 still much waS left to be desired Therefore additional exshyperiments having the same major obje(tives were planned

A few minor modifications were made in the procedures The sliding temperatnre scale~ waS again emp]flyed but the interYals between temperatures of treatment for rice ot each moisture content were 3deg C in the lower portion of each range and 2deg in the upper For example the temperatures of treatment selected for samples of rice of 216-pereent moisture content were 45deg 48deg51deg ii4deg 57deg~ 59 61deg G3deg 65deg and H7deg and (onle(1 a rlnle of 2~0 Dep(nding upon the moisture content 10 to 17 sllmpl(s were heat-tr(ated over lanles of 21deg to 40deg Data ar( nol- r(Cor(](d (table 12) how((r for all the unples treated at thehillwr temperatur(s that sho((1 zero I(lminashytion Manometric m(asllrNnents of the total presllres developed in the rice-packed test tub(s 16 by 150 mm durinl 11lat IT(atnwnt wpr( made by the nwthod described in Experimental Materials nnd ProCedures (pp 11-12)

In th( eXI)(riment on tile dlect of temperature and time (duration) of heatinl on viability (lable 15) samples (Ie h(at-treateel from 10 to 120 minutes in 3deg inh_lals from 5~0 t010deg C

Oerm ination tlstR were made only ttt the 8-e(1 period beea URl

in Ul50 and 1)51 neither the air-driCd controls nOl thC heat-tr(at-Ccl samples showed marked or (onRistCntly IHOlreivl eli flelpneeR in bullyiability between the 16- 2-t- 01 3~-wl(k p(riod and the R-welk period

Bluebo1111(t and ((ntur 2 ri(( nrl used in the 1)ii~ (xperillwnts (table 1) The Bluebonnet was of the same rll(I( used in 11 The Century 52 was a variety developed by the Riel Expcrinwnt Stashytion Crowley La Hlmbonnet was obtained in suflieient qunntity to permit mechanical eleanin (onlmelciul-type ckanel utilizing both air blast and shaker nll1on~d the stm and other 1 ilht debris

TEMPERATURE AND lUOISTURECONTENT VARIABLES

rhe efrects of eli fler(nt temperatllres of treatment on tlle IelminashytiOll capnciti(s of samples of ri(e 01 c1ifler(nt rnoiRture contents (table 12) followed the same trendR ttS in ll50 and H)51 (tables 2 (i and 8) Also the tempcratule at which riel of a inn moistule content was just dnl1lagecl could not be approximated with any Ireater deshygree of accuracy in 1)52 Presumably the lot of B1uebonn(t rice used either was lOt of the blt quality or else ha(l not been thoroulhly cleaned of lInmatUll and (lamaed seed Possibly it was dallHlld slightly in me(hanical elpoundallinl 1Is gprmination capaCity basld on 18 tests rt1ngeel flOm 8710 Hj perC(nt with an averac of)l percent rhe pelCentttles of seed Ierminahll nfter 57 10 and 1-1- days cal-Ciliated 101 the 18 tests were 8i~ 1 and () peLClnt Iesp~ctively (0111- bull plete kills were not obtninec1 at t1~ higher tempPlahll(s at which samples with 1110islllre COlltens of ki i and iiS pPI((nt were treated (table 12) At the time of heat treatment the moisture contents of

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

bull bull bull TABL1~ 12-0()mination 0 Bluebonnet lolll711 lice atel I(at realm (l1t 01 30 minutes at different telnlJeratures

0 bull

Jl)j lgtj 1

Moisturu COli-I 15deg 47deg 48deg 1500 51- ~~o I 54deg 15~0 56deg 1570 58deg 59deg 600 I~10 63deg 64deg 65deg 66deg ~ contlnt Irol C C C C C c I C C C C C C C C C C C C(ponCIlt) ~ Per-l p Per- p~j Jcr- p-~r r-jl Per-- per-I] Per- Pcr- I Pcr- f pcr_ Pcr- Pcr- Per- Per- ol j bull T 1

C(II~ cent j CCllt cent ccnt cCII I cellt cent cent cent f cl1n cent cent I

cellt cent cent cent cent cent _16__________ 8f SS 1----- 90 ----- Jl -----1 9L ----- ----or 79 ----- 76 ----- 80 78 20 tIlshyIn3 ________ n2 _____ sn l----~I )3 __ -_ no ----+----1 93 L___ _____ 86 ____ 80 82 76 lgtj172 __ __ 2 ______________ ~ _____ flO _____ 1 n2 1_____ _____ 9] _____ _____ 95 94 82 e150__________ )i _________bull ____________________ 1 89 I_____~----- 93 ----- ----- ni _____ 93 _____ _____ 95 130 ______ _ no -----1----- 1----- ----- _____ -----1 J3 _____ 1_____ J1 _____ _____ 91 _____ 95 _____ _____ 931]Jo4_____ III __________ j_____ I_____ __________ 1_____ )I _____ _____ 88 _____ _____ 85 90 _________ _ ~ 97 ________ 01 __________ _____ 1 _______________ +--___ 80 )_____ _____ 88 1_____ ____ 90 _____ 81 _________ _ IIshy

1-381 _______ __ 03 ----1---------- _____ -_________ _____ no -____ _____ n] 1_____ ____ 9L _____ 91 _________ _ a

lgtj12 8---------- ll ---------- ----T---- ----T--------l 90 i----- ----- 89 1----- ____ oj 91 1----- 91 ----- ----shy~~~==~~-= ~ =============Ct gg g I ~~ j= g~ ~

rvroiSlllrc (OlltlJIt 07deg 6So I 60deg I 70deg I 71deg I 72deg I 73deg 74deg I 760 1 78deg 1800 82deg i 8deg j 8(jdeg 1880 j 90deg 92deg 94deg (pcrcllIt) C C C C C C C I C I C C C l C C I C C I C c C ~ ---~- - - --- -~-- ---~ -I --~I-I----

PCI- PCI- PIr- Pemiddot PCI- PIr- I PCI- Prr- Permiddot I PCI- Pcr- i Per- Per- Per- Per- Pcr- Per- Per- lgtj

cent celli C(lIt eell celli cenl I cent CIllt CIII i cent l cent f cent Iccn cellt Iccnt cent cent ceril lt ~ t~t-~~~~jj~-~j ~~) ~ ~ ~~~1 i~_1i~~~ ~ii~~~ j~~~i~~ ~~~~ jjli~j j~~ )j~))I~j~j j~ijii j i~~iij)i i)ii) iiii) ~

97__________________ 77 _____ _____ 55 24 1 0 ___________ bull ___ bull ____________________________ _ ~ 81_~________________ 88 _____ _____ 75 73 26 1 0 __ bull ___bull ____________________ bull ___________ _ lO58__________________ + 88[_____ _____ 9] 92 87 94 91 91 89 79 ________________________ _ 850-_________________1 90 _____ _____ 89 _____ _____ 91 92 93 91 91 92 90 86 88 _________ _ toJ 47__________________ 88 _____ _____ 87 _____ _____ 90 ____ 89 i 89 89 89 90 90 88 85 68 25

_-- ~ _ lt0

~

~ ltlt-~ - bullbull 1gt f~ ~gtr l~YCmiddot ~ ~ ~ L)Iwmiddot~_tbullbull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

30 TECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

these three batches of Bluebonnet were estimated to be 25 to 27 pershycent higher than they actually were Hence the temperatures invesshytigated were thought to be adequate and the error us not discovered bull until more accurate moisture determinations were made in the Southshyern Regiopal Research Laboratory on sealed samples

No particultr significance is attached to the Hessures deTeloped in the test tubs of Bluebonnet durin heat treatment insofar as effect on germination capacity 01 geLl11ination igor is concerned As one WOll1cl expect in iew of the laws powtning ga-es and vnpo1 pressures the highest p(sslles (Ie c1e(loped in 1l1Ose test tnbes that contained the rice of highest moistUle Coltrnt or that (re hentrc at the highest temperatille (table 13) To this (xtent the deleterious effect of pressllleif any coillci(le~ ith that of hl11peratlirc and moisture contlnt In sceml sClies of fr-s (tablcs l~ nlH1 1~) thc rough rice in fest tllbh (h~Tlotling apploximately thc same presslires did not always sho [Ill sallie (1PTN~ of 11lat clnlllae to Ullmination capacity This fact illdienres tlutt of tlll ~ nlliabli-pleSlIlC temshyperature and 1l1Oistull (ontllIt-thc last2 all Illore important in these heat-treatment experi 111 ell ts

The loet tlIll]lHnrUle that Yill just (HII1 (1ltl(tahle heat danHl~( in Blucbonnet riel of t inlI Illnitnl( (ontpnt ill lO Illinutes i 1I0t

Iyid(nt l10III tllp dnta ill table 1~ Thi ohPITntioll i likCip t Ilip for the sampleR of Bluebonnet and ~C1 (jI-~j-l~ that were limilarly heat-treated in (loNl tpt tllbp fot 1() minutel in U)) I (tablps (i and S) Tn tllpst thlep lXlPIiIllPnts tllp first noti(pahle IPRPOIlP of loul-tll rice to the (fred of hlnt n lr)Il oftpll a loss ill Ulrlllinlltion yiuol bull than a loss in gtrlllinltoll (alnlil B((al11 of thi lindinp all the cll11ination tllt data wert npxHlIlilJCd trtlltioll wa ien to tlw l)erClntares of seed of pal11 llmplp that hHl Ulrllliuntl(l aftlr i T and 10 ciays as (gt11 n aftpl I h days B) (()lIlpllling tIllt diflelrncl in rcll11inntion iuol of amplls of ricl of tht alll 1l1OitlllP eontpnt thlt had been hlatmiddottlpllted tit s(pml tPIlI]l(IIWIlS it Wn po-ibh to apploxilllatp the 10(1 tlIlI1ll1ltUIl tbat 11Iidlt IJP lXPl(tld to (ltlUSl heat damage

bull

bull bull TIILE )1-lotal jiJISWIl8 d(Idopcd ill l(UCr tegt tubn of HlllCbolillc rOllf1i ire of ditffJpnt moi8tllle cont(3nts

1111(11 hell-treated to) JO milillelf at elitnell tCIII1(NtlUIC8 llJ52

[oiR(ur( l1)n1Cnt middotlilo 17deg ISo 50deg 51deg iW 1)1deg 55deg 5()0 fi70 5So 59deg 60deg i mo 630 64deg 65deg I 66deg tltj

(]lpnPI11 ) C ( C ( C C C C C C C C I C C C ~ C C I C tltj

Ci--- ------]---------- gt-3 C ( C ( ( ( C ( ( (t 0 0 0 0 0 1 O 0111 III III 111 III 11 Jl III Ill mm u Im 11 In I m In

lJl

~3 bull 117 - ~ __ bull _____ I~ _Tt=----~-- ~~I~ I - I))- bull - 1)Smiddot - 157179bull )04i _ _ o

17 ---------- 6middott 7 S _ - D 9 _ _ ll S ____ i13 3 j bull 15 2 16 7 ___ bull bull 18 9 ____ _ Ij 150----middotmiddot---middotmiddotmiddot--- -- J - )3 ___ bull middot11 S -- -- _14 7 ----I--- ISo I- ___ 11 0 _____ 21 9 i- shy

13l- - - - - - - - bull -- - - - - - - _ bull - - - - -- 7 9 - - - _ __ Ill 5 ___ __ 11 7 _ 1(i 1 ______ j 19 6 tl

114--------middot---- - - - - - -- - - - -- - - 9 n - - -- -bull 1 L 9 -- - -- 16 0 bull - 1S 2 - - - - - - -1 21 7 e3 - -gt - -- -- 100 -_ ____ ]07 _ 10 J bull 170 _____ ____ _ ~ -- - bull - - --- - - -- O S - - - 11 1 bull - __ 76 _ - 1641----- ____ _ l - 1- - - - - n1 J --- --- 11 () -_ _ bull _127 143 _____ 1____ _um~~m ~ - 8 ) D7 1107 125 _____1____ _ ~

~ i - SG nG_ I l5 11 [ ________ _ I n 3 S n _ O 5 11 5 ___ _ __ tltj

Z I gt-3

ll)i~i urlt rOIlC1l1 (170 GSo Gndeg 70deg 71 deg 72deg 73deg 74 deg 70deg 78deg SOo S2deg SI deg SOO SSo 00deg l20 i 9lo ~ J)P re(11 t) C C c c c c c C c e c C c 1 c c C c I c

~ - - ------- -~- -- --- --- ~- - _- -~ -- --middot--1------)__j__ tl

(m Cm (lit Cm Cm Om i (m Om Cm Cm Cm Cm Om am Om Om 10m i Om lt td

____________ _I _ 223 27l 30-0 31 S30 I 1 __t=============150 Ttg J~ g 207 _ ~j~ 337_ ====____________________________ ===== ========= ====1=== ~ 13l _______________ i _ 23524 S bull 2(1 __ 1302 322 31l ) _ _ _____________________________ _ ~ llL ______________ I) 418 I 1 __ 235 ---1207 26328 23n 0 __________________________ bull __ O1- _______________ IS5 __ 203 1bull ___ 222 - ____ 2561274 2lO 330 850 ____________________________ _

o 81 ______________ 175 _____ _ 202 ___ )207 _bullbull 232 12t 2 )27 2 31 0 322 1

i

__________________________ __ 5S _______________ 147 j _______ p6 2 ___ 103 ___ 202205 21 0 222 126l 120 6 __________ ____________ bull

~

50_______ ________ 1140 -- bullbullbull _____1153 __________ 166 _____ 100 1205 231 1231 j23 7 125 2 j264 287 _________ _ lI 41- ________________ jJ34 ----- ----_ H 4 - ______ __ 15 1 _____ 17 1 pl 7 1223 121 6 1234 255 25 0 286 i 290

5 3o 0

C)

lt~~I _ - _~ ~ lt_ ~~ 1 I ~ ~ ~~ ~ - bltmiddott bull~~ bull 1 1

TECI4~ICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Approxiniated temperatures at which heat damage to viability just ~starts and is just complete are given in table 14 for Bluebonnet and

a bull BLUEBONNET (1951)HEAT DAMAGE JUST STARTED 0 HEAT DAMAGE JUST COMPLETE bullD

SEL 61-25-12 (1951)HEAT DAMAGE JUST STARTED A HEAT DAMAGE JUST COMPLETE 80 ~ bull

o U D

BLUEBONNET (1952)

~ bull bull bull

HEAT DAMAGE JUST STARTED D lampJ HEAT DAMAGE JUST COMPLETEbulloU bull

bull~

o bullbullbullbull 70 Ishy

lampJ ~ o ) A

bullbullbullbull bull~

~ o

o bull bull bullbull

~ -1Ca00 A IampJ ~ CL DA

~ 80 Ishy o ~ OA

A o

o o

o 50 ~ o

I I I I 5 15 25bull

MOISTURE CONTENT OF RICE

FIGURE 3-Approximate limitations of the zonc of heal damallc for B1uehonnet and ScI 6f-25-12 and the relutionship of the moisture contcnts of the rkc to th( damug ing tcmperatures (Data from tahltmiddot 14)

SeI 61-25-12 of several moisture contents Table 14 and figure 3 show the relationship of the moishlle ltontpnts of the ricp to the damaging tem pelatur(middot~

Figure 3 is II ~ctUer-type diagllll11 of the data plpHelltp(J in table 14 ]~ach tempellltnreiR plotteci against the 11l0istlln~ contpnt of the riel A zone of hent damage is clplIl1y pidulcd but its upppt and lower boundaries are noto sharply and lcglliady defined as one might hope

__________ _ ______________ _

EFFECTS OF HEAT TREATMENT ON THE VIABILIlY OF RICE 33

TABLE 14-AlPlo-citnated te1nperatules at 1oMah heat damage just starts an~l is just complete 1m rough 1ice 01 diff81ent moisture conshy tents 1951-5CJ

Variety and pereent mOisture content

BluebonIlet (BBl) (1951)252________________________________ bull ______

i~i~~~~-~~-~~~~ii-~_~~I 107_______ 99__________ 03___ bull __ -- -

Sel 01-25-12 (8middotJ BH23) (1liil) 198 _____ ___ __ 182____ 156___ bull _

__

] 4middot0_____ _____ _ 121____ bull __ _ 101_____ __ 77_____ bull

BlueboIlIlPt (BBIO) (1952) 210_____ __ ll3___ bull _ _ _ 172bullbull __ _ 150______ __ 189______ __] 14 ______ __ l7 _____ bull __ __ 81 ________ 58__________ 50_________ 17__________ _bull __ _ _

_j_ ____

- _ - ___ --I

- shy~--- ~

i - - - --I

I

Heat damage starts

o c 50 51 53 58 01 (j3(jj 64 (j~

7()

)j 58 ()~ (j3 0middot ()4 67

52 )4 (i0 (i2 1i3 (j5 fl4 (j8 j

8~ 78 1---------shy80 __________

i iHeat

damage complete

- o C

61 62 65 70 71 73 74 73 76 87

68 69 71 73 74 74 77

06 69 72

I 72 73 75 7-l 77

TEMPERATURE AND TIlIE VAlUABLES

Peltentages of rough I ice in snmples of Century 52 germinating 8 weeks after being heat-tlentel1 101 Iwrioc1s of 10 to 120 minutes aIs gien in table Ii) Hele the same timc-tempeltltul( efreets 011 gennishylultioll capl(ity (tre delllon3trted but in greater detail thall for BtxOo (table I) 01 Bluebollll(t (table D) 0

The germinal-ion Cllpaeitv of the (entur) 32 air-dried (ontrol based on I testmiddots lllllounttd to n+ ptI(enL Hi gerIllillation rigor is txppsselt1 by till pCI(pntaglS gClllllnating aftel 0 7 10 and 1+ clays which CI( HH ii 1 and 0 respcdiOely

bull The germination eapaeitics of thc heat-fIpate( Slllllpl(middots WPIC but

slightly nfleetld by iPIllpemturps oi~ trpatlllcnf bel() (HO CO ~t 61deg 101 20 minutps 01 longer tht connts dlOPPNl to H7-l2 pel((nL On the ol11eL hand all samples heat-treated at (+0 for 10 to 120 minutes underwent an appleeiaiJly gnateJ plogrlssive loss ill gtrIlliIlation shycapacity with increased tillle of treatl11elit and the eounts droppcd to J

J

bull bull

TBL1J15-Gcrmination of Oentury 51B rough rice aftet heat t1catment fol diffp1(Vnt l)e1iods of time 1951B ---~ - bullbullbulllt ~ --- -----T--- --- --shy- -

Temperature of COIl- 10 I 20 i 30 40 I 50 I 60 I 70 80 00 100 llO 120 _tleit~(llt C)___trol_~~~ ~~-~in~I~Jill~~~ -=in~ min~ ~nin~ 1l1in~ in~ in~

Percrn i Pcrc(nl

-~) - 115 0355 __ U5 l558 __ n4 n3OJ bull 05 Oil(lmiddotI bull 04 IIIIii bullbull l1 iO l5 ~~ I 8 5g 36 5 6 2 1___ 1 __ O

--~------~ ~-------~~--

t Ii Prrceni Pcrccnt Perera I Prrccn Perclnl PlIcfni Prrcrnl Penen

l

)1) j 03 I fl4 01 )(l l)j 1)2 0middot1 04 92 02 07 07 )middotI nmiddot )3 SO 1)2 0 I 02 no 87 no 02 SO 87 00 so SU S8 S5 82 8middot1 60 fi8I

Percen i PCIceni Percent

95 fl5 95 95 95 )3 04 01 90 88 88 89 07 62 47

___ ~__ bull ___ ~___ _ bullbull~ l

lti

~ l Ij tj Id ~ ogtIj bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 35

47-91 percent The destructjon of germination cnpacity was corshyrespondingly greater at the two highest temperatures There were no viable sreds in samples tTeattd for DO minutes 01 longer at 67deg or for 30 minutes or longer at 70deg

A loss jn germination igor oCeUlT(tlin samples of Century 52 heat-treated for 80 minlltes or longer al- fiiO C and in L11 those heatshytreated at the higher telllpelatlll(fi The extent of this loss is reflected in the germination data in (-able Hi rile 1)(gtI(pntages of Iice germishynating after 5710 and U days nrc giell for all samples heat-treated at 61deg (14deg 6T 11 nd TO- -lIlt t Pili plrat lins I hat lc(1n itely affettecl germination eapaeity The plIeentages sho tlw(- the longer thn treilhnent or the hipllIr the tpIllperat1l1e of tTeahllPnt for rice of a given moisture lontpnt (he longPI it tnkl tlH lelllnining middotiablp SPlds 111 thp sample to PIllIinnte -gain I-his ous(lnLtion holds only if the tel1l])(lallllC of ITPatll1llIt fall ithin the zOl1e of heat (lanmiC for rice of the SI)PCified moisture onlpni

TABLE 1G-E1f((middotf oj till( (dllraioll) of 1fat tJ((ltmcilt of dijfll(lIt t(mp((tIIJ(N Oil till glJmillatioll of ((lItlll ) IOU(lh Iire ((Jtm 57 JO ((lid 14 l(ls HJJ

t filo C At GmiddotI (Duration of ----_- - - __--_ -------_ ------shy

bull hlU-t trpatlllPI1t

(lltillil tCs) i 7 10 JmiddotI i 7 10 IJ shyT()talclaIs dnls days days dnys days days days Total

---~ --------- -- --- --------- ------ ---shy ~--

1 r- Pr- Plr- Pa- Plr- Per- I) rshy PI- Pa- Pershycent CUlt Cflll cellt Cl1lt CI Ilt cl-ni cellI cent celll

( ontrol 02 2 I 0 nij -8 middot1 2 0 9410 lt3 8 3 I gj in 2a ] 8 9120 7fi 11 1 l2

-) It 3a jmiddot1 1 8930 1- II

i() 1 00 XI ao 1middot1 2 Sl

-10 il 22 2 8-( 22 )1 10 2 88iO i) 2) (j I 00 17 iii 11 1 Sf)iO (il C)Iii 7 2 l2 Ji d_ 13 2 8270 iX 2) (i 2 80 I-I in 11 3 8middot1xo -II 3a ]() a 87 0 -1i ll i G9 no In aa l 2 no 0 38 22 8 (iX100 -10 al - 3 8X () 3D 2X ) 67

)110 18 l 3 -s () a2 23 7 li2120_ -w aa fi -0 0 22 17 L8 17

At Oi ( At 70 (

Control X) 7 I 0 n3 ltX Ii I 0 ni) 10 X ltiX tj I bullX-I I 27 18 (j 5220_ 2 iO I ~ 2 7G 0 () (i -I 1080 0 8( Lj I pl) () 0 0 0 0middot10 0 I) IX I 37

bull )0 () 2 7 J2 flO 0 I a a 7 70 () 0 0 2 2 SO - n () 0 I 1~ ~~~-flO _____________

(J () () ()0 - - - - - ~ j

36 lECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

THE GERMINATION TESTS

SEEDLING ABNORMALITIES bull~ltJthough several hundred germination tests were made during the 3-year investigations no clistinctive abnormalities in the stUlcturc of the seedlings were obselTec1 that could be c1pfinitely attributed to heat injury lhe same kinds of abnormal seedlings wC1e observed when heat-treated samples of 1middotice 111c1 unh(gtatCc1 air-c1riCd controls we Ie germinated Abnormal types were most often found among seedlings counted ttt 7 10 anc114 clays The nlost (ol11mon type had t spindly primary root and seeoncJary lOotS There were also otlw1 kinds simishyJar in appearan(e to thosc illustratpd in gricultUlil1 Handbook Ko 30 (84)

That high-temperature injury lIIay bC I(flpcild in sppdling c1evelopshymentis well known HabCrlandtmiddot UI) h(lat(d diflpl(lni kinds of sepds for 48 hours af WOO C Yh(ln f IIpy (r( trminaild Ill found fhaf the plulllule c1(p]oppd bpfore til( rO(ltht al1(1 PYln that the sfpl11 might start to dCwlop though thp )(Jot lpIIWill((] entirlly UndHlloppd Sachs (08) tahulations rp(orci a hirilC1 Iatio of -hrllr((l to 1I0lma I pmbyros til( higlH1 till tplllp(mtull of tl(dmpllt Dixon (2(j) ohshyselYed in f11P lIlIlinnfioll of hlnf-trlated -eC(s t-Ililt Till mosf 1Ipshyquent nhllolmt1if) is til( plotrllsion of til( cofyllr1onsillstpad of thp radicle from thp seld EnII if thl mtliell does lmplge normally it is oft(lf) abnormal in its SU)(cfllent Iwhlyiol HlIt(hinsol1 (31) repoltrd that his hCat-tlpaf(d hpaf s(p(l germinating aftCI sl ighf dClay lIp nII normal as IPga Ids )Oos a lid shoots but a few of thos(l showing fWllC dllay (1( stuntwl

Hut(himon et al (]4) Iwyp stat(d thaf _s with Ot]H1 lo1111 S of bullbiological damage III i Id ]llat damagr ill oats Ila rI( andyh(nt is IcYPlsiblC but 5(ele dama( (HUR(S dtlfh of the ((II Tn adrlition theil pyi(en(( indi(ted tllaf ll(at((1 glaill IHlded opfillllllll (onditioll of watpl and aelntion in fhl plill1alY sfag(s bllt fhat afel growth had (OllllllpllCpd if hrhapd in n nOlIl1d l1U1nnrl TIICy fpH that till heat-dalllag(d (II had lost SOliI( (rf its pOWl1 of sCI(cfip ]gtPIshymeability and fhnf itnlify as jlldgp(] hy abilify to withstIIHI excess wat(I and othpl sub-opt imal gclTnillatioll (olHlif ions is plohably ad(lsply a flC(j(d Thl) notld tytologilal d i fllllnecs in nOlllml and heat-c1a III agC(] gla i 11

DRY SEED

In tlH~ l()in pxpplill1pnts the Iollh Ii(t wifh moistllre contenfs of 33-3H PC)C(IIt had SitOIl roots alld -hoofs than lonflol s((d of higlll) moisture COIlUns (l1l whell til( t(nlpllaflllp of fTlntmpllt of fhe low

~l moistirre-contlnt in III pies IS (ollsidlIld 1ltlow the (Iit ita I rang( On the othel hand no diflelelwPs ill gCIllIillation (apn(ity atp Ieflletpd in the datnin tablp 2 Thl tlason is thaf sunples of ail-dlied contlol wHh both the low a 11(1 flH lrighCl 1l10iStlll( tontlllf vichlpd (ss(lItiaIly the saine 1I11111)l) of cOllilfabln sepdlillgs afttI fi i 10 and l~ days in the gllmillafol i(IIlY mom of filp sNdlings howcvlr hom the drier salllp]rgts banl) met tire albitralily sel((te(] minimum requilcshyments to be counted i ( poslsstd hoth root and shoot with one bull strucfule at hast olle-Jourth inch long

bull

bull

bull

EFFECTS OF HEAT TREATlmNl ON THE VIABILITY OF RICE 37

H~berlandt (31) beHeved that a hardening of the seeds [md seed coats as a result of extensive drying at a high temperature might be the partial explanation for retardation in growth This condition would permit only the ery gradual entmnce of moisture into the inner seed rust (43) and Dixon (26) exprescd similar thoughts

EXCESSIVELY WET SEEDBED

Somctimcs in thc germination tests the beds of paper toweling became extrcmelv (t Seeds in the exCcsfinly wct bcds germishynat-cd m01C 5101) Hoot (radiClc) formation Wl rctarded and when the root did form it was usuall frcc of root hairs This kind of clrnlopmcnt is attributed to rc(111(rd oxygen tension

The plllnomcnon has blln cxtensi nly n~portecl in the 1i tera ture and has bern obscrvcd to o(Cur in ail with reclll(ed oxygen in nitTogen and in watcr and to I)e aflcded hy diflcrcllt dcpths of water slnd rnd soil Klebs ()) in ISHi Yokoi U)J) in IH)8~ and TakahaRhi (80) in 1905 wcre amOIl tIle filstmiddot to rtlonl obRtITntl0n il11ilar to tIll above Since Own thc pilCnOIlHnon has wen Ippoltc(l by ()thtrsin(lllltlill~ Atemine (iV) Xagai ((lj) olillaga (j) ~asaki (fjQ) bullJones (4() Dastur I1(l nlsai (J) lam () Taylor (S) and Ylamis anclDlvis (86) In the gcrmillation of ricc s((d thc ihoot aplwals first lnd lc(olding- to t(lIlille if tl1( api(] root elllllg(gtS first it is probably b(cause of dcfit-icnt 1Il0iRtlr( Ialll aitliblltNl thc failurc of s(eondalV and adnntitiolls roots to dt(lop in Rcedlings plant-Pll algl(atpl c1CI)ths in soil to fhe greatpl lPRtriction of thc ()xyg(1l uppl) Elygill (SO) found thc enzrnlP adiih 10 1)(gt Itss in R((d (llllinatNll1lHlcl water IolinagH ((JJ) drnlollstlnt((j that thl ealall-p adiity of sccdlings gl(Yll U1HItl alpl is Ieltiu(pd tlH gllafl1 til( (ltplh of tlll al(l A (On1l110n plactitP in thl SOlltlrCIl1 Ii(e-gloing ShIfps is tmiddoto plant at a dlptlt or 1 to ~in(]II ith a dlill and to flood the field after the rice is middot1middot to Ii inclHs high (JolH 111(111)

HESISTANCE TO FUNGI

Hough Ii(e iNdi whosl nlJilit- to gellllinall had betn (ompletely (ipstroy((l PI( III 0 Il Ipad i I Y nttHlktti b fll ni thn n iabll sterls Hal)(Ilalldt (-J1) found tltat If tl( gCIlllinting 10(1 iR lhtIO)Nl the ll10ist s(ltls igtPlOnH st ilY and ill-middotmlPlling within 1 fp days whereas -ith liv( R(pds til( ((lt1 (oat 1I1a IPlIlain 1I1lt1tplld for 1(111 w((ks Tusf (~I) iaI1l111tld data -h(Jl~d pari pllt IlIad iOIl of hiR Ilolliahl( htat-tlpl(d s((d stlllpips )ixon ((j) tprilizpt t II( Rand Sallt(rs and wdI u=Cd 101 till (ll11illltion ((1 I LC 10( ThiR pr((lltioll IPPPtIS IINal as IIll dilllilli]lPd itality of p((hi -lllll (xposcd to tNlllwla t UIP lIP I t Irl iI 1I11X i1111111 IPlIllplS thtlil (~Iy SlISttpt i b Ie to the 1 Uat 0 r III iiIO-Olgl1l iII1Smiddot

DIPUOVED GErOIlNATION

Ex(ppt for tht nlO~finllllntUlp Ii(( snmplts hent-tlrntNl Iluring the l)ill cxperimCl1tR (tablc II )lIo(middotiltlII1(t wlsoiJfaillCd flrat hcat tnatshymellts m SI1lt1l illlplO(d irbi Iit Ioll (iclPII(l lIIight hY( been obtaincd hall nil (IP 111It h~ or roots all(L shoots l)((11 detNmined in nil heat-trelt(ll SUlll)l(s 1I1ld (ollt1ols

- -shy

38 TECHITJCAL BULLETIN 1129) U S DEPT OF AGRICULTURE

No experiJnental evidence wns obtained to indicate hether the heat treatments had any elfect in overcoming dOlmancy of the different yarieties of rice Germinatjon tests were not made until 8 weeks after heat treatment Any dormancy existing at the time of harvest might have disappeared (luring this interntl

According to Wiesners (90) york wit11 conifer seeds the effects of heat treatment maybe heneficial to germination Jnst (41) reshyporteel one (xperiment in which thegelll1ination capac-ity and vigor of barley were improved by heat tr(gtailnrnt The hnrley seed was held2 days oYer suHnrie fleid then put in a test tube with calcinm (h10ric1( anrlldt for 2 more clays thrn heIdI day at10deg tncl3 days at GOdeg 0 Kiessling (~4) in stu(lying the ell(Is of henl lIeatnwnt on dormancy found that heat tJeatments i III prowd the ~(Imi nating flUB lity of nonshygerm-ripe barlr) bnt th(y did 110t 1nlly (omprnsaie for eompkte storage rippl1(ss AlloilHI illlpolimt obsPITation was Ihat the il11shyproycment in germinnting q11ality lS illd(lwllclent of the aHernliol1 of the moisture eontpnt TfC Ill l(f(1li 11~ to those losses tha I 0((11 I when srerls alr elI-ipd at the salllp limC nley lle hein~ l1ett-ITCnle(1 Dn Fanos datn (21) ~llOimplOpd Qprmiimtion 01 lice after heatshying at loo-iOo and of (orll aflPI heatillp at 30deg_(0deg

GENEHAL DISCUSSION

Yenthel (onditions toupthel witll otlll1 cinu111slnn(Ps in UHj() HHil nnd 1)52 pleYclltelt1 the allthoJs 110111 obtaining lois (rl flpshl) COIll shy

bined rough riee of higher than ~5~-ppl(enl llloihllC content- It yould l1nyc bpel1 dpsiluhle to 111e included pxperinlPnts on the elleets of temperatllle of tTCntment on lots of riel of 2(i- 10 lO-pel(pnt moisshyIl1le (on tents These 11l0istUIp (on 1(gt 11 11 lllthnllh II 11(0111 1110n 11(

possible FUlthellIlole it yould hn n iJNn (]pilaiJlt fronl til( standshypoint of e0l11111el(ial huTpsting eOllditiol1s to have IIsHl lots of rice fleshl combined nt (fI(lJ 2-pcl((nt (Ii 110r(gtl1(e in Illoistmclevel at Ipnst within 111( IHnl 01 ](j to 2G pel(enl B((tllsc it was not I)nICshy

lien1 to th)) pf to Olll hi I( Jil at sppi fitd 11IOislIIIc-eonfent l~nIs l(lnll1fngc IS Inkpn of llll llllpllIatie 1)IO(pdlllC in which n hallpl 01 molp of Ii(e Ill tnkpll froll1 a flpshlv(ol1lhillPd lot of hith IIlnistIIp eontpilt lind IHlItions (1(gt ail-ltiJipd to diflCIPllt lI1oistlllpI()middot(ls

H ns uIficipHtpd tiJlt IIPn tJpntlllPllts ilt illlI(lsillgly higlwl tPIlI shy

p(rahlllS wOllld Illillg aholl ilwl(nsiI1J_dy glpntpl INlllltt iOIl ill the abilitmiddot of Ii(p to PIllIillafp Till pnlliPl illpsliatOIR I((onized till Bigl1iiil~HHe of til( IplIllWlalII Il alinblp llwiIllllntCIOIISeXpelilllClIts del1lonstTuled till gl(ttPI ltleslludivPllpss 01 the highlI iell1ppmtilles to germinability X(lltlwlpss sPPIal rpasolls pxi~f for not acceptshying theil clufa fllld eOlHlllSiolls ns linnl alld ltiilpctly appli(ahle to Ihe heat tlcahllCll of Iiet Fol lxnlllple specilic (lltails regalciing Ihe moisture contellts of the s((gtlt1s tlIP 1lHlholtlR of llent tlfatmel1l nlHl the age of till s(gt((is W(Le frequently ollliiJec1 Seeds yere sonlpIilJl(gtS Cxposed to PIT higit trll1pCrahllPS Hnd fol 1l1lllSllfllly lon~ ])pliolt(s of ii me TIHV (1( [ 11 i licin 11 IIlOist Piled whpn it vas clcsilNl to detelmine tlH (Ireds 01 hllIt 011 s(I(ds of hih moisture eOIlipllt Oplshymination tests (Ie gPIIPln II made i I1lll1e(lia tel v 01 sholt I y dt(1 it(al treatment ~rnllr 01 titp s(((is stlldipcl difllJpd slludlllllly floll1lice

bull

bull

bull MOleover most of thp illVltignols had different objediycs in planshyning their (Xjlllillltllts

TECI4~ICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

Approxiniated temperatures at which heat damage to viability just ~starts and is just complete are given in table 14 for Bluebonnet and

a bull BLUEBONNET (1951)HEAT DAMAGE JUST STARTED 0 HEAT DAMAGE JUST COMPLETE bullD

SEL 61-25-12 (1951)HEAT DAMAGE JUST STARTED A HEAT DAMAGE JUST COMPLETE 80 ~ bull

o U D

BLUEBONNET (1952)

~ bull bull bull

HEAT DAMAGE JUST STARTED D lampJ HEAT DAMAGE JUST COMPLETEbulloU bull

bull~

o bullbullbullbull 70 Ishy

lampJ ~ o ) A

bullbullbullbull bull~

~ o

o bull bull bullbull

~ -1Ca00 A IampJ ~ CL DA

~ 80 Ishy o ~ OA

A o

o o

o 50 ~ o

I I I I 5 15 25bull

MOISTURE CONTENT OF RICE

FIGURE 3-Approximate limitations of the zonc of heal damallc for B1uehonnet and ScI 6f-25-12 and the relutionship of the moisture contcnts of the rkc to th( damug ing tcmperatures (Data from tahltmiddot 14)

SeI 61-25-12 of several moisture contents Table 14 and figure 3 show the relationship of the moishlle ltontpnts of the ricp to the damaging tem pelatur(middot~

Figure 3 is II ~ctUer-type diagllll11 of the data plpHelltp(J in table 14 ]~ach tempellltnreiR plotteci against the 11l0istlln~ contpnt of the riel A zone of hent damage is clplIl1y pidulcd but its upppt and lower boundaries are noto sharply and lcglliady defined as one might hope

__________ _ ______________ _

EFFECTS OF HEAT TREATMENT ON THE VIABILIlY OF RICE 33

TABLE 14-AlPlo-citnated te1nperatules at 1oMah heat damage just starts an~l is just complete 1m rough 1ice 01 diff81ent moisture conshy tents 1951-5CJ

Variety and pereent mOisture content

BluebonIlet (BBl) (1951)252________________________________ bull ______

i~i~~~~-~~-~~~~ii-~_~~I 107_______ 99__________ 03___ bull __ -- -

Sel 01-25-12 (8middotJ BH23) (1liil) 198 _____ ___ __ 182____ 156___ bull _

__

] 4middot0_____ _____ _ 121____ bull __ _ 101_____ __ 77_____ bull

BlueboIlIlPt (BBIO) (1952) 210_____ __ ll3___ bull _ _ _ 172bullbull __ _ 150______ __ 189______ __] 14 ______ __ l7 _____ bull __ __ 81 ________ 58__________ 50_________ 17__________ _bull __ _ _

_j_ ____

- _ - ___ --I

- shy~--- ~

i - - - --I

I

Heat damage starts

o c 50 51 53 58 01 (j3(jj 64 (j~

7()

)j 58 ()~ (j3 0middot ()4 67

52 )4 (i0 (i2 1i3 (j5 fl4 (j8 j

8~ 78 1---------shy80 __________

i iHeat

damage complete

- o C

61 62 65 70 71 73 74 73 76 87

68 69 71 73 74 74 77

06 69 72

I 72 73 75 7-l 77

TEMPERATURE AND TIlIE VAlUABLES

Peltentages of rough I ice in snmples of Century 52 germinating 8 weeks after being heat-tlentel1 101 Iwrioc1s of 10 to 120 minutes aIs gien in table Ii) Hele the same timc-tempeltltul( efreets 011 gennishylultioll capl(ity (tre delllon3trted but in greater detail thall for BtxOo (table I) 01 Bluebollll(t (table D) 0

The germinal-ion Cllpaeitv of the (entur) 32 air-dried (ontrol based on I testmiddots lllllounttd to n+ ptI(enL Hi gerIllillation rigor is txppsselt1 by till pCI(pntaglS gClllllnating aftel 0 7 10 and 1+ clays which CI( HH ii 1 and 0 respcdiOely

bull The germination eapaeitics of thc heat-fIpate( Slllllpl(middots WPIC but

slightly nfleetld by iPIllpemturps oi~ trpatlllcnf bel() (HO CO ~t 61deg 101 20 minutps 01 longer tht connts dlOPPNl to H7-l2 pel((nL On the ol11eL hand all samples heat-treated at (+0 for 10 to 120 minutes underwent an appleeiaiJly gnateJ plogrlssive loss ill gtrIlliIlation shycapacity with increased tillle of treatl11elit and the eounts droppcd to J

J

bull bull

TBL1J15-Gcrmination of Oentury 51B rough rice aftet heat t1catment fol diffp1(Vnt l)e1iods of time 1951B ---~ - bullbullbulllt ~ --- -----T--- --- --shy- -

Temperature of COIl- 10 I 20 i 30 40 I 50 I 60 I 70 80 00 100 llO 120 _tleit~(llt C)___trol_~~~ ~~-~in~I~Jill~~~ -=in~ min~ ~nin~ 1l1in~ in~ in~

Percrn i Pcrc(nl

-~) - 115 0355 __ U5 l558 __ n4 n3OJ bull 05 Oil(lmiddotI bull 04 IIIIii bullbull l1 iO l5 ~~ I 8 5g 36 5 6 2 1___ 1 __ O

--~------~ ~-------~~--

t Ii Prrceni Pcrccnt Perera I Prrccn Perclnl PlIcfni Prrcrnl Penen

l

)1) j 03 I fl4 01 )(l l)j 1)2 0middot1 04 92 02 07 07 )middotI nmiddot )3 SO 1)2 0 I 02 no 87 no 02 SO 87 00 so SU S8 S5 82 8middot1 60 fi8I

Percen i PCIceni Percent

95 fl5 95 95 95 )3 04 01 90 88 88 89 07 62 47

___ ~__ bull ___ ~___ _ bullbull~ l

lti

~ l Ij tj Id ~ ogtIj bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 35

47-91 percent The destructjon of germination cnpacity was corshyrespondingly greater at the two highest temperatures There were no viable sreds in samples tTeattd for DO minutes 01 longer at 67deg or for 30 minutes or longer at 70deg

A loss jn germination igor oCeUlT(tlin samples of Century 52 heat-treated for 80 minlltes or longer al- fiiO C and in L11 those heatshytreated at the higher telllpelatlll(fi The extent of this loss is reflected in the germination data in (-able Hi rile 1)(gtI(pntages of Iice germishynating after 5710 and U days nrc giell for all samples heat-treated at 61deg (14deg 6T 11 nd TO- -lIlt t Pili plrat lins I hat lc(1n itely affettecl germination eapaeity The plIeentages sho tlw(- the longer thn treilhnent or the hipllIr the tpIllperat1l1e of tTeahllPnt for rice of a given moisture lontpnt (he longPI it tnkl tlH lelllnining middotiablp SPlds 111 thp sample to PIllIinnte -gain I-his ous(lnLtion holds only if the tel1l])(lallllC of ITPatll1llIt fall ithin the zOl1e of heat (lanmiC for rice of the SI)PCified moisture onlpni

TABLE 1G-E1f((middotf oj till( (dllraioll) of 1fat tJ((ltmcilt of dijfll(lIt t(mp((tIIJ(N Oil till glJmillatioll of ((lItlll ) IOU(lh Iire ((Jtm 57 JO ((lid 14 l(ls HJJ

t filo C At GmiddotI (Duration of ----_- - - __--_ -------_ ------shy

bull hlU-t trpatlllPI1t

(lltillil tCs) i 7 10 JmiddotI i 7 10 IJ shyT()talclaIs dnls days days dnys days days days Total

---~ --------- -- --- --------- ------ ---shy ~--

1 r- Pr- Plr- Pa- Plr- Per- I) rshy PI- Pa- Pershycent CUlt Cflll cellt Cl1lt CI Ilt cl-ni cellI cent celll

( ontrol 02 2 I 0 nij -8 middot1 2 0 9410 lt3 8 3 I gj in 2a ] 8 9120 7fi 11 1 l2

-) It 3a jmiddot1 1 8930 1- II

i() 1 00 XI ao 1middot1 2 Sl

-10 il 22 2 8-( 22 )1 10 2 88iO i) 2) (j I 00 17 iii 11 1 Sf)iO (il C)Iii 7 2 l2 Ji d_ 13 2 8270 iX 2) (i 2 80 I-I in 11 3 8middot1xo -II 3a ]() a 87 0 -1i ll i G9 no In aa l 2 no 0 38 22 8 (iX100 -10 al - 3 8X () 3D 2X ) 67

)110 18 l 3 -s () a2 23 7 li2120_ -w aa fi -0 0 22 17 L8 17

At Oi ( At 70 (

Control X) 7 I 0 n3 ltX Ii I 0 ni) 10 X ltiX tj I bullX-I I 27 18 (j 5220_ 2 iO I ~ 2 7G 0 () (i -I 1080 0 8( Lj I pl) () 0 0 0 0middot10 0 I) IX I 37

bull )0 () 2 7 J2 flO 0 I a a 7 70 () 0 0 2 2 SO - n () 0 I 1~ ~~~-flO _____________

(J () () ()0 - - - - - ~ j

36 lECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

THE GERMINATION TESTS

SEEDLING ABNORMALITIES bull~ltJthough several hundred germination tests were made during the 3-year investigations no clistinctive abnormalities in the stUlcturc of the seedlings were obselTec1 that could be c1pfinitely attributed to heat injury lhe same kinds of abnormal seedlings wC1e observed when heat-treated samples of 1middotice 111c1 unh(gtatCc1 air-c1riCd controls we Ie germinated Abnormal types were most often found among seedlings counted ttt 7 10 anc114 clays The nlost (ol11mon type had t spindly primary root and seeoncJary lOotS There were also otlw1 kinds simishyJar in appearan(e to thosc illustratpd in gricultUlil1 Handbook Ko 30 (84)

That high-temperature injury lIIay bC I(flpcild in sppdling c1evelopshymentis well known HabCrlandtmiddot UI) h(lat(d diflpl(lni kinds of sepds for 48 hours af WOO C Yh(ln f IIpy (r( trminaild Ill found fhaf the plulllule c1(p]oppd bpfore til( rO(ltht al1(1 PYln that the sfpl11 might start to dCwlop though thp )(Jot lpIIWill((] entirlly UndHlloppd Sachs (08) tahulations rp(orci a hirilC1 Iatio of -hrllr((l to 1I0lma I pmbyros til( higlH1 till tplllp(mtull of tl(dmpllt Dixon (2(j) ohshyselYed in f11P lIlIlinnfioll of hlnf-trlated -eC(s t-Ililt Till mosf 1Ipshyquent nhllolmt1if) is til( plotrllsion of til( cofyllr1onsillstpad of thp radicle from thp seld EnII if thl mtliell does lmplge normally it is oft(lf) abnormal in its SU)(cfllent Iwhlyiol HlIt(hinsol1 (31) repoltrd that his hCat-tlpaf(d hpaf s(p(l germinating aftCI sl ighf dClay lIp nII normal as IPga Ids )Oos a lid shoots but a few of thos(l showing fWllC dllay (1( stuntwl

Hut(himon et al (]4) Iwyp stat(d thaf _s with Ot]H1 lo1111 S of bullbiological damage III i Id ]llat damagr ill oats Ila rI( andyh(nt is IcYPlsiblC but 5(ele dama( (HUR(S dtlfh of the ((II Tn adrlition theil pyi(en(( indi(ted tllaf ll(at((1 glaill IHlded opfillllllll (onditioll of watpl and aelntion in fhl plill1alY sfag(s bllt fhat afel growth had (OllllllpllCpd if hrhapd in n nOlIl1d l1U1nnrl TIICy fpH that till heat-dalllag(d (II had lost SOliI( (rf its pOWl1 of sCI(cfip ]gtPIshymeability and fhnf itnlify as jlldgp(] hy abilify to withstIIHI excess wat(I and othpl sub-opt imal gclTnillatioll (olHlif ions is plohably ad(lsply a flC(j(d Thl) notld tytologilal d i fllllnecs in nOlllml and heat-c1a III agC(] gla i 11

DRY SEED

In tlH~ l()in pxpplill1pnts the Iollh Ii(t wifh moistllre contenfs of 33-3H PC)C(IIt had SitOIl roots alld -hoofs than lonflol s((d of higlll) moisture COIlUns (l1l whell til( t(nlpllaflllp of fTlntmpllt of fhe low

~l moistirre-contlnt in III pies IS (ollsidlIld 1ltlow the (Iit ita I rang( On the othel hand no diflelelwPs ill gCIllIillation (apn(ity atp Ieflletpd in the datnin tablp 2 Thl tlason is thaf sunples of ail-dlied contlol wHh both the low a 11(1 flH lrighCl 1l10iStlll( tontlllf vichlpd (ss(lItiaIly the saine 1I11111)l) of cOllilfabln sepdlillgs afttI fi i 10 and l~ days in the gllmillafol i(IIlY mom of filp sNdlings howcvlr hom the drier salllp]rgts banl) met tire albitralily sel((te(] minimum requilcshyments to be counted i ( poslsstd hoth root and shoot with one bull strucfule at hast olle-Jourth inch long

bull

bull

bull

EFFECTS OF HEAT TREATlmNl ON THE VIABILITY OF RICE 37

H~berlandt (31) beHeved that a hardening of the seeds [md seed coats as a result of extensive drying at a high temperature might be the partial explanation for retardation in growth This condition would permit only the ery gradual entmnce of moisture into the inner seed rust (43) and Dixon (26) exprescd similar thoughts

EXCESSIVELY WET SEEDBED

Somctimcs in thc germination tests the beds of paper toweling became extrcmelv (t Seeds in the exCcsfinly wct bcds germishynat-cd m01C 5101) Hoot (radiClc) formation Wl rctarded and when the root did form it was usuall frcc of root hairs This kind of clrnlopmcnt is attributed to rc(111(rd oxygen tension

The plllnomcnon has blln cxtensi nly n~portecl in the 1i tera ture and has bern obscrvcd to o(Cur in ail with reclll(ed oxygen in nitTogen and in watcr and to I)e aflcded hy diflcrcllt dcpths of water slnd rnd soil Klebs ()) in ISHi Yokoi U)J) in IH)8~ and TakahaRhi (80) in 1905 wcre amOIl tIle filstmiddot to rtlonl obRtITntl0n il11ilar to tIll above Since Own thc pilCnOIlHnon has wen Ippoltc(l by ()thtrsin(lllltlill~ Atemine (iV) Xagai ((lj) olillaga (j) ~asaki (fjQ) bullJones (4() Dastur I1(l nlsai (J) lam () Taylor (S) and Ylamis anclDlvis (86) In the gcrmillation of ricc s((d thc ihoot aplwals first lnd lc(olding- to t(lIlille if tl1( api(] root elllllg(gtS first it is probably b(cause of dcfit-icnt 1Il0iRtlr( Ialll aitliblltNl thc failurc of s(eondalV and adnntitiolls roots to dt(lop in Rcedlings plant-Pll algl(atpl c1CI)ths in soil to fhe greatpl lPRtriction of thc ()xyg(1l uppl) Elygill (SO) found thc enzrnlP adiih 10 1)(gt Itss in R((d (llllinatNll1lHlcl water IolinagH ((JJ) drnlollstlnt((j that thl ealall-p adiity of sccdlings gl(Yll U1HItl alpl is Ieltiu(pd tlH gllafl1 til( (ltplh of tlll al(l A (On1l110n plactitP in thl SOlltlrCIl1 Ii(e-gloing ShIfps is tmiddoto plant at a dlptlt or 1 to ~in(]II ith a dlill and to flood the field after the rice is middot1middot to Ii inclHs high (JolH 111(111)

HESISTANCE TO FUNGI

Hough Ii(e iNdi whosl nlJilit- to gellllinall had betn (ompletely (ipstroy((l PI( III 0 Il Ipad i I Y nttHlktti b fll ni thn n iabll sterls Hal)(Ilalldt (-J1) found tltat If tl( gCIlllinting 10(1 iR lhtIO)Nl the ll10ist s(ltls igtPlOnH st ilY and ill-middotmlPlling within 1 fp days whereas -ith liv( R(pds til( ((lt1 (oat 1I1a IPlIlain 1I1lt1tplld for 1(111 w((ks Tusf (~I) iaI1l111tld data -h(Jl~d pari pllt IlIad iOIl of hiR Ilolliahl( htat-tlpl(d s((d stlllpips )ixon ((j) tprilizpt t II( Rand Sallt(rs and wdI u=Cd 101 till (ll11illltion ((1 I LC 10( ThiR pr((lltioll IPPPtIS IINal as IIll dilllilli]lPd itality of p((hi -lllll (xposcd to tNlllwla t UIP lIP I t Irl iI 1I11X i1111111 IPlIllplS thtlil (~Iy SlISttpt i b Ie to the 1 Uat 0 r III iiIO-Olgl1l iII1Smiddot

DIPUOVED GErOIlNATION

Ex(ppt for tht nlO~finllllntUlp Ii(( snmplts hent-tlrntNl Iluring the l)ill cxperimCl1tR (tablc II )lIo(middotiltlII1(t wlsoiJfaillCd flrat hcat tnatshymellts m SI1lt1l illlplO(d irbi Iit Ioll (iclPII(l lIIight hY( been obtaincd hall nil (IP 111It h~ or roots all(L shoots l)((11 detNmined in nil heat-trelt(ll SUlll)l(s 1I1ld (ollt1ols

- -shy

38 TECHITJCAL BULLETIN 1129) U S DEPT OF AGRICULTURE

No experiJnental evidence wns obtained to indicate hether the heat treatments had any elfect in overcoming dOlmancy of the different yarieties of rice Germinatjon tests were not made until 8 weeks after heat treatment Any dormancy existing at the time of harvest might have disappeared (luring this interntl

According to Wiesners (90) york wit11 conifer seeds the effects of heat treatment maybe heneficial to germination Jnst (41) reshyporteel one (xperiment in which thegelll1ination capac-ity and vigor of barley were improved by heat tr(gtailnrnt The hnrley seed was held2 days oYer suHnrie fleid then put in a test tube with calcinm (h10ric1( anrlldt for 2 more clays thrn heIdI day at10deg tncl3 days at GOdeg 0 Kiessling (~4) in stu(lying the ell(Is of henl lIeatnwnt on dormancy found that heat tJeatments i III prowd the ~(Imi nating flUB lity of nonshygerm-ripe barlr) bnt th(y did 110t 1nlly (omprnsaie for eompkte storage rippl1(ss AlloilHI illlpolimt obsPITation was Ihat the il11shyproycment in germinnting q11ality lS illd(lwllclent of the aHernliol1 of the moisture eontpnt TfC Ill l(f(1li 11~ to those losses tha I 0((11 I when srerls alr elI-ipd at the salllp limC nley lle hein~ l1ett-ITCnle(1 Dn Fanos datn (21) ~llOimplOpd Qprmiimtion 01 lice after heatshying at loo-iOo and of (orll aflPI heatillp at 30deg_(0deg

GENEHAL DISCUSSION

Yenthel (onditions toupthel witll otlll1 cinu111slnn(Ps in UHj() HHil nnd 1)52 pleYclltelt1 the allthoJs 110111 obtaining lois (rl flpshl) COIll shy

bined rough riee of higher than ~5~-ppl(enl llloihllC content- It yould l1nyc bpel1 dpsiluhle to 111e included pxperinlPnts on the elleets of temperatllle of tTCntment on lots of riel of 2(i- 10 lO-pel(pnt moisshyIl1le (on tents These 11l0istUIp (on 1(gt 11 11 lllthnllh II 11(0111 1110n 11(

possible FUlthellIlole it yould hn n iJNn (]pilaiJlt fronl til( standshypoint of e0l11111el(ial huTpsting eOllditiol1s to have IIsHl lots of rice fleshl combined nt (fI(lJ 2-pcl((nt (Ii 110r(gtl1(e in Illoistmclevel at Ipnst within 111( IHnl 01 ](j to 2G pel(enl B((tllsc it was not I)nICshy

lien1 to th)) pf to Olll hi I( Jil at sppi fitd 11IOislIIIc-eonfent l~nIs l(lnll1fngc IS Inkpn of llll llllpllIatie 1)IO(pdlllC in which n hallpl 01 molp of Ii(e Ill tnkpll froll1 a flpshlv(ol1lhillPd lot of hith IIlnistIIp eontpilt lind IHlItions (1(gt ail-ltiJipd to diflCIPllt lI1oistlllpI()middot(ls

H ns uIficipHtpd tiJlt IIPn tJpntlllPllts ilt illlI(lsillgly higlwl tPIlI shy

p(rahlllS wOllld Illillg aholl ilwl(nsiI1J_dy glpntpl INlllltt iOIl ill the abilitmiddot of Ii(p to PIllIillafp Till pnlliPl illpsliatOIR I((onized till Bigl1iiil~HHe of til( IplIllWlalII Il alinblp llwiIllllntCIOIISeXpelilllClIts del1lonstTuled till gl(ttPI ltleslludivPllpss 01 the highlI iell1ppmtilles to germinability X(lltlwlpss sPPIal rpasolls pxi~f for not acceptshying theil clufa fllld eOlHlllSiolls ns linnl alld ltiilpctly appli(ahle to Ihe heat tlcahllCll of Iiet Fol lxnlllple specilic (lltails regalciing Ihe moisture contellts of the s((gtlt1s tlIP 1lHlholtlR of llent tlfatmel1l nlHl the age of till s(gt((is W(Le frequently ollliiJec1 Seeds yere sonlpIilJl(gtS Cxposed to PIT higit trll1pCrahllPS Hnd fol 1l1lllSllfllly lon~ ])pliolt(s of ii me TIHV (1( [ 11 i licin 11 IIlOist Piled whpn it vas clcsilNl to detelmine tlH (Ireds 01 hllIt 011 s(I(ds of hih moisture eOIlipllt Oplshymination tests (Ie gPIIPln II made i I1lll1e(lia tel v 01 sholt I y dt(1 it(al treatment ~rnllr 01 titp s(((is stlldipcl difllJpd slludlllllly floll1lice

bull

bull

bull MOleover most of thp illVltignols had different objediycs in planshyning their (Xjlllillltllts

__________ _ ______________ _

EFFECTS OF HEAT TREATMENT ON THE VIABILIlY OF RICE 33

TABLE 14-AlPlo-citnated te1nperatules at 1oMah heat damage just starts an~l is just complete 1m rough 1ice 01 diff81ent moisture conshy tents 1951-5CJ

Variety and pereent mOisture content

BluebonIlet (BBl) (1951)252________________________________ bull ______

i~i~~~~-~~-~~~~ii-~_~~I 107_______ 99__________ 03___ bull __ -- -

Sel 01-25-12 (8middotJ BH23) (1liil) 198 _____ ___ __ 182____ 156___ bull _

__

] 4middot0_____ _____ _ 121____ bull __ _ 101_____ __ 77_____ bull

BlueboIlIlPt (BBIO) (1952) 210_____ __ ll3___ bull _ _ _ 172bullbull __ _ 150______ __ 189______ __] 14 ______ __ l7 _____ bull __ __ 81 ________ 58__________ 50_________ 17__________ _bull __ _ _

_j_ ____

- _ - ___ --I

- shy~--- ~

i - - - --I

I

Heat damage starts

o c 50 51 53 58 01 (j3(jj 64 (j~

7()

)j 58 ()~ (j3 0middot ()4 67

52 )4 (i0 (i2 1i3 (j5 fl4 (j8 j

8~ 78 1---------shy80 __________

i iHeat

damage complete

- o C

61 62 65 70 71 73 74 73 76 87

68 69 71 73 74 74 77

06 69 72

I 72 73 75 7-l 77

TEMPERATURE AND TIlIE VAlUABLES

Peltentages of rough I ice in snmples of Century 52 germinating 8 weeks after being heat-tlentel1 101 Iwrioc1s of 10 to 120 minutes aIs gien in table Ii) Hele the same timc-tempeltltul( efreets 011 gennishylultioll capl(ity (tre delllon3trted but in greater detail thall for BtxOo (table I) 01 Bluebollll(t (table D) 0

The germinal-ion Cllpaeitv of the (entur) 32 air-dried (ontrol based on I testmiddots lllllounttd to n+ ptI(enL Hi gerIllillation rigor is txppsselt1 by till pCI(pntaglS gClllllnating aftel 0 7 10 and 1+ clays which CI( HH ii 1 and 0 respcdiOely

bull The germination eapaeitics of thc heat-fIpate( Slllllpl(middots WPIC but

slightly nfleetld by iPIllpemturps oi~ trpatlllcnf bel() (HO CO ~t 61deg 101 20 minutps 01 longer tht connts dlOPPNl to H7-l2 pel((nL On the ol11eL hand all samples heat-treated at (+0 for 10 to 120 minutes underwent an appleeiaiJly gnateJ plogrlssive loss ill gtrIlliIlation shycapacity with increased tillle of treatl11elit and the eounts droppcd to J

J

bull bull

TBL1J15-Gcrmination of Oentury 51B rough rice aftet heat t1catment fol diffp1(Vnt l)e1iods of time 1951B ---~ - bullbullbulllt ~ --- -----T--- --- --shy- -

Temperature of COIl- 10 I 20 i 30 40 I 50 I 60 I 70 80 00 100 llO 120 _tleit~(llt C)___trol_~~~ ~~-~in~I~Jill~~~ -=in~ min~ ~nin~ 1l1in~ in~ in~

Percrn i Pcrc(nl

-~) - 115 0355 __ U5 l558 __ n4 n3OJ bull 05 Oil(lmiddotI bull 04 IIIIii bullbull l1 iO l5 ~~ I 8 5g 36 5 6 2 1___ 1 __ O

--~------~ ~-------~~--

t Ii Prrceni Pcrccnt Perera I Prrccn Perclnl PlIcfni Prrcrnl Penen

l

)1) j 03 I fl4 01 )(l l)j 1)2 0middot1 04 92 02 07 07 )middotI nmiddot )3 SO 1)2 0 I 02 no 87 no 02 SO 87 00 so SU S8 S5 82 8middot1 60 fi8I

Percen i PCIceni Percent

95 fl5 95 95 95 )3 04 01 90 88 88 89 07 62 47

___ ~__ bull ___ ~___ _ bullbull~ l

lti

~ l Ij tj Id ~ ogtIj bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 35

47-91 percent The destructjon of germination cnpacity was corshyrespondingly greater at the two highest temperatures There were no viable sreds in samples tTeattd for DO minutes 01 longer at 67deg or for 30 minutes or longer at 70deg

A loss jn germination igor oCeUlT(tlin samples of Century 52 heat-treated for 80 minlltes or longer al- fiiO C and in L11 those heatshytreated at the higher telllpelatlll(fi The extent of this loss is reflected in the germination data in (-able Hi rile 1)(gtI(pntages of Iice germishynating after 5710 and U days nrc giell for all samples heat-treated at 61deg (14deg 6T 11 nd TO- -lIlt t Pili plrat lins I hat lc(1n itely affettecl germination eapaeity The plIeentages sho tlw(- the longer thn treilhnent or the hipllIr the tpIllperat1l1e of tTeahllPnt for rice of a given moisture lontpnt (he longPI it tnkl tlH lelllnining middotiablp SPlds 111 thp sample to PIllIinnte -gain I-his ous(lnLtion holds only if the tel1l])(lallllC of ITPatll1llIt fall ithin the zOl1e of heat (lanmiC for rice of the SI)PCified moisture onlpni

TABLE 1G-E1f((middotf oj till( (dllraioll) of 1fat tJ((ltmcilt of dijfll(lIt t(mp((tIIJ(N Oil till glJmillatioll of ((lItlll ) IOU(lh Iire ((Jtm 57 JO ((lid 14 l(ls HJJ

t filo C At GmiddotI (Duration of ----_- - - __--_ -------_ ------shy

bull hlU-t trpatlllPI1t

(lltillil tCs) i 7 10 JmiddotI i 7 10 IJ shyT()talclaIs dnls days days dnys days days days Total

---~ --------- -- --- --------- ------ ---shy ~--

1 r- Pr- Plr- Pa- Plr- Per- I) rshy PI- Pa- Pershycent CUlt Cflll cellt Cl1lt CI Ilt cl-ni cellI cent celll

( ontrol 02 2 I 0 nij -8 middot1 2 0 9410 lt3 8 3 I gj in 2a ] 8 9120 7fi 11 1 l2

-) It 3a jmiddot1 1 8930 1- II

i() 1 00 XI ao 1middot1 2 Sl

-10 il 22 2 8-( 22 )1 10 2 88iO i) 2) (j I 00 17 iii 11 1 Sf)iO (il C)Iii 7 2 l2 Ji d_ 13 2 8270 iX 2) (i 2 80 I-I in 11 3 8middot1xo -II 3a ]() a 87 0 -1i ll i G9 no In aa l 2 no 0 38 22 8 (iX100 -10 al - 3 8X () 3D 2X ) 67

)110 18 l 3 -s () a2 23 7 li2120_ -w aa fi -0 0 22 17 L8 17

At Oi ( At 70 (

Control X) 7 I 0 n3 ltX Ii I 0 ni) 10 X ltiX tj I bullX-I I 27 18 (j 5220_ 2 iO I ~ 2 7G 0 () (i -I 1080 0 8( Lj I pl) () 0 0 0 0middot10 0 I) IX I 37

bull )0 () 2 7 J2 flO 0 I a a 7 70 () 0 0 2 2 SO - n () 0 I 1~ ~~~-flO _____________

(J () () ()0 - - - - - ~ j

36 lECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

THE GERMINATION TESTS

SEEDLING ABNORMALITIES bull~ltJthough several hundred germination tests were made during the 3-year investigations no clistinctive abnormalities in the stUlcturc of the seedlings were obselTec1 that could be c1pfinitely attributed to heat injury lhe same kinds of abnormal seedlings wC1e observed when heat-treated samples of 1middotice 111c1 unh(gtatCc1 air-c1riCd controls we Ie germinated Abnormal types were most often found among seedlings counted ttt 7 10 anc114 clays The nlost (ol11mon type had t spindly primary root and seeoncJary lOotS There were also otlw1 kinds simishyJar in appearan(e to thosc illustratpd in gricultUlil1 Handbook Ko 30 (84)

That high-temperature injury lIIay bC I(flpcild in sppdling c1evelopshymentis well known HabCrlandtmiddot UI) h(lat(d diflpl(lni kinds of sepds for 48 hours af WOO C Yh(ln f IIpy (r( trminaild Ill found fhaf the plulllule c1(p]oppd bpfore til( rO(ltht al1(1 PYln that the sfpl11 might start to dCwlop though thp )(Jot lpIIWill((] entirlly UndHlloppd Sachs (08) tahulations rp(orci a hirilC1 Iatio of -hrllr((l to 1I0lma I pmbyros til( higlH1 till tplllp(mtull of tl(dmpllt Dixon (2(j) ohshyselYed in f11P lIlIlinnfioll of hlnf-trlated -eC(s t-Ililt Till mosf 1Ipshyquent nhllolmt1if) is til( plotrllsion of til( cofyllr1onsillstpad of thp radicle from thp seld EnII if thl mtliell does lmplge normally it is oft(lf) abnormal in its SU)(cfllent Iwhlyiol HlIt(hinsol1 (31) repoltrd that his hCat-tlpaf(d hpaf s(p(l germinating aftCI sl ighf dClay lIp nII normal as IPga Ids )Oos a lid shoots but a few of thos(l showing fWllC dllay (1( stuntwl

Hut(himon et al (]4) Iwyp stat(d thaf _s with Ot]H1 lo1111 S of bullbiological damage III i Id ]llat damagr ill oats Ila rI( andyh(nt is IcYPlsiblC but 5(ele dama( (HUR(S dtlfh of the ((II Tn adrlition theil pyi(en(( indi(ted tllaf ll(at((1 glaill IHlded opfillllllll (onditioll of watpl and aelntion in fhl plill1alY sfag(s bllt fhat afel growth had (OllllllpllCpd if hrhapd in n nOlIl1d l1U1nnrl TIICy fpH that till heat-dalllag(d (II had lost SOliI( (rf its pOWl1 of sCI(cfip ]gtPIshymeability and fhnf itnlify as jlldgp(] hy abilify to withstIIHI excess wat(I and othpl sub-opt imal gclTnillatioll (olHlif ions is plohably ad(lsply a flC(j(d Thl) notld tytologilal d i fllllnecs in nOlllml and heat-c1a III agC(] gla i 11

DRY SEED

In tlH~ l()in pxpplill1pnts the Iollh Ii(t wifh moistllre contenfs of 33-3H PC)C(IIt had SitOIl roots alld -hoofs than lonflol s((d of higlll) moisture COIlUns (l1l whell til( t(nlpllaflllp of fTlntmpllt of fhe low

~l moistirre-contlnt in III pies IS (ollsidlIld 1ltlow the (Iit ita I rang( On the othel hand no diflelelwPs ill gCIllIillation (apn(ity atp Ieflletpd in the datnin tablp 2 Thl tlason is thaf sunples of ail-dlied contlol wHh both the low a 11(1 flH lrighCl 1l10iStlll( tontlllf vichlpd (ss(lItiaIly the saine 1I11111)l) of cOllilfabln sepdlillgs afttI fi i 10 and l~ days in the gllmillafol i(IIlY mom of filp sNdlings howcvlr hom the drier salllp]rgts banl) met tire albitralily sel((te(] minimum requilcshyments to be counted i ( poslsstd hoth root and shoot with one bull strucfule at hast olle-Jourth inch long

bull

bull

bull

EFFECTS OF HEAT TREATlmNl ON THE VIABILITY OF RICE 37

H~berlandt (31) beHeved that a hardening of the seeds [md seed coats as a result of extensive drying at a high temperature might be the partial explanation for retardation in growth This condition would permit only the ery gradual entmnce of moisture into the inner seed rust (43) and Dixon (26) exprescd similar thoughts

EXCESSIVELY WET SEEDBED

Somctimcs in thc germination tests the beds of paper toweling became extrcmelv (t Seeds in the exCcsfinly wct bcds germishynat-cd m01C 5101) Hoot (radiClc) formation Wl rctarded and when the root did form it was usuall frcc of root hairs This kind of clrnlopmcnt is attributed to rc(111(rd oxygen tension

The plllnomcnon has blln cxtensi nly n~portecl in the 1i tera ture and has bern obscrvcd to o(Cur in ail with reclll(ed oxygen in nitTogen and in watcr and to I)e aflcded hy diflcrcllt dcpths of water slnd rnd soil Klebs ()) in ISHi Yokoi U)J) in IH)8~ and TakahaRhi (80) in 1905 wcre amOIl tIle filstmiddot to rtlonl obRtITntl0n il11ilar to tIll above Since Own thc pilCnOIlHnon has wen Ippoltc(l by ()thtrsin(lllltlill~ Atemine (iV) Xagai ((lj) olillaga (j) ~asaki (fjQ) bullJones (4() Dastur I1(l nlsai (J) lam () Taylor (S) and Ylamis anclDlvis (86) In the gcrmillation of ricc s((d thc ihoot aplwals first lnd lc(olding- to t(lIlille if tl1( api(] root elllllg(gtS first it is probably b(cause of dcfit-icnt 1Il0iRtlr( Ialll aitliblltNl thc failurc of s(eondalV and adnntitiolls roots to dt(lop in Rcedlings plant-Pll algl(atpl c1CI)ths in soil to fhe greatpl lPRtriction of thc ()xyg(1l uppl) Elygill (SO) found thc enzrnlP adiih 10 1)(gt Itss in R((d (llllinatNll1lHlcl water IolinagH ((JJ) drnlollstlnt((j that thl ealall-p adiity of sccdlings gl(Yll U1HItl alpl is Ieltiu(pd tlH gllafl1 til( (ltplh of tlll al(l A (On1l110n plactitP in thl SOlltlrCIl1 Ii(e-gloing ShIfps is tmiddoto plant at a dlptlt or 1 to ~in(]II ith a dlill and to flood the field after the rice is middot1middot to Ii inclHs high (JolH 111(111)

HESISTANCE TO FUNGI

Hough Ii(e iNdi whosl nlJilit- to gellllinall had betn (ompletely (ipstroy((l PI( III 0 Il Ipad i I Y nttHlktti b fll ni thn n iabll sterls Hal)(Ilalldt (-J1) found tltat If tl( gCIlllinting 10(1 iR lhtIO)Nl the ll10ist s(ltls igtPlOnH st ilY and ill-middotmlPlling within 1 fp days whereas -ith liv( R(pds til( ((lt1 (oat 1I1a IPlIlain 1I1lt1tplld for 1(111 w((ks Tusf (~I) iaI1l111tld data -h(Jl~d pari pllt IlIad iOIl of hiR Ilolliahl( htat-tlpl(d s((d stlllpips )ixon ((j) tprilizpt t II( Rand Sallt(rs and wdI u=Cd 101 till (ll11illltion ((1 I LC 10( ThiR pr((lltioll IPPPtIS IINal as IIll dilllilli]lPd itality of p((hi -lllll (xposcd to tNlllwla t UIP lIP I t Irl iI 1I11X i1111111 IPlIllplS thtlil (~Iy SlISttpt i b Ie to the 1 Uat 0 r III iiIO-Olgl1l iII1Smiddot

DIPUOVED GErOIlNATION

Ex(ppt for tht nlO~finllllntUlp Ii(( snmplts hent-tlrntNl Iluring the l)ill cxperimCl1tR (tablc II )lIo(middotiltlII1(t wlsoiJfaillCd flrat hcat tnatshymellts m SI1lt1l illlplO(d irbi Iit Ioll (iclPII(l lIIight hY( been obtaincd hall nil (IP 111It h~ or roots all(L shoots l)((11 detNmined in nil heat-trelt(ll SUlll)l(s 1I1ld (ollt1ols

- -shy

38 TECHITJCAL BULLETIN 1129) U S DEPT OF AGRICULTURE

No experiJnental evidence wns obtained to indicate hether the heat treatments had any elfect in overcoming dOlmancy of the different yarieties of rice Germinatjon tests were not made until 8 weeks after heat treatment Any dormancy existing at the time of harvest might have disappeared (luring this interntl

According to Wiesners (90) york wit11 conifer seeds the effects of heat treatment maybe heneficial to germination Jnst (41) reshyporteel one (xperiment in which thegelll1ination capac-ity and vigor of barley were improved by heat tr(gtailnrnt The hnrley seed was held2 days oYer suHnrie fleid then put in a test tube with calcinm (h10ric1( anrlldt for 2 more clays thrn heIdI day at10deg tncl3 days at GOdeg 0 Kiessling (~4) in stu(lying the ell(Is of henl lIeatnwnt on dormancy found that heat tJeatments i III prowd the ~(Imi nating flUB lity of nonshygerm-ripe barlr) bnt th(y did 110t 1nlly (omprnsaie for eompkte storage rippl1(ss AlloilHI illlpolimt obsPITation was Ihat the il11shyproycment in germinnting q11ality lS illd(lwllclent of the aHernliol1 of the moisture eontpnt TfC Ill l(f(1li 11~ to those losses tha I 0((11 I when srerls alr elI-ipd at the salllp limC nley lle hein~ l1ett-ITCnle(1 Dn Fanos datn (21) ~llOimplOpd Qprmiimtion 01 lice after heatshying at loo-iOo and of (orll aflPI heatillp at 30deg_(0deg

GENEHAL DISCUSSION

Yenthel (onditions toupthel witll otlll1 cinu111slnn(Ps in UHj() HHil nnd 1)52 pleYclltelt1 the allthoJs 110111 obtaining lois (rl flpshl) COIll shy

bined rough riee of higher than ~5~-ppl(enl llloihllC content- It yould l1nyc bpel1 dpsiluhle to 111e included pxperinlPnts on the elleets of temperatllle of tTCntment on lots of riel of 2(i- 10 lO-pel(pnt moisshyIl1le (on tents These 11l0istUIp (on 1(gt 11 11 lllthnllh II 11(0111 1110n 11(

possible FUlthellIlole it yould hn n iJNn (]pilaiJlt fronl til( standshypoint of e0l11111el(ial huTpsting eOllditiol1s to have IIsHl lots of rice fleshl combined nt (fI(lJ 2-pcl((nt (Ii 110r(gtl1(e in Illoistmclevel at Ipnst within 111( IHnl 01 ](j to 2G pel(enl B((tllsc it was not I)nICshy

lien1 to th)) pf to Olll hi I( Jil at sppi fitd 11IOislIIIc-eonfent l~nIs l(lnll1fngc IS Inkpn of llll llllpllIatie 1)IO(pdlllC in which n hallpl 01 molp of Ii(e Ill tnkpll froll1 a flpshlv(ol1lhillPd lot of hith IIlnistIIp eontpilt lind IHlItions (1(gt ail-ltiJipd to diflCIPllt lI1oistlllpI()middot(ls

H ns uIficipHtpd tiJlt IIPn tJpntlllPllts ilt illlI(lsillgly higlwl tPIlI shy

p(rahlllS wOllld Illillg aholl ilwl(nsiI1J_dy glpntpl INlllltt iOIl ill the abilitmiddot of Ii(p to PIllIillafp Till pnlliPl illpsliatOIR I((onized till Bigl1iiil~HHe of til( IplIllWlalII Il alinblp llwiIllllntCIOIISeXpelilllClIts del1lonstTuled till gl(ttPI ltleslludivPllpss 01 the highlI iell1ppmtilles to germinability X(lltlwlpss sPPIal rpasolls pxi~f for not acceptshying theil clufa fllld eOlHlllSiolls ns linnl alld ltiilpctly appli(ahle to Ihe heat tlcahllCll of Iiet Fol lxnlllple specilic (lltails regalciing Ihe moisture contellts of the s((gtlt1s tlIP 1lHlholtlR of llent tlfatmel1l nlHl the age of till s(gt((is W(Le frequently ollliiJec1 Seeds yere sonlpIilJl(gtS Cxposed to PIT higit trll1pCrahllPS Hnd fol 1l1lllSllfllly lon~ ])pliolt(s of ii me TIHV (1( [ 11 i licin 11 IIlOist Piled whpn it vas clcsilNl to detelmine tlH (Ireds 01 hllIt 011 s(I(ds of hih moisture eOIlipllt Oplshymination tests (Ie gPIIPln II made i I1lll1e(lia tel v 01 sholt I y dt(1 it(al treatment ~rnllr 01 titp s(((is stlldipcl difllJpd slludlllllly floll1lice

bull

bull

bull MOleover most of thp illVltignols had different objediycs in planshyning their (Xjlllillltllts

bull bull

TBL1J15-Gcrmination of Oentury 51B rough rice aftet heat t1catment fol diffp1(Vnt l)e1iods of time 1951B ---~ - bullbullbulllt ~ --- -----T--- --- --shy- -

Temperature of COIl- 10 I 20 i 30 40 I 50 I 60 I 70 80 00 100 llO 120 _tleit~(llt C)___trol_~~~ ~~-~in~I~Jill~~~ -=in~ min~ ~nin~ 1l1in~ in~ in~

Percrn i Pcrc(nl

-~) - 115 0355 __ U5 l558 __ n4 n3OJ bull 05 Oil(lmiddotI bull 04 IIIIii bullbull l1 iO l5 ~~ I 8 5g 36 5 6 2 1___ 1 __ O

--~------~ ~-------~~--

t Ii Prrceni Pcrccnt Perera I Prrccn Perclnl PlIcfni Prrcrnl Penen

l

)1) j 03 I fl4 01 )(l l)j 1)2 0middot1 04 92 02 07 07 )middotI nmiddot )3 SO 1)2 0 I 02 no 87 no 02 SO 87 00 so SU S8 S5 82 8middot1 60 fi8I

Percen i PCIceni Percent

95 fl5 95 95 95 )3 04 01 90 88 88 89 07 62 47

___ ~__ bull ___ ~___ _ bullbull~ l

lti

~ l Ij tj Id ~ ogtIj bull

bull

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 35

47-91 percent The destructjon of germination cnpacity was corshyrespondingly greater at the two highest temperatures There were no viable sreds in samples tTeattd for DO minutes 01 longer at 67deg or for 30 minutes or longer at 70deg

A loss jn germination igor oCeUlT(tlin samples of Century 52 heat-treated for 80 minlltes or longer al- fiiO C and in L11 those heatshytreated at the higher telllpelatlll(fi The extent of this loss is reflected in the germination data in (-able Hi rile 1)(gtI(pntages of Iice germishynating after 5710 and U days nrc giell for all samples heat-treated at 61deg (14deg 6T 11 nd TO- -lIlt t Pili plrat lins I hat lc(1n itely affettecl germination eapaeity The plIeentages sho tlw(- the longer thn treilhnent or the hipllIr the tpIllperat1l1e of tTeahllPnt for rice of a given moisture lontpnt (he longPI it tnkl tlH lelllnining middotiablp SPlds 111 thp sample to PIllIinnte -gain I-his ous(lnLtion holds only if the tel1l])(lallllC of ITPatll1llIt fall ithin the zOl1e of heat (lanmiC for rice of the SI)PCified moisture onlpni

TABLE 1G-E1f((middotf oj till( (dllraioll) of 1fat tJ((ltmcilt of dijfll(lIt t(mp((tIIJ(N Oil till glJmillatioll of ((lItlll ) IOU(lh Iire ((Jtm 57 JO ((lid 14 l(ls HJJ

t filo C At GmiddotI (Duration of ----_- - - __--_ -------_ ------shy

bull hlU-t trpatlllPI1t

(lltillil tCs) i 7 10 JmiddotI i 7 10 IJ shyT()talclaIs dnls days days dnys days days days Total

---~ --------- -- --- --------- ------ ---shy ~--

1 r- Pr- Plr- Pa- Plr- Per- I) rshy PI- Pa- Pershycent CUlt Cflll cellt Cl1lt CI Ilt cl-ni cellI cent celll

( ontrol 02 2 I 0 nij -8 middot1 2 0 9410 lt3 8 3 I gj in 2a ] 8 9120 7fi 11 1 l2

-) It 3a jmiddot1 1 8930 1- II

i() 1 00 XI ao 1middot1 2 Sl

-10 il 22 2 8-( 22 )1 10 2 88iO i) 2) (j I 00 17 iii 11 1 Sf)iO (il C)Iii 7 2 l2 Ji d_ 13 2 8270 iX 2) (i 2 80 I-I in 11 3 8middot1xo -II 3a ]() a 87 0 -1i ll i G9 no In aa l 2 no 0 38 22 8 (iX100 -10 al - 3 8X () 3D 2X ) 67

)110 18 l 3 -s () a2 23 7 li2120_ -w aa fi -0 0 22 17 L8 17

At Oi ( At 70 (

Control X) 7 I 0 n3 ltX Ii I 0 ni) 10 X ltiX tj I bullX-I I 27 18 (j 5220_ 2 iO I ~ 2 7G 0 () (i -I 1080 0 8( Lj I pl) () 0 0 0 0middot10 0 I) IX I 37

bull )0 () 2 7 J2 flO 0 I a a 7 70 () 0 0 2 2 SO - n () 0 I 1~ ~~~-flO _____________

(J () () ()0 - - - - - ~ j

36 lECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

THE GERMINATION TESTS

SEEDLING ABNORMALITIES bull~ltJthough several hundred germination tests were made during the 3-year investigations no clistinctive abnormalities in the stUlcturc of the seedlings were obselTec1 that could be c1pfinitely attributed to heat injury lhe same kinds of abnormal seedlings wC1e observed when heat-treated samples of 1middotice 111c1 unh(gtatCc1 air-c1riCd controls we Ie germinated Abnormal types were most often found among seedlings counted ttt 7 10 anc114 clays The nlost (ol11mon type had t spindly primary root and seeoncJary lOotS There were also otlw1 kinds simishyJar in appearan(e to thosc illustratpd in gricultUlil1 Handbook Ko 30 (84)

That high-temperature injury lIIay bC I(flpcild in sppdling c1evelopshymentis well known HabCrlandtmiddot UI) h(lat(d diflpl(lni kinds of sepds for 48 hours af WOO C Yh(ln f IIpy (r( trminaild Ill found fhaf the plulllule c1(p]oppd bpfore til( rO(ltht al1(1 PYln that the sfpl11 might start to dCwlop though thp )(Jot lpIIWill((] entirlly UndHlloppd Sachs (08) tahulations rp(orci a hirilC1 Iatio of -hrllr((l to 1I0lma I pmbyros til( higlH1 till tplllp(mtull of tl(dmpllt Dixon (2(j) ohshyselYed in f11P lIlIlinnfioll of hlnf-trlated -eC(s t-Ililt Till mosf 1Ipshyquent nhllolmt1if) is til( plotrllsion of til( cofyllr1onsillstpad of thp radicle from thp seld EnII if thl mtliell does lmplge normally it is oft(lf) abnormal in its SU)(cfllent Iwhlyiol HlIt(hinsol1 (31) repoltrd that his hCat-tlpaf(d hpaf s(p(l germinating aftCI sl ighf dClay lIp nII normal as IPga Ids )Oos a lid shoots but a few of thos(l showing fWllC dllay (1( stuntwl

Hut(himon et al (]4) Iwyp stat(d thaf _s with Ot]H1 lo1111 S of bullbiological damage III i Id ]llat damagr ill oats Ila rI( andyh(nt is IcYPlsiblC but 5(ele dama( (HUR(S dtlfh of the ((II Tn adrlition theil pyi(en(( indi(ted tllaf ll(at((1 glaill IHlded opfillllllll (onditioll of watpl and aelntion in fhl plill1alY sfag(s bllt fhat afel growth had (OllllllpllCpd if hrhapd in n nOlIl1d l1U1nnrl TIICy fpH that till heat-dalllag(d (II had lost SOliI( (rf its pOWl1 of sCI(cfip ]gtPIshymeability and fhnf itnlify as jlldgp(] hy abilify to withstIIHI excess wat(I and othpl sub-opt imal gclTnillatioll (olHlif ions is plohably ad(lsply a flC(j(d Thl) notld tytologilal d i fllllnecs in nOlllml and heat-c1a III agC(] gla i 11

DRY SEED

In tlH~ l()in pxpplill1pnts the Iollh Ii(t wifh moistllre contenfs of 33-3H PC)C(IIt had SitOIl roots alld -hoofs than lonflol s((d of higlll) moisture COIlUns (l1l whell til( t(nlpllaflllp of fTlntmpllt of fhe low

~l moistirre-contlnt in III pies IS (ollsidlIld 1ltlow the (Iit ita I rang( On the othel hand no diflelelwPs ill gCIllIillation (apn(ity atp Ieflletpd in the datnin tablp 2 Thl tlason is thaf sunples of ail-dlied contlol wHh both the low a 11(1 flH lrighCl 1l10iStlll( tontlllf vichlpd (ss(lItiaIly the saine 1I11111)l) of cOllilfabln sepdlillgs afttI fi i 10 and l~ days in the gllmillafol i(IIlY mom of filp sNdlings howcvlr hom the drier salllp]rgts banl) met tire albitralily sel((te(] minimum requilcshyments to be counted i ( poslsstd hoth root and shoot with one bull strucfule at hast olle-Jourth inch long

bull

bull

bull

EFFECTS OF HEAT TREATlmNl ON THE VIABILITY OF RICE 37

H~berlandt (31) beHeved that a hardening of the seeds [md seed coats as a result of extensive drying at a high temperature might be the partial explanation for retardation in growth This condition would permit only the ery gradual entmnce of moisture into the inner seed rust (43) and Dixon (26) exprescd similar thoughts

EXCESSIVELY WET SEEDBED

Somctimcs in thc germination tests the beds of paper toweling became extrcmelv (t Seeds in the exCcsfinly wct bcds germishynat-cd m01C 5101) Hoot (radiClc) formation Wl rctarded and when the root did form it was usuall frcc of root hairs This kind of clrnlopmcnt is attributed to rc(111(rd oxygen tension

The plllnomcnon has blln cxtensi nly n~portecl in the 1i tera ture and has bern obscrvcd to o(Cur in ail with reclll(ed oxygen in nitTogen and in watcr and to I)e aflcded hy diflcrcllt dcpths of water slnd rnd soil Klebs ()) in ISHi Yokoi U)J) in IH)8~ and TakahaRhi (80) in 1905 wcre amOIl tIle filstmiddot to rtlonl obRtITntl0n il11ilar to tIll above Since Own thc pilCnOIlHnon has wen Ippoltc(l by ()thtrsin(lllltlill~ Atemine (iV) Xagai ((lj) olillaga (j) ~asaki (fjQ) bullJones (4() Dastur I1(l nlsai (J) lam () Taylor (S) and Ylamis anclDlvis (86) In the gcrmillation of ricc s((d thc ihoot aplwals first lnd lc(olding- to t(lIlille if tl1( api(] root elllllg(gtS first it is probably b(cause of dcfit-icnt 1Il0iRtlr( Ialll aitliblltNl thc failurc of s(eondalV and adnntitiolls roots to dt(lop in Rcedlings plant-Pll algl(atpl c1CI)ths in soil to fhe greatpl lPRtriction of thc ()xyg(1l uppl) Elygill (SO) found thc enzrnlP adiih 10 1)(gt Itss in R((d (llllinatNll1lHlcl water IolinagH ((JJ) drnlollstlnt((j that thl ealall-p adiity of sccdlings gl(Yll U1HItl alpl is Ieltiu(pd tlH gllafl1 til( (ltplh of tlll al(l A (On1l110n plactitP in thl SOlltlrCIl1 Ii(e-gloing ShIfps is tmiddoto plant at a dlptlt or 1 to ~in(]II ith a dlill and to flood the field after the rice is middot1middot to Ii inclHs high (JolH 111(111)

HESISTANCE TO FUNGI

Hough Ii(e iNdi whosl nlJilit- to gellllinall had betn (ompletely (ipstroy((l PI( III 0 Il Ipad i I Y nttHlktti b fll ni thn n iabll sterls Hal)(Ilalldt (-J1) found tltat If tl( gCIlllinting 10(1 iR lhtIO)Nl the ll10ist s(ltls igtPlOnH st ilY and ill-middotmlPlling within 1 fp days whereas -ith liv( R(pds til( ((lt1 (oat 1I1a IPlIlain 1I1lt1tplld for 1(111 w((ks Tusf (~I) iaI1l111tld data -h(Jl~d pari pllt IlIad iOIl of hiR Ilolliahl( htat-tlpl(d s((d stlllpips )ixon ((j) tprilizpt t II( Rand Sallt(rs and wdI u=Cd 101 till (ll11illltion ((1 I LC 10( ThiR pr((lltioll IPPPtIS IINal as IIll dilllilli]lPd itality of p((hi -lllll (xposcd to tNlllwla t UIP lIP I t Irl iI 1I11X i1111111 IPlIllplS thtlil (~Iy SlISttpt i b Ie to the 1 Uat 0 r III iiIO-Olgl1l iII1Smiddot

DIPUOVED GErOIlNATION

Ex(ppt for tht nlO~finllllntUlp Ii(( snmplts hent-tlrntNl Iluring the l)ill cxperimCl1tR (tablc II )lIo(middotiltlII1(t wlsoiJfaillCd flrat hcat tnatshymellts m SI1lt1l illlplO(d irbi Iit Ioll (iclPII(l lIIight hY( been obtaincd hall nil (IP 111It h~ or roots all(L shoots l)((11 detNmined in nil heat-trelt(ll SUlll)l(s 1I1ld (ollt1ols

- -shy

38 TECHITJCAL BULLETIN 1129) U S DEPT OF AGRICULTURE

No experiJnental evidence wns obtained to indicate hether the heat treatments had any elfect in overcoming dOlmancy of the different yarieties of rice Germinatjon tests were not made until 8 weeks after heat treatment Any dormancy existing at the time of harvest might have disappeared (luring this interntl

According to Wiesners (90) york wit11 conifer seeds the effects of heat treatment maybe heneficial to germination Jnst (41) reshyporteel one (xperiment in which thegelll1ination capac-ity and vigor of barley were improved by heat tr(gtailnrnt The hnrley seed was held2 days oYer suHnrie fleid then put in a test tube with calcinm (h10ric1( anrlldt for 2 more clays thrn heIdI day at10deg tncl3 days at GOdeg 0 Kiessling (~4) in stu(lying the ell(Is of henl lIeatnwnt on dormancy found that heat tJeatments i III prowd the ~(Imi nating flUB lity of nonshygerm-ripe barlr) bnt th(y did 110t 1nlly (omprnsaie for eompkte storage rippl1(ss AlloilHI illlpolimt obsPITation was Ihat the il11shyproycment in germinnting q11ality lS illd(lwllclent of the aHernliol1 of the moisture eontpnt TfC Ill l(f(1li 11~ to those losses tha I 0((11 I when srerls alr elI-ipd at the salllp limC nley lle hein~ l1ett-ITCnle(1 Dn Fanos datn (21) ~llOimplOpd Qprmiimtion 01 lice after heatshying at loo-iOo and of (orll aflPI heatillp at 30deg_(0deg

GENEHAL DISCUSSION

Yenthel (onditions toupthel witll otlll1 cinu111slnn(Ps in UHj() HHil nnd 1)52 pleYclltelt1 the allthoJs 110111 obtaining lois (rl flpshl) COIll shy

bined rough riee of higher than ~5~-ppl(enl llloihllC content- It yould l1nyc bpel1 dpsiluhle to 111e included pxperinlPnts on the elleets of temperatllle of tTCntment on lots of riel of 2(i- 10 lO-pel(pnt moisshyIl1le (on tents These 11l0istUIp (on 1(gt 11 11 lllthnllh II 11(0111 1110n 11(

possible FUlthellIlole it yould hn n iJNn (]pilaiJlt fronl til( standshypoint of e0l11111el(ial huTpsting eOllditiol1s to have IIsHl lots of rice fleshl combined nt (fI(lJ 2-pcl((nt (Ii 110r(gtl1(e in Illoistmclevel at Ipnst within 111( IHnl 01 ](j to 2G pel(enl B((tllsc it was not I)nICshy

lien1 to th)) pf to Olll hi I( Jil at sppi fitd 11IOislIIIc-eonfent l~nIs l(lnll1fngc IS Inkpn of llll llllpllIatie 1)IO(pdlllC in which n hallpl 01 molp of Ii(e Ill tnkpll froll1 a flpshlv(ol1lhillPd lot of hith IIlnistIIp eontpilt lind IHlItions (1(gt ail-ltiJipd to diflCIPllt lI1oistlllpI()middot(ls

H ns uIficipHtpd tiJlt IIPn tJpntlllPllts ilt illlI(lsillgly higlwl tPIlI shy

p(rahlllS wOllld Illillg aholl ilwl(nsiI1J_dy glpntpl INlllltt iOIl ill the abilitmiddot of Ii(p to PIllIillafp Till pnlliPl illpsliatOIR I((onized till Bigl1iiil~HHe of til( IplIllWlalII Il alinblp llwiIllllntCIOIISeXpelilllClIts del1lonstTuled till gl(ttPI ltleslludivPllpss 01 the highlI iell1ppmtilles to germinability X(lltlwlpss sPPIal rpasolls pxi~f for not acceptshying theil clufa fllld eOlHlllSiolls ns linnl alld ltiilpctly appli(ahle to Ihe heat tlcahllCll of Iiet Fol lxnlllple specilic (lltails regalciing Ihe moisture contellts of the s((gtlt1s tlIP 1lHlholtlR of llent tlfatmel1l nlHl the age of till s(gt((is W(Le frequently ollliiJec1 Seeds yere sonlpIilJl(gtS Cxposed to PIT higit trll1pCrahllPS Hnd fol 1l1lllSllfllly lon~ ])pliolt(s of ii me TIHV (1( [ 11 i licin 11 IIlOist Piled whpn it vas clcsilNl to detelmine tlH (Ireds 01 hllIt 011 s(I(ds of hih moisture eOIlipllt Oplshymination tests (Ie gPIIPln II made i I1lll1e(lia tel v 01 sholt I y dt(1 it(al treatment ~rnllr 01 titp s(((is stlldipcl difllJpd slludlllllly floll1lice

bull

bull

bull MOleover most of thp illVltignols had different objediycs in planshyning their (Xjlllillltllts

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 35

47-91 percent The destructjon of germination cnpacity was corshyrespondingly greater at the two highest temperatures There were no viable sreds in samples tTeattd for DO minutes 01 longer at 67deg or for 30 minutes or longer at 70deg

A loss jn germination igor oCeUlT(tlin samples of Century 52 heat-treated for 80 minlltes or longer al- fiiO C and in L11 those heatshytreated at the higher telllpelatlll(fi The extent of this loss is reflected in the germination data in (-able Hi rile 1)(gtI(pntages of Iice germishynating after 5710 and U days nrc giell for all samples heat-treated at 61deg (14deg 6T 11 nd TO- -lIlt t Pili plrat lins I hat lc(1n itely affettecl germination eapaeity The plIeentages sho tlw(- the longer thn treilhnent or the hipllIr the tpIllperat1l1e of tTeahllPnt for rice of a given moisture lontpnt (he longPI it tnkl tlH lelllnining middotiablp SPlds 111 thp sample to PIllIinnte -gain I-his ous(lnLtion holds only if the tel1l])(lallllC of ITPatll1llIt fall ithin the zOl1e of heat (lanmiC for rice of the SI)PCified moisture onlpni

TABLE 1G-E1f((middotf oj till( (dllraioll) of 1fat tJ((ltmcilt of dijfll(lIt t(mp((tIIJ(N Oil till glJmillatioll of ((lItlll ) IOU(lh Iire ((Jtm 57 JO ((lid 14 l(ls HJJ

t filo C At GmiddotI (Duration of ----_- - - __--_ -------_ ------shy

bull hlU-t trpatlllPI1t

(lltillil tCs) i 7 10 JmiddotI i 7 10 IJ shyT()talclaIs dnls days days dnys days days days Total

---~ --------- -- --- --------- ------ ---shy ~--

1 r- Pr- Plr- Pa- Plr- Per- I) rshy PI- Pa- Pershycent CUlt Cflll cellt Cl1lt CI Ilt cl-ni cellI cent celll

( ontrol 02 2 I 0 nij -8 middot1 2 0 9410 lt3 8 3 I gj in 2a ] 8 9120 7fi 11 1 l2

-) It 3a jmiddot1 1 8930 1- II

i() 1 00 XI ao 1middot1 2 Sl

-10 il 22 2 8-( 22 )1 10 2 88iO i) 2) (j I 00 17 iii 11 1 Sf)iO (il C)Iii 7 2 l2 Ji d_ 13 2 8270 iX 2) (i 2 80 I-I in 11 3 8middot1xo -II 3a ]() a 87 0 -1i ll i G9 no In aa l 2 no 0 38 22 8 (iX100 -10 al - 3 8X () 3D 2X ) 67

)110 18 l 3 -s () a2 23 7 li2120_ -w aa fi -0 0 22 17 L8 17

At Oi ( At 70 (

Control X) 7 I 0 n3 ltX Ii I 0 ni) 10 X ltiX tj I bullX-I I 27 18 (j 5220_ 2 iO I ~ 2 7G 0 () (i -I 1080 0 8( Lj I pl) () 0 0 0 0middot10 0 I) IX I 37

bull )0 () 2 7 J2 flO 0 I a a 7 70 () 0 0 2 2 SO - n () 0 I 1~ ~~~-flO _____________

(J () () ()0 - - - - - ~ j

36 lECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

THE GERMINATION TESTS

SEEDLING ABNORMALITIES bull~ltJthough several hundred germination tests were made during the 3-year investigations no clistinctive abnormalities in the stUlcturc of the seedlings were obselTec1 that could be c1pfinitely attributed to heat injury lhe same kinds of abnormal seedlings wC1e observed when heat-treated samples of 1middotice 111c1 unh(gtatCc1 air-c1riCd controls we Ie germinated Abnormal types were most often found among seedlings counted ttt 7 10 anc114 clays The nlost (ol11mon type had t spindly primary root and seeoncJary lOotS There were also otlw1 kinds simishyJar in appearan(e to thosc illustratpd in gricultUlil1 Handbook Ko 30 (84)

That high-temperature injury lIIay bC I(flpcild in sppdling c1evelopshymentis well known HabCrlandtmiddot UI) h(lat(d diflpl(lni kinds of sepds for 48 hours af WOO C Yh(ln f IIpy (r( trminaild Ill found fhaf the plulllule c1(p]oppd bpfore til( rO(ltht al1(1 PYln that the sfpl11 might start to dCwlop though thp )(Jot lpIIWill((] entirlly UndHlloppd Sachs (08) tahulations rp(orci a hirilC1 Iatio of -hrllr((l to 1I0lma I pmbyros til( higlH1 till tplllp(mtull of tl(dmpllt Dixon (2(j) ohshyselYed in f11P lIlIlinnfioll of hlnf-trlated -eC(s t-Ililt Till mosf 1Ipshyquent nhllolmt1if) is til( plotrllsion of til( cofyllr1onsillstpad of thp radicle from thp seld EnII if thl mtliell does lmplge normally it is oft(lf) abnormal in its SU)(cfllent Iwhlyiol HlIt(hinsol1 (31) repoltrd that his hCat-tlpaf(d hpaf s(p(l germinating aftCI sl ighf dClay lIp nII normal as IPga Ids )Oos a lid shoots but a few of thos(l showing fWllC dllay (1( stuntwl

Hut(himon et al (]4) Iwyp stat(d thaf _s with Ot]H1 lo1111 S of bullbiological damage III i Id ]llat damagr ill oats Ila rI( andyh(nt is IcYPlsiblC but 5(ele dama( (HUR(S dtlfh of the ((II Tn adrlition theil pyi(en(( indi(ted tllaf ll(at((1 glaill IHlded opfillllllll (onditioll of watpl and aelntion in fhl plill1alY sfag(s bllt fhat afel growth had (OllllllpllCpd if hrhapd in n nOlIl1d l1U1nnrl TIICy fpH that till heat-dalllag(d (II had lost SOliI( (rf its pOWl1 of sCI(cfip ]gtPIshymeability and fhnf itnlify as jlldgp(] hy abilify to withstIIHI excess wat(I and othpl sub-opt imal gclTnillatioll (olHlif ions is plohably ad(lsply a flC(j(d Thl) notld tytologilal d i fllllnecs in nOlllml and heat-c1a III agC(] gla i 11

DRY SEED

In tlH~ l()in pxpplill1pnts the Iollh Ii(t wifh moistllre contenfs of 33-3H PC)C(IIt had SitOIl roots alld -hoofs than lonflol s((d of higlll) moisture COIlUns (l1l whell til( t(nlpllaflllp of fTlntmpllt of fhe low

~l moistirre-contlnt in III pies IS (ollsidlIld 1ltlow the (Iit ita I rang( On the othel hand no diflelelwPs ill gCIllIillation (apn(ity atp Ieflletpd in the datnin tablp 2 Thl tlason is thaf sunples of ail-dlied contlol wHh both the low a 11(1 flH lrighCl 1l10iStlll( tontlllf vichlpd (ss(lItiaIly the saine 1I11111)l) of cOllilfabln sepdlillgs afttI fi i 10 and l~ days in the gllmillafol i(IIlY mom of filp sNdlings howcvlr hom the drier salllp]rgts banl) met tire albitralily sel((te(] minimum requilcshyments to be counted i ( poslsstd hoth root and shoot with one bull strucfule at hast olle-Jourth inch long

bull

bull

bull

EFFECTS OF HEAT TREATlmNl ON THE VIABILITY OF RICE 37

H~berlandt (31) beHeved that a hardening of the seeds [md seed coats as a result of extensive drying at a high temperature might be the partial explanation for retardation in growth This condition would permit only the ery gradual entmnce of moisture into the inner seed rust (43) and Dixon (26) exprescd similar thoughts

EXCESSIVELY WET SEEDBED

Somctimcs in thc germination tests the beds of paper toweling became extrcmelv (t Seeds in the exCcsfinly wct bcds germishynat-cd m01C 5101) Hoot (radiClc) formation Wl rctarded and when the root did form it was usuall frcc of root hairs This kind of clrnlopmcnt is attributed to rc(111(rd oxygen tension

The plllnomcnon has blln cxtensi nly n~portecl in the 1i tera ture and has bern obscrvcd to o(Cur in ail with reclll(ed oxygen in nitTogen and in watcr and to I)e aflcded hy diflcrcllt dcpths of water slnd rnd soil Klebs ()) in ISHi Yokoi U)J) in IH)8~ and TakahaRhi (80) in 1905 wcre amOIl tIle filstmiddot to rtlonl obRtITntl0n il11ilar to tIll above Since Own thc pilCnOIlHnon has wen Ippoltc(l by ()thtrsin(lllltlill~ Atemine (iV) Xagai ((lj) olillaga (j) ~asaki (fjQ) bullJones (4() Dastur I1(l nlsai (J) lam () Taylor (S) and Ylamis anclDlvis (86) In the gcrmillation of ricc s((d thc ihoot aplwals first lnd lc(olding- to t(lIlille if tl1( api(] root elllllg(gtS first it is probably b(cause of dcfit-icnt 1Il0iRtlr( Ialll aitliblltNl thc failurc of s(eondalV and adnntitiolls roots to dt(lop in Rcedlings plant-Pll algl(atpl c1CI)ths in soil to fhe greatpl lPRtriction of thc ()xyg(1l uppl) Elygill (SO) found thc enzrnlP adiih 10 1)(gt Itss in R((d (llllinatNll1lHlcl water IolinagH ((JJ) drnlollstlnt((j that thl ealall-p adiity of sccdlings gl(Yll U1HItl alpl is Ieltiu(pd tlH gllafl1 til( (ltplh of tlll al(l A (On1l110n plactitP in thl SOlltlrCIl1 Ii(e-gloing ShIfps is tmiddoto plant at a dlptlt or 1 to ~in(]II ith a dlill and to flood the field after the rice is middot1middot to Ii inclHs high (JolH 111(111)

HESISTANCE TO FUNGI

Hough Ii(e iNdi whosl nlJilit- to gellllinall had betn (ompletely (ipstroy((l PI( III 0 Il Ipad i I Y nttHlktti b fll ni thn n iabll sterls Hal)(Ilalldt (-J1) found tltat If tl( gCIlllinting 10(1 iR lhtIO)Nl the ll10ist s(ltls igtPlOnH st ilY and ill-middotmlPlling within 1 fp days whereas -ith liv( R(pds til( ((lt1 (oat 1I1a IPlIlain 1I1lt1tplld for 1(111 w((ks Tusf (~I) iaI1l111tld data -h(Jl~d pari pllt IlIad iOIl of hiR Ilolliahl( htat-tlpl(d s((d stlllpips )ixon ((j) tprilizpt t II( Rand Sallt(rs and wdI u=Cd 101 till (ll11illltion ((1 I LC 10( ThiR pr((lltioll IPPPtIS IINal as IIll dilllilli]lPd itality of p((hi -lllll (xposcd to tNlllwla t UIP lIP I t Irl iI 1I11X i1111111 IPlIllplS thtlil (~Iy SlISttpt i b Ie to the 1 Uat 0 r III iiIO-Olgl1l iII1Smiddot

DIPUOVED GErOIlNATION

Ex(ppt for tht nlO~finllllntUlp Ii(( snmplts hent-tlrntNl Iluring the l)ill cxperimCl1tR (tablc II )lIo(middotiltlII1(t wlsoiJfaillCd flrat hcat tnatshymellts m SI1lt1l illlplO(d irbi Iit Ioll (iclPII(l lIIight hY( been obtaincd hall nil (IP 111It h~ or roots all(L shoots l)((11 detNmined in nil heat-trelt(ll SUlll)l(s 1I1ld (ollt1ols

- -shy

38 TECHITJCAL BULLETIN 1129) U S DEPT OF AGRICULTURE

No experiJnental evidence wns obtained to indicate hether the heat treatments had any elfect in overcoming dOlmancy of the different yarieties of rice Germinatjon tests were not made until 8 weeks after heat treatment Any dormancy existing at the time of harvest might have disappeared (luring this interntl

According to Wiesners (90) york wit11 conifer seeds the effects of heat treatment maybe heneficial to germination Jnst (41) reshyporteel one (xperiment in which thegelll1ination capac-ity and vigor of barley were improved by heat tr(gtailnrnt The hnrley seed was held2 days oYer suHnrie fleid then put in a test tube with calcinm (h10ric1( anrlldt for 2 more clays thrn heIdI day at10deg tncl3 days at GOdeg 0 Kiessling (~4) in stu(lying the ell(Is of henl lIeatnwnt on dormancy found that heat tJeatments i III prowd the ~(Imi nating flUB lity of nonshygerm-ripe barlr) bnt th(y did 110t 1nlly (omprnsaie for eompkte storage rippl1(ss AlloilHI illlpolimt obsPITation was Ihat the il11shyproycment in germinnting q11ality lS illd(lwllclent of the aHernliol1 of the moisture eontpnt TfC Ill l(f(1li 11~ to those losses tha I 0((11 I when srerls alr elI-ipd at the salllp limC nley lle hein~ l1ett-ITCnle(1 Dn Fanos datn (21) ~llOimplOpd Qprmiimtion 01 lice after heatshying at loo-iOo and of (orll aflPI heatillp at 30deg_(0deg

GENEHAL DISCUSSION

Yenthel (onditions toupthel witll otlll1 cinu111slnn(Ps in UHj() HHil nnd 1)52 pleYclltelt1 the allthoJs 110111 obtaining lois (rl flpshl) COIll shy

bined rough riee of higher than ~5~-ppl(enl llloihllC content- It yould l1nyc bpel1 dpsiluhle to 111e included pxperinlPnts on the elleets of temperatllle of tTCntment on lots of riel of 2(i- 10 lO-pel(pnt moisshyIl1le (on tents These 11l0istUIp (on 1(gt 11 11 lllthnllh II 11(0111 1110n 11(

possible FUlthellIlole it yould hn n iJNn (]pilaiJlt fronl til( standshypoint of e0l11111el(ial huTpsting eOllditiol1s to have IIsHl lots of rice fleshl combined nt (fI(lJ 2-pcl((nt (Ii 110r(gtl1(e in Illoistmclevel at Ipnst within 111( IHnl 01 ](j to 2G pel(enl B((tllsc it was not I)nICshy

lien1 to th)) pf to Olll hi I( Jil at sppi fitd 11IOislIIIc-eonfent l~nIs l(lnll1fngc IS Inkpn of llll llllpllIatie 1)IO(pdlllC in which n hallpl 01 molp of Ii(e Ill tnkpll froll1 a flpshlv(ol1lhillPd lot of hith IIlnistIIp eontpilt lind IHlItions (1(gt ail-ltiJipd to diflCIPllt lI1oistlllpI()middot(ls

H ns uIficipHtpd tiJlt IIPn tJpntlllPllts ilt illlI(lsillgly higlwl tPIlI shy

p(rahlllS wOllld Illillg aholl ilwl(nsiI1J_dy glpntpl INlllltt iOIl ill the abilitmiddot of Ii(p to PIllIillafp Till pnlliPl illpsliatOIR I((onized till Bigl1iiil~HHe of til( IplIllWlalII Il alinblp llwiIllllntCIOIISeXpelilllClIts del1lonstTuled till gl(ttPI ltleslludivPllpss 01 the highlI iell1ppmtilles to germinability X(lltlwlpss sPPIal rpasolls pxi~f for not acceptshying theil clufa fllld eOlHlllSiolls ns linnl alld ltiilpctly appli(ahle to Ihe heat tlcahllCll of Iiet Fol lxnlllple specilic (lltails regalciing Ihe moisture contellts of the s((gtlt1s tlIP 1lHlholtlR of llent tlfatmel1l nlHl the age of till s(gt((is W(Le frequently ollliiJec1 Seeds yere sonlpIilJl(gtS Cxposed to PIT higit trll1pCrahllPS Hnd fol 1l1lllSllfllly lon~ ])pliolt(s of ii me TIHV (1( [ 11 i licin 11 IIlOist Piled whpn it vas clcsilNl to detelmine tlH (Ireds 01 hllIt 011 s(I(ds of hih moisture eOIlipllt Oplshymination tests (Ie gPIIPln II made i I1lll1e(lia tel v 01 sholt I y dt(1 it(al treatment ~rnllr 01 titp s(((is stlldipcl difllJpd slludlllllly floll1lice

bull

bull

bull MOleover most of thp illVltignols had different objediycs in planshyning their (Xjlllillltllts

36 lECHNICAL BULLETIN 1129 U S DEPT OF AGRICULTURE

THE GERMINATION TESTS

SEEDLING ABNORMALITIES bull~ltJthough several hundred germination tests were made during the 3-year investigations no clistinctive abnormalities in the stUlcturc of the seedlings were obselTec1 that could be c1pfinitely attributed to heat injury lhe same kinds of abnormal seedlings wC1e observed when heat-treated samples of 1middotice 111c1 unh(gtatCc1 air-c1riCd controls we Ie germinated Abnormal types were most often found among seedlings counted ttt 7 10 anc114 clays The nlost (ol11mon type had t spindly primary root and seeoncJary lOotS There were also otlw1 kinds simishyJar in appearan(e to thosc illustratpd in gricultUlil1 Handbook Ko 30 (84)

That high-temperature injury lIIay bC I(flpcild in sppdling c1evelopshymentis well known HabCrlandtmiddot UI) h(lat(d diflpl(lni kinds of sepds for 48 hours af WOO C Yh(ln f IIpy (r( trminaild Ill found fhaf the plulllule c1(p]oppd bpfore til( rO(ltht al1(1 PYln that the sfpl11 might start to dCwlop though thp )(Jot lpIIWill((] entirlly UndHlloppd Sachs (08) tahulations rp(orci a hirilC1 Iatio of -hrllr((l to 1I0lma I pmbyros til( higlH1 till tplllp(mtull of tl(dmpllt Dixon (2(j) ohshyselYed in f11P lIlIlinnfioll of hlnf-trlated -eC(s t-Ililt Till mosf 1Ipshyquent nhllolmt1if) is til( plotrllsion of til( cofyllr1onsillstpad of thp radicle from thp seld EnII if thl mtliell does lmplge normally it is oft(lf) abnormal in its SU)(cfllent Iwhlyiol HlIt(hinsol1 (31) repoltrd that his hCat-tlpaf(d hpaf s(p(l germinating aftCI sl ighf dClay lIp nII normal as IPga Ids )Oos a lid shoots but a few of thos(l showing fWllC dllay (1( stuntwl

Hut(himon et al (]4) Iwyp stat(d thaf _s with Ot]H1 lo1111 S of bullbiological damage III i Id ]llat damagr ill oats Ila rI( andyh(nt is IcYPlsiblC but 5(ele dama( (HUR(S dtlfh of the ((II Tn adrlition theil pyi(en(( indi(ted tllaf ll(at((1 glaill IHlded opfillllllll (onditioll of watpl and aelntion in fhl plill1alY sfag(s bllt fhat afel growth had (OllllllpllCpd if hrhapd in n nOlIl1d l1U1nnrl TIICy fpH that till heat-dalllag(d (II had lost SOliI( (rf its pOWl1 of sCI(cfip ]gtPIshymeability and fhnf itnlify as jlldgp(] hy abilify to withstIIHI excess wat(I and othpl sub-opt imal gclTnillatioll (olHlif ions is plohably ad(lsply a flC(j(d Thl) notld tytologilal d i fllllnecs in nOlllml and heat-c1a III agC(] gla i 11

DRY SEED

In tlH~ l()in pxpplill1pnts the Iollh Ii(t wifh moistllre contenfs of 33-3H PC)C(IIt had SitOIl roots alld -hoofs than lonflol s((d of higlll) moisture COIlUns (l1l whell til( t(nlpllaflllp of fTlntmpllt of fhe low

~l moistirre-contlnt in III pies IS (ollsidlIld 1ltlow the (Iit ita I rang( On the othel hand no diflelelwPs ill gCIllIillation (apn(ity atp Ieflletpd in the datnin tablp 2 Thl tlason is thaf sunples of ail-dlied contlol wHh both the low a 11(1 flH lrighCl 1l10iStlll( tontlllf vichlpd (ss(lItiaIly the saine 1I11111)l) of cOllilfabln sepdlillgs afttI fi i 10 and l~ days in the gllmillafol i(IIlY mom of filp sNdlings howcvlr hom the drier salllp]rgts banl) met tire albitralily sel((te(] minimum requilcshyments to be counted i ( poslsstd hoth root and shoot with one bull strucfule at hast olle-Jourth inch long

bull

bull

bull

EFFECTS OF HEAT TREATlmNl ON THE VIABILITY OF RICE 37

H~berlandt (31) beHeved that a hardening of the seeds [md seed coats as a result of extensive drying at a high temperature might be the partial explanation for retardation in growth This condition would permit only the ery gradual entmnce of moisture into the inner seed rust (43) and Dixon (26) exprescd similar thoughts

EXCESSIVELY WET SEEDBED

Somctimcs in thc germination tests the beds of paper toweling became extrcmelv (t Seeds in the exCcsfinly wct bcds germishynat-cd m01C 5101) Hoot (radiClc) formation Wl rctarded and when the root did form it was usuall frcc of root hairs This kind of clrnlopmcnt is attributed to rc(111(rd oxygen tension

The plllnomcnon has blln cxtensi nly n~portecl in the 1i tera ture and has bern obscrvcd to o(Cur in ail with reclll(ed oxygen in nitTogen and in watcr and to I)e aflcded hy diflcrcllt dcpths of water slnd rnd soil Klebs ()) in ISHi Yokoi U)J) in IH)8~ and TakahaRhi (80) in 1905 wcre amOIl tIle filstmiddot to rtlonl obRtITntl0n il11ilar to tIll above Since Own thc pilCnOIlHnon has wen Ippoltc(l by ()thtrsin(lllltlill~ Atemine (iV) Xagai ((lj) olillaga (j) ~asaki (fjQ) bullJones (4() Dastur I1(l nlsai (J) lam () Taylor (S) and Ylamis anclDlvis (86) In the gcrmillation of ricc s((d thc ihoot aplwals first lnd lc(olding- to t(lIlille if tl1( api(] root elllllg(gtS first it is probably b(cause of dcfit-icnt 1Il0iRtlr( Ialll aitliblltNl thc failurc of s(eondalV and adnntitiolls roots to dt(lop in Rcedlings plant-Pll algl(atpl c1CI)ths in soil to fhe greatpl lPRtriction of thc ()xyg(1l uppl) Elygill (SO) found thc enzrnlP adiih 10 1)(gt Itss in R((d (llllinatNll1lHlcl water IolinagH ((JJ) drnlollstlnt((j that thl ealall-p adiity of sccdlings gl(Yll U1HItl alpl is Ieltiu(pd tlH gllafl1 til( (ltplh of tlll al(l A (On1l110n plactitP in thl SOlltlrCIl1 Ii(e-gloing ShIfps is tmiddoto plant at a dlptlt or 1 to ~in(]II ith a dlill and to flood the field after the rice is middot1middot to Ii inclHs high (JolH 111(111)

HESISTANCE TO FUNGI

Hough Ii(e iNdi whosl nlJilit- to gellllinall had betn (ompletely (ipstroy((l PI( III 0 Il Ipad i I Y nttHlktti b fll ni thn n iabll sterls Hal)(Ilalldt (-J1) found tltat If tl( gCIlllinting 10(1 iR lhtIO)Nl the ll10ist s(ltls igtPlOnH st ilY and ill-middotmlPlling within 1 fp days whereas -ith liv( R(pds til( ((lt1 (oat 1I1a IPlIlain 1I1lt1tplld for 1(111 w((ks Tusf (~I) iaI1l111tld data -h(Jl~d pari pllt IlIad iOIl of hiR Ilolliahl( htat-tlpl(d s((d stlllpips )ixon ((j) tprilizpt t II( Rand Sallt(rs and wdI u=Cd 101 till (ll11illltion ((1 I LC 10( ThiR pr((lltioll IPPPtIS IINal as IIll dilllilli]lPd itality of p((hi -lllll (xposcd to tNlllwla t UIP lIP I t Irl iI 1I11X i1111111 IPlIllplS thtlil (~Iy SlISttpt i b Ie to the 1 Uat 0 r III iiIO-Olgl1l iII1Smiddot

DIPUOVED GErOIlNATION

Ex(ppt for tht nlO~finllllntUlp Ii(( snmplts hent-tlrntNl Iluring the l)ill cxperimCl1tR (tablc II )lIo(middotiltlII1(t wlsoiJfaillCd flrat hcat tnatshymellts m SI1lt1l illlplO(d irbi Iit Ioll (iclPII(l lIIight hY( been obtaincd hall nil (IP 111It h~ or roots all(L shoots l)((11 detNmined in nil heat-trelt(ll SUlll)l(s 1I1ld (ollt1ols

- -shy

38 TECHITJCAL BULLETIN 1129) U S DEPT OF AGRICULTURE

No experiJnental evidence wns obtained to indicate hether the heat treatments had any elfect in overcoming dOlmancy of the different yarieties of rice Germinatjon tests were not made until 8 weeks after heat treatment Any dormancy existing at the time of harvest might have disappeared (luring this interntl

According to Wiesners (90) york wit11 conifer seeds the effects of heat treatment maybe heneficial to germination Jnst (41) reshyporteel one (xperiment in which thegelll1ination capac-ity and vigor of barley were improved by heat tr(gtailnrnt The hnrley seed was held2 days oYer suHnrie fleid then put in a test tube with calcinm (h10ric1( anrlldt for 2 more clays thrn heIdI day at10deg tncl3 days at GOdeg 0 Kiessling (~4) in stu(lying the ell(Is of henl lIeatnwnt on dormancy found that heat tJeatments i III prowd the ~(Imi nating flUB lity of nonshygerm-ripe barlr) bnt th(y did 110t 1nlly (omprnsaie for eompkte storage rippl1(ss AlloilHI illlpolimt obsPITation was Ihat the il11shyproycment in germinnting q11ality lS illd(lwllclent of the aHernliol1 of the moisture eontpnt TfC Ill l(f(1li 11~ to those losses tha I 0((11 I when srerls alr elI-ipd at the salllp limC nley lle hein~ l1ett-ITCnle(1 Dn Fanos datn (21) ~llOimplOpd Qprmiimtion 01 lice after heatshying at loo-iOo and of (orll aflPI heatillp at 30deg_(0deg

GENEHAL DISCUSSION

Yenthel (onditions toupthel witll otlll1 cinu111slnn(Ps in UHj() HHil nnd 1)52 pleYclltelt1 the allthoJs 110111 obtaining lois (rl flpshl) COIll shy

bined rough riee of higher than ~5~-ppl(enl llloihllC content- It yould l1nyc bpel1 dpsiluhle to 111e included pxperinlPnts on the elleets of temperatllle of tTCntment on lots of riel of 2(i- 10 lO-pel(pnt moisshyIl1le (on tents These 11l0istUIp (on 1(gt 11 11 lllthnllh II 11(0111 1110n 11(

possible FUlthellIlole it yould hn n iJNn (]pilaiJlt fronl til( standshypoint of e0l11111el(ial huTpsting eOllditiol1s to have IIsHl lots of rice fleshl combined nt (fI(lJ 2-pcl((nt (Ii 110r(gtl1(e in Illoistmclevel at Ipnst within 111( IHnl 01 ](j to 2G pel(enl B((tllsc it was not I)nICshy

lien1 to th)) pf to Olll hi I( Jil at sppi fitd 11IOislIIIc-eonfent l~nIs l(lnll1fngc IS Inkpn of llll llllpllIatie 1)IO(pdlllC in which n hallpl 01 molp of Ii(e Ill tnkpll froll1 a flpshlv(ol1lhillPd lot of hith IIlnistIIp eontpilt lind IHlItions (1(gt ail-ltiJipd to diflCIPllt lI1oistlllpI()middot(ls

H ns uIficipHtpd tiJlt IIPn tJpntlllPllts ilt illlI(lsillgly higlwl tPIlI shy

p(rahlllS wOllld Illillg aholl ilwl(nsiI1J_dy glpntpl INlllltt iOIl ill the abilitmiddot of Ii(p to PIllIillafp Till pnlliPl illpsliatOIR I((onized till Bigl1iiil~HHe of til( IplIllWlalII Il alinblp llwiIllllntCIOIISeXpelilllClIts del1lonstTuled till gl(ttPI ltleslludivPllpss 01 the highlI iell1ppmtilles to germinability X(lltlwlpss sPPIal rpasolls pxi~f for not acceptshying theil clufa fllld eOlHlllSiolls ns linnl alld ltiilpctly appli(ahle to Ihe heat tlcahllCll of Iiet Fol lxnlllple specilic (lltails regalciing Ihe moisture contellts of the s((gtlt1s tlIP 1lHlholtlR of llent tlfatmel1l nlHl the age of till s(gt((is W(Le frequently ollliiJec1 Seeds yere sonlpIilJl(gtS Cxposed to PIT higit trll1pCrahllPS Hnd fol 1l1lllSllfllly lon~ ])pliolt(s of ii me TIHV (1( [ 11 i licin 11 IIlOist Piled whpn it vas clcsilNl to detelmine tlH (Ireds 01 hllIt 011 s(I(ds of hih moisture eOIlipllt Oplshymination tests (Ie gPIIPln II made i I1lll1e(lia tel v 01 sholt I y dt(1 it(al treatment ~rnllr 01 titp s(((is stlldipcl difllJpd slludlllllly floll1lice

bull

bull

bull MOleover most of thp illVltignols had different objediycs in planshyning their (Xjlllillltllts

bull

bull

bull

EFFECTS OF HEAT TREATlmNl ON THE VIABILITY OF RICE 37

H~berlandt (31) beHeved that a hardening of the seeds [md seed coats as a result of extensive drying at a high temperature might be the partial explanation for retardation in growth This condition would permit only the ery gradual entmnce of moisture into the inner seed rust (43) and Dixon (26) exprescd similar thoughts

EXCESSIVELY WET SEEDBED

Somctimcs in thc germination tests the beds of paper toweling became extrcmelv (t Seeds in the exCcsfinly wct bcds germishynat-cd m01C 5101) Hoot (radiClc) formation Wl rctarded and when the root did form it was usuall frcc of root hairs This kind of clrnlopmcnt is attributed to rc(111(rd oxygen tension

The plllnomcnon has blln cxtensi nly n~portecl in the 1i tera ture and has bern obscrvcd to o(Cur in ail with reclll(ed oxygen in nitTogen and in watcr and to I)e aflcded hy diflcrcllt dcpths of water slnd rnd soil Klebs ()) in ISHi Yokoi U)J) in IH)8~ and TakahaRhi (80) in 1905 wcre amOIl tIle filstmiddot to rtlonl obRtITntl0n il11ilar to tIll above Since Own thc pilCnOIlHnon has wen Ippoltc(l by ()thtrsin(lllltlill~ Atemine (iV) Xagai ((lj) olillaga (j) ~asaki (fjQ) bullJones (4() Dastur I1(l nlsai (J) lam () Taylor (S) and Ylamis anclDlvis (86) In the gcrmillation of ricc s((d thc ihoot aplwals first lnd lc(olding- to t(lIlille if tl1( api(] root elllllg(gtS first it is probably b(cause of dcfit-icnt 1Il0iRtlr( Ialll aitliblltNl thc failurc of s(eondalV and adnntitiolls roots to dt(lop in Rcedlings plant-Pll algl(atpl c1CI)ths in soil to fhe greatpl lPRtriction of thc ()xyg(1l uppl) Elygill (SO) found thc enzrnlP adiih 10 1)(gt Itss in R((d (llllinatNll1lHlcl water IolinagH ((JJ) drnlollstlnt((j that thl ealall-p adiity of sccdlings gl(Yll U1HItl alpl is Ieltiu(pd tlH gllafl1 til( (ltplh of tlll al(l A (On1l110n plactitP in thl SOlltlrCIl1 Ii(e-gloing ShIfps is tmiddoto plant at a dlptlt or 1 to ~in(]II ith a dlill and to flood the field after the rice is middot1middot to Ii inclHs high (JolH 111(111)

HESISTANCE TO FUNGI

Hough Ii(e iNdi whosl nlJilit- to gellllinall had betn (ompletely (ipstroy((l PI( III 0 Il Ipad i I Y nttHlktti b fll ni thn n iabll sterls Hal)(Ilalldt (-J1) found tltat If tl( gCIlllinting 10(1 iR lhtIO)Nl the ll10ist s(ltls igtPlOnH st ilY and ill-middotmlPlling within 1 fp days whereas -ith liv( R(pds til( ((lt1 (oat 1I1a IPlIlain 1I1lt1tplld for 1(111 w((ks Tusf (~I) iaI1l111tld data -h(Jl~d pari pllt IlIad iOIl of hiR Ilolliahl( htat-tlpl(d s((d stlllpips )ixon ((j) tprilizpt t II( Rand Sallt(rs and wdI u=Cd 101 till (ll11illltion ((1 I LC 10( ThiR pr((lltioll IPPPtIS IINal as IIll dilllilli]lPd itality of p((hi -lllll (xposcd to tNlllwla t UIP lIP I t Irl iI 1I11X i1111111 IPlIllplS thtlil (~Iy SlISttpt i b Ie to the 1 Uat 0 r III iiIO-Olgl1l iII1Smiddot

DIPUOVED GErOIlNATION

Ex(ppt for tht nlO~finllllntUlp Ii(( snmplts hent-tlrntNl Iluring the l)ill cxperimCl1tR (tablc II )lIo(middotiltlII1(t wlsoiJfaillCd flrat hcat tnatshymellts m SI1lt1l illlplO(d irbi Iit Ioll (iclPII(l lIIight hY( been obtaincd hall nil (IP 111It h~ or roots all(L shoots l)((11 detNmined in nil heat-trelt(ll SUlll)l(s 1I1ld (ollt1ols

- -shy

38 TECHITJCAL BULLETIN 1129) U S DEPT OF AGRICULTURE

No experiJnental evidence wns obtained to indicate hether the heat treatments had any elfect in overcoming dOlmancy of the different yarieties of rice Germinatjon tests were not made until 8 weeks after heat treatment Any dormancy existing at the time of harvest might have disappeared (luring this interntl

According to Wiesners (90) york wit11 conifer seeds the effects of heat treatment maybe heneficial to germination Jnst (41) reshyporteel one (xperiment in which thegelll1ination capac-ity and vigor of barley were improved by heat tr(gtailnrnt The hnrley seed was held2 days oYer suHnrie fleid then put in a test tube with calcinm (h10ric1( anrlldt for 2 more clays thrn heIdI day at10deg tncl3 days at GOdeg 0 Kiessling (~4) in stu(lying the ell(Is of henl lIeatnwnt on dormancy found that heat tJeatments i III prowd the ~(Imi nating flUB lity of nonshygerm-ripe barlr) bnt th(y did 110t 1nlly (omprnsaie for eompkte storage rippl1(ss AlloilHI illlpolimt obsPITation was Ihat the il11shyproycment in germinnting q11ality lS illd(lwllclent of the aHernliol1 of the moisture eontpnt TfC Ill l(f(1li 11~ to those losses tha I 0((11 I when srerls alr elI-ipd at the salllp limC nley lle hein~ l1ett-ITCnle(1 Dn Fanos datn (21) ~llOimplOpd Qprmiimtion 01 lice after heatshying at loo-iOo and of (orll aflPI heatillp at 30deg_(0deg

GENEHAL DISCUSSION

Yenthel (onditions toupthel witll otlll1 cinu111slnn(Ps in UHj() HHil nnd 1)52 pleYclltelt1 the allthoJs 110111 obtaining lois (rl flpshl) COIll shy

bined rough riee of higher than ~5~-ppl(enl llloihllC content- It yould l1nyc bpel1 dpsiluhle to 111e included pxperinlPnts on the elleets of temperatllle of tTCntment on lots of riel of 2(i- 10 lO-pel(pnt moisshyIl1le (on tents These 11l0istUIp (on 1(gt 11 11 lllthnllh II 11(0111 1110n 11(

possible FUlthellIlole it yould hn n iJNn (]pilaiJlt fronl til( standshypoint of e0l11111el(ial huTpsting eOllditiol1s to have IIsHl lots of rice fleshl combined nt (fI(lJ 2-pcl((nt (Ii 110r(gtl1(e in Illoistmclevel at Ipnst within 111( IHnl 01 ](j to 2G pel(enl B((tllsc it was not I)nICshy

lien1 to th)) pf to Olll hi I( Jil at sppi fitd 11IOislIIIc-eonfent l~nIs l(lnll1fngc IS Inkpn of llll llllpllIatie 1)IO(pdlllC in which n hallpl 01 molp of Ii(e Ill tnkpll froll1 a flpshlv(ol1lhillPd lot of hith IIlnistIIp eontpilt lind IHlItions (1(gt ail-ltiJipd to diflCIPllt lI1oistlllpI()middot(ls

H ns uIficipHtpd tiJlt IIPn tJpntlllPllts ilt illlI(lsillgly higlwl tPIlI shy

p(rahlllS wOllld Illillg aholl ilwl(nsiI1J_dy glpntpl INlllltt iOIl ill the abilitmiddot of Ii(p to PIllIillafp Till pnlliPl illpsliatOIR I((onized till Bigl1iiil~HHe of til( IplIllWlalII Il alinblp llwiIllllntCIOIISeXpelilllClIts del1lonstTuled till gl(ttPI ltleslludivPllpss 01 the highlI iell1ppmtilles to germinability X(lltlwlpss sPPIal rpasolls pxi~f for not acceptshying theil clufa fllld eOlHlllSiolls ns linnl alld ltiilpctly appli(ahle to Ihe heat tlcahllCll of Iiet Fol lxnlllple specilic (lltails regalciing Ihe moisture contellts of the s((gtlt1s tlIP 1lHlholtlR of llent tlfatmel1l nlHl the age of till s(gt((is W(Le frequently ollliiJec1 Seeds yere sonlpIilJl(gtS Cxposed to PIT higit trll1pCrahllPS Hnd fol 1l1lllSllfllly lon~ ])pliolt(s of ii me TIHV (1( [ 11 i licin 11 IIlOist Piled whpn it vas clcsilNl to detelmine tlH (Ireds 01 hllIt 011 s(I(ds of hih moisture eOIlipllt Oplshymination tests (Ie gPIIPln II made i I1lll1e(lia tel v 01 sholt I y dt(1 it(al treatment ~rnllr 01 titp s(((is stlldipcl difllJpd slludlllllly floll1lice

bull

bull

bull MOleover most of thp illVltignols had different objediycs in planshyning their (Xjlllillltllts

- -shy

38 TECHITJCAL BULLETIN 1129) U S DEPT OF AGRICULTURE

No experiJnental evidence wns obtained to indicate hether the heat treatments had any elfect in overcoming dOlmancy of the different yarieties of rice Germinatjon tests were not made until 8 weeks after heat treatment Any dormancy existing at the time of harvest might have disappeared (luring this interntl

According to Wiesners (90) york wit11 conifer seeds the effects of heat treatment maybe heneficial to germination Jnst (41) reshyporteel one (xperiment in which thegelll1ination capac-ity and vigor of barley were improved by heat tr(gtailnrnt The hnrley seed was held2 days oYer suHnrie fleid then put in a test tube with calcinm (h10ric1( anrlldt for 2 more clays thrn heIdI day at10deg tncl3 days at GOdeg 0 Kiessling (~4) in stu(lying the ell(Is of henl lIeatnwnt on dormancy found that heat tJeatments i III prowd the ~(Imi nating flUB lity of nonshygerm-ripe barlr) bnt th(y did 110t 1nlly (omprnsaie for eompkte storage rippl1(ss AlloilHI illlpolimt obsPITation was Ihat the il11shyproycment in germinnting q11ality lS illd(lwllclent of the aHernliol1 of the moisture eontpnt TfC Ill l(f(1li 11~ to those losses tha I 0((11 I when srerls alr elI-ipd at the salllp limC nley lle hein~ l1ett-ITCnle(1 Dn Fanos datn (21) ~llOimplOpd Qprmiimtion 01 lice after heatshying at loo-iOo and of (orll aflPI heatillp at 30deg_(0deg

GENEHAL DISCUSSION

Yenthel (onditions toupthel witll otlll1 cinu111slnn(Ps in UHj() HHil nnd 1)52 pleYclltelt1 the allthoJs 110111 obtaining lois (rl flpshl) COIll shy

bined rough riee of higher than ~5~-ppl(enl llloihllC content- It yould l1nyc bpel1 dpsiluhle to 111e included pxperinlPnts on the elleets of temperatllle of tTCntment on lots of riel of 2(i- 10 lO-pel(pnt moisshyIl1le (on tents These 11l0istUIp (on 1(gt 11 11 lllthnllh II 11(0111 1110n 11(

possible FUlthellIlole it yould hn n iJNn (]pilaiJlt fronl til( standshypoint of e0l11111el(ial huTpsting eOllditiol1s to have IIsHl lots of rice fleshl combined nt (fI(lJ 2-pcl((nt (Ii 110r(gtl1(e in Illoistmclevel at Ipnst within 111( IHnl 01 ](j to 2G pel(enl B((tllsc it was not I)nICshy

lien1 to th)) pf to Olll hi I( Jil at sppi fitd 11IOislIIIc-eonfent l~nIs l(lnll1fngc IS Inkpn of llll llllpllIatie 1)IO(pdlllC in which n hallpl 01 molp of Ii(e Ill tnkpll froll1 a flpshlv(ol1lhillPd lot of hith IIlnistIIp eontpilt lind IHlItions (1(gt ail-ltiJipd to diflCIPllt lI1oistlllpI()middot(ls

H ns uIficipHtpd tiJlt IIPn tJpntlllPllts ilt illlI(lsillgly higlwl tPIlI shy

p(rahlllS wOllld Illillg aholl ilwl(nsiI1J_dy glpntpl INlllltt iOIl ill the abilitmiddot of Ii(p to PIllIillafp Till pnlliPl illpsliatOIR I((onized till Bigl1iiil~HHe of til( IplIllWlalII Il alinblp llwiIllllntCIOIISeXpelilllClIts del1lonstTuled till gl(ttPI ltleslludivPllpss 01 the highlI iell1ppmtilles to germinability X(lltlwlpss sPPIal rpasolls pxi~f for not acceptshying theil clufa fllld eOlHlllSiolls ns linnl alld ltiilpctly appli(ahle to Ihe heat tlcahllCll of Iiet Fol lxnlllple specilic (lltails regalciing Ihe moisture contellts of the s((gtlt1s tlIP 1lHlholtlR of llent tlfatmel1l nlHl the age of till s(gt((is W(Le frequently ollliiJec1 Seeds yere sonlpIilJl(gtS Cxposed to PIT higit trll1pCrahllPS Hnd fol 1l1lllSllfllly lon~ ])pliolt(s of ii me TIHV (1( [ 11 i licin 11 IIlOist Piled whpn it vas clcsilNl to detelmine tlH (Ireds 01 hllIt 011 s(I(ds of hih moisture eOIlipllt Oplshymination tests (Ie gPIIPln II made i I1lll1e(lia tel v 01 sholt I y dt(1 it(al treatment ~rnllr 01 titp s(((is stlldipcl difllJpd slludlllllly floll1lice

bull

bull

bull MOleover most of thp illVltignols had different objediycs in planshyning their (Xjlllillltllts

EFFECTS OF ID~Nr TREAllifEWr ON lHE VIABILITY OF RICE 39

The experiments leported in thls bulletin eli flelec1 in the followingyttys iom those of earlier yorkers

1 Heat treatments were cOlldllcted ollly with fleshly andor reshycently combinedrongh rice

2 Naturally moist rOllgh rice wns llsrc1 in rxperiments requiring rongh rice of high moistllre cont(ni

3 Times and tempeJltt-lIllS of treatment included thmje within rnnges covered in present-dny pmdiees of cOJllllleleia llicr drying

+ Containels in whieh the rough riecfls to be heajmiddot-treated were packed full and tightly stoppered SO tlmt there ould be little moisshyture loss 110111 tIll seed mltfS (llIling thr application of heat

5 Samples oJ heat-treated rough liccerc tested for tlwir contents of gelll1illable secds after clifielrnt pcriods of st-orage

~lthough there are numcrollS rcnsons -for not accepting ill toto all tbe earlier observations concerning the effects of heat on the ability of sercl to germinate nIHn of t-lw earlier more general observations do apply to rice Theil chlOl1010gy is briefly levieyed llCre This is done to give prior research cledit to approximate the order of deyeloplllent- of the pertinent obfelvations to indicate similarities in the responses o-L different kinds of seccls and to -faeilitate the lCarlelS eyalllation 01 the data prespnted in this bllllet-in

bull lYorkers ho haye demonstrated that hent trentment at- a high temshy

peraturp l((lIlCCrl 01 entirely destroyed the ability of seeds to geiminate inclnde Ednrds and Colin (28) in IHlL Habrrlnndt Uf) in IH(j3 Snells (08) ill 11-161 YiCsnlI (Fl()) ill lii7I Jllst (1243) in 1877 Von Hahnel (iB) in 1877 Dixon (35 ]0 27) in 1 )01-3 White (89) in IHO) nn( Bltrgess (1) in In]l This finding has sinCc IJren confirmed by Ua Fano (21) in 1016 and Jones (19) in 1l2G -for rice It may be asslll1lPd that- all these in nmiddotti ators -fully r((()nizecl that dry seeds haw IlT Cntel I(sishll]( too higb tIllj)CIlhps thull seeds with highmoisturr content

Hab(rlancli- UZ) Cxpos(cl fiR kinds of SPf(Is ill -I-R lIonrs in t drying appalatus at n5deg fiG075deg 876deg und 100deg C He reported his dahl in terms 0-1 the 1ll1mber of days it- took scpds exposcd at ench tem perat-llle to germ inate Two kinds lost their n bi I it) to germinate when treated at- 87)0 and 10 moJC at 100deg Althongh losses in gershymination capacity Imd(1 100 pelcent- nre nor pviclent horn the tabushyIntpd clara thpy fiR pll [IS los(s in g(~lminntiOn vigor nle discussed Haberlandt Iote that the s(Nls of Illost- cultivated plants with few lx(cptmiddotiolls tll( aiJlp to pmIul( a tpllljlPlaillrp of 100deg without losing their ability to grllllillnte

bull

Sachs (r(~) )((o1(ld his datn ill telnlS of the Humbcr of seeds that wnninatcc out of HIP IOO plnntrd X(lIIllnl Inc stunted embryos llre s(parHtelr it-emiz((1 Dahl are ginn foJ (liT pen rye barley wheat alld corn sped heat-tTPa(-ncI in test tniJ(s for ] hou in a water bath n tmiddot tem pemtuJPs lllngi np -from 570 01 fiRO toHO C Dat1 arc also given -for the sallle ki 11(1 of serel wet a lid si Illi lar]) hel (-treated 11 t t-em perashyturps lalllillg -I(JIll middotID o

01 )0 0 t-o 5-1- 01 Bilo Sadls fOllnd t-hnt the loss in viabilIty ItS gleaJcl the big-hrl tmiddothc tCllllWlntlllp of tT(aiment and that it WHS m11(h grellter ill (~( t-han ill (lry s((1

Justs (4middot)) eomplehensiY() stndy is probably the first to show

-j

SCVEm lin tellelatiollsll i ps lllt(rn tmiddot he t-em jlPIaIIIe of treatment the duration of treatmpnt- and tillt HlOishHP Contmiddotmiddotpnt of the sped He lleatshytreated oats and buhy of rlifrlIPllt Illoistulc contClltsin a eonstantshy

TECHNJCAL BULLETIN 1129 U S DEPT OF AGRICULTURE

teinperature oven at di fferent temperatures uld for different periods of time He tabulated germination data for each clay of the test ~-period Consequently his data show the effects of heat on the gershymination capacity and the germination vigor and the day of maximum germination Moreoyer they show tllat the grentel the injnry the longer is the intmval preceding the cly of Jrmximum germination and that in severe injury a day of maximum germination is not eishydent Just veri1ied the findings of his predecessolsin that he clearly demonstrated greater clestruetion of viability the hightr the telllpe1lshyture the longer the treatment and tlle highpr the moisture content of the seed

bullJust (43) and Yon Hiilll1Pl (38) -ho also pnblislled in 1877 sumshymed up the elfeets of helt on the viability of seell much as we undershystand it today Both investigators realized that one could not give a definite maximum temperature at which seeds could be heat-treated without injury Von Hlti1mel has point-eel out more clearly perhaps than Just that the first symptom of injl1lY through heating consists of a loss in germination vigor and that it llllty oecur eyell though no loss in germination eapacity is notiCeable

Twenty-five years aiter the publiCtltions of rust and Yon Hiihnel Dixon (86) made a sign i [-icant enerll I ization in analyzing 11 is seed heat-treatment data He rote it appears that for each scP(1 there is a temperatllle up to which it may be rnised without suffering appreciable alteration in the period of time needed for germination Once this point is passed the ermination period is increased the bull increase pel degree being greater the nearcr the mnximum is ap- proached This generalization had apparently been assumed or else overlooked by earlicr investigators bpel11se t-heir intelcst was pri shymarily in determining the maximum temperatures seeds could endure without injury It is the range of tcmpelatmes overwlrich a iven lot of seed may be lleat-treated wHhont injury that is recognized today as being highly important for the c1evelopnwnt of (ommcIcial dryill and storage metho(ls TIle 10n~1 the moistllre (ontent of the seed the greater the tcmpprature range opr which it may be safely heatshytre11ted

In 1011 Kiessling U-i) conclllc1ed that the effect of hpat in OW1shy

com ing the dormancY of 1gtarlpY thnt as not storage ri pc was i nr1pshypendent of the loss of moistllle From this fillding we may assume that the more accnrate datiL in the literature on the eflects of lleat pel se ere probnbly obtained by those in vestiatols who exposed thei I seeds in clo(gt(l eontainers or uncleI conditions in which the moisture loss was negligible In 1017 Yagonel (87) emphasized that the dilJieulty in interpreting dahl in the older literature with respect to the letha] temperatures of seeds wns to be sought in the initial water content of the seeds or in the method em ployed thai- would allow an increase 01 decrease of this wat-er Content during the heating process

Yaggoners experiments it-h radish seed and Hutchinsons (33) with whent confirm previons obslnations of the eneel of heat Oil nlC bull viability of seed

The geneml obselvations made by the llllt-hors of this bullptin 011

theil rough pire investigatiolls arc lally a l((apihllation of those that llllve just lwen 1lyi(mecl The viability of rough rice has becn

EFFECTS OF HEAT TREAllfENT ON THE VIABILITY OF RICE 41

shown to be affected by heat in the same manner as the yjabilities oT

bull

radish -wheat and other seeds similarly treated Differences in reshysistance between the different kinds of seeds as judged fronl the present rice study and the literature are more of degree than of kind

On the othlr hal1fL some observations were made cluring these inshylstigations that hn W not pnnriollsly bl(l1 pnlpltnsi7lcl Rough riel was heated in closed (ontaineJs llld appaleMly withollt the developshy))lent of injurious pressllre efeds In hlat-heat-illg immature rice moisture eOlltent mthlr than st-age of Illahllity as I-he major factol deterl1Jining rlie degree of 11ltt injulY Heat-trlnte(1 rice even heatshydanllged samples did not show an appl((iablf change in viability i e in the pel((ntages of 81((1 )(Illiinatingmiddot lllhYePll the R- and i12shyreek periods of stolllge

Houdllice that Ias natllrall moist and flpshlr lol1lbined was lIsecl in the experiments because it lS thought that the data Ionld be more represenative of data obtained uncler large-seale (onllnercial operashytions Whether this reasOllinp YtS correct was not determined

Certain disnclll1tagcs in llsing hlshly eOlllbineclliee soon became

appalent The lots lOt only Jackrd uni-lolmity but sometimes C011- ta i ned large pelcentages of nOlwiablt seNl s a lCSll It the tempeltlshy hlles at hich heat damage to iability just started and at which it Ins just complete for rice of a gien moisture content- could be only rough Iy apptOximn ted This fad el is(oll rageel an enc1ea VOl to deshyrive mathemati(al equations sueh as thosr of Hutehinson (33) for whea t h ich might ha Te praetica I ntlue in deterlll i ni ng sa-le com mershy(inl operating (onc1itions for heat-tleating rough rice It is evident (rigme 3) thnt the approximations defining the critical tempeJature

bull

range for ricp o-f paell nloishllp(ollt-ent inVtstigatllt1 do outline a zone of Ileat dllnagl It is also euroYident that flwil pattern is tooirreglllal to define thr lower andllpp(r 1 illl it of the 7onl of heat clamage

lTnder eliTelellt expCIinlCntal (onelitions it- Illight have bpen possible to obtain data that mnIlc1lllore aCTlIrafely illnstllte the limits of the zonp 0-1 heat dallIagr for lOl1h ri(( of (]i Ilelpnl 1110ishll(gt (ontents Von H6hl1el (32) found tha t a c1efin itp maximlllli temperature at which a giwl1 sanlplp of sepds may be safpl htatp(1I111Y 1I0t- )( obtailHd heshy(ausr of the eli rh(n(Cs in thp resistul(es of lnciic1utl sl(cls IIutchshyillson (])) Oil tl1( other hallcl was able o estahlish rather definite and practical tel11pemlllle end points defining the (ritieal rang(s -101 eteh of his stmpl(s of wheat 0-1 eli rllllllt 1l10istllre eontrnts Flom his plIbshyI i(a fioll ii- 011 Ie a pppa I I lin t t ill ~( Ipd i()) () f 1111 if01111 sred sam pIes Hnd (lip (lIoi(p of OIlP- (onfnillillg n IlP1 J()n pelC(nt of ial)I( se(d as possibll PI( illlPOIhillt adolmiddots

_lthollgh (lierp may b( all PITOI of )O C 01 mole in the apploxishyIllatpltl illlJ)elttllJe- plottrcl ill figl1le 1 fhl scatter-type cliaglam has plldi(a I va I l( It Pllables 011( fo n pploxi mat( tIl( maximum tcmpcrlshyI mps at hi(11 baj(hls otollh liee of ltIi rTennt IlloistllJP (ontcnts rna be hput-tr(ntl1 unclll (()ll(litlolls like (host des(Iibp(1 ill Experimentil atelials a 1)(1 Prrlllc11 Ip (pp H-I~) To Ihis IxtPllt it- 1IIt) seJve as a hent-damagp plldi((-ion 01 saity elIalt Xo claims may be Illade that it would ~eln Ipliably fol plpd(tpJrninill) the tellljlelltllrc nt hi(h a ir(sl1 I COI1lIgt i ned lot of 1i(( III itdl t be 511( II ellied i II a (0111 Il 1lICi a I (1Ii(I The Ipaso) is thd the tlialgtl( illl loclIclaquolll tillt loss of lIloi sli I11 cllllshying the heating PIO(ISS wns 1I0t (111111((1 i1 the ill(lstigatiolls

42 TECHNICAL BULLETIN 1120 U S DEP1 OF AGRICULTURE

However it appears possible that diarrams similar to figure 3 could be developecl for use as heat-damure prediction charts for guiclillg experimental and commercial dlyinr operations for both seed and -~illing purposes Charts for the latter wOllldneed to be based upon ririlling instead of germination test dntn

SEED HEATmiddotTUEATIUENT METHODS AND THEIn APPLICATIONS

Plant physiolorists plnnt patiloloriI tnlOlllOlorists lnd arlielllshytural enrilleels hnn lllu(hmiddot 111( mujo) lonlTibuiolls to OUI knowl((hre of the effects of heat on seeds

Atanasoff and Tollllson ((J) poi nled oul that thl Iii orbIs 10 investigate the effects of ditJ(rellt tpllI]lelalurrs of tJlulnHllt on seeds were principally plnllt physiolopists al1lI thpn plant pntholorists Thr plant physiologists were interested in establ ish i Ilr the efrects of 11(at on germination enpllcity and r(rlllination YigOl and ill onrcoming dormancy Often they employe(l Yery high iel1lpelatlllcs and long exposure periods hieh ( tOI)i(ler to(lay to Ill lXII(Il)( anel illJpracshytical fOl (oll1lJ1rlcial tpplhatiol)

The pla nt pa thologi-t- PP1TPingtltl fhn I hpltl I 1llih I 1)( 11-(111 I f(lI

destroyillg seld-tollullinatiJ1 fllllri hiIll Inifht la0l 11P(OIlI( 1(shy

tively pathogrni( to tliP p(d 01 to tIl( ltllnlopill PllliJrYo alld plalll These workels had (0 dli-p lXPPlilllPllb that WOII Id dpl1lollsfTltl tI whether a clrtain finH-tell1]lp]atll[p (olllbillntiOIl might be rlllploy((l ill treating a gien kind of sepd that wOllld (lpstroY the eOllttllllinatillr vathogenic fungi hut ihM wouhlnot alr(f tlIP inhililY of the SPl(1

Shortly the entomologists beClIlllP jnt(1(~t(c1 T1HY had pSfpnfialIy the same ploblenls a~ the plant patllOlorists ~ill(p 111lt) l1P((hd 10 (gtIPshyserve seed for extPlIded ppliods for boll pllIltinr and lI1ilIill~ PIII_ poses ~poundost of the litplatl1lP Oll thr liSP of IHtt to ltI(-tlO) flll1i and insects in seeds has ap]Jpand yithil1 the pnst j() )(IIS This is I10t becanse the coneepts -fOI hel Im) plaetieal applications of IIlat an by any means new Hahlllnnltlt (]1) di-(l1ss((1 Ih(111 in U(j3 and 110 doubt others twfole him

Vithin the pasl ) ylal- arri(lIltula 1 lI1giI1PPI nnd ass()cin(cl workers haTP made IlUIlI()OIiS oltln (Ollllibn ions to ilH lifl1Hurl on the heat treatmellt of pra TlwlL dUllI oiljP(tin hI-( hlCn b

means of dlying and C011(I01led telllpltIltI11PS lnd l1ulllidijies to ])ngtshyvent the dlvelopment and tl(tivity of fungi Hnd inspd in Iond lNI and either to il1lj)Ior oj to lSSUle tJ(gt lPipntioll of high milling qunlshyity in g1ains

Sen~ntl llIethocls 101 IHlt-tTlntill~ (pcb JtlYP h((ll dpisld bv 111lt various -mhrs 111( kind of nHlllOdis lIot llf((s~lIih (OI1(lilnblf -ith the plor(s-ionnl in[(Ipt of thp i n(1 ill Imlnd 110 stich infpLshyence is intenlt1ld Th(middot methods may Ill f[lOu]llllas foIIOY

1 Direct contn(t with hot wat(I 2 Direct (ontaet with heat(middot(l ni]

Trays in tl (ollstant-lllllIHlufuIP 0(11 ail (il(IIInliol1 jl1il1(ishypally convl(tiol1

Opltn t(st [ub(s or flask- paltinll~ SUhIlHIr(d ill a lmth ail (il shy

enlation r(stTid((] sOllwtillJlS Ply nllllh HJ byt tHpil11ry 0plnillg inshysignificant total and VlI)(lI IgtI(SSIII(S

bull

bull

E~FECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 43

Forced-drait experimental apparatus or equipment Heated dry ah Heated moist air

Vapor-heat machines Commercial chjers and bins aerated ~with artificially heated air

3 Closed containers Submerged in a heated liquid bath moisture Joss fr~111 seed and avt~i1nble ~AJgen and air supply restricted

+ DIrect contact nth liquIds other than yater In most of the inwstigatons cited seeds haw been exposed to

a gi~n t~empemtule in direct contact jth yater or air or in a clo~ed cOlltamer

DIRECT CONTACT WITH HOT WATER

bull

Seeds in direct contact yith hot water are said to be sensitive to heat Possibly this condition is in part attributable to the more rapid and uniform penetmtion of the heat The method although fairly eIlicient in destroying fungi has some objectionabJe features ~~ mashyjor one is thnt there is -elY little eli (rerence between the temperatures at which -iability lmel contaminating fungi are destroyed Tisdale (83) Adair and (rnlley (1) and (alley (18) have llsed hot water for the treatment of rice with fnnrri and nematodes Additional inshyfOlmation on th~ hot-wat0l tr~atl1lellt is to be found in the publications of Edwards Hnd (olin (8) T~nsPJl urn Kiessling (44) 1Vaggoner (8) Lehman (1) nnd ~atsoLl ct al (88)

DIRECT CONTACT WiTH HEATED AIR

Primal obj~etiol1s to tiltgt use of uti(icinlly heated dry air in treatshyill 1((lt1 is that it rrel1erally tnkes too lonrr to obtain effective lesults lllld Ow seed may berome too dry ren~en (JO) was unsuccessful ~iJl destJoing sm1lt in oat and hall(y seed in I hours at either 50deg OJ ii~)C ( OJI tlw otllC1 11al1(1 tanamiddot~o(r and Johnson (0) IOlmel that by expoli ng thee ]]-ltl1i((1 sepltls of bn rle h(at Iye nnd oats to dn~ heat for )0 houn- hadelmiddotinl and fmll inf(dions could be reshy([tired or eliminated middotit-1Iout ilia t(riall) i lij uring the germination of the epd Thl1lall (JJ) r(gt(OJlJlllel1C1((1 a dl-htl t tem perature of 95deg ror 1~ 1101115 101 dest 10 i 11 thegt Hnthlaellos( fllnrrlll of cottonseed To Hyoid slriolls Ims or middotjlhil it tIll sepcls ri Ist lind to be preclriecl to H 1II0itlll(-COllUllt -1111( pqlli-llcJlt to l~ ]gtpIT(nt of theil air-drywihL

1Ie lise of dJY hPllt for (IlHlloyin weevils and other insects in glmiddottill iJlcltlltlingli(p ws 1]((gt11 illestlgntNl by Popenoe (00) Deall (li 24) and Colton (li) Bnek ancl Cotton (1) were able to kill the

bull rice ~weeil (8itophilll8 (J11za (L)) at J~R)O C in B hous and at jL_J

C

within 30 lJIilllltS Ballr nlHl Cotton (i()) found that exposure of 10 minutes to a tpllI[l(lratllrl of (iOO ii fatal to nil insects infesting stored rice However tl(Y (JP 1I0t sue-cessful in obbtining t satisshyfactoy kill of imects ill Ike ill a (ol1ll11(I(inl ellmiddotier operated at (iDO 101 W minutes b((nn~( tll trenhlJllt did not raise the t(mpelllture of the rice above j(J0 They stnted that Iwating fOI insect control is not Jaorpd by thl 1i((gt iJl(fllS(TY IJPel1Ie the ric( is npi to check and btllusl too ll11wll Illoi4ul( is 1(IIJ(Jmiddot(d

44 TECHNICAL BULLErIN 1120 U S DEPT OF AGRICULTCRE

Edwards and (olin (g8) and focli]) (37) haTc shown that Illoist heat is only slightly Jess destrnctive to seed viability and Jensen (3(j) observed it to be less effective than the hot-mter treatment in the bullprevention of smut in oats and barley On the other hand Miller and Mc1Vhorter (61) have demonstrated the usefnlness of vapor heat (steam-ail mixture) ns a practical means of disinfectin~ seed These investigators found that certain kinds of sc(ds -ill apparently endure considembly hil-her yapor-h(at t(Ill)l(ratII I(S than arc Ieqniled to kill all associated flln~i Thus table be(t s(ed balls will pmiddotidently tolerate a va]1or-Iwllt temperatule of about (j~8deg C Jor as 10n~ as 30 1n1nutes without siglli fkant r(duction o retnnlation of ellninntion Pl1011a behlC an nss()(iatecl patho~cn is kilkd wh(n (xposed at )72deg for 20 minutes which is about 10 loer than the phytolptha I tPllIperashytUIt Lathl ()2) uNl yaV01 h(at ill (11ldiv(ly cOlltrolling nltlcisSIIS pests

CLOSED CONTAINERS

1h( 11Iet11oltl of hNltill o((d in (Iopd conhlilHls is mOle nearly comparable -ith the 1110isl- alHl -apor-lwa nlltho(l than with litlwl the hot-water or the ntilieinllr hent(d ltIn-air I1WthOlh 1hl e~slntial differences between the 1loi-t-ll(at and (loe([-lonLaiIlPI llIethods are that in the latter the atmospheric moitule 1))esll1t is largely derived from the seed and a presoure c1eelops 1n the container which is proportional to the antilable free moisture and timl nnd temperature of treatment Yhether these lt1 i Iferll1ces oller ad1 Htnges was not cleterm i ned

rolt1il1 (J7) and agonPI (8i) IPjloltNl Ihat seeds Iwalp(l ill bulln closed COl1hlilHI cOlllll not stand -0 hih I tlmpenttlllc as 1H11 heated in nn open ye~ll or in nil (Well -hidl prrmiited the rapid elimination of atel f]()111 the (p(1 raggonpls (lain aloo shoNl clenrly that radish setlt1- llelt((l dirpdly in alel had less ltsistaneC than when they PIe l1patpltl in a elosld container

No studies (ollpajll~ tlw I(lative pfl1CiPllciCs of Ihp (lill(IPIII methods of heat trettnHllt llan l)pplI 1l11lk ill wlli(h tIll SHlIlp lot or Iiee waS used ] [owpnl in-ola I as ma V be dpt(11Il illCd I10 III Ill( litelltUle the expClin1Pllial data IPIHlltl(C 101 Iollgh Ii(( in Ihis IJltIshyIttin indicate that ric( ean toltIatp highpl t-el11l)(IlIIII(S withoul loss of viabilitv than a1( Ic(onll1HIHlld for liSP in (Ollllltpl(ial (In-ill opershyations Til (ol11lllercial dlTin the Illoislllre is (ontinuolII 1(1110((1 hom the rice and thpo)eticall the kernels sholll bl(ollle in(reasin~l resistant If it is tlll~ that the inbililV of rice mw he dp~tTold ( 10pl (emlwraflIllS ill a C011I111I(il1 dlipl han in Ii elospd tpsi ul)( ii 0111(1 pm( thai fld)r ot her Ihan hpat are also ill operatioll whi(1t aI( dl(rlldin (t) yiahilily

DIRECT CONTACT WITH LIQUII)S OTlllm TitAN WATER

Yllhon rd (88) p]Pdp(1 Cvllal IllHtplial possihlp (Ipatill~ nglIIUlt Im peasHIlIlS Hildlillla h(HI1~ Th(~( Illatllials (In (a rho II (ptladtlolid( milllIal oil Shpll eltaIlPI PIPIOlll (lthrhlll gIYIol) 111011)1 oil (S E 10) 1I)((a1 1IHlh1 alcohol kllos(II ~TI()1 lalti( bull altid sollltiollS tolllllll a(IOIH gly(rrilll lNlaL oil anilille oil olie

t~~~

bull

bull

~ C

EFFEC1S OF HEA1 TREA1lIENT ON THE VIABILITY OF RICE 45

oil sodium chloride solutions and cotton seed oil Data were tabushylated for seeds treated in carbon tetrachloride motor oil fuel oil and water at temperatures ranging from 60deg to 90deg C and for periods of 10 to 60 minutes Beans peas and lima beans were able to survive extended exposures in hot caJbon tetrachloride but they were killed in a relatiely short time ylwn exposed in water of the same temperashyture Carbon tetlachlOlide appeared to be the best medium tested and the use of hot carbon tetrachloride for destroying seed-bome organisms in peas and beans is suggested HoweveJ these ttllthors have pointed 0111 that Further researcil ill be necesSl1rY to evaluate the pJactienl IIS( of the nmte1ials amI heat on t11e control of seedshyborne pathogens

C(uiekshnnk (JQ) has nc(ntly eallie(] out a selies of prelil11ilUtry r

experiments to cleteJmine the el1ecl of n carbon fetlachloricle steep OIL

the gerl11ination and control of Spll(((I(ll(( lilwl1l1n Vollenw in two nlrieties of ]illHed-0olden Viking and Koto ] [c obtained a signifshyieant depression of ~led gelminn(lon only at 70deg a11(] 75deg O fOl 30 minuhmiddots -ith Golden Vikin and 20 minutes with Koto Germinashytion of tl1( funglls spores ns 110t obselTec1 to occur atter treatment for20 minutes at (j)Ci TOO lind )0 01 for ao minutes at GOdeg He found that carbon tetrH(hlolidc has the followin nc1Yantaes over water for th0 heat trpatnlCnt of linsNl It- i snft1 illl I(ped to ermination and 110 Hrtificial drying of till sepd i 1l(eesst1Y ~

lEW )IETHODS AND -IODlFrCATJONS

It is e-ident fr011l till information in this bulletin nwt man is a long way f1Olll ha ill) n (0111 JlIphp11si e sciPJlti fien II de1i Igtd know]shypdgp oi till (Ireets of hpllt on rice Hough riel has been c1emnnshystliltedin the expe1inlents in 1050~ 1J)l and ID32 to have It high lpsislance to hpnt fhi dlHraCtlrili( SIIutsts that heat lllight be lIsN1 eypn more extpnsiwiy than no for th0 im]lroYernent and ~tabilishyzntion of s(((l quality Certainly t 1]( tllhniqups for applying heat ill till tJpafnwnt of rite l11e by 110 means bpell fuJiy explored The pltltti(aiJility of usinl a nly hilh lpl11lWlature uHI flash-heating as well as thl llent ITPallllPnf of iee in llllc1ia other than ail and WlItpl should 1)( inlmiddotpsli)l(prl Till possibility of simultaneously ill(OrpOIat ill fllnli(iltial ubII1)(( Hnd nutrients in the hulls should a Iso bl lonsirl(ICd

SIT])mlA RY

ExpPIil1l(nU II(JP IIllcl(Ilakpll dUlin) the riee-harvesting spasons of ID) 10 and 1l)~ to ltiPlllOlI-tla(p fill (Ired of lin1( and tPlI1pemshyIUlpol hpatingoll tilt iltlJililyol~ lOlllh or pnddy riCegt (()I1jzusath(() of ltlilrel(l1t IlJOistlll[ (ontpnts Both IllPtiilll11-glain (S(1 GI-25-12 11 n(l ZCl1i til) a I1d IOllg-gla i n (HCXOIO B1mbon npl an(l Cent-ulV 5d) 1I1i(ti(s (1( used (Illllinalion laquost dala 101 Ii([ and s(p(J Jwalshy1](af111l1l1 llpi h()(ls and t Iwil applications nl( ltlisclISSP(1

If(nt tlpainHnts PI( Illa(]( nlal SOllr((fi of fnshlv (ornbineshy1Il1(S(ltI rice-Oil tIl( plpl1lisps of tll(gt ni(pExperilll(n( Siaion at Cl()WIIY La Salllpips of natllrally Illoist lol1il 1ice (1P packed in htat-1Psistant t(~st (dIes TIll Ils fllilps 1(1( light Iy stoppeled

f

46 TECHNICAL BULLETIN 1129 lJ S DEP~ OF AOlUCULTURE

and submerged ill water baths maintained at di Ife1(11 t cOllstant tem pershyatures 111 experiments to demonstrate Owelreet of temperature on viability the usual period of exposure was RO minutes after the rice reached the temperature of the hath In experim(nts to demonstrate the effect of time (duration) of heating 011 viability the periods of exposure ranged from 10 to 120 minutes Xo moisture was lost iol1l or gained acce~s to tlll rice-filled tet tubes (lmillg the periods of heat treatment The riC( in the t(st tubes was alloHltlup to 8 minutes to reach the temperature of th( bath On Colllplltioll of the heal- treatshyment the contents of the test tubes were eompoitecl and spread in a paper tray to air-dry At the conclusiol1 of ptch sensons York all the air-dried heat-tren ted sn III pl(s fOlIll hpl it 11 apploprinfp n i 1shydried controls (non-hen t-trentpltl) Yele paekagc1 in pap I balIS tmmshyfelTec1 too the Sontll(ll1 R(iolHd U(sarelt fJa bOIa IOIV X CY o11 NI ns La and stol(d at ~+c_2nl C CPllllil1al-iol1 tlcJS W(jp made on aell sampJe by the nHtholt1 pnsclilp(lIJ Ill( Flllplal S(ld cI- and were run 8 1G H and ~2 nll dlpl HI dnle of l)(at tl(ahlllnL

The gellninafiol1 ht data (OldilllI (hal high Ipl1lpltml lins a flpdld the inbilitv of naIlall 11loi1 lOlIh Iie( ill 11ll1eh tlIP -lI1W I1lal1nrl as they tllct(lt1 tlIP viabilitip of oth~r kind of SPlcls similallv lrat(d TIH iolloil1 llPlal ohcPlTati()l1- (()1l1ltl IJl 11 1lt1 c1(

FOI rOllgh li~e of (neh Illoisillll (011t(111 IIIlIl i n tllllpplatUl( of hent- treatn1(nt Iwlow hidl tlllIp is 110 ([l(Ila( ill inlJilitT

For amiddot gi(~n stlllpll of [in flIP Z01H of IIpat dnlllapvmiddot i ( Ill( range beh(Pl1 th( tlllppralllp at hiclt ltpnl- dnl1lagp (0 riahilit) just starhi amI th( tlllp(Iatml nt which it- ic ill lOlllphtl i a IIHlTO Olll

The (xtent 01 this nlllgl 101 n IllHt-tlpntllllllt plliod 0110 Illillllj-PS as not definitelv (stnlgtlishpd fDI tIH IHllIralh lIloit (ollliJilll-hantld rough rice 115((1 but ha-I] Oil nppIoxillwtioll of ill( lilllitinp Itlllshyj)erahllcs it aplwals to 1)( IJphYltlll i alld 12 ( This Inngl is aboul t11( same for 1i(p or difllIPllt 1ll0itlllt (ontpnl- hilt it i hillll 011

I lIP t(111 p(ra tlll( s(a It till 1()wPl 111( IllOiIIIIp (ontent () r t lip li(( rithin tllP ZOIlP of IW(l( ltlnlllal -101 Ii(( of a i PI1 llloilIIP (on-pnl

tIllt (llgle( or dlstTlldioll ill(I([SPS as t-1l( IPIllIPlatl1lp illCJ(ases al() 111( 101l(r tl1lt ri(( is Iwnt-tl(atpd tlll gnulPI llP ifs los-ps ill (IshyllIil1tfi()1l (npaeif-y alld gPll1lillalioll IWmiddotlI

The 1lsishll)(P of I(llgh Iicl fo (h( illlpnilIlll111 of ils Iahilily hy hpnt VflliN il1PIsP as its 1ll0i-t1l1P (middot011[(1lt

1hplI the i n b iii h () r Ii(l is cla Illn pcl by lIP t loss ill PIIll i Iln i Oil

yigor is appnr(llt lwiorc los ill PIll1iJIaI iOl1 (apa(il 1-11(111(1 tlHl( is pmiddotidI1N or Ill( laltll dq)Plllls UpOIl tlH ((Iilmiddot of nIP ITPnIlIPIlL

OClTllillatiOI1 (psis Iluul( S Hi 21 alld 2 ((ks afPI Iwatmiddot tlpallll(nlshyon ri(e f)()1H llip SHill hltlmiddotIICn((1 -lIl1plp S(OIltI at 21middot-~(iO ( did llotlcYcnl Hp[)Ipciallll (IIlllgl ill till gPlIllill1lioll igol alld IICll1linnshytion eapnCily of ihp salllpit

In (x]l(lil1Hllts wilh il1l1l1allll( Ii(p thp 11Ioistl1lllOIlI(lIi Yaliahll exc]eisp(j lpalaquo1 influllwP IlUl Ih( IIWllllit nUinhlp ill (1(tl)milliwr

Ill( rcsishilJcp of fliP i1l1l1lnllll( Hllt1 to IlP1 ltInIlUll H(clusP of lillliftd dala if (oHld lIot Il( (lp((IllliIlP(j lIPh(I the

varieties of li(Pllspd (jillpIPltl sillilicHlllh ill t Iwil 1(~i~hlIH( to 11(at ObsPlv(gtltl clillIP1HlH Pll Illill~)] lud hllip((1 ilhil1 exp(liIlHnhtl limitatiolls Fc) till lIlt 1(1lt011 i[ could 1101 )( dlfpllllillld ltcIIH1

bull

bull

bull

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

TECHNJCAL BULLETIN 1129 U S DEPT OF AGRICULTURE

teinperature oven at di fferent temperatures uld for different periods of time He tabulated germination data for each clay of the test ~-period Consequently his data show the effects of heat on the gershymination capacity and the germination vigor and the day of maximum germination Moreoyer they show tllat the grentel the injnry the longer is the intmval preceding the cly of Jrmximum germination and that in severe injury a day of maximum germination is not eishydent Just veri1ied the findings of his predecessolsin that he clearly demonstrated greater clestruetion of viability the hightr the telllpe1lshyture the longer the treatment and tlle highpr the moisture content of the seed

bullJust (43) and Yon Hiilll1Pl (38) -ho also pnblislled in 1877 sumshymed up the elfeets of helt on the viability of seell much as we undershystand it today Both investigators realized that one could not give a definite maximum temperature at which seeds could be heat-treated without injury Von Hlti1mel has point-eel out more clearly perhaps than Just that the first symptom of injl1lY through heating consists of a loss in germination vigor and that it llllty oecur eyell though no loss in germination eapacity is notiCeable

Twenty-five years aiter the publiCtltions of rust and Yon Hiihnel Dixon (86) made a sign i [-icant enerll I ization in analyzing 11 is seed heat-treatment data He rote it appears that for each scP(1 there is a temperatllle up to which it may be rnised without suffering appreciable alteration in the period of time needed for germination Once this point is passed the ermination period is increased the bull increase pel degree being greater the nearcr the mnximum is ap- proached This generalization had apparently been assumed or else overlooked by earlicr investigators bpel11se t-heir intelcst was pri shymarily in determining the maximum temperatures seeds could endure without injury It is the range of tcmpelatmes overwlrich a iven lot of seed may be lleat-treated wHhont injury that is recognized today as being highly important for the c1evelopnwnt of (ommcIcial dryill and storage metho(ls TIle 10n~1 the moistllre (ontent of the seed the greater the tcmpprature range opr which it may be safely heatshytre11ted

In 1011 Kiessling U-i) conclllc1ed that the effect of hpat in OW1shy

com ing the dormancY of 1gtarlpY thnt as not storage ri pc was i nr1pshypendent of the loss of moistllle From this fillding we may assume that the more accnrate datiL in the literature on the eflects of lleat pel se ere probnbly obtained by those in vestiatols who exposed thei I seeds in clo(gt(l eontainers or uncleI conditions in which the moisture loss was negligible In 1017 Yagonel (87) emphasized that the dilJieulty in interpreting dahl in the older literature with respect to the letha] temperatures of seeds wns to be sought in the initial water content of the seeds or in the method em ployed thai- would allow an increase 01 decrease of this wat-er Content during the heating process

Yaggoners experiments it-h radish seed and Hutchinsons (33) with whent confirm previons obslnations of the eneel of heat Oil nlC bull viability of seed

The geneml obselvations made by the llllt-hors of this bullptin 011

theil rough pire investigatiolls arc lally a l((apihllation of those that llllve just lwen 1lyi(mecl The viability of rough rice has becn

EFFECTS OF HEAT TREAllfENT ON THE VIABILITY OF RICE 41

shown to be affected by heat in the same manner as the yjabilities oT

bull

radish -wheat and other seeds similarly treated Differences in reshysistance between the different kinds of seeds as judged fronl the present rice study and the literature are more of degree than of kind

On the othlr hal1fL some observations were made cluring these inshylstigations that hn W not pnnriollsly bl(l1 pnlpltnsi7lcl Rough riel was heated in closed (ontaineJs llld appaleMly withollt the developshy))lent of injurious pressllre efeds In hlat-heat-illg immature rice moisture eOlltent mthlr than st-age of Illahllity as I-he major factol deterl1Jining rlie degree of 11ltt injulY Heat-trlnte(1 rice even heatshydanllged samples did not show an appl((iablf change in viability i e in the pel((ntages of 81((1 )(Illiinatingmiddot lllhYePll the R- and i12shyreek periods of stolllge

Houdllice that Ias natllrall moist and flpshlr lol1lbined was lIsecl in the experiments because it lS thought that the data Ionld be more represenative of data obtained uncler large-seale (onllnercial operashytions Whether this reasOllinp YtS correct was not determined

Certain disnclll1tagcs in llsing hlshly eOlllbineclliee soon became

appalent The lots lOt only Jackrd uni-lolmity but sometimes C011- ta i ned large pelcentages of nOlwiablt seNl s a lCSll It the tempeltlshy hlles at hich heat damage to iability just started and at which it Ins just complete for rice of a gien moisture content- could be only rough Iy apptOximn ted This fad el is(oll rageel an enc1ea VOl to deshyrive mathemati(al equations sueh as thosr of Hutehinson (33) for whea t h ich might ha Te praetica I ntlue in deterlll i ni ng sa-le com mershy(inl operating (onc1itions for heat-tleating rough rice It is evident (rigme 3) thnt the approximations defining the critical tempeJature

bull

range for ricp o-f paell nloishllp(ollt-ent inVtstigatllt1 do outline a zone of Ileat dllnagl It is also euroYident that flwil pattern is tooirreglllal to define thr lower andllpp(r 1 illl it of the 7onl of heat clamage

lTnder eliTelellt expCIinlCntal (onelitions it- Illight have bpen possible to obtain data that mnIlc1lllore aCTlIrafely illnstllte the limits of the zonp 0-1 heat dallIagr for lOl1h ri(( of (]i Ilelpnl 1110ishll(gt (ontents Von H6hl1el (32) found tha t a c1efin itp maximlllli temperature at which a giwl1 sanlplp of sepds may be safpl htatp(1I111Y 1I0t- )( obtailHd heshy(ausr of the eli rh(n(Cs in thp resistul(es of lnciic1utl sl(cls IIutchshyillson (])) Oil tl1( other hallcl was able o estahlish rather definite and practical tel11pemlllle end points defining the (ritieal rang(s -101 eteh of his stmpl(s of wheat 0-1 eli rllllllt 1l10istllre eontrnts Flom his plIbshyI i(a fioll ii- 011 Ie a pppa I I lin t t ill ~( Ipd i()) () f 1111 if01111 sred sam pIes Hnd (lip (lIoi(p of OIlP- (onfnillillg n IlP1 J()n pelC(nt of ial)I( se(d as possibll PI( illlPOIhillt adolmiddots

_lthollgh (lierp may b( all PITOI of )O C 01 mole in the apploxishyIllatpltl illlJ)elttllJe- plottrcl ill figl1le 1 fhl scatter-type cliaglam has plldi(a I va I l( It Pllables 011( fo n pploxi mat( tIl( maximum tcmpcrlshyI mps at hi(11 baj(hls otollh liee of ltIi rTennt IlloistllJP (ontcnts rna be hput-tr(ntl1 unclll (()ll(litlolls like (host des(Iibp(1 ill Experimentil atelials a 1)(1 Prrlllc11 Ip (pp H-I~) To Ihis IxtPllt it- 1IIt) seJve as a hent-damagp plldi((-ion 01 saity elIalt Xo claims may be Illade that it would ~eln Ipliably fol plpd(tpJrninill) the tellljlelltllrc nt hi(h a ir(sl1 I COI1lIgt i ned lot of 1i(( III itdl t be 511( II ellied i II a (0111 Il 1lICi a I (1Ii(I The Ipaso) is thd the tlialgtl( illl loclIclaquolll tillt loss of lIloi sli I11 cllllshying the heating PIO(ISS wns 1I0t (111111((1 i1 the ill(lstigatiolls

42 TECHNICAL BULLETIN 1120 U S DEP1 OF AGRICULTURE

However it appears possible that diarrams similar to figure 3 could be developecl for use as heat-damure prediction charts for guiclillg experimental and commercial dlyinr operations for both seed and -~illing purposes Charts for the latter wOllldneed to be based upon ririlling instead of germination test dntn

SEED HEATmiddotTUEATIUENT METHODS AND THEIn APPLICATIONS

Plant physiolorists plnnt patiloloriI tnlOlllOlorists lnd arlielllshytural enrilleels hnn lllu(hmiddot 111( mujo) lonlTibuiolls to OUI knowl((hre of the effects of heat on seeds

Atanasoff and Tollllson ((J) poi nled oul that thl Iii orbIs 10 investigate the effects of ditJ(rellt tpllI]lelalurrs of tJlulnHllt on seeds were principally plnllt physiolopists al1lI thpn plant pntholorists Thr plant physiologists were interested in establ ish i Ilr the efrects of 11(at on germination enpllcity and r(rlllination YigOl and ill onrcoming dormancy Often they employe(l Yery high iel1lpelatlllcs and long exposure periods hieh ( tOI)i(ler to(lay to Ill lXII(Il)( anel illJpracshytical fOl (oll1lJ1rlcial tpplhatiol)

The pla nt pa thologi-t- PP1TPingtltl fhn I hpltl I 1llih I 1)( 11-(111 I f(lI

destroyillg seld-tollullinatiJ1 fllllri hiIll Inifht la0l 11P(OIlI( 1(shy

tively pathogrni( to tliP p(d 01 to tIl( ltllnlopill PllliJrYo alld plalll These workels had (0 dli-p lXPPlilllPllb that WOII Id dpl1lollsfTltl tI whether a clrtain finH-tell1]lp]atll[p (olllbillntiOIl might be rlllploy((l ill treating a gien kind of sepd that wOllld (lpstroY the eOllttllllinatillr vathogenic fungi hut ihM wouhlnot alr(f tlIP inhililY of the SPl(1

Shortly the entomologists beClIlllP jnt(1(~t(c1 T1HY had pSfpnfialIy the same ploblenls a~ the plant patllOlorists ~ill(p 111lt) l1P((hd 10 (gtIPshyserve seed for extPlIded ppliods for boll pllIltinr and lI1ilIill~ PIII_ poses ~poundost of the litplatl1lP Oll thr liSP of IHtt to ltI(-tlO) flll1i and insects in seeds has ap]Jpand yithil1 the pnst j() )(IIS This is I10t becanse the coneepts -fOI hel Im) plaetieal applications of IIlat an by any means new Hahlllnnltlt (]1) di-(l1ss((1 Ih(111 in U(j3 and 110 doubt others twfole him

Vithin the pasl ) ylal- arri(lIltula 1 lI1giI1PPI nnd ass()cin(cl workers haTP made IlUIlI()OIiS oltln (Ollllibn ions to ilH lifl1Hurl on the heat treatmellt of pra TlwlL dUllI oiljP(tin hI-( hlCn b

means of dlying and C011(I01led telllpltIltI11PS lnd l1ulllidijies to ])ngtshyvent the dlvelopment and tl(tivity of fungi Hnd inspd in Iond lNI and either to il1lj)Ior oj to lSSUle tJ(gt lPipntioll of high milling qunlshyity in g1ains

Sen~ntl llIethocls 101 IHlt-tTlntill~ (pcb JtlYP h((ll dpisld bv 111lt various -mhrs 111( kind of nHlllOdis lIot llf((s~lIih (OI1(lilnblf -ith the plor(s-ionnl in[(Ipt of thp i n(1 ill Imlnd 110 stich infpLshyence is intenlt1ld Th(middot methods may Ill f[lOu]llllas foIIOY

1 Direct contn(t with hot wat(I 2 Direct (ontaet with heat(middot(l ni]

Trays in tl (ollstant-lllllIHlufuIP 0(11 ail (il(IIInliol1 jl1il1(ishypally convl(tiol1

Opltn t(st [ub(s or flask- paltinll~ SUhIlHIr(d ill a lmth ail (il shy

enlation r(stTid((] sOllwtillJlS Ply nllllh HJ byt tHpil11ry 0plnillg inshysignificant total and VlI)(lI IgtI(SSIII(S

bull

bull

E~FECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 43

Forced-drait experimental apparatus or equipment Heated dry ah Heated moist air

Vapor-heat machines Commercial chjers and bins aerated ~with artificially heated air

3 Closed containers Submerged in a heated liquid bath moisture Joss fr~111 seed and avt~i1nble ~AJgen and air supply restricted

+ DIrect contact nth liquIds other than yater In most of the inwstigatons cited seeds haw been exposed to

a gi~n t~empemtule in direct contact jth yater or air or in a clo~ed cOlltamer

DIRECT CONTACT WITH HOT WATER

bull

Seeds in direct contact yith hot water are said to be sensitive to heat Possibly this condition is in part attributable to the more rapid and uniform penetmtion of the heat The method although fairly eIlicient in destroying fungi has some objectionabJe features ~~ mashyjor one is thnt there is -elY little eli (rerence between the temperatures at which -iability lmel contaminating fungi are destroyed Tisdale (83) Adair and (rnlley (1) and (alley (18) have llsed hot water for the treatment of rice with fnnrri and nematodes Additional inshyfOlmation on th~ hot-wat0l tr~atl1lellt is to be found in the publications of Edwards Hnd (olin (8) T~nsPJl urn Kiessling (44) 1Vaggoner (8) Lehman (1) nnd ~atsoLl ct al (88)

DIRECT CONTACT WiTH HEATED AIR

Primal obj~etiol1s to tiltgt use of uti(icinlly heated dry air in treatshyill 1((lt1 is that it rrel1erally tnkes too lonrr to obtain effective lesults lllld Ow seed may berome too dry ren~en (JO) was unsuccessful ~iJl destJoing sm1lt in oat and hall(y seed in I hours at either 50deg OJ ii~)C ( OJI tlw otllC1 11al1(1 tanamiddot~o(r and Johnson (0) IOlmel that by expoli ng thee ]]-ltl1i((1 sepltls of bn rle h(at Iye nnd oats to dn~ heat for )0 houn- hadelmiddotinl and fmll inf(dions could be reshy([tired or eliminated middotit-1Iout ilia t(riall) i lij uring the germination of the epd Thl1lall (JJ) r(gt(OJlJlllel1C1((1 a dl-htl t tem perature of 95deg ror 1~ 1101115 101 dest 10 i 11 thegt Hnthlaellos( fllnrrlll of cottonseed To Hyoid slriolls Ims or middotjlhil it tIll sepcls ri Ist lind to be preclriecl to H 1II0itlll(-COllUllt -1111( pqlli-llcJlt to l~ ]gtpIT(nt of theil air-drywihL

1Ie lise of dJY hPllt for (IlHlloyin weevils and other insects in glmiddottill iJlcltlltlingli(p ws 1]((gt11 illestlgntNl by Popenoe (00) Deall (li 24) and Colton (li) Bnek ancl Cotton (1) were able to kill the

bull rice ~weeil (8itophilll8 (J11za (L)) at J~R)O C in B hous and at jL_J

C

within 30 lJIilllltS Ballr nlHl Cotton (i()) found that exposure of 10 minutes to a tpllI[l(lratllrl of (iOO ii fatal to nil insects infesting stored rice However tl(Y (JP 1I0t sue-cessful in obbtining t satisshyfactoy kill of imects ill Ike ill a (ol1ll11(I(inl ellmiddotier operated at (iDO 101 W minutes b((nn~( tll trenhlJllt did not raise the t(mpelllture of the rice above j(J0 They stnted that Iwating fOI insect control is not Jaorpd by thl 1i((gt iJl(fllS(TY IJPel1Ie the ric( is npi to check and btllusl too ll11wll Illoi4ul( is 1(IIJ(Jmiddot(d

44 TECHNICAL BULLErIN 1120 U S DEPT OF AGRICULTCRE

Edwards and (olin (g8) and focli]) (37) haTc shown that Illoist heat is only slightly Jess destrnctive to seed viability and Jensen (3(j) observed it to be less effective than the hot-mter treatment in the bullprevention of smut in oats and barley On the other hand Miller and Mc1Vhorter (61) have demonstrated the usefnlness of vapor heat (steam-ail mixture) ns a practical means of disinfectin~ seed These investigators found that certain kinds of sc(ds -ill apparently endure considembly hil-her yapor-h(at t(Ill)l(ratII I(S than arc Ieqniled to kill all associated flln~i Thus table be(t s(ed balls will pmiddotidently tolerate a va]1or-Iwllt temperatule of about (j~8deg C Jor as 10n~ as 30 1n1nutes without siglli fkant r(duction o retnnlation of ellninntion Pl1011a behlC an nss()(iatecl patho~cn is kilkd wh(n (xposed at )72deg for 20 minutes which is about 10 loer than the phytolptha I tPllIperashytUIt Lathl ()2) uNl yaV01 h(at ill (11ldiv(ly cOlltrolling nltlcisSIIS pests

CLOSED CONTAINERS

1h( 11Iet11oltl of hNltill o((d in (Iopd conhlilHls is mOle nearly comparable -ith the 1110isl- alHl -apor-lwa nlltho(l than with litlwl the hot-water or the ntilieinllr hent(d ltIn-air I1WthOlh 1hl e~slntial differences between the 1loi-t-ll(at and (loe([-lonLaiIlPI llIethods are that in the latter the atmospheric moitule 1))esll1t is largely derived from the seed and a presoure c1eelops 1n the container which is proportional to the antilable free moisture and timl nnd temperature of treatment Yhether these lt1 i Iferll1ces oller ad1 Htnges was not cleterm i ned

rolt1il1 (J7) and agonPI (8i) IPjloltNl Ihat seeds Iwalp(l ill bulln closed COl1hlilHI cOlllll not stand -0 hih I tlmpenttlllc as 1H11 heated in nn open ye~ll or in nil (Well -hidl prrmiited the rapid elimination of atel f]()111 the (p(1 raggonpls (lain aloo shoNl clenrly that radish setlt1- llelt((l dirpdly in alel had less ltsistaneC than when they PIe l1patpltl in a elosld container

No studies (ollpajll~ tlw I(lative pfl1CiPllciCs of Ihp (lill(IPIII methods of heat trettnHllt llan l)pplI 1l11lk ill wlli(h tIll SHlIlp lot or Iiee waS used ] [owpnl in-ola I as ma V be dpt(11Il illCd I10 III Ill( litelltUle the expClin1Pllial data IPIHlltl(C 101 Iollgh Ii(( in Ihis IJltIshyIttin indicate that ric( ean toltIatp highpl t-el11l)(IlIIII(S withoul loss of viabilitv than a1( Ic(onll1HIHlld for liSP in (Ollllltpl(ial (In-ill opershyations Til (ol11lllercial dlTin the Illoislllre is (ontinuolII 1(1110((1 hom the rice and thpo)eticall the kernels sholll bl(ollle in(reasin~l resistant If it is tlll~ that the inbililV of rice mw he dp~tTold ( 10pl (emlwraflIllS ill a C011I111I(il1 dlipl han in Ii elospd tpsi ul)( ii 0111(1 pm( thai fld)r ot her Ihan hpat are also ill operatioll whi(1t aI( dl(rlldin (t) yiahilily

DIRECT CONTACT WITH LIQUII)S OTlllm TitAN WATER

Yllhon rd (88) p]Pdp(1 Cvllal IllHtplial possihlp (Ipatill~ nglIIUlt Im peasHIlIlS Hildlillla h(HI1~ Th(~( Illatllials (In (a rho II (ptladtlolid( milllIal oil Shpll eltaIlPI PIPIOlll (lthrhlll gIYIol) 111011)1 oil (S E 10) 1I)((a1 1IHlh1 alcohol kllos(II ~TI()1 lalti( bull altid sollltiollS tolllllll a(IOIH gly(rrilll lNlaL oil anilille oil olie

t~~~

bull

bull

~ C

EFFEC1S OF HEA1 TREA1lIENT ON THE VIABILITY OF RICE 45

oil sodium chloride solutions and cotton seed oil Data were tabushylated for seeds treated in carbon tetrachloride motor oil fuel oil and water at temperatures ranging from 60deg to 90deg C and for periods of 10 to 60 minutes Beans peas and lima beans were able to survive extended exposures in hot caJbon tetrachloride but they were killed in a relatiely short time ylwn exposed in water of the same temperashyture Carbon tetlachlOlide appeared to be the best medium tested and the use of hot carbon tetrachloride for destroying seed-bome organisms in peas and beans is suggested HoweveJ these ttllthors have pointed 0111 that Further researcil ill be necesSl1rY to evaluate the pJactienl IIS( of the nmte1ials amI heat on t11e control of seedshyborne pathogens

C(uiekshnnk (JQ) has nc(ntly eallie(] out a selies of prelil11ilUtry r

experiments to cleteJmine the el1ecl of n carbon fetlachloricle steep OIL

the gerl11ination and control of Spll(((I(ll(( lilwl1l1n Vollenw in two nlrieties of ]illHed-0olden Viking and Koto ] [c obtained a signifshyieant depression of ~led gelminn(lon only at 70deg a11(] 75deg O fOl 30 minuhmiddots -ith Golden Vikin and 20 minutes with Koto Germinashytion of tl1( funglls spores ns 110t obselTec1 to occur atter treatment for20 minutes at (j)Ci TOO lind )0 01 for ao minutes at GOdeg He found that carbon tetrH(hlolidc has the followin nc1Yantaes over water for th0 heat trpatnlCnt of linsNl It- i snft1 illl I(ped to ermination and 110 Hrtificial drying of till sepd i 1l(eesst1Y ~

lEW )IETHODS AND -IODlFrCATJONS

It is e-ident fr011l till information in this bulletin nwt man is a long way f1Olll ha ill) n (0111 JlIphp11si e sciPJlti fien II de1i Igtd know]shypdgp oi till (Ireets of hpllt on rice Hough riel has been c1emnnshystliltedin the expe1inlents in 1050~ 1J)l and ID32 to have It high lpsislance to hpnt fhi dlHraCtlrili( SIIutsts that heat lllight be lIsN1 eypn more extpnsiwiy than no for th0 im]lroYernent and ~tabilishyzntion of s(((l quality Certainly t 1]( tllhniqups for applying heat ill till tJpafnwnt of rite l11e by 110 means bpell fuJiy explored The pltltti(aiJility of usinl a nly hilh lpl11lWlature uHI flash-heating as well as thl llent ITPallllPnf of iee in llllc1ia other than ail and WlItpl should 1)( inlmiddotpsli)l(prl Till possibility of simultaneously ill(OrpOIat ill fllnli(iltial ubII1)(( Hnd nutrients in the hulls should a Iso bl lonsirl(ICd

SIT])mlA RY

ExpPIil1l(nU II(JP IIllcl(Ilakpll dUlin) the riee-harvesting spasons of ID) 10 and 1l)~ to ltiPlllOlI-tla(p fill (Ired of lin1( and tPlI1pemshyIUlpol hpatingoll tilt iltlJililyol~ lOlllh or pnddy riCegt (()I1jzusath(() of ltlilrel(l1t IlJOistlll[ (ontpnts Both IllPtiilll11-glain (S(1 GI-25-12 11 n(l ZCl1i til) a I1d IOllg-gla i n (HCXOIO B1mbon npl an(l Cent-ulV 5d) 1I1i(ti(s (1( used (Illllinalion laquost dala 101 Ii([ and s(p(J Jwalshy1](af111l1l1 llpi h()(ls and t Iwil applications nl( ltlisclISSP(1

If(nt tlpainHnts PI( Illa(]( nlal SOllr((fi of fnshlv (ornbineshy1Il1(S(ltI rice-Oil tIl( plpl1lisps of tll(gt ni(pExperilll(n( Siaion at Cl()WIIY La Salllpips of natllrally Illoist lol1il 1ice (1P packed in htat-1Psistant t(~st (dIes TIll Ils fllilps 1(1( light Iy stoppeled

f

46 TECHNICAL BULLETIN 1129 lJ S DEP~ OF AOlUCULTURE

and submerged ill water baths maintained at di Ife1(11 t cOllstant tem pershyatures 111 experiments to demonstrate Owelreet of temperature on viability the usual period of exposure was RO minutes after the rice reached the temperature of the hath In experim(nts to demonstrate the effect of time (duration) of heating 011 viability the periods of exposure ranged from 10 to 120 minutes Xo moisture was lost iol1l or gained acce~s to tlll rice-filled tet tubes (lmillg the periods of heat treatment The riC( in the t(st tubes was alloHltlup to 8 minutes to reach the temperature of th( bath On Colllplltioll of the heal- treatshyment the contents of the test tubes were eompoitecl and spread in a paper tray to air-dry At the conclusiol1 of ptch sensons York all the air-dried heat-tren ted sn III pl(s fOlIll hpl it 11 apploprinfp n i 1shydried controls (non-hen t-trentpltl) Yele paekagc1 in pap I balIS tmmshyfelTec1 too the Sontll(ll1 R(iolHd U(sarelt fJa bOIa IOIV X CY o11 NI ns La and stol(d at ~+c_2nl C CPllllil1al-iol1 tlcJS W(jp made on aell sampJe by the nHtholt1 pnsclilp(lIJ Ill( Flllplal S(ld cI- and were run 8 1G H and ~2 nll dlpl HI dnle of l)(at tl(ahlllnL

The gellninafiol1 ht data (OldilllI (hal high Ipl1lpltml lins a flpdld the inbilitv of naIlall 11loi1 lOlIh Iie( ill 11ll1eh tlIP -lI1W I1lal1nrl as they tllct(lt1 tlIP viabilitip of oth~r kind of SPlcls similallv lrat(d TIH iolloil1 llPlal ohcPlTati()l1- (()1l1ltl IJl 11 1lt1 c1(

FOI rOllgh li~e of (neh Illoisillll (011t(111 IIIlIl i n tllllpplatUl( of hent- treatn1(nt Iwlow hidl tlllIp is 110 ([l(Ila( ill inlJilitT

For amiddot gi(~n stlllpll of [in flIP Z01H of IIpat dnlllapvmiddot i ( Ill( range beh(Pl1 th( tlllppralllp at hiclt ltpnl- dnl1lagp (0 riahilit) just starhi amI th( tlllp(Iatml nt which it- ic ill lOlllphtl i a IIHlTO Olll

The (xtent 01 this nlllgl 101 n IllHt-tlpntllllllt plliod 0110 Illillllj-PS as not definitelv (stnlgtlishpd fDI tIH IHllIralh lIloit (ollliJilll-hantld rough rice 115((1 but ha-I] Oil nppIoxillwtioll of ill( lilllitinp Itlllshyj)erahllcs it aplwals to 1)( IJphYltlll i alld 12 ( This Inngl is aboul t11( same for 1i(p or difllIPllt 1ll0itlllt (ontpnl- hilt it i hillll 011

I lIP t(111 p(ra tlll( s(a It till 1()wPl 111( IllOiIIIIp (ontent () r t lip li(( rithin tllP ZOIlP of IW(l( ltlnlllal -101 Ii(( of a i PI1 llloilIIP (on-pnl

tIllt (llgle( or dlstTlldioll ill(I([SPS as t-1l( IPIllIPlatl1lp illCJ(ases al() 111( 101l(r tl1lt ri(( is Iwnt-tl(atpd tlll gnulPI llP ifs los-ps ill (IshyllIil1tfi()1l (npaeif-y alld gPll1lillalioll IWmiddotlI

The 1lsishll)(P of I(llgh Iicl fo (h( illlpnilIlll111 of ils Iahilily hy hpnt VflliN il1PIsP as its 1ll0i-t1l1P (middot011[(1lt

1hplI the i n b iii h () r Ii(l is cla Illn pcl by lIP t loss ill PIIll i Iln i Oil

yigor is appnr(llt lwiorc los ill PIll1iJIaI iOl1 (apa(il 1-11(111(1 tlHl( is pmiddotidI1N or Ill( laltll dq)Plllls UpOIl tlH ((Iilmiddot of nIP ITPnIlIPIlL

OClTllillatiOI1 (psis Iluul( S Hi 21 alld 2 ((ks afPI Iwatmiddot tlpallll(nlshyon ri(e f)()1H llip SHill hltlmiddotIICn((1 -lIl1plp S(OIltI at 21middot-~(iO ( did llotlcYcnl Hp[)Ipciallll (IIlllgl ill till gPlIllill1lioll igol alld IICll1linnshytion eapnCily of ihp salllpit

In (x]l(lil1Hllts wilh il1l1l1allll( Ii(p thp 11Ioistl1lllOIlI(lIi Yaliahll exc]eisp(j lpalaquo1 influllwP IlUl Ih( IIWllllit nUinhlp ill (1(tl)milliwr

Ill( rcsishilJcp of fliP i1l1l1lnllll( Hllt1 to IlP1 ltInIlUll H(clusP of lillliftd dala if (oHld lIot Il( (lp((IllliIlP(j lIPh(I the

varieties of li(Pllspd (jillpIPltl sillilicHlllh ill t Iwil 1(~i~hlIH( to 11(at ObsPlv(gtltl clillIP1HlH Pll Illill~)] lud hllip((1 ilhil1 exp(liIlHnhtl limitatiolls Fc) till lIlt 1(1lt011 i[ could 1101 )( dlfpllllillld ltcIIH1

bull

bull

bull

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

EFFECTS OF HEAT TREAllfENT ON THE VIABILITY OF RICE 41

shown to be affected by heat in the same manner as the yjabilities oT

bull

radish -wheat and other seeds similarly treated Differences in reshysistance between the different kinds of seeds as judged fronl the present rice study and the literature are more of degree than of kind

On the othlr hal1fL some observations were made cluring these inshylstigations that hn W not pnnriollsly bl(l1 pnlpltnsi7lcl Rough riel was heated in closed (ontaineJs llld appaleMly withollt the developshy))lent of injurious pressllre efeds In hlat-heat-illg immature rice moisture eOlltent mthlr than st-age of Illahllity as I-he major factol deterl1Jining rlie degree of 11ltt injulY Heat-trlnte(1 rice even heatshydanllged samples did not show an appl((iablf change in viability i e in the pel((ntages of 81((1 )(Illiinatingmiddot lllhYePll the R- and i12shyreek periods of stolllge

Houdllice that Ias natllrall moist and flpshlr lol1lbined was lIsecl in the experiments because it lS thought that the data Ionld be more represenative of data obtained uncler large-seale (onllnercial operashytions Whether this reasOllinp YtS correct was not determined

Certain disnclll1tagcs in llsing hlshly eOlllbineclliee soon became

appalent The lots lOt only Jackrd uni-lolmity but sometimes C011- ta i ned large pelcentages of nOlwiablt seNl s a lCSll It the tempeltlshy hlles at hich heat damage to iability just started and at which it Ins just complete for rice of a gien moisture content- could be only rough Iy apptOximn ted This fad el is(oll rageel an enc1ea VOl to deshyrive mathemati(al equations sueh as thosr of Hutehinson (33) for whea t h ich might ha Te praetica I ntlue in deterlll i ni ng sa-le com mershy(inl operating (onc1itions for heat-tleating rough rice It is evident (rigme 3) thnt the approximations defining the critical tempeJature

bull

range for ricp o-f paell nloishllp(ollt-ent inVtstigatllt1 do outline a zone of Ileat dllnagl It is also euroYident that flwil pattern is tooirreglllal to define thr lower andllpp(r 1 illl it of the 7onl of heat clamage

lTnder eliTelellt expCIinlCntal (onelitions it- Illight have bpen possible to obtain data that mnIlc1lllore aCTlIrafely illnstllte the limits of the zonp 0-1 heat dallIagr for lOl1h ri(( of (]i Ilelpnl 1110ishll(gt (ontents Von H6hl1el (32) found tha t a c1efin itp maximlllli temperature at which a giwl1 sanlplp of sepds may be safpl htatp(1I111Y 1I0t- )( obtailHd heshy(ausr of the eli rh(n(Cs in thp resistul(es of lnciic1utl sl(cls IIutchshyillson (])) Oil tl1( other hallcl was able o estahlish rather definite and practical tel11pemlllle end points defining the (ritieal rang(s -101 eteh of his stmpl(s of wheat 0-1 eli rllllllt 1l10istllre eontrnts Flom his plIbshyI i(a fioll ii- 011 Ie a pppa I I lin t t ill ~( Ipd i()) () f 1111 if01111 sred sam pIes Hnd (lip (lIoi(p of OIlP- (onfnillillg n IlP1 J()n pelC(nt of ial)I( se(d as possibll PI( illlPOIhillt adolmiddots

_lthollgh (lierp may b( all PITOI of )O C 01 mole in the apploxishyIllatpltl illlJ)elttllJe- plottrcl ill figl1le 1 fhl scatter-type cliaglam has plldi(a I va I l( It Pllables 011( fo n pploxi mat( tIl( maximum tcmpcrlshyI mps at hi(11 baj(hls otollh liee of ltIi rTennt IlloistllJP (ontcnts rna be hput-tr(ntl1 unclll (()ll(litlolls like (host des(Iibp(1 ill Experimentil atelials a 1)(1 Prrlllc11 Ip (pp H-I~) To Ihis IxtPllt it- 1IIt) seJve as a hent-damagp plldi((-ion 01 saity elIalt Xo claims may be Illade that it would ~eln Ipliably fol plpd(tpJrninill) the tellljlelltllrc nt hi(h a ir(sl1 I COI1lIgt i ned lot of 1i(( III itdl t be 511( II ellied i II a (0111 Il 1lICi a I (1Ii(I The Ipaso) is thd the tlialgtl( illl loclIclaquolll tillt loss of lIloi sli I11 cllllshying the heating PIO(ISS wns 1I0t (111111((1 i1 the ill(lstigatiolls

42 TECHNICAL BULLETIN 1120 U S DEP1 OF AGRICULTURE

However it appears possible that diarrams similar to figure 3 could be developecl for use as heat-damure prediction charts for guiclillg experimental and commercial dlyinr operations for both seed and -~illing purposes Charts for the latter wOllldneed to be based upon ririlling instead of germination test dntn

SEED HEATmiddotTUEATIUENT METHODS AND THEIn APPLICATIONS

Plant physiolorists plnnt patiloloriI tnlOlllOlorists lnd arlielllshytural enrilleels hnn lllu(hmiddot 111( mujo) lonlTibuiolls to OUI knowl((hre of the effects of heat on seeds

Atanasoff and Tollllson ((J) poi nled oul that thl Iii orbIs 10 investigate the effects of ditJ(rellt tpllI]lelalurrs of tJlulnHllt on seeds were principally plnllt physiolopists al1lI thpn plant pntholorists Thr plant physiologists were interested in establ ish i Ilr the efrects of 11(at on germination enpllcity and r(rlllination YigOl and ill onrcoming dormancy Often they employe(l Yery high iel1lpelatlllcs and long exposure periods hieh ( tOI)i(ler to(lay to Ill lXII(Il)( anel illJpracshytical fOl (oll1lJ1rlcial tpplhatiol)

The pla nt pa thologi-t- PP1TPingtltl fhn I hpltl I 1llih I 1)( 11-(111 I f(lI

destroyillg seld-tollullinatiJ1 fllllri hiIll Inifht la0l 11P(OIlI( 1(shy

tively pathogrni( to tliP p(d 01 to tIl( ltllnlopill PllliJrYo alld plalll These workels had (0 dli-p lXPPlilllPllb that WOII Id dpl1lollsfTltl tI whether a clrtain finH-tell1]lp]atll[p (olllbillntiOIl might be rlllploy((l ill treating a gien kind of sepd that wOllld (lpstroY the eOllttllllinatillr vathogenic fungi hut ihM wouhlnot alr(f tlIP inhililY of the SPl(1

Shortly the entomologists beClIlllP jnt(1(~t(c1 T1HY had pSfpnfialIy the same ploblenls a~ the plant patllOlorists ~ill(p 111lt) l1P((hd 10 (gtIPshyserve seed for extPlIded ppliods for boll pllIltinr and lI1ilIill~ PIII_ poses ~poundost of the litplatl1lP Oll thr liSP of IHtt to ltI(-tlO) flll1i and insects in seeds has ap]Jpand yithil1 the pnst j() )(IIS This is I10t becanse the coneepts -fOI hel Im) plaetieal applications of IIlat an by any means new Hahlllnnltlt (]1) di-(l1ss((1 Ih(111 in U(j3 and 110 doubt others twfole him

Vithin the pasl ) ylal- arri(lIltula 1 lI1giI1PPI nnd ass()cin(cl workers haTP made IlUIlI()OIiS oltln (Ollllibn ions to ilH lifl1Hurl on the heat treatmellt of pra TlwlL dUllI oiljP(tin hI-( hlCn b

means of dlying and C011(I01led telllpltIltI11PS lnd l1ulllidijies to ])ngtshyvent the dlvelopment and tl(tivity of fungi Hnd inspd in Iond lNI and either to il1lj)Ior oj to lSSUle tJ(gt lPipntioll of high milling qunlshyity in g1ains

Sen~ntl llIethocls 101 IHlt-tTlntill~ (pcb JtlYP h((ll dpisld bv 111lt various -mhrs 111( kind of nHlllOdis lIot llf((s~lIih (OI1(lilnblf -ith the plor(s-ionnl in[(Ipt of thp i n(1 ill Imlnd 110 stich infpLshyence is intenlt1ld Th(middot methods may Ill f[lOu]llllas foIIOY

1 Direct contn(t with hot wat(I 2 Direct (ontaet with heat(middot(l ni]

Trays in tl (ollstant-lllllIHlufuIP 0(11 ail (il(IIInliol1 jl1il1(ishypally convl(tiol1

Opltn t(st [ub(s or flask- paltinll~ SUhIlHIr(d ill a lmth ail (il shy

enlation r(stTid((] sOllwtillJlS Ply nllllh HJ byt tHpil11ry 0plnillg inshysignificant total and VlI)(lI IgtI(SSIII(S

bull

bull

E~FECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 43

Forced-drait experimental apparatus or equipment Heated dry ah Heated moist air

Vapor-heat machines Commercial chjers and bins aerated ~with artificially heated air

3 Closed containers Submerged in a heated liquid bath moisture Joss fr~111 seed and avt~i1nble ~AJgen and air supply restricted

+ DIrect contact nth liquIds other than yater In most of the inwstigatons cited seeds haw been exposed to

a gi~n t~empemtule in direct contact jth yater or air or in a clo~ed cOlltamer

DIRECT CONTACT WITH HOT WATER

bull

Seeds in direct contact yith hot water are said to be sensitive to heat Possibly this condition is in part attributable to the more rapid and uniform penetmtion of the heat The method although fairly eIlicient in destroying fungi has some objectionabJe features ~~ mashyjor one is thnt there is -elY little eli (rerence between the temperatures at which -iability lmel contaminating fungi are destroyed Tisdale (83) Adair and (rnlley (1) and (alley (18) have llsed hot water for the treatment of rice with fnnrri and nematodes Additional inshyfOlmation on th~ hot-wat0l tr~atl1lellt is to be found in the publications of Edwards Hnd (olin (8) T~nsPJl urn Kiessling (44) 1Vaggoner (8) Lehman (1) nnd ~atsoLl ct al (88)

DIRECT CONTACT WiTH HEATED AIR

Primal obj~etiol1s to tiltgt use of uti(icinlly heated dry air in treatshyill 1((lt1 is that it rrel1erally tnkes too lonrr to obtain effective lesults lllld Ow seed may berome too dry ren~en (JO) was unsuccessful ~iJl destJoing sm1lt in oat and hall(y seed in I hours at either 50deg OJ ii~)C ( OJI tlw otllC1 11al1(1 tanamiddot~o(r and Johnson (0) IOlmel that by expoli ng thee ]]-ltl1i((1 sepltls of bn rle h(at Iye nnd oats to dn~ heat for )0 houn- hadelmiddotinl and fmll inf(dions could be reshy([tired or eliminated middotit-1Iout ilia t(riall) i lij uring the germination of the epd Thl1lall (JJ) r(gt(OJlJlllel1C1((1 a dl-htl t tem perature of 95deg ror 1~ 1101115 101 dest 10 i 11 thegt Hnthlaellos( fllnrrlll of cottonseed To Hyoid slriolls Ims or middotjlhil it tIll sepcls ri Ist lind to be preclriecl to H 1II0itlll(-COllUllt -1111( pqlli-llcJlt to l~ ]gtpIT(nt of theil air-drywihL

1Ie lise of dJY hPllt for (IlHlloyin weevils and other insects in glmiddottill iJlcltlltlingli(p ws 1]((gt11 illestlgntNl by Popenoe (00) Deall (li 24) and Colton (li) Bnek ancl Cotton (1) were able to kill the

bull rice ~weeil (8itophilll8 (J11za (L)) at J~R)O C in B hous and at jL_J

C

within 30 lJIilllltS Ballr nlHl Cotton (i()) found that exposure of 10 minutes to a tpllI[l(lratllrl of (iOO ii fatal to nil insects infesting stored rice However tl(Y (JP 1I0t sue-cessful in obbtining t satisshyfactoy kill of imects ill Ike ill a (ol1ll11(I(inl ellmiddotier operated at (iDO 101 W minutes b((nn~( tll trenhlJllt did not raise the t(mpelllture of the rice above j(J0 They stnted that Iwating fOI insect control is not Jaorpd by thl 1i((gt iJl(fllS(TY IJPel1Ie the ric( is npi to check and btllusl too ll11wll Illoi4ul( is 1(IIJ(Jmiddot(d

44 TECHNICAL BULLErIN 1120 U S DEPT OF AGRICULTCRE

Edwards and (olin (g8) and focli]) (37) haTc shown that Illoist heat is only slightly Jess destrnctive to seed viability and Jensen (3(j) observed it to be less effective than the hot-mter treatment in the bullprevention of smut in oats and barley On the other hand Miller and Mc1Vhorter (61) have demonstrated the usefnlness of vapor heat (steam-ail mixture) ns a practical means of disinfectin~ seed These investigators found that certain kinds of sc(ds -ill apparently endure considembly hil-her yapor-h(at t(Ill)l(ratII I(S than arc Ieqniled to kill all associated flln~i Thus table be(t s(ed balls will pmiddotidently tolerate a va]1or-Iwllt temperatule of about (j~8deg C Jor as 10n~ as 30 1n1nutes without siglli fkant r(duction o retnnlation of ellninntion Pl1011a behlC an nss()(iatecl patho~cn is kilkd wh(n (xposed at )72deg for 20 minutes which is about 10 loer than the phytolptha I tPllIperashytUIt Lathl ()2) uNl yaV01 h(at ill (11ldiv(ly cOlltrolling nltlcisSIIS pests

CLOSED CONTAINERS

1h( 11Iet11oltl of hNltill o((d in (Iopd conhlilHls is mOle nearly comparable -ith the 1110isl- alHl -apor-lwa nlltho(l than with litlwl the hot-water or the ntilieinllr hent(d ltIn-air I1WthOlh 1hl e~slntial differences between the 1loi-t-ll(at and (loe([-lonLaiIlPI llIethods are that in the latter the atmospheric moitule 1))esll1t is largely derived from the seed and a presoure c1eelops 1n the container which is proportional to the antilable free moisture and timl nnd temperature of treatment Yhether these lt1 i Iferll1ces oller ad1 Htnges was not cleterm i ned

rolt1il1 (J7) and agonPI (8i) IPjloltNl Ihat seeds Iwalp(l ill bulln closed COl1hlilHI cOlllll not stand -0 hih I tlmpenttlllc as 1H11 heated in nn open ye~ll or in nil (Well -hidl prrmiited the rapid elimination of atel f]()111 the (p(1 raggonpls (lain aloo shoNl clenrly that radish setlt1- llelt((l dirpdly in alel had less ltsistaneC than when they PIe l1patpltl in a elosld container

No studies (ollpajll~ tlw I(lative pfl1CiPllciCs of Ihp (lill(IPIII methods of heat trettnHllt llan l)pplI 1l11lk ill wlli(h tIll SHlIlp lot or Iiee waS used ] [owpnl in-ola I as ma V be dpt(11Il illCd I10 III Ill( litelltUle the expClin1Pllial data IPIHlltl(C 101 Iollgh Ii(( in Ihis IJltIshyIttin indicate that ric( ean toltIatp highpl t-el11l)(IlIIII(S withoul loss of viabilitv than a1( Ic(onll1HIHlld for liSP in (Ollllltpl(ial (In-ill opershyations Til (ol11lllercial dlTin the Illoislllre is (ontinuolII 1(1110((1 hom the rice and thpo)eticall the kernels sholll bl(ollle in(reasin~l resistant If it is tlll~ that the inbililV of rice mw he dp~tTold ( 10pl (emlwraflIllS ill a C011I111I(il1 dlipl han in Ii elospd tpsi ul)( ii 0111(1 pm( thai fld)r ot her Ihan hpat are also ill operatioll whi(1t aI( dl(rlldin (t) yiahilily

DIRECT CONTACT WITH LIQUII)S OTlllm TitAN WATER

Yllhon rd (88) p]Pdp(1 Cvllal IllHtplial possihlp (Ipatill~ nglIIUlt Im peasHIlIlS Hildlillla h(HI1~ Th(~( Illatllials (In (a rho II (ptladtlolid( milllIal oil Shpll eltaIlPI PIPIOlll (lthrhlll gIYIol) 111011)1 oil (S E 10) 1I)((a1 1IHlh1 alcohol kllos(II ~TI()1 lalti( bull altid sollltiollS tolllllll a(IOIH gly(rrilll lNlaL oil anilille oil olie

t~~~

bull

bull

~ C

EFFEC1S OF HEA1 TREA1lIENT ON THE VIABILITY OF RICE 45

oil sodium chloride solutions and cotton seed oil Data were tabushylated for seeds treated in carbon tetrachloride motor oil fuel oil and water at temperatures ranging from 60deg to 90deg C and for periods of 10 to 60 minutes Beans peas and lima beans were able to survive extended exposures in hot caJbon tetrachloride but they were killed in a relatiely short time ylwn exposed in water of the same temperashyture Carbon tetlachlOlide appeared to be the best medium tested and the use of hot carbon tetrachloride for destroying seed-bome organisms in peas and beans is suggested HoweveJ these ttllthors have pointed 0111 that Further researcil ill be necesSl1rY to evaluate the pJactienl IIS( of the nmte1ials amI heat on t11e control of seedshyborne pathogens

C(uiekshnnk (JQ) has nc(ntly eallie(] out a selies of prelil11ilUtry r

experiments to cleteJmine the el1ecl of n carbon fetlachloricle steep OIL

the gerl11ination and control of Spll(((I(ll(( lilwl1l1n Vollenw in two nlrieties of ]illHed-0olden Viking and Koto ] [c obtained a signifshyieant depression of ~led gelminn(lon only at 70deg a11(] 75deg O fOl 30 minuhmiddots -ith Golden Vikin and 20 minutes with Koto Germinashytion of tl1( funglls spores ns 110t obselTec1 to occur atter treatment for20 minutes at (j)Ci TOO lind )0 01 for ao minutes at GOdeg He found that carbon tetrH(hlolidc has the followin nc1Yantaes over water for th0 heat trpatnlCnt of linsNl It- i snft1 illl I(ped to ermination and 110 Hrtificial drying of till sepd i 1l(eesst1Y ~

lEW )IETHODS AND -IODlFrCATJONS

It is e-ident fr011l till information in this bulletin nwt man is a long way f1Olll ha ill) n (0111 JlIphp11si e sciPJlti fien II de1i Igtd know]shypdgp oi till (Ireets of hpllt on rice Hough riel has been c1emnnshystliltedin the expe1inlents in 1050~ 1J)l and ID32 to have It high lpsislance to hpnt fhi dlHraCtlrili( SIIutsts that heat lllight be lIsN1 eypn more extpnsiwiy than no for th0 im]lroYernent and ~tabilishyzntion of s(((l quality Certainly t 1]( tllhniqups for applying heat ill till tJpafnwnt of rite l11e by 110 means bpell fuJiy explored The pltltti(aiJility of usinl a nly hilh lpl11lWlature uHI flash-heating as well as thl llent ITPallllPnf of iee in llllc1ia other than ail and WlItpl should 1)( inlmiddotpsli)l(prl Till possibility of simultaneously ill(OrpOIat ill fllnli(iltial ubII1)(( Hnd nutrients in the hulls should a Iso bl lonsirl(ICd

SIT])mlA RY

ExpPIil1l(nU II(JP IIllcl(Ilakpll dUlin) the riee-harvesting spasons of ID) 10 and 1l)~ to ltiPlllOlI-tla(p fill (Ired of lin1( and tPlI1pemshyIUlpol hpatingoll tilt iltlJililyol~ lOlllh or pnddy riCegt (()I1jzusath(() of ltlilrel(l1t IlJOistlll[ (ontpnts Both IllPtiilll11-glain (S(1 GI-25-12 11 n(l ZCl1i til) a I1d IOllg-gla i n (HCXOIO B1mbon npl an(l Cent-ulV 5d) 1I1i(ti(s (1( used (Illllinalion laquost dala 101 Ii([ and s(p(J Jwalshy1](af111l1l1 llpi h()(ls and t Iwil applications nl( ltlisclISSP(1

If(nt tlpainHnts PI( Illa(]( nlal SOllr((fi of fnshlv (ornbineshy1Il1(S(ltI rice-Oil tIl( plpl1lisps of tll(gt ni(pExperilll(n( Siaion at Cl()WIIY La Salllpips of natllrally Illoist lol1il 1ice (1P packed in htat-1Psistant t(~st (dIes TIll Ils fllilps 1(1( light Iy stoppeled

f

46 TECHNICAL BULLETIN 1129 lJ S DEP~ OF AOlUCULTURE

and submerged ill water baths maintained at di Ife1(11 t cOllstant tem pershyatures 111 experiments to demonstrate Owelreet of temperature on viability the usual period of exposure was RO minutes after the rice reached the temperature of the hath In experim(nts to demonstrate the effect of time (duration) of heating 011 viability the periods of exposure ranged from 10 to 120 minutes Xo moisture was lost iol1l or gained acce~s to tlll rice-filled tet tubes (lmillg the periods of heat treatment The riC( in the t(st tubes was alloHltlup to 8 minutes to reach the temperature of th( bath On Colllplltioll of the heal- treatshyment the contents of the test tubes were eompoitecl and spread in a paper tray to air-dry At the conclusiol1 of ptch sensons York all the air-dried heat-tren ted sn III pl(s fOlIll hpl it 11 apploprinfp n i 1shydried controls (non-hen t-trentpltl) Yele paekagc1 in pap I balIS tmmshyfelTec1 too the Sontll(ll1 R(iolHd U(sarelt fJa bOIa IOIV X CY o11 NI ns La and stol(d at ~+c_2nl C CPllllil1al-iol1 tlcJS W(jp made on aell sampJe by the nHtholt1 pnsclilp(lIJ Ill( Flllplal S(ld cI- and were run 8 1G H and ~2 nll dlpl HI dnle of l)(at tl(ahlllnL

The gellninafiol1 ht data (OldilllI (hal high Ipl1lpltml lins a flpdld the inbilitv of naIlall 11loi1 lOlIh Iie( ill 11ll1eh tlIP -lI1W I1lal1nrl as they tllct(lt1 tlIP viabilitip of oth~r kind of SPlcls similallv lrat(d TIH iolloil1 llPlal ohcPlTati()l1- (()1l1ltl IJl 11 1lt1 c1(

FOI rOllgh li~e of (neh Illoisillll (011t(111 IIIlIl i n tllllpplatUl( of hent- treatn1(nt Iwlow hidl tlllIp is 110 ([l(Ila( ill inlJilitT

For amiddot gi(~n stlllpll of [in flIP Z01H of IIpat dnlllapvmiddot i ( Ill( range beh(Pl1 th( tlllppralllp at hiclt ltpnl- dnl1lagp (0 riahilit) just starhi amI th( tlllp(Iatml nt which it- ic ill lOlllphtl i a IIHlTO Olll

The (xtent 01 this nlllgl 101 n IllHt-tlpntllllllt plliod 0110 Illillllj-PS as not definitelv (stnlgtlishpd fDI tIH IHllIralh lIloit (ollliJilll-hantld rough rice 115((1 but ha-I] Oil nppIoxillwtioll of ill( lilllitinp Itlllshyj)erahllcs it aplwals to 1)( IJphYltlll i alld 12 ( This Inngl is aboul t11( same for 1i(p or difllIPllt 1ll0itlllt (ontpnl- hilt it i hillll 011

I lIP t(111 p(ra tlll( s(a It till 1()wPl 111( IllOiIIIIp (ontent () r t lip li(( rithin tllP ZOIlP of IW(l( ltlnlllal -101 Ii(( of a i PI1 llloilIIP (on-pnl

tIllt (llgle( or dlstTlldioll ill(I([SPS as t-1l( IPIllIPlatl1lp illCJ(ases al() 111( 101l(r tl1lt ri(( is Iwnt-tl(atpd tlll gnulPI llP ifs los-ps ill (IshyllIil1tfi()1l (npaeif-y alld gPll1lillalioll IWmiddotlI

The 1lsishll)(P of I(llgh Iicl fo (h( illlpnilIlll111 of ils Iahilily hy hpnt VflliN il1PIsP as its 1ll0i-t1l1P (middot011[(1lt

1hplI the i n b iii h () r Ii(l is cla Illn pcl by lIP t loss ill PIIll i Iln i Oil

yigor is appnr(llt lwiorc los ill PIll1iJIaI iOl1 (apa(il 1-11(111(1 tlHl( is pmiddotidI1N or Ill( laltll dq)Plllls UpOIl tlH ((Iilmiddot of nIP ITPnIlIPIlL

OClTllillatiOI1 (psis Iluul( S Hi 21 alld 2 ((ks afPI Iwatmiddot tlpallll(nlshyon ri(e f)()1H llip SHill hltlmiddotIICn((1 -lIl1plp S(OIltI at 21middot-~(iO ( did llotlcYcnl Hp[)Ipciallll (IIlllgl ill till gPlIllill1lioll igol alld IICll1linnshytion eapnCily of ihp salllpit

In (x]l(lil1Hllts wilh il1l1l1allll( Ii(p thp 11Ioistl1lllOIlI(lIi Yaliahll exc]eisp(j lpalaquo1 influllwP IlUl Ih( IIWllllit nUinhlp ill (1(tl)milliwr

Ill( rcsishilJcp of fliP i1l1l1lnllll( Hllt1 to IlP1 ltInIlUll H(clusP of lillliftd dala if (oHld lIot Il( (lp((IllliIlP(j lIPh(I the

varieties of li(Pllspd (jillpIPltl sillilicHlllh ill t Iwil 1(~i~hlIH( to 11(at ObsPlv(gtltl clillIP1HlH Pll Illill~)] lud hllip((1 ilhil1 exp(liIlHnhtl limitatiolls Fc) till lIlt 1(1lt011 i[ could 1101 )( dlfpllllillld ltcIIH1

bull

bull

bull

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

42 TECHNICAL BULLETIN 1120 U S DEP1 OF AGRICULTURE

However it appears possible that diarrams similar to figure 3 could be developecl for use as heat-damure prediction charts for guiclillg experimental and commercial dlyinr operations for both seed and -~illing purposes Charts for the latter wOllldneed to be based upon ririlling instead of germination test dntn

SEED HEATmiddotTUEATIUENT METHODS AND THEIn APPLICATIONS

Plant physiolorists plnnt patiloloriI tnlOlllOlorists lnd arlielllshytural enrilleels hnn lllu(hmiddot 111( mujo) lonlTibuiolls to OUI knowl((hre of the effects of heat on seeds

Atanasoff and Tollllson ((J) poi nled oul that thl Iii orbIs 10 investigate the effects of ditJ(rellt tpllI]lelalurrs of tJlulnHllt on seeds were principally plnllt physiolopists al1lI thpn plant pntholorists Thr plant physiologists were interested in establ ish i Ilr the efrects of 11(at on germination enpllcity and r(rlllination YigOl and ill onrcoming dormancy Often they employe(l Yery high iel1lpelatlllcs and long exposure periods hieh ( tOI)i(ler to(lay to Ill lXII(Il)( anel illJpracshytical fOl (oll1lJ1rlcial tpplhatiol)

The pla nt pa thologi-t- PP1TPingtltl fhn I hpltl I 1llih I 1)( 11-(111 I f(lI

destroyillg seld-tollullinatiJ1 fllllri hiIll Inifht la0l 11P(OIlI( 1(shy

tively pathogrni( to tliP p(d 01 to tIl( ltllnlopill PllliJrYo alld plalll These workels had (0 dli-p lXPPlilllPllb that WOII Id dpl1lollsfTltl tI whether a clrtain finH-tell1]lp]atll[p (olllbillntiOIl might be rlllploy((l ill treating a gien kind of sepd that wOllld (lpstroY the eOllttllllinatillr vathogenic fungi hut ihM wouhlnot alr(f tlIP inhililY of the SPl(1

Shortly the entomologists beClIlllP jnt(1(~t(c1 T1HY had pSfpnfialIy the same ploblenls a~ the plant patllOlorists ~ill(p 111lt) l1P((hd 10 (gtIPshyserve seed for extPlIded ppliods for boll pllIltinr and lI1ilIill~ PIII_ poses ~poundost of the litplatl1lP Oll thr liSP of IHtt to ltI(-tlO) flll1i and insects in seeds has ap]Jpand yithil1 the pnst j() )(IIS This is I10t becanse the coneepts -fOI hel Im) plaetieal applications of IIlat an by any means new Hahlllnnltlt (]1) di-(l1ss((1 Ih(111 in U(j3 and 110 doubt others twfole him

Vithin the pasl ) ylal- arri(lIltula 1 lI1giI1PPI nnd ass()cin(cl workers haTP made IlUIlI()OIiS oltln (Ollllibn ions to ilH lifl1Hurl on the heat treatmellt of pra TlwlL dUllI oiljP(tin hI-( hlCn b

means of dlying and C011(I01led telllpltIltI11PS lnd l1ulllidijies to ])ngtshyvent the dlvelopment and tl(tivity of fungi Hnd inspd in Iond lNI and either to il1lj)Ior oj to lSSUle tJ(gt lPipntioll of high milling qunlshyity in g1ains

Sen~ntl llIethocls 101 IHlt-tTlntill~ (pcb JtlYP h((ll dpisld bv 111lt various -mhrs 111( kind of nHlllOdis lIot llf((s~lIih (OI1(lilnblf -ith the plor(s-ionnl in[(Ipt of thp i n(1 ill Imlnd 110 stich infpLshyence is intenlt1ld Th(middot methods may Ill f[lOu]llllas foIIOY

1 Direct contn(t with hot wat(I 2 Direct (ontaet with heat(middot(l ni]

Trays in tl (ollstant-lllllIHlufuIP 0(11 ail (il(IIInliol1 jl1il1(ishypally convl(tiol1

Opltn t(st [ub(s or flask- paltinll~ SUhIlHIr(d ill a lmth ail (il shy

enlation r(stTid((] sOllwtillJlS Ply nllllh HJ byt tHpil11ry 0plnillg inshysignificant total and VlI)(lI IgtI(SSIII(S

bull

bull

E~FECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 43

Forced-drait experimental apparatus or equipment Heated dry ah Heated moist air

Vapor-heat machines Commercial chjers and bins aerated ~with artificially heated air

3 Closed containers Submerged in a heated liquid bath moisture Joss fr~111 seed and avt~i1nble ~AJgen and air supply restricted

+ DIrect contact nth liquIds other than yater In most of the inwstigatons cited seeds haw been exposed to

a gi~n t~empemtule in direct contact jth yater or air or in a clo~ed cOlltamer

DIRECT CONTACT WITH HOT WATER

bull

Seeds in direct contact yith hot water are said to be sensitive to heat Possibly this condition is in part attributable to the more rapid and uniform penetmtion of the heat The method although fairly eIlicient in destroying fungi has some objectionabJe features ~~ mashyjor one is thnt there is -elY little eli (rerence between the temperatures at which -iability lmel contaminating fungi are destroyed Tisdale (83) Adair and (rnlley (1) and (alley (18) have llsed hot water for the treatment of rice with fnnrri and nematodes Additional inshyfOlmation on th~ hot-wat0l tr~atl1lellt is to be found in the publications of Edwards Hnd (olin (8) T~nsPJl urn Kiessling (44) 1Vaggoner (8) Lehman (1) nnd ~atsoLl ct al (88)

DIRECT CONTACT WiTH HEATED AIR

Primal obj~etiol1s to tiltgt use of uti(icinlly heated dry air in treatshyill 1((lt1 is that it rrel1erally tnkes too lonrr to obtain effective lesults lllld Ow seed may berome too dry ren~en (JO) was unsuccessful ~iJl destJoing sm1lt in oat and hall(y seed in I hours at either 50deg OJ ii~)C ( OJI tlw otllC1 11al1(1 tanamiddot~o(r and Johnson (0) IOlmel that by expoli ng thee ]]-ltl1i((1 sepltls of bn rle h(at Iye nnd oats to dn~ heat for )0 houn- hadelmiddotinl and fmll inf(dions could be reshy([tired or eliminated middotit-1Iout ilia t(riall) i lij uring the germination of the epd Thl1lall (JJ) r(gt(OJlJlllel1C1((1 a dl-htl t tem perature of 95deg ror 1~ 1101115 101 dest 10 i 11 thegt Hnthlaellos( fllnrrlll of cottonseed To Hyoid slriolls Ims or middotjlhil it tIll sepcls ri Ist lind to be preclriecl to H 1II0itlll(-COllUllt -1111( pqlli-llcJlt to l~ ]gtpIT(nt of theil air-drywihL

1Ie lise of dJY hPllt for (IlHlloyin weevils and other insects in glmiddottill iJlcltlltlingli(p ws 1]((gt11 illestlgntNl by Popenoe (00) Deall (li 24) and Colton (li) Bnek ancl Cotton (1) were able to kill the

bull rice ~weeil (8itophilll8 (J11za (L)) at J~R)O C in B hous and at jL_J

C

within 30 lJIilllltS Ballr nlHl Cotton (i()) found that exposure of 10 minutes to a tpllI[l(lratllrl of (iOO ii fatal to nil insects infesting stored rice However tl(Y (JP 1I0t sue-cessful in obbtining t satisshyfactoy kill of imects ill Ike ill a (ol1ll11(I(inl ellmiddotier operated at (iDO 101 W minutes b((nn~( tll trenhlJllt did not raise the t(mpelllture of the rice above j(J0 They stnted that Iwating fOI insect control is not Jaorpd by thl 1i((gt iJl(fllS(TY IJPel1Ie the ric( is npi to check and btllusl too ll11wll Illoi4ul( is 1(IIJ(Jmiddot(d

44 TECHNICAL BULLErIN 1120 U S DEPT OF AGRICULTCRE

Edwards and (olin (g8) and focli]) (37) haTc shown that Illoist heat is only slightly Jess destrnctive to seed viability and Jensen (3(j) observed it to be less effective than the hot-mter treatment in the bullprevention of smut in oats and barley On the other hand Miller and Mc1Vhorter (61) have demonstrated the usefnlness of vapor heat (steam-ail mixture) ns a practical means of disinfectin~ seed These investigators found that certain kinds of sc(ds -ill apparently endure considembly hil-her yapor-h(at t(Ill)l(ratII I(S than arc Ieqniled to kill all associated flln~i Thus table be(t s(ed balls will pmiddotidently tolerate a va]1or-Iwllt temperatule of about (j~8deg C Jor as 10n~ as 30 1n1nutes without siglli fkant r(duction o retnnlation of ellninntion Pl1011a behlC an nss()(iatecl patho~cn is kilkd wh(n (xposed at )72deg for 20 minutes which is about 10 loer than the phytolptha I tPllIperashytUIt Lathl ()2) uNl yaV01 h(at ill (11ldiv(ly cOlltrolling nltlcisSIIS pests

CLOSED CONTAINERS

1h( 11Iet11oltl of hNltill o((d in (Iopd conhlilHls is mOle nearly comparable -ith the 1110isl- alHl -apor-lwa nlltho(l than with litlwl the hot-water or the ntilieinllr hent(d ltIn-air I1WthOlh 1hl e~slntial differences between the 1loi-t-ll(at and (loe([-lonLaiIlPI llIethods are that in the latter the atmospheric moitule 1))esll1t is largely derived from the seed and a presoure c1eelops 1n the container which is proportional to the antilable free moisture and timl nnd temperature of treatment Yhether these lt1 i Iferll1ces oller ad1 Htnges was not cleterm i ned

rolt1il1 (J7) and agonPI (8i) IPjloltNl Ihat seeds Iwalp(l ill bulln closed COl1hlilHI cOlllll not stand -0 hih I tlmpenttlllc as 1H11 heated in nn open ye~ll or in nil (Well -hidl prrmiited the rapid elimination of atel f]()111 the (p(1 raggonpls (lain aloo shoNl clenrly that radish setlt1- llelt((l dirpdly in alel had less ltsistaneC than when they PIe l1patpltl in a elosld container

No studies (ollpajll~ tlw I(lative pfl1CiPllciCs of Ihp (lill(IPIII methods of heat trettnHllt llan l)pplI 1l11lk ill wlli(h tIll SHlIlp lot or Iiee waS used ] [owpnl in-ola I as ma V be dpt(11Il illCd I10 III Ill( litelltUle the expClin1Pllial data IPIHlltl(C 101 Iollgh Ii(( in Ihis IJltIshyIttin indicate that ric( ean toltIatp highpl t-el11l)(IlIIII(S withoul loss of viabilitv than a1( Ic(onll1HIHlld for liSP in (Ollllltpl(ial (In-ill opershyations Til (ol11lllercial dlTin the Illoislllre is (ontinuolII 1(1110((1 hom the rice and thpo)eticall the kernels sholll bl(ollle in(reasin~l resistant If it is tlll~ that the inbililV of rice mw he dp~tTold ( 10pl (emlwraflIllS ill a C011I111I(il1 dlipl han in Ii elospd tpsi ul)( ii 0111(1 pm( thai fld)r ot her Ihan hpat are also ill operatioll whi(1t aI( dl(rlldin (t) yiahilily

DIRECT CONTACT WITH LIQUII)S OTlllm TitAN WATER

Yllhon rd (88) p]Pdp(1 Cvllal IllHtplial possihlp (Ipatill~ nglIIUlt Im peasHIlIlS Hildlillla h(HI1~ Th(~( Illatllials (In (a rho II (ptladtlolid( milllIal oil Shpll eltaIlPI PIPIOlll (lthrhlll gIYIol) 111011)1 oil (S E 10) 1I)((a1 1IHlh1 alcohol kllos(II ~TI()1 lalti( bull altid sollltiollS tolllllll a(IOIH gly(rrilll lNlaL oil anilille oil olie

t~~~

bull

bull

~ C

EFFEC1S OF HEA1 TREA1lIENT ON THE VIABILITY OF RICE 45

oil sodium chloride solutions and cotton seed oil Data were tabushylated for seeds treated in carbon tetrachloride motor oil fuel oil and water at temperatures ranging from 60deg to 90deg C and for periods of 10 to 60 minutes Beans peas and lima beans were able to survive extended exposures in hot caJbon tetrachloride but they were killed in a relatiely short time ylwn exposed in water of the same temperashyture Carbon tetlachlOlide appeared to be the best medium tested and the use of hot carbon tetrachloride for destroying seed-bome organisms in peas and beans is suggested HoweveJ these ttllthors have pointed 0111 that Further researcil ill be necesSl1rY to evaluate the pJactienl IIS( of the nmte1ials amI heat on t11e control of seedshyborne pathogens

C(uiekshnnk (JQ) has nc(ntly eallie(] out a selies of prelil11ilUtry r

experiments to cleteJmine the el1ecl of n carbon fetlachloricle steep OIL

the gerl11ination and control of Spll(((I(ll(( lilwl1l1n Vollenw in two nlrieties of ]illHed-0olden Viking and Koto ] [c obtained a signifshyieant depression of ~led gelminn(lon only at 70deg a11(] 75deg O fOl 30 minuhmiddots -ith Golden Vikin and 20 minutes with Koto Germinashytion of tl1( funglls spores ns 110t obselTec1 to occur atter treatment for20 minutes at (j)Ci TOO lind )0 01 for ao minutes at GOdeg He found that carbon tetrH(hlolidc has the followin nc1Yantaes over water for th0 heat trpatnlCnt of linsNl It- i snft1 illl I(ped to ermination and 110 Hrtificial drying of till sepd i 1l(eesst1Y ~

lEW )IETHODS AND -IODlFrCATJONS

It is e-ident fr011l till information in this bulletin nwt man is a long way f1Olll ha ill) n (0111 JlIphp11si e sciPJlti fien II de1i Igtd know]shypdgp oi till (Ireets of hpllt on rice Hough riel has been c1emnnshystliltedin the expe1inlents in 1050~ 1J)l and ID32 to have It high lpsislance to hpnt fhi dlHraCtlrili( SIIutsts that heat lllight be lIsN1 eypn more extpnsiwiy than no for th0 im]lroYernent and ~tabilishyzntion of s(((l quality Certainly t 1]( tllhniqups for applying heat ill till tJpafnwnt of rite l11e by 110 means bpell fuJiy explored The pltltti(aiJility of usinl a nly hilh lpl11lWlature uHI flash-heating as well as thl llent ITPallllPnf of iee in llllc1ia other than ail and WlItpl should 1)( inlmiddotpsli)l(prl Till possibility of simultaneously ill(OrpOIat ill fllnli(iltial ubII1)(( Hnd nutrients in the hulls should a Iso bl lonsirl(ICd

SIT])mlA RY

ExpPIil1l(nU II(JP IIllcl(Ilakpll dUlin) the riee-harvesting spasons of ID) 10 and 1l)~ to ltiPlllOlI-tla(p fill (Ired of lin1( and tPlI1pemshyIUlpol hpatingoll tilt iltlJililyol~ lOlllh or pnddy riCegt (()I1jzusath(() of ltlilrel(l1t IlJOistlll[ (ontpnts Both IllPtiilll11-glain (S(1 GI-25-12 11 n(l ZCl1i til) a I1d IOllg-gla i n (HCXOIO B1mbon npl an(l Cent-ulV 5d) 1I1i(ti(s (1( used (Illllinalion laquost dala 101 Ii([ and s(p(J Jwalshy1](af111l1l1 llpi h()(ls and t Iwil applications nl( ltlisclISSP(1

If(nt tlpainHnts PI( Illa(]( nlal SOllr((fi of fnshlv (ornbineshy1Il1(S(ltI rice-Oil tIl( plpl1lisps of tll(gt ni(pExperilll(n( Siaion at Cl()WIIY La Salllpips of natllrally Illoist lol1il 1ice (1P packed in htat-1Psistant t(~st (dIes TIll Ils fllilps 1(1( light Iy stoppeled

f

46 TECHNICAL BULLETIN 1129 lJ S DEP~ OF AOlUCULTURE

and submerged ill water baths maintained at di Ife1(11 t cOllstant tem pershyatures 111 experiments to demonstrate Owelreet of temperature on viability the usual period of exposure was RO minutes after the rice reached the temperature of the hath In experim(nts to demonstrate the effect of time (duration) of heating 011 viability the periods of exposure ranged from 10 to 120 minutes Xo moisture was lost iol1l or gained acce~s to tlll rice-filled tet tubes (lmillg the periods of heat treatment The riC( in the t(st tubes was alloHltlup to 8 minutes to reach the temperature of th( bath On Colllplltioll of the heal- treatshyment the contents of the test tubes were eompoitecl and spread in a paper tray to air-dry At the conclusiol1 of ptch sensons York all the air-dried heat-tren ted sn III pl(s fOlIll hpl it 11 apploprinfp n i 1shydried controls (non-hen t-trentpltl) Yele paekagc1 in pap I balIS tmmshyfelTec1 too the Sontll(ll1 R(iolHd U(sarelt fJa bOIa IOIV X CY o11 NI ns La and stol(d at ~+c_2nl C CPllllil1al-iol1 tlcJS W(jp made on aell sampJe by the nHtholt1 pnsclilp(lIJ Ill( Flllplal S(ld cI- and were run 8 1G H and ~2 nll dlpl HI dnle of l)(at tl(ahlllnL

The gellninafiol1 ht data (OldilllI (hal high Ipl1lpltml lins a flpdld the inbilitv of naIlall 11loi1 lOlIh Iie( ill 11ll1eh tlIP -lI1W I1lal1nrl as they tllct(lt1 tlIP viabilitip of oth~r kind of SPlcls similallv lrat(d TIH iolloil1 llPlal ohcPlTati()l1- (()1l1ltl IJl 11 1lt1 c1(

FOI rOllgh li~e of (neh Illoisillll (011t(111 IIIlIl i n tllllpplatUl( of hent- treatn1(nt Iwlow hidl tlllIp is 110 ([l(Ila( ill inlJilitT

For amiddot gi(~n stlllpll of [in flIP Z01H of IIpat dnlllapvmiddot i ( Ill( range beh(Pl1 th( tlllppralllp at hiclt ltpnl- dnl1lagp (0 riahilit) just starhi amI th( tlllp(Iatml nt which it- ic ill lOlllphtl i a IIHlTO Olll

The (xtent 01 this nlllgl 101 n IllHt-tlpntllllllt plliod 0110 Illillllj-PS as not definitelv (stnlgtlishpd fDI tIH IHllIralh lIloit (ollliJilll-hantld rough rice 115((1 but ha-I] Oil nppIoxillwtioll of ill( lilllitinp Itlllshyj)erahllcs it aplwals to 1)( IJphYltlll i alld 12 ( This Inngl is aboul t11( same for 1i(p or difllIPllt 1ll0itlllt (ontpnl- hilt it i hillll 011

I lIP t(111 p(ra tlll( s(a It till 1()wPl 111( IllOiIIIIp (ontent () r t lip li(( rithin tllP ZOIlP of IW(l( ltlnlllal -101 Ii(( of a i PI1 llloilIIP (on-pnl

tIllt (llgle( or dlstTlldioll ill(I([SPS as t-1l( IPIllIPlatl1lp illCJ(ases al() 111( 101l(r tl1lt ri(( is Iwnt-tl(atpd tlll gnulPI llP ifs los-ps ill (IshyllIil1tfi()1l (npaeif-y alld gPll1lillalioll IWmiddotlI

The 1lsishll)(P of I(llgh Iicl fo (h( illlpnilIlll111 of ils Iahilily hy hpnt VflliN il1PIsP as its 1ll0i-t1l1P (middot011[(1lt

1hplI the i n b iii h () r Ii(l is cla Illn pcl by lIP t loss ill PIIll i Iln i Oil

yigor is appnr(llt lwiorc los ill PIll1iJIaI iOl1 (apa(il 1-11(111(1 tlHl( is pmiddotidI1N or Ill( laltll dq)Plllls UpOIl tlH ((Iilmiddot of nIP ITPnIlIPIlL

OClTllillatiOI1 (psis Iluul( S Hi 21 alld 2 ((ks afPI Iwatmiddot tlpallll(nlshyon ri(e f)()1H llip SHill hltlmiddotIICn((1 -lIl1plp S(OIltI at 21middot-~(iO ( did llotlcYcnl Hp[)Ipciallll (IIlllgl ill till gPlIllill1lioll igol alld IICll1linnshytion eapnCily of ihp salllpit

In (x]l(lil1Hllts wilh il1l1l1allll( Ii(p thp 11Ioistl1lllOIlI(lIi Yaliahll exc]eisp(j lpalaquo1 influllwP IlUl Ih( IIWllllit nUinhlp ill (1(tl)milliwr

Ill( rcsishilJcp of fliP i1l1l1lnllll( Hllt1 to IlP1 ltInIlUll H(clusP of lillliftd dala if (oHld lIot Il( (lp((IllliIlP(j lIPh(I the

varieties of li(Pllspd (jillpIPltl sillilicHlllh ill t Iwil 1(~i~hlIH( to 11(at ObsPlv(gtltl clillIP1HlH Pll Illill~)] lud hllip((1 ilhil1 exp(liIlHnhtl limitatiolls Fc) till lIlt 1(1lt011 i[ could 1101 )( dlfpllllillld ltcIIH1

bull

bull

bull

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

E~FECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 43

Forced-drait experimental apparatus or equipment Heated dry ah Heated moist air

Vapor-heat machines Commercial chjers and bins aerated ~with artificially heated air

3 Closed containers Submerged in a heated liquid bath moisture Joss fr~111 seed and avt~i1nble ~AJgen and air supply restricted

+ DIrect contact nth liquIds other than yater In most of the inwstigatons cited seeds haw been exposed to

a gi~n t~empemtule in direct contact jth yater or air or in a clo~ed cOlltamer

DIRECT CONTACT WITH HOT WATER

bull

Seeds in direct contact yith hot water are said to be sensitive to heat Possibly this condition is in part attributable to the more rapid and uniform penetmtion of the heat The method although fairly eIlicient in destroying fungi has some objectionabJe features ~~ mashyjor one is thnt there is -elY little eli (rerence between the temperatures at which -iability lmel contaminating fungi are destroyed Tisdale (83) Adair and (rnlley (1) and (alley (18) have llsed hot water for the treatment of rice with fnnrri and nematodes Additional inshyfOlmation on th~ hot-wat0l tr~atl1lellt is to be found in the publications of Edwards Hnd (olin (8) T~nsPJl urn Kiessling (44) 1Vaggoner (8) Lehman (1) nnd ~atsoLl ct al (88)

DIRECT CONTACT WiTH HEATED AIR

Primal obj~etiol1s to tiltgt use of uti(icinlly heated dry air in treatshyill 1((lt1 is that it rrel1erally tnkes too lonrr to obtain effective lesults lllld Ow seed may berome too dry ren~en (JO) was unsuccessful ~iJl destJoing sm1lt in oat and hall(y seed in I hours at either 50deg OJ ii~)C ( OJI tlw otllC1 11al1(1 tanamiddot~o(r and Johnson (0) IOlmel that by expoli ng thee ]]-ltl1i((1 sepltls of bn rle h(at Iye nnd oats to dn~ heat for )0 houn- hadelmiddotinl and fmll inf(dions could be reshy([tired or eliminated middotit-1Iout ilia t(riall) i lij uring the germination of the epd Thl1lall (JJ) r(gt(OJlJlllel1C1((1 a dl-htl t tem perature of 95deg ror 1~ 1101115 101 dest 10 i 11 thegt Hnthlaellos( fllnrrlll of cottonseed To Hyoid slriolls Ims or middotjlhil it tIll sepcls ri Ist lind to be preclriecl to H 1II0itlll(-COllUllt -1111( pqlli-llcJlt to l~ ]gtpIT(nt of theil air-drywihL

1Ie lise of dJY hPllt for (IlHlloyin weevils and other insects in glmiddottill iJlcltlltlingli(p ws 1]((gt11 illestlgntNl by Popenoe (00) Deall (li 24) and Colton (li) Bnek ancl Cotton (1) were able to kill the

bull rice ~weeil (8itophilll8 (J11za (L)) at J~R)O C in B hous and at jL_J

C

within 30 lJIilllltS Ballr nlHl Cotton (i()) found that exposure of 10 minutes to a tpllI[l(lratllrl of (iOO ii fatal to nil insects infesting stored rice However tl(Y (JP 1I0t sue-cessful in obbtining t satisshyfactoy kill of imects ill Ike ill a (ol1ll11(I(inl ellmiddotier operated at (iDO 101 W minutes b((nn~( tll trenhlJllt did not raise the t(mpelllture of the rice above j(J0 They stnted that Iwating fOI insect control is not Jaorpd by thl 1i((gt iJl(fllS(TY IJPel1Ie the ric( is npi to check and btllusl too ll11wll Illoi4ul( is 1(IIJ(Jmiddot(d

44 TECHNICAL BULLErIN 1120 U S DEPT OF AGRICULTCRE

Edwards and (olin (g8) and focli]) (37) haTc shown that Illoist heat is only slightly Jess destrnctive to seed viability and Jensen (3(j) observed it to be less effective than the hot-mter treatment in the bullprevention of smut in oats and barley On the other hand Miller and Mc1Vhorter (61) have demonstrated the usefnlness of vapor heat (steam-ail mixture) ns a practical means of disinfectin~ seed These investigators found that certain kinds of sc(ds -ill apparently endure considembly hil-her yapor-h(at t(Ill)l(ratII I(S than arc Ieqniled to kill all associated flln~i Thus table be(t s(ed balls will pmiddotidently tolerate a va]1or-Iwllt temperatule of about (j~8deg C Jor as 10n~ as 30 1n1nutes without siglli fkant r(duction o retnnlation of ellninntion Pl1011a behlC an nss()(iatecl patho~cn is kilkd wh(n (xposed at )72deg for 20 minutes which is about 10 loer than the phytolptha I tPllIperashytUIt Lathl ()2) uNl yaV01 h(at ill (11ldiv(ly cOlltrolling nltlcisSIIS pests

CLOSED CONTAINERS

1h( 11Iet11oltl of hNltill o((d in (Iopd conhlilHls is mOle nearly comparable -ith the 1110isl- alHl -apor-lwa nlltho(l than with litlwl the hot-water or the ntilieinllr hent(d ltIn-air I1WthOlh 1hl e~slntial differences between the 1loi-t-ll(at and (loe([-lonLaiIlPI llIethods are that in the latter the atmospheric moitule 1))esll1t is largely derived from the seed and a presoure c1eelops 1n the container which is proportional to the antilable free moisture and timl nnd temperature of treatment Yhether these lt1 i Iferll1ces oller ad1 Htnges was not cleterm i ned

rolt1il1 (J7) and agonPI (8i) IPjloltNl Ihat seeds Iwalp(l ill bulln closed COl1hlilHI cOlllll not stand -0 hih I tlmpenttlllc as 1H11 heated in nn open ye~ll or in nil (Well -hidl prrmiited the rapid elimination of atel f]()111 the (p(1 raggonpls (lain aloo shoNl clenrly that radish setlt1- llelt((l dirpdly in alel had less ltsistaneC than when they PIe l1patpltl in a elosld container

No studies (ollpajll~ tlw I(lative pfl1CiPllciCs of Ihp (lill(IPIII methods of heat trettnHllt llan l)pplI 1l11lk ill wlli(h tIll SHlIlp lot or Iiee waS used ] [owpnl in-ola I as ma V be dpt(11Il illCd I10 III Ill( litelltUle the expClin1Pllial data IPIHlltl(C 101 Iollgh Ii(( in Ihis IJltIshyIttin indicate that ric( ean toltIatp highpl t-el11l)(IlIIII(S withoul loss of viabilitv than a1( Ic(onll1HIHlld for liSP in (Ollllltpl(ial (In-ill opershyations Til (ol11lllercial dlTin the Illoislllre is (ontinuolII 1(1110((1 hom the rice and thpo)eticall the kernels sholll bl(ollle in(reasin~l resistant If it is tlll~ that the inbililV of rice mw he dp~tTold ( 10pl (emlwraflIllS ill a C011I111I(il1 dlipl han in Ii elospd tpsi ul)( ii 0111(1 pm( thai fld)r ot her Ihan hpat are also ill operatioll whi(1t aI( dl(rlldin (t) yiahilily

DIRECT CONTACT WITH LIQUII)S OTlllm TitAN WATER

Yllhon rd (88) p]Pdp(1 Cvllal IllHtplial possihlp (Ipatill~ nglIIUlt Im peasHIlIlS Hildlillla h(HI1~ Th(~( Illatllials (In (a rho II (ptladtlolid( milllIal oil Shpll eltaIlPI PIPIOlll (lthrhlll gIYIol) 111011)1 oil (S E 10) 1I)((a1 1IHlh1 alcohol kllos(II ~TI()1 lalti( bull altid sollltiollS tolllllll a(IOIH gly(rrilll lNlaL oil anilille oil olie

t~~~

bull

bull

~ C

EFFEC1S OF HEA1 TREA1lIENT ON THE VIABILITY OF RICE 45

oil sodium chloride solutions and cotton seed oil Data were tabushylated for seeds treated in carbon tetrachloride motor oil fuel oil and water at temperatures ranging from 60deg to 90deg C and for periods of 10 to 60 minutes Beans peas and lima beans were able to survive extended exposures in hot caJbon tetrachloride but they were killed in a relatiely short time ylwn exposed in water of the same temperashyture Carbon tetlachlOlide appeared to be the best medium tested and the use of hot carbon tetrachloride for destroying seed-bome organisms in peas and beans is suggested HoweveJ these ttllthors have pointed 0111 that Further researcil ill be necesSl1rY to evaluate the pJactienl IIS( of the nmte1ials amI heat on t11e control of seedshyborne pathogens

C(uiekshnnk (JQ) has nc(ntly eallie(] out a selies of prelil11ilUtry r

experiments to cleteJmine the el1ecl of n carbon fetlachloricle steep OIL

the gerl11ination and control of Spll(((I(ll(( lilwl1l1n Vollenw in two nlrieties of ]illHed-0olden Viking and Koto ] [c obtained a signifshyieant depression of ~led gelminn(lon only at 70deg a11(] 75deg O fOl 30 minuhmiddots -ith Golden Vikin and 20 minutes with Koto Germinashytion of tl1( funglls spores ns 110t obselTec1 to occur atter treatment for20 minutes at (j)Ci TOO lind )0 01 for ao minutes at GOdeg He found that carbon tetrH(hlolidc has the followin nc1Yantaes over water for th0 heat trpatnlCnt of linsNl It- i snft1 illl I(ped to ermination and 110 Hrtificial drying of till sepd i 1l(eesst1Y ~

lEW )IETHODS AND -IODlFrCATJONS

It is e-ident fr011l till information in this bulletin nwt man is a long way f1Olll ha ill) n (0111 JlIphp11si e sciPJlti fien II de1i Igtd know]shypdgp oi till (Ireets of hpllt on rice Hough riel has been c1emnnshystliltedin the expe1inlents in 1050~ 1J)l and ID32 to have It high lpsislance to hpnt fhi dlHraCtlrili( SIIutsts that heat lllight be lIsN1 eypn more extpnsiwiy than no for th0 im]lroYernent and ~tabilishyzntion of s(((l quality Certainly t 1]( tllhniqups for applying heat ill till tJpafnwnt of rite l11e by 110 means bpell fuJiy explored The pltltti(aiJility of usinl a nly hilh lpl11lWlature uHI flash-heating as well as thl llent ITPallllPnf of iee in llllc1ia other than ail and WlItpl should 1)( inlmiddotpsli)l(prl Till possibility of simultaneously ill(OrpOIat ill fllnli(iltial ubII1)(( Hnd nutrients in the hulls should a Iso bl lonsirl(ICd

SIT])mlA RY

ExpPIil1l(nU II(JP IIllcl(Ilakpll dUlin) the riee-harvesting spasons of ID) 10 and 1l)~ to ltiPlllOlI-tla(p fill (Ired of lin1( and tPlI1pemshyIUlpol hpatingoll tilt iltlJililyol~ lOlllh or pnddy riCegt (()I1jzusath(() of ltlilrel(l1t IlJOistlll[ (ontpnts Both IllPtiilll11-glain (S(1 GI-25-12 11 n(l ZCl1i til) a I1d IOllg-gla i n (HCXOIO B1mbon npl an(l Cent-ulV 5d) 1I1i(ti(s (1( used (Illllinalion laquost dala 101 Ii([ and s(p(J Jwalshy1](af111l1l1 llpi h()(ls and t Iwil applications nl( ltlisclISSP(1

If(nt tlpainHnts PI( Illa(]( nlal SOllr((fi of fnshlv (ornbineshy1Il1(S(ltI rice-Oil tIl( plpl1lisps of tll(gt ni(pExperilll(n( Siaion at Cl()WIIY La Salllpips of natllrally Illoist lol1il 1ice (1P packed in htat-1Psistant t(~st (dIes TIll Ils fllilps 1(1( light Iy stoppeled

f

46 TECHNICAL BULLETIN 1129 lJ S DEP~ OF AOlUCULTURE

and submerged ill water baths maintained at di Ife1(11 t cOllstant tem pershyatures 111 experiments to demonstrate Owelreet of temperature on viability the usual period of exposure was RO minutes after the rice reached the temperature of the hath In experim(nts to demonstrate the effect of time (duration) of heating 011 viability the periods of exposure ranged from 10 to 120 minutes Xo moisture was lost iol1l or gained acce~s to tlll rice-filled tet tubes (lmillg the periods of heat treatment The riC( in the t(st tubes was alloHltlup to 8 minutes to reach the temperature of th( bath On Colllplltioll of the heal- treatshyment the contents of the test tubes were eompoitecl and spread in a paper tray to air-dry At the conclusiol1 of ptch sensons York all the air-dried heat-tren ted sn III pl(s fOlIll hpl it 11 apploprinfp n i 1shydried controls (non-hen t-trentpltl) Yele paekagc1 in pap I balIS tmmshyfelTec1 too the Sontll(ll1 R(iolHd U(sarelt fJa bOIa IOIV X CY o11 NI ns La and stol(d at ~+c_2nl C CPllllil1al-iol1 tlcJS W(jp made on aell sampJe by the nHtholt1 pnsclilp(lIJ Ill( Flllplal S(ld cI- and were run 8 1G H and ~2 nll dlpl HI dnle of l)(at tl(ahlllnL

The gellninafiol1 ht data (OldilllI (hal high Ipl1lpltml lins a flpdld the inbilitv of naIlall 11loi1 lOlIh Iie( ill 11ll1eh tlIP -lI1W I1lal1nrl as they tllct(lt1 tlIP viabilitip of oth~r kind of SPlcls similallv lrat(d TIH iolloil1 llPlal ohcPlTati()l1- (()1l1ltl IJl 11 1lt1 c1(

FOI rOllgh li~e of (neh Illoisillll (011t(111 IIIlIl i n tllllpplatUl( of hent- treatn1(nt Iwlow hidl tlllIp is 110 ([l(Ila( ill inlJilitT

For amiddot gi(~n stlllpll of [in flIP Z01H of IIpat dnlllapvmiddot i ( Ill( range beh(Pl1 th( tlllppralllp at hiclt ltpnl- dnl1lagp (0 riahilit) just starhi amI th( tlllp(Iatml nt which it- ic ill lOlllphtl i a IIHlTO Olll

The (xtent 01 this nlllgl 101 n IllHt-tlpntllllllt plliod 0110 Illillllj-PS as not definitelv (stnlgtlishpd fDI tIH IHllIralh lIloit (ollliJilll-hantld rough rice 115((1 but ha-I] Oil nppIoxillwtioll of ill( lilllitinp Itlllshyj)erahllcs it aplwals to 1)( IJphYltlll i alld 12 ( This Inngl is aboul t11( same for 1i(p or difllIPllt 1ll0itlllt (ontpnl- hilt it i hillll 011

I lIP t(111 p(ra tlll( s(a It till 1()wPl 111( IllOiIIIIp (ontent () r t lip li(( rithin tllP ZOIlP of IW(l( ltlnlllal -101 Ii(( of a i PI1 llloilIIP (on-pnl

tIllt (llgle( or dlstTlldioll ill(I([SPS as t-1l( IPIllIPlatl1lp illCJ(ases al() 111( 101l(r tl1lt ri(( is Iwnt-tl(atpd tlll gnulPI llP ifs los-ps ill (IshyllIil1tfi()1l (npaeif-y alld gPll1lillalioll IWmiddotlI

The 1lsishll)(P of I(llgh Iicl fo (h( illlpnilIlll111 of ils Iahilily hy hpnt VflliN il1PIsP as its 1ll0i-t1l1P (middot011[(1lt

1hplI the i n b iii h () r Ii(l is cla Illn pcl by lIP t loss ill PIIll i Iln i Oil

yigor is appnr(llt lwiorc los ill PIll1iJIaI iOl1 (apa(il 1-11(111(1 tlHl( is pmiddotidI1N or Ill( laltll dq)Plllls UpOIl tlH ((Iilmiddot of nIP ITPnIlIPIlL

OClTllillatiOI1 (psis Iluul( S Hi 21 alld 2 ((ks afPI Iwatmiddot tlpallll(nlshyon ri(e f)()1H llip SHill hltlmiddotIICn((1 -lIl1plp S(OIltI at 21middot-~(iO ( did llotlcYcnl Hp[)Ipciallll (IIlllgl ill till gPlIllill1lioll igol alld IICll1linnshytion eapnCily of ihp salllpit

In (x]l(lil1Hllts wilh il1l1l1allll( Ii(p thp 11Ioistl1lllOIlI(lIi Yaliahll exc]eisp(j lpalaquo1 influllwP IlUl Ih( IIWllllit nUinhlp ill (1(tl)milliwr

Ill( rcsishilJcp of fliP i1l1l1lnllll( Hllt1 to IlP1 ltInIlUll H(clusP of lillliftd dala if (oHld lIot Il( (lp((IllliIlP(j lIPh(I the

varieties of li(Pllspd (jillpIPltl sillilicHlllh ill t Iwil 1(~i~hlIH( to 11(at ObsPlv(gtltl clillIP1HlH Pll Illill~)] lud hllip((1 ilhil1 exp(liIlHnhtl limitatiolls Fc) till lIlt 1(1lt011 i[ could 1101 )( dlfpllllillld ltcIIH1

bull

bull

bull

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

44 TECHNICAL BULLErIN 1120 U S DEPT OF AGRICULTCRE

Edwards and (olin (g8) and focli]) (37) haTc shown that Illoist heat is only slightly Jess destrnctive to seed viability and Jensen (3(j) observed it to be less effective than the hot-mter treatment in the bullprevention of smut in oats and barley On the other hand Miller and Mc1Vhorter (61) have demonstrated the usefnlness of vapor heat (steam-ail mixture) ns a practical means of disinfectin~ seed These investigators found that certain kinds of sc(ds -ill apparently endure considembly hil-her yapor-h(at t(Ill)l(ratII I(S than arc Ieqniled to kill all associated flln~i Thus table be(t s(ed balls will pmiddotidently tolerate a va]1or-Iwllt temperatule of about (j~8deg C Jor as 10n~ as 30 1n1nutes without siglli fkant r(duction o retnnlation of ellninntion Pl1011a behlC an nss()(iatecl patho~cn is kilkd wh(n (xposed at )72deg for 20 minutes which is about 10 loer than the phytolptha I tPllIperashytUIt Lathl ()2) uNl yaV01 h(at ill (11ldiv(ly cOlltrolling nltlcisSIIS pests

CLOSED CONTAINERS

1h( 11Iet11oltl of hNltill o((d in (Iopd conhlilHls is mOle nearly comparable -ith the 1110isl- alHl -apor-lwa nlltho(l than with litlwl the hot-water or the ntilieinllr hent(d ltIn-air I1WthOlh 1hl e~slntial differences between the 1loi-t-ll(at and (loe([-lonLaiIlPI llIethods are that in the latter the atmospheric moitule 1))esll1t is largely derived from the seed and a presoure c1eelops 1n the container which is proportional to the antilable free moisture and timl nnd temperature of treatment Yhether these lt1 i Iferll1ces oller ad1 Htnges was not cleterm i ned

rolt1il1 (J7) and agonPI (8i) IPjloltNl Ihat seeds Iwalp(l ill bulln closed COl1hlilHI cOlllll not stand -0 hih I tlmpenttlllc as 1H11 heated in nn open ye~ll or in nil (Well -hidl prrmiited the rapid elimination of atel f]()111 the (p(1 raggonpls (lain aloo shoNl clenrly that radish setlt1- llelt((l dirpdly in alel had less ltsistaneC than when they PIe l1patpltl in a elosld container

No studies (ollpajll~ tlw I(lative pfl1CiPllciCs of Ihp (lill(IPIII methods of heat trettnHllt llan l)pplI 1l11lk ill wlli(h tIll SHlIlp lot or Iiee waS used ] [owpnl in-ola I as ma V be dpt(11Il illCd I10 III Ill( litelltUle the expClin1Pllial data IPIHlltl(C 101 Iollgh Ii(( in Ihis IJltIshyIttin indicate that ric( ean toltIatp highpl t-el11l)(IlIIII(S withoul loss of viabilitv than a1( Ic(onll1HIHlld for liSP in (Ollllltpl(ial (In-ill opershyations Til (ol11lllercial dlTin the Illoislllre is (ontinuolII 1(1110((1 hom the rice and thpo)eticall the kernels sholll bl(ollle in(reasin~l resistant If it is tlll~ that the inbililV of rice mw he dp~tTold ( 10pl (emlwraflIllS ill a C011I111I(il1 dlipl han in Ii elospd tpsi ul)( ii 0111(1 pm( thai fld)r ot her Ihan hpat are also ill operatioll whi(1t aI( dl(rlldin (t) yiahilily

DIRECT CONTACT WITH LIQUII)S OTlllm TitAN WATER

Yllhon rd (88) p]Pdp(1 Cvllal IllHtplial possihlp (Ipatill~ nglIIUlt Im peasHIlIlS Hildlillla h(HI1~ Th(~( Illatllials (In (a rho II (ptladtlolid( milllIal oil Shpll eltaIlPI PIPIOlll (lthrhlll gIYIol) 111011)1 oil (S E 10) 1I)((a1 1IHlh1 alcohol kllos(II ~TI()1 lalti( bull altid sollltiollS tolllllll a(IOIH gly(rrilll lNlaL oil anilille oil olie

t~~~

bull

bull

~ C

EFFEC1S OF HEA1 TREA1lIENT ON THE VIABILITY OF RICE 45

oil sodium chloride solutions and cotton seed oil Data were tabushylated for seeds treated in carbon tetrachloride motor oil fuel oil and water at temperatures ranging from 60deg to 90deg C and for periods of 10 to 60 minutes Beans peas and lima beans were able to survive extended exposures in hot caJbon tetrachloride but they were killed in a relatiely short time ylwn exposed in water of the same temperashyture Carbon tetlachlOlide appeared to be the best medium tested and the use of hot carbon tetrachloride for destroying seed-bome organisms in peas and beans is suggested HoweveJ these ttllthors have pointed 0111 that Further researcil ill be necesSl1rY to evaluate the pJactienl IIS( of the nmte1ials amI heat on t11e control of seedshyborne pathogens

C(uiekshnnk (JQ) has nc(ntly eallie(] out a selies of prelil11ilUtry r

experiments to cleteJmine the el1ecl of n carbon fetlachloricle steep OIL

the gerl11ination and control of Spll(((I(ll(( lilwl1l1n Vollenw in two nlrieties of ]illHed-0olden Viking and Koto ] [c obtained a signifshyieant depression of ~led gelminn(lon only at 70deg a11(] 75deg O fOl 30 minuhmiddots -ith Golden Vikin and 20 minutes with Koto Germinashytion of tl1( funglls spores ns 110t obselTec1 to occur atter treatment for20 minutes at (j)Ci TOO lind )0 01 for ao minutes at GOdeg He found that carbon tetrH(hlolidc has the followin nc1Yantaes over water for th0 heat trpatnlCnt of linsNl It- i snft1 illl I(ped to ermination and 110 Hrtificial drying of till sepd i 1l(eesst1Y ~

lEW )IETHODS AND -IODlFrCATJONS

It is e-ident fr011l till information in this bulletin nwt man is a long way f1Olll ha ill) n (0111 JlIphp11si e sciPJlti fien II de1i Igtd know]shypdgp oi till (Ireets of hpllt on rice Hough riel has been c1emnnshystliltedin the expe1inlents in 1050~ 1J)l and ID32 to have It high lpsislance to hpnt fhi dlHraCtlrili( SIIutsts that heat lllight be lIsN1 eypn more extpnsiwiy than no for th0 im]lroYernent and ~tabilishyzntion of s(((l quality Certainly t 1]( tllhniqups for applying heat ill till tJpafnwnt of rite l11e by 110 means bpell fuJiy explored The pltltti(aiJility of usinl a nly hilh lpl11lWlature uHI flash-heating as well as thl llent ITPallllPnf of iee in llllc1ia other than ail and WlItpl should 1)( inlmiddotpsli)l(prl Till possibility of simultaneously ill(OrpOIat ill fllnli(iltial ubII1)(( Hnd nutrients in the hulls should a Iso bl lonsirl(ICd

SIT])mlA RY

ExpPIil1l(nU II(JP IIllcl(Ilakpll dUlin) the riee-harvesting spasons of ID) 10 and 1l)~ to ltiPlllOlI-tla(p fill (Ired of lin1( and tPlI1pemshyIUlpol hpatingoll tilt iltlJililyol~ lOlllh or pnddy riCegt (()I1jzusath(() of ltlilrel(l1t IlJOistlll[ (ontpnts Both IllPtiilll11-glain (S(1 GI-25-12 11 n(l ZCl1i til) a I1d IOllg-gla i n (HCXOIO B1mbon npl an(l Cent-ulV 5d) 1I1i(ti(s (1( used (Illllinalion laquost dala 101 Ii([ and s(p(J Jwalshy1](af111l1l1 llpi h()(ls and t Iwil applications nl( ltlisclISSP(1

If(nt tlpainHnts PI( Illa(]( nlal SOllr((fi of fnshlv (ornbineshy1Il1(S(ltI rice-Oil tIl( plpl1lisps of tll(gt ni(pExperilll(n( Siaion at Cl()WIIY La Salllpips of natllrally Illoist lol1il 1ice (1P packed in htat-1Psistant t(~st (dIes TIll Ils fllilps 1(1( light Iy stoppeled

f

46 TECHNICAL BULLETIN 1129 lJ S DEP~ OF AOlUCULTURE

and submerged ill water baths maintained at di Ife1(11 t cOllstant tem pershyatures 111 experiments to demonstrate Owelreet of temperature on viability the usual period of exposure was RO minutes after the rice reached the temperature of the hath In experim(nts to demonstrate the effect of time (duration) of heating 011 viability the periods of exposure ranged from 10 to 120 minutes Xo moisture was lost iol1l or gained acce~s to tlll rice-filled tet tubes (lmillg the periods of heat treatment The riC( in the t(st tubes was alloHltlup to 8 minutes to reach the temperature of th( bath On Colllplltioll of the heal- treatshyment the contents of the test tubes were eompoitecl and spread in a paper tray to air-dry At the conclusiol1 of ptch sensons York all the air-dried heat-tren ted sn III pl(s fOlIll hpl it 11 apploprinfp n i 1shydried controls (non-hen t-trentpltl) Yele paekagc1 in pap I balIS tmmshyfelTec1 too the Sontll(ll1 R(iolHd U(sarelt fJa bOIa IOIV X CY o11 NI ns La and stol(d at ~+c_2nl C CPllllil1al-iol1 tlcJS W(jp made on aell sampJe by the nHtholt1 pnsclilp(lIJ Ill( Flllplal S(ld cI- and were run 8 1G H and ~2 nll dlpl HI dnle of l)(at tl(ahlllnL

The gellninafiol1 ht data (OldilllI (hal high Ipl1lpltml lins a flpdld the inbilitv of naIlall 11loi1 lOlIh Iie( ill 11ll1eh tlIP -lI1W I1lal1nrl as they tllct(lt1 tlIP viabilitip of oth~r kind of SPlcls similallv lrat(d TIH iolloil1 llPlal ohcPlTati()l1- (()1l1ltl IJl 11 1lt1 c1(

FOI rOllgh li~e of (neh Illoisillll (011t(111 IIIlIl i n tllllpplatUl( of hent- treatn1(nt Iwlow hidl tlllIp is 110 ([l(Ila( ill inlJilitT

For amiddot gi(~n stlllpll of [in flIP Z01H of IIpat dnlllapvmiddot i ( Ill( range beh(Pl1 th( tlllppralllp at hiclt ltpnl- dnl1lagp (0 riahilit) just starhi amI th( tlllp(Iatml nt which it- ic ill lOlllphtl i a IIHlTO Olll

The (xtent 01 this nlllgl 101 n IllHt-tlpntllllllt plliod 0110 Illillllj-PS as not definitelv (stnlgtlishpd fDI tIH IHllIralh lIloit (ollliJilll-hantld rough rice 115((1 but ha-I] Oil nppIoxillwtioll of ill( lilllitinp Itlllshyj)erahllcs it aplwals to 1)( IJphYltlll i alld 12 ( This Inngl is aboul t11( same for 1i(p or difllIPllt 1ll0itlllt (ontpnl- hilt it i hillll 011

I lIP t(111 p(ra tlll( s(a It till 1()wPl 111( IllOiIIIIp (ontent () r t lip li(( rithin tllP ZOIlP of IW(l( ltlnlllal -101 Ii(( of a i PI1 llloilIIP (on-pnl

tIllt (llgle( or dlstTlldioll ill(I([SPS as t-1l( IPIllIPlatl1lp illCJ(ases al() 111( 101l(r tl1lt ri(( is Iwnt-tl(atpd tlll gnulPI llP ifs los-ps ill (IshyllIil1tfi()1l (npaeif-y alld gPll1lillalioll IWmiddotlI

The 1lsishll)(P of I(llgh Iicl fo (h( illlpnilIlll111 of ils Iahilily hy hpnt VflliN il1PIsP as its 1ll0i-t1l1P (middot011[(1lt

1hplI the i n b iii h () r Ii(l is cla Illn pcl by lIP t loss ill PIIll i Iln i Oil

yigor is appnr(llt lwiorc los ill PIll1iJIaI iOl1 (apa(il 1-11(111(1 tlHl( is pmiddotidI1N or Ill( laltll dq)Plllls UpOIl tlH ((Iilmiddot of nIP ITPnIlIPIlL

OClTllillatiOI1 (psis Iluul( S Hi 21 alld 2 ((ks afPI Iwatmiddot tlpallll(nlshyon ri(e f)()1H llip SHill hltlmiddotIICn((1 -lIl1plp S(OIltI at 21middot-~(iO ( did llotlcYcnl Hp[)Ipciallll (IIlllgl ill till gPlIllill1lioll igol alld IICll1linnshytion eapnCily of ihp salllpit

In (x]l(lil1Hllts wilh il1l1l1allll( Ii(p thp 11Ioistl1lllOIlI(lIi Yaliahll exc]eisp(j lpalaquo1 influllwP IlUl Ih( IIWllllit nUinhlp ill (1(tl)milliwr

Ill( rcsishilJcp of fliP i1l1l1lnllll( Hllt1 to IlP1 ltInIlUll H(clusP of lillliftd dala if (oHld lIot Il( (lp((IllliIlP(j lIPh(I the

varieties of li(Pllspd (jillpIPltl sillilicHlllh ill t Iwil 1(~i~hlIH( to 11(at ObsPlv(gtltl clillIP1HlH Pll Illill~)] lud hllip((1 ilhil1 exp(liIlHnhtl limitatiolls Fc) till lIlt 1(1lt011 i[ could 1101 )( dlfpllllillld ltcIIH1

bull

bull

bull

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

t~~~

bull

bull

~ C

EFFEC1S OF HEA1 TREA1lIENT ON THE VIABILITY OF RICE 45

oil sodium chloride solutions and cotton seed oil Data were tabushylated for seeds treated in carbon tetrachloride motor oil fuel oil and water at temperatures ranging from 60deg to 90deg C and for periods of 10 to 60 minutes Beans peas and lima beans were able to survive extended exposures in hot caJbon tetrachloride but they were killed in a relatiely short time ylwn exposed in water of the same temperashyture Carbon tetlachlOlide appeared to be the best medium tested and the use of hot carbon tetrachloride for destroying seed-bome organisms in peas and beans is suggested HoweveJ these ttllthors have pointed 0111 that Further researcil ill be necesSl1rY to evaluate the pJactienl IIS( of the nmte1ials amI heat on t11e control of seedshyborne pathogens

C(uiekshnnk (JQ) has nc(ntly eallie(] out a selies of prelil11ilUtry r

experiments to cleteJmine the el1ecl of n carbon fetlachloricle steep OIL

the gerl11ination and control of Spll(((I(ll(( lilwl1l1n Vollenw in two nlrieties of ]illHed-0olden Viking and Koto ] [c obtained a signifshyieant depression of ~led gelminn(lon only at 70deg a11(] 75deg O fOl 30 minuhmiddots -ith Golden Vikin and 20 minutes with Koto Germinashytion of tl1( funglls spores ns 110t obselTec1 to occur atter treatment for20 minutes at (j)Ci TOO lind )0 01 for ao minutes at GOdeg He found that carbon tetrH(hlolidc has the followin nc1Yantaes over water for th0 heat trpatnlCnt of linsNl It- i snft1 illl I(ped to ermination and 110 Hrtificial drying of till sepd i 1l(eesst1Y ~

lEW )IETHODS AND -IODlFrCATJONS

It is e-ident fr011l till information in this bulletin nwt man is a long way f1Olll ha ill) n (0111 JlIphp11si e sciPJlti fien II de1i Igtd know]shypdgp oi till (Ireets of hpllt on rice Hough riel has been c1emnnshystliltedin the expe1inlents in 1050~ 1J)l and ID32 to have It high lpsislance to hpnt fhi dlHraCtlrili( SIIutsts that heat lllight be lIsN1 eypn more extpnsiwiy than no for th0 im]lroYernent and ~tabilishyzntion of s(((l quality Certainly t 1]( tllhniqups for applying heat ill till tJpafnwnt of rite l11e by 110 means bpell fuJiy explored The pltltti(aiJility of usinl a nly hilh lpl11lWlature uHI flash-heating as well as thl llent ITPallllPnf of iee in llllc1ia other than ail and WlItpl should 1)( inlmiddotpsli)l(prl Till possibility of simultaneously ill(OrpOIat ill fllnli(iltial ubII1)(( Hnd nutrients in the hulls should a Iso bl lonsirl(ICd

SIT])mlA RY

ExpPIil1l(nU II(JP IIllcl(Ilakpll dUlin) the riee-harvesting spasons of ID) 10 and 1l)~ to ltiPlllOlI-tla(p fill (Ired of lin1( and tPlI1pemshyIUlpol hpatingoll tilt iltlJililyol~ lOlllh or pnddy riCegt (()I1jzusath(() of ltlilrel(l1t IlJOistlll[ (ontpnts Both IllPtiilll11-glain (S(1 GI-25-12 11 n(l ZCl1i til) a I1d IOllg-gla i n (HCXOIO B1mbon npl an(l Cent-ulV 5d) 1I1i(ti(s (1( used (Illllinalion laquost dala 101 Ii([ and s(p(J Jwalshy1](af111l1l1 llpi h()(ls and t Iwil applications nl( ltlisclISSP(1

If(nt tlpainHnts PI( Illa(]( nlal SOllr((fi of fnshlv (ornbineshy1Il1(S(ltI rice-Oil tIl( plpl1lisps of tll(gt ni(pExperilll(n( Siaion at Cl()WIIY La Salllpips of natllrally Illoist lol1il 1ice (1P packed in htat-1Psistant t(~st (dIes TIll Ils fllilps 1(1( light Iy stoppeled

f

46 TECHNICAL BULLETIN 1129 lJ S DEP~ OF AOlUCULTURE

and submerged ill water baths maintained at di Ife1(11 t cOllstant tem pershyatures 111 experiments to demonstrate Owelreet of temperature on viability the usual period of exposure was RO minutes after the rice reached the temperature of the hath In experim(nts to demonstrate the effect of time (duration) of heating 011 viability the periods of exposure ranged from 10 to 120 minutes Xo moisture was lost iol1l or gained acce~s to tlll rice-filled tet tubes (lmillg the periods of heat treatment The riC( in the t(st tubes was alloHltlup to 8 minutes to reach the temperature of th( bath On Colllplltioll of the heal- treatshyment the contents of the test tubes were eompoitecl and spread in a paper tray to air-dry At the conclusiol1 of ptch sensons York all the air-dried heat-tren ted sn III pl(s fOlIll hpl it 11 apploprinfp n i 1shydried controls (non-hen t-trentpltl) Yele paekagc1 in pap I balIS tmmshyfelTec1 too the Sontll(ll1 R(iolHd U(sarelt fJa bOIa IOIV X CY o11 NI ns La and stol(d at ~+c_2nl C CPllllil1al-iol1 tlcJS W(jp made on aell sampJe by the nHtholt1 pnsclilp(lIJ Ill( Flllplal S(ld cI- and were run 8 1G H and ~2 nll dlpl HI dnle of l)(at tl(ahlllnL

The gellninafiol1 ht data (OldilllI (hal high Ipl1lpltml lins a flpdld the inbilitv of naIlall 11loi1 lOlIh Iie( ill 11ll1eh tlIP -lI1W I1lal1nrl as they tllct(lt1 tlIP viabilitip of oth~r kind of SPlcls similallv lrat(d TIH iolloil1 llPlal ohcPlTati()l1- (()1l1ltl IJl 11 1lt1 c1(

FOI rOllgh li~e of (neh Illoisillll (011t(111 IIIlIl i n tllllpplatUl( of hent- treatn1(nt Iwlow hidl tlllIp is 110 ([l(Ila( ill inlJilitT

For amiddot gi(~n stlllpll of [in flIP Z01H of IIpat dnlllapvmiddot i ( Ill( range beh(Pl1 th( tlllppralllp at hiclt ltpnl- dnl1lagp (0 riahilit) just starhi amI th( tlllp(Iatml nt which it- ic ill lOlllphtl i a IIHlTO Olll

The (xtent 01 this nlllgl 101 n IllHt-tlpntllllllt plliod 0110 Illillllj-PS as not definitelv (stnlgtlishpd fDI tIH IHllIralh lIloit (ollliJilll-hantld rough rice 115((1 but ha-I] Oil nppIoxillwtioll of ill( lilllitinp Itlllshyj)erahllcs it aplwals to 1)( IJphYltlll i alld 12 ( This Inngl is aboul t11( same for 1i(p or difllIPllt 1ll0itlllt (ontpnl- hilt it i hillll 011

I lIP t(111 p(ra tlll( s(a It till 1()wPl 111( IllOiIIIIp (ontent () r t lip li(( rithin tllP ZOIlP of IW(l( ltlnlllal -101 Ii(( of a i PI1 llloilIIP (on-pnl

tIllt (llgle( or dlstTlldioll ill(I([SPS as t-1l( IPIllIPlatl1lp illCJ(ases al() 111( 101l(r tl1lt ri(( is Iwnt-tl(atpd tlll gnulPI llP ifs los-ps ill (IshyllIil1tfi()1l (npaeif-y alld gPll1lillalioll IWmiddotlI

The 1lsishll)(P of I(llgh Iicl fo (h( illlpnilIlll111 of ils Iahilily hy hpnt VflliN il1PIsP as its 1ll0i-t1l1P (middot011[(1lt

1hplI the i n b iii h () r Ii(l is cla Illn pcl by lIP t loss ill PIIll i Iln i Oil

yigor is appnr(llt lwiorc los ill PIll1iJIaI iOl1 (apa(il 1-11(111(1 tlHl( is pmiddotidI1N or Ill( laltll dq)Plllls UpOIl tlH ((Iilmiddot of nIP ITPnIlIPIlL

OClTllillatiOI1 (psis Iluul( S Hi 21 alld 2 ((ks afPI Iwatmiddot tlpallll(nlshyon ri(e f)()1H llip SHill hltlmiddotIICn((1 -lIl1plp S(OIltI at 21middot-~(iO ( did llotlcYcnl Hp[)Ipciallll (IIlllgl ill till gPlIllill1lioll igol alld IICll1linnshytion eapnCily of ihp salllpit

In (x]l(lil1Hllts wilh il1l1l1allll( Ii(p thp 11Ioistl1lllOIlI(lIi Yaliahll exc]eisp(j lpalaquo1 influllwP IlUl Ih( IIWllllit nUinhlp ill (1(tl)milliwr

Ill( rcsishilJcp of fliP i1l1l1lnllll( Hllt1 to IlP1 ltInIlUll H(clusP of lillliftd dala if (oHld lIot Il( (lp((IllliIlP(j lIPh(I the

varieties of li(Pllspd (jillpIPltl sillilicHlllh ill t Iwil 1(~i~hlIH( to 11(at ObsPlv(gtltl clillIP1HlH Pll Illill~)] lud hllip((1 ilhil1 exp(liIlHnhtl limitatiolls Fc) till lIlt 1(1lt011 i[ could 1101 )( dlfpllllillld ltcIIH1

bull

bull

bull

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

46 TECHNICAL BULLETIN 1129 lJ S DEP~ OF AOlUCULTURE

and submerged ill water baths maintained at di Ife1(11 t cOllstant tem pershyatures 111 experiments to demonstrate Owelreet of temperature on viability the usual period of exposure was RO minutes after the rice reached the temperature of the hath In experim(nts to demonstrate the effect of time (duration) of heating 011 viability the periods of exposure ranged from 10 to 120 minutes Xo moisture was lost iol1l or gained acce~s to tlll rice-filled tet tubes (lmillg the periods of heat treatment The riC( in the t(st tubes was alloHltlup to 8 minutes to reach the temperature of th( bath On Colllplltioll of the heal- treatshyment the contents of the test tubes were eompoitecl and spread in a paper tray to air-dry At the conclusiol1 of ptch sensons York all the air-dried heat-tren ted sn III pl(s fOlIll hpl it 11 apploprinfp n i 1shydried controls (non-hen t-trentpltl) Yele paekagc1 in pap I balIS tmmshyfelTec1 too the Sontll(ll1 R(iolHd U(sarelt fJa bOIa IOIV X CY o11 NI ns La and stol(d at ~+c_2nl C CPllllil1al-iol1 tlcJS W(jp made on aell sampJe by the nHtholt1 pnsclilp(lIJ Ill( Flllplal S(ld cI- and were run 8 1G H and ~2 nll dlpl HI dnle of l)(at tl(ahlllnL

The gellninafiol1 ht data (OldilllI (hal high Ipl1lpltml lins a flpdld the inbilitv of naIlall 11loi1 lOlIh Iie( ill 11ll1eh tlIP -lI1W I1lal1nrl as they tllct(lt1 tlIP viabilitip of oth~r kind of SPlcls similallv lrat(d TIH iolloil1 llPlal ohcPlTati()l1- (()1l1ltl IJl 11 1lt1 c1(

FOI rOllgh li~e of (neh Illoisillll (011t(111 IIIlIl i n tllllpplatUl( of hent- treatn1(nt Iwlow hidl tlllIp is 110 ([l(Ila( ill inlJilitT

For amiddot gi(~n stlllpll of [in flIP Z01H of IIpat dnlllapvmiddot i ( Ill( range beh(Pl1 th( tlllppralllp at hiclt ltpnl- dnl1lagp (0 riahilit) just starhi amI th( tlllp(Iatml nt which it- ic ill lOlllphtl i a IIHlTO Olll

The (xtent 01 this nlllgl 101 n IllHt-tlpntllllllt plliod 0110 Illillllj-PS as not definitelv (stnlgtlishpd fDI tIH IHllIralh lIloit (ollliJilll-hantld rough rice 115((1 but ha-I] Oil nppIoxillwtioll of ill( lilllitinp Itlllshyj)erahllcs it aplwals to 1)( IJphYltlll i alld 12 ( This Inngl is aboul t11( same for 1i(p or difllIPllt 1ll0itlllt (ontpnl- hilt it i hillll 011

I lIP t(111 p(ra tlll( s(a It till 1()wPl 111( IllOiIIIIp (ontent () r t lip li(( rithin tllP ZOIlP of IW(l( ltlnlllal -101 Ii(( of a i PI1 llloilIIP (on-pnl

tIllt (llgle( or dlstTlldioll ill(I([SPS as t-1l( IPIllIPlatl1lp illCJ(ases al() 111( 101l(r tl1lt ri(( is Iwnt-tl(atpd tlll gnulPI llP ifs los-ps ill (IshyllIil1tfi()1l (npaeif-y alld gPll1lillalioll IWmiddotlI

The 1lsishll)(P of I(llgh Iicl fo (h( illlpnilIlll111 of ils Iahilily hy hpnt VflliN il1PIsP as its 1ll0i-t1l1P (middot011[(1lt

1hplI the i n b iii h () r Ii(l is cla Illn pcl by lIP t loss ill PIIll i Iln i Oil

yigor is appnr(llt lwiorc los ill PIll1iJIaI iOl1 (apa(il 1-11(111(1 tlHl( is pmiddotidI1N or Ill( laltll dq)Plllls UpOIl tlH ((Iilmiddot of nIP ITPnIlIPIlL

OClTllillatiOI1 (psis Iluul( S Hi 21 alld 2 ((ks afPI Iwatmiddot tlpallll(nlshyon ri(e f)()1H llip SHill hltlmiddotIICn((1 -lIl1plp S(OIltI at 21middot-~(iO ( did llotlcYcnl Hp[)Ipciallll (IIlllgl ill till gPlIllill1lioll igol alld IICll1linnshytion eapnCily of ihp salllpit

In (x]l(lil1Hllts wilh il1l1l1allll( Ii(p thp 11Ioistl1lllOIlI(lIi Yaliahll exc]eisp(j lpalaquo1 influllwP IlUl Ih( IIWllllit nUinhlp ill (1(tl)milliwr

Ill( rcsishilJcp of fliP i1l1l1lnllll( Hllt1 to IlP1 ltInIlUll H(clusP of lillliftd dala if (oHld lIot Il( (lp((IllliIlP(j lIPh(I the

varieties of li(Pllspd (jillpIPltl sillilicHlllh ill t Iwil 1(~i~hlIH( to 11(at ObsPlv(gtltl clillIP1HlH Pll Illill~)] lud hllip((1 ilhil1 exp(liIlHnhtl limitatiolls Fc) till lIlt 1(1lt011 i[ could 1101 )( dlfpllllillld ltcIIH1

bull

bull

bull

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

EFFECTS OF HEAT TREATlIENT ON THE VIABILITY OF RICE 47

the total pressures deye]oped ]n the test tubes of packed rice durin heat treatment had ailY significant effect on the viabi1ity of the heat~ treated seed

Vh(ll the approximated temperatures defining the range of heat damage to yiability were plotted for seyeral samples of rice of (lijferent moisture contents scatter-type diagram was obtained in w11ic11 n

zone of heat damage is clearly jndicated Such lL diagram should have practical value in research and CommelTitll operations invohing the heat treatment of rice and it might Hccorcling to the meth-od of dershyivation SetTe as a hc t-c1amagc prediction chart for viability or milling quality

LITERATITRE CITED (1) AnAIII ( nOY Inltl (nLlIY E1

Il)) 11(1 IlItEImiddotJlIn 111 nII~RI (OXTIOL ITIlIE IX AIKAXSAS 1JI0 TO 1 HII Imiddotk -rr EXJlI SII Hul )) uP

() ALAI CU 10W fWmXrIFIC IIEIDI OF TIll HItI IESIll( II TTIOX SIlUllI BTiL1l

Xl) (1ISS FOit TIlE YIH EXIJlXlt lIBT ~II( 1ll4 Uihnr Ind ()Ii~s( Dlt111 Ag Illll of Il) 11 pp illll

(l)

ArIIJIW PICIt) L niH] KI I1J 11110111

ll)O Hf(E 1l1Y1XG T(gtxbull I IxpL ~tn lrog Rpt 12(4 2 PIl [11O((gtgtptl ]

(4) --- and KUAIlI1 IJUOl1l

IIl5( CO~Dmlltl] UItI IlllJER ~TliJ)lImiddotS Tlxbullbullgr Expt Rtl Irog- Rpt

bull 1)~1 PL) [Pro((~ld1 [10 ill Ri(p Iour )0 (-I) 2R 4G 1)jtJ

()) ASSO(lATIOX OF OFFHTH EIW XArYSTSbull

ll4l In-IE FOR TIlI1( 1111gt 0( 01T ~((ltl Alllll ]loC 10 2J-)(u) CTXSDFl- U wa ollxnx A (

] )() TllE I iT OF (J-IWL REEIIS BY nllY 1111 Jour g-1 Res l8 )-WO

el bull ElIXI 1

llH nl 1ltXTXIS Dim KJoIIlxnsPIIYSlOLOGTE OX OIY STIA (ulns) Fiihlillg LnIH] Ztr n IS-l~

(R) AUTH~Y HJtRY ~ GHlGOUI~FF IVbullITs(lln ~1 nlJ(l Bonlx J T 10)) HICE IILrJX(-~FFE(lS n[middot- ~IIILIX( (OIlITIOXB O 1I11middotKm OF HICE

(iItIIXS four Ag1 and Food Ch(llI H )n)i)) illusen B(K K lnd (OTTDX It T Y ] )1 IlEITImiddotI IEI1-(I OF TIl Elan IEYIL SITClI II 111 S OIYZA 1 AXil

lIIE (ltAXIY I-Enl S GIAXAHIlS 1 TO lfrclll AXil 10 TI~IshylFIAT(middotIIS fUIIIbullbullrlmiddot rllS 2l 1O-1--1O-1

110) JbCzln nImiddotST r l n(J (orros n ~r 1 nmiddotlT 1XSI-(I PESTS OF STOHlW Ill(l~ AXil nmllt COXIIOI U S D([Jt Agr

Fa rnJ(ls Bill H)(H I(Y 2-1 )1)1 illlls (II J nlIcam E L ImiddotJ(iJImiddotn KYII- nnd ill0 [PSOl bull H

WmiddotI( 111 lXIT IllJEn FOrt (O~IIl[SEIJ lI(nbullbullgI I~l1gil1 -l a)-~nil I liS

( 1 1 Blel H 1 111(1 (ooxnon L G I)) IIlLK IlllnX( 11 STltlJI(iJ OF Iln ox Ill E FAIDI AI Engin 31

158 ](jO IG Himiddotl ill us r1) BOIlXAIl GJonm- 1

1l OI)lAflOX OF mn wnms rx 1IIFOnXrA WITH rOw Alit TE~lllmAshyITIWS Arr Eugin 1 middotI)~l illll

(l-I) I3nx IJ XED JI FS Tn

bull 1l)I Tnmiddot IJI-SIX AXil OJgtIIIIn III 1-111 SlF GIIlX 11I(mn [)Iastcls

th(i 1 ppbull illu Ln Stll lTIli rn(on Houg-pl(Hi) B lI(rass 1 ~IIS L

])]) JI~INI[()X 01lt AltnXU UEcnEIS (W 111gt1 TO THE n)IIITY OJ SlmllS N C DlpL _-rlmiddot BulmiddotHl lliJ 0-11 [10 iii IIllI ~(ltmiddot AglOll JOIlI 11 ]] lO Iml shy

(H) (ooxnl) L (kollm

In IJllnXU AXil STOIIA( OF HOlIm H[I ilkI Ann llJ 2R

Jt-~ oilt ~ ~ f j

TECHNICAL BULLETIN 1129 u S DEPT OF AGRICULTURE

(IT) COTTON HICHAm) I IJplusmnl 1O(SI(I P~STS (lb STOftEIl GIIAIX XIl GHAIX IHOIltCTS IfHXfIfrc shy

l[ON lIAflIfS A(1l ~Ef1I0flS 01 CONTIWL 2-12 JIll illm llIinueshyIIpolis

(18) CRAILEr E )I 102 CONTftOL O~ WHITE TTl OF RllI Ark Farm Rps 1 (1) [oj

(IU) CRUICKSIIANK 1 A M IO)-L 11IEIDIO-CIII_IlCL SEEIl THIAfmNl Nntllrl [Londonl 11 2l7shy

21K iIIllS (20) CftU~ 8NII(10 R lnd LFOHTI~ AX81)IO

100 1(lIlllII mY1(o (W ItlllGII m(E EnginTolll pranilnl 1 20-21 iI I IIi

(21) DA FA(O AXXA

I)Hl snI HEIDIINABIIIT DEI mso [OHYZ STImiddot1 Ill GitfIR(O [Zlc )IYs1 1X ItAllOWIO 11 n)IIIXITH Ill 11 1-~IIIIIT lt Bot flllll n I-nh- Pali tti Ispr II I Hi 1-0 illui

(22) DASITIt R H lind I )E8AI R ~1 [ IUiJ ~Ifm ltIIIOX 1l10XIIII (IIIOIlYIlITI IITIO I 1111 EICOBIl AXil TilE0 XAImiddotftOIliC IISIIItTIOX OF Iun 1111 Bot ILondpnl Il) -(lf i1lmi

(23) nEA GEOHI A- JJlll IIENI S A ~IENS OF (middotOIICOIII 1 I~E(TS TOlil [lt(011 EliI-

H-Hil il1S

(20 101 gt llIIIIII I)TA os 11 A8 1 E~ nv (()ST10LII so 1111 [XE(IS

10111 1-(011 J111t Ii -IO~- (2) DIXOS lIEItY H

1001 IIAIIIY IW Ims atIl~ [Lonrlol11 Ii- (j-2(20)

1)()2 ox Tlfl~ 111DIISTIOX OF SEEIlS AITEIl ESIORIln TO IIIGH m)IfIWAshyIlI1oS Tliliity (01 Dllhlill nol ~(liofll ((11( I 1(-1S(i

(2) 1)O HESISTXCg IW slmns Tn IIIGII 1111111111gt Blit SOC ~l

Sc-i Rpt -(11 K 11 Ill I -0 (21) EIlWAlWS ~L 111111 (OII~_

lR1-t IH lrILE(I IlE r I1IIIIlITII Wlt I (iEIt~1 rXATW AIIII d(gts ~(i Nn t 11m 111 2) 1 2 -20

(2)) l~N(1L1~Il Knbull I lid ICEJ ZIX

HI-lJ AIIIII(middotII IIIYIG W (()~IIIIXEIl IIIl1- gr 1IIgili 2 )middotno ill 1~

10) ]1RYOfN P R ])In (IIX( IX IIIITY OF I~)IImiddotS SOIIIII1- (middotI1I0IlYIIHTESbullbull~D Xshy

EXSII) OV IlESIIHA1I0X (IF 11(10 sllms IDIIII( (IIEIl nl Iallt Ihysiol 11 x21-K~2 ills

(31) HAIIEIIIANflT IHnIlI

lS(i3 EIIEI 111 11 11 lS 1 EH II Ii II EIEX IElIIIAII1l IF 1111 III 11_

1I1(KII IIEIl ~IX ImiddotXSII1l (IITtmiddotIlIFIAX~I AliI Llnd- u FOIt Zt~ (~(l f) 1 1S)-nt

(H2) HijlfXEI FIl~

IS EI(I WiIDIIlilIJImiddot TIlOIKIXi SII IHTH 11 0111 DII KEIIshy-XIIIIIImiddotII 1middotI)wllisSImiddotX i-llakL [111(111111 Opil Iflnll shyzPlliln IIli 2 bullbull-SD

(~l) HIICIT fNS() 1 H ln4-1 rIJi IlftYIn 01 WIlImiddotI III ITIE 11lt1-1(1 ()V TI~IIUTmiddotIIE ON

11111 S TIOX (ITI) rIII -0( lI1III 111lt1 Ii 10middot110 ill II S

(3-1) --- GlOmI R find Tllos 1 T lJlli 1111 111(1 IN n1t11 SEI(IlS iia(lIl( I LOIHlolI] 11 lO 121

illn (3) ) hSKINS I ~l 11(11111

1l-1J 11111 (JIlSI-HIIOXS AI 1111 IHI XII-II)IISI 8middotIII()1 (11011 1 Io01t 1111 TIIIII-IIIH1E-YIAlt IIUIOII 11I0 TO IllI IX(flSII~bullt Ln A~Imiddot Imiddotxpi ~In Iul 10 2j lip

(ao) J~SImiddotX J rI 11-- 1111 IIIOIltlmiddotImiddotIO 11 IHInmiddotIIO OF tI TN OATS AII BAItIIY

bull

bullHoy AgT ~II( ElIgl lid J (llil Ipl 2) 2-1 J--11

EFFECTS OF HEAT TREATMENT ON THE VIABILITY OF RICE 49

(37) JOUlN VlUTon l~n) SUit IA ItiSTST~INCE Ims GItAINES ATN n~(IIltNILItES 1~IEJhs

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EJEAT TREAlMENT ON THE VIABILITY ~F JUCE 51

(79) STIltNHlAN E JBODNAR G P and HATES E N 10l1 TESTS ON RESISTNCE TO TH~ 1ASSAGE m All lllHOeGII IWUGU lUCE

IN ~ DEEP BIN Agr Engin 12 145-148 illus (80) ~AxAHAsIn T

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(81) TAYIOIl DfIJ L lH2 INFJnNCE on OXYGEN TENSION ON RESPIllATION FEIDIFNTAIION AND

GROWTH IN WHEAr AND BICE Amer Jour Hot- W 721-718 ilius (82) TISnu r II

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EJEAT TREAlMENT ON THE VIABILITY ~F JUCE 51

(79) STIltNHlAN E JBODNAR G P and HATES E N 10l1 TESTS ON RESISTNCE TO TH~ 1ASSAGE m All lllHOeGII IWUGU lUCE

IN ~ DEEP BIN Agr Engin 12 145-148 illus (80) ~AxAHAsIn T

lOOG IS GEID[1NATION 10ssmLE IN AllSENCE OF AIR Tokyo Imp Cuiv Col Lgr Dul (j 480-442

(81) TAYIOIl DfIJ L lH2 INFJnNCE on OXYGEN TENSION ON RESPIllATION FEIDIFNTAIION AND

GROWTH IN WHEAr AND BICE Amer Jour Hot- W 721-718 ilius (82) TISnu r II

1J22 SggnlIXG BTGn] AND STACK-BeBN (1 nWE AND TIlE I[OT-WTER SEED TlaADrEltT r_ R Dept Agr Bnl 1116 11 l1P ilIds

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