international rice research newsletter vol.1 no.1

2 IRRN 1:1 (OCTOBER 1976)

Editorial THIS IS THE FIRST ISSUE of the International Rice Research Newsletter (IRRN).

Its primary objective is to expedite communication among scientists concerned with the development of improved technology for rice and for rice-based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land-scarce nations in the world.

The international community of rice scientists at present has no ready means of communicating with each other on timely topics of mutual interest. Formal research papers are generally sent to the various discipline-oriented scientific journals, while papers of more local interest are distributed as mimeographed reports, station bulletins, or workshop reports. In most cases, such reports receive only local distribution. The net effect is that currently rice scientists have no ready channel for communicating with each other, particularly on the international level. Furthermore, the communication is slow and time consuming. Scientists must have access to well-stocked libraries to review papers published in the many discipline-oriented journals. And most libraries do not have a collection of local research reports from other countries.

The IRRN is a mechanism to help rice scientists keep each other informed of current research findings. Scientists working on rice and rice-based cropping systems are invited to contribute short, concisely written summaries of significant research. The IRRN is organized on a problem-area basis to make it convenient for scientists in one discipline to keep abreast of the work in other disciplines on problems of mutual interest and concern. These areas are: • Genetic evaluation and utilization • Constraints on rice yields • Pest management and control • Consequences of new rice technology • Irrigation water management • Rice-based cropping systems • Soil and crop management • Machinery development and testing • Rice and the environment • Post-harvest management

It is expected that the concise articles contained in the IRRN will encourage rice scientists and workers to communicate with each other. In this way, readers can obtain more detailed information on research reported in this newsletter.

The International Rice Research Institute is pleased to publish this new newsletter. We hope it will improve the level and rate of exchange of information among scientists concerned with rice and rice-based cropping systems.

N. C. Brady Directo General

Genetic evaluation & utilization OVERALL PROGRESS

Sources of disease and insect resistance in selections of improved plant type

Gurdev S. Khush, Rodolfo Aquino, and Rizal Herrera, International Rice Research Institute

Incorporation of disease and insect resistance into improved germ plasm is a major objective of the IRRI GEU program. The several donor parents that have been used as sources of resistance to each major disease and insect have poor plant type (tall with weak stems and droopy leaves). They were crossed with rices of improved plant type such as

Semidwarf lines with good grain quality and resistance to specific diseases or insects were selected and evaluated for several seasons and intercrossed to develop lines with multiple resistance. The combining ability of each line was determined from the performance of hybrid progeny that resulted from a series of crosses involving the line. Only the progeny with good combining ability were saved.

TN1, IR8, IR262-43-8, and IR24.

We used several sources of resistance to each pest and disease except grassy stunt virus, for which Oryza nivara is the only source of resistance. For blast, such donor parents as Gam Pai 15, H 105, Sigadis, Nahng Mon S-4, Dawn, Zenith, Kam Bau Ngan, and Tetep were used. For bacterial blight we used Zenith, Malagkit Sungsong, TKM6, Sigadis, Wase Aikoku 3, BJ1, and DZ 192. For tungro, we used Gam Pai 15, TKM6, Peta, Pankhari 203, Malagkit Sungsong, HR21, C013, and Ptb 18.

Five genes for resistance to green leafhopper are known; three of them have been incorporated into rices of the semidwarf plant type. Of the four known genes for resistance to brown planthopper, two have been transferred into selections of improved plant type. Genes for resistance to different diseases and insects have been studied in various combinations.

A list of 110 selections, with data on their parents, their accession numbers, and their reactions to blast, bacterial blight, tungro, and grassy stunt diseases, and to the green leafhopper and brown

IRRI can provide scientists with seeds and a description of 110 elite rice lines that have been selected for disease and insect resistance. A major aim of IRRI's GEU program is to incorporate resistance into improved germ plasm. Rizal Herrera, senior research assistant, plant breeding, makes cross.

planthopper, is available at the IRRI plant breeding department. The lines may be used instead of tall donor parents in hybridization programs as sources of disease and insect resistance. Scientists in national programs may obtain lists of these 110 elite lines, and their seeds, from the IRRI Plant Breeding Department.

Impact of semidwarfs on the area planted, production, and yield of rice in the Punjab of India

S. S. Saini, Punjab Agricultural University Regional Rice Research Station, Kapurthala, Punjab, India

The landlocked state of the Punjab lies within latitudes 29°30' to 39°30' north and longitudes 73°55' to 76º50' east in the Indo-Gangetic Plain of northern India. One of the smaller states of India, it has an area of 50,376 sq km which is alluvial in nature. It has two main crop-sowing seasons, the rabi (October – November) and kharif (June – July). The important rabi crops are wheat, gram, barley, grapes, and mustard. The main kharif crops are rice, maize, cotton, groundnuts, bajra (pearl millet), and sugarcane. The Punjab gained importance for its wheat production which increased by more than 2½ times: from 1,900,000 tons in 1965 – 66 to 5,300,000 tons in 1975 – 76. Average wheat yields have gone up from 1.2 to 2.3 t/ha over the same period.

Rce yields in the Punjab are among the highest in India. Rice now seems to be the most profitable kharif crop. The traditional rice varieties such as Jhona 20, Jhona 277, Jhona 349, Palman 246, Basmati 217, and Basmati 370 are weak strawed and tall (150 – 200 cm). They lodge badly when fertilized, so their yield is stabilized at around 1 t/ha. Rice cultivation was previously confined to fields where no other kharif crop could be grown – fields that were waterlogged or affected by salinity or alkalinity. After the introduction of varieties of the semidwarf plant type that are responsive to high fertilization – such as Taichung Native 1 in 1965, IR8 in 1968, Jaya

IRRN 1:1 (OCTOBER 1976) 3

The RD series of rice varieties developed in Thailand from 1969 to 1975

Rice Division, Department of Agriculture, Ministry of Agriculture and Cooperatives, Thailand

The release of the RD (Rice Division) series of varieties began in 1969 with RDl, RD2, and RD3 and has now progressed to RD9. Glutinous varieties are denoted by even numbers. So far, all releases are essentially insensitive to photoperiod, fall into the general classification of high-yielding varieties, and conform to the Thai grain standards for class 1 milled grain.

The most widely grown new variety is RD1 (LT/IR8). More than 70 percent of the dry-season planting in irrigated areas is estimated to be devoted to it. In recent years, however, its spread has been slowed by bacterial blight and, recently, by brown planthoppers in some fields.

RD2 (TN1/Gam Pai 15) was intended for the areas of north and northeast Thailand where consumers prefer glutinous rice. But it has not been popular among farmers in the northeast, probably because it is short and lacks photoperiod sensitivity. Susceptibility to bacterial blight and to gall midge may also limit its use.

RD3 (LT/IR8) was intended for areas where farmers apply only minimal inputs of fertilizer and other management practices. Data collected before its release suggest that it competes better with weeds and produces higher yields than RD1 at low fertilizer levels. But RD3 has not found favor with most farmers, probably because of its extreme susceptibility to bacterial blight, and long flag leaves that prevent easy visibility of panicles.

it has also yielded higher than Ratna or Jaya. Kranti matures in 120 days when planted in kharif (June-October) so it fits well into double and multiple cropping patterns.

Its grain is short and bold with shiny strawcolored husk. Its cooking quality is good. Kranti has field resistance to bacterial blight, blast, and false smut.

Changes in rice area, production, and yield after the introduction of varieties of the new plant type. Punjab Agricultural University Rice Research Station, Kapurthala, Punjab, India.

Year Area planted

to rice (1000 ha)

Production of milled rice (1000 t) (t/ha)

Yield Area planted to

semidwarf varieties (1000 ha) (%)

1950 1955 1960 1965

1966 1967 1968 1969 1970

1971 1972 1973 1974 1975

120 149 227 292

285 314 345 350 390

450 476 498 570 566

107 107 220 292

338 415 470 535 688

920 955

1140 1181 1445

0.79 0.72 1.1 1.0

1.2 1.3 1.4 1.5 1.8

2.0 2.0 2.1 2.1 2.6

1 5 8

20 38

73 79 84 88 91

4 17 27 72

143

31 1 378 450 500 500

in 1969, and Palman 579 (IR579-48-1-2) in 1971—the rice crop in the state changed progressively (see table). The area under high-yielding varieties (HYV) increased from 1 percent in 1966 to more than 90 percent in 1975. Correspondingly, rice yield increased from 1.2 to 2.6 t/ha. Total area in rice also increased from 285,000 to 566,000 ha and rice is now being grown on soils where other kharif crops were previously grown. All these factors— particularly the area under HYV—are

responsible for an increase in rice production in the state from 292,000 tons in 1965 to 1,445,000 tons in 1975—about a fivefold increase. Because the majority of the Punjab population do not consume rice, most of the state’s production is saved for the Central Rice Pool. In 1975, the Punjab made the highest contribution of any state, 1,100,000 tons of rice, which made up more than 35 percent of the pool.

A new rice variety, Kranti, bred by Jawaharlal Nehru Agricultural University Research Station, Raipur

P. S. Shrivastava, rice breeder, Rice Research Station, Raipur, India

A new rice variety, Kranti (sel. no. R 2022), has been developed by the Central Rice Research Station, Raipur,

India, working under Jawaharlal Nehru Agricultural University, Madhya Pradesh. It derives from the cross C-l16/IR8. C-116 is a variety bred from a cross between two local varieties, Bhondu and Parewa. Kranti is slightly taller than Jaya (105 vs. 95 cm) so it does better under rainfed conditions than other semidwarfs. Under irrigated conditions

Mean paddy yield of Kranti (R 2022) in several villages. Rice Research Station, Raipur, India.

Paddy yield (kg/ha)

1974 1975 Variety

Irrigated Nonirrigated Irrigated

4813 3890 -

607

Nonirrigated

6812

5689 -

Kranti (R 2022) Ratna Anupama

1739 1499

4537

3204 -

-

C.D. 5% - 428 399


- - - -

- - - -

RD4 is a short-strawed, early variety from the cross LT/IR8//W1252///RD2. & was intended as a stopgap measure for Farmers in areas of heavy gall midge infestation (in parts of the north and northeast, gall midge losses of as much as 75% occur frequently). A major complaint against RD4 has been its poor eating quality due to high gelatinization temperature which is not typical of the local varieties. RD4 is expected to make inroads in localities where gall midge is severe.

RD5 (PN 16/Sigadis) was the first attempt to produce an intermediate- height, stiff-strawed, late-maturing variety especially adapted to semideep water conditions of the central plain in the monsoon season. It is popular where farmers do not have water control and where bacterial blight is a problem. It is not as responsive to nitrogen as RD1, but farmers have reported yields of 5.6 t/ha. RD5 also shows promise

under the rainfed lowland conditions of the northeast, apparently due to some drought tolerance.

(C4-63/GR88//Sigadis) appears to be spreading almost as rapidly as RDl did in its earlier years. Farmers prefer it to RD1 because of its good cooking quality, resistance to bacterial blight, and showy panicles which resemble those of C4-63. It also promises to become popular in the southern region because of good panicle exsertion and disease resistance. RD7 is the first RD variety with intermediate amylose content.

planthopper and the need for a gall- midge-resistant, nonglutinous variety prompted the release of RD9 (LY34/TN1//W1256///RD2). Nonwaxy rice is preferred in areas on the east coast of Thailand where gall midge is endemic.

Although only released in 1975, RD7

The threat of an outbreak of brown

a) Indian rice breeders used Taichung Native 1 and IR8 intensively in the mid-1960’s, but they had largely switched to locally developed semidwarfs and improved IRRI lines by 1974 – 75.

b) Ninety-four percent of the local semidwarfs were progeny of IR8 or TN1. Analysis of 336 rices used as parents in 158 randomly selected crosses, 10 experiment stations, India, 1975.

The diffusion of genetic materials among rice breeders in India

Thomas R. Hargrove, associate editor, International Rice Research Institute

Through analysis of breeding records and in-depth interviews, we traced the flow of rice genetic materials among collaborating Indian research stations through three periods over a decade: 1965 – 67, 1970 – 71, and 1974 – 75. We also determined breeding objectives of 1974 – 75 crosses as part of a collaborative project with the Agricultural Education Department of Iowa State University, U.S.A. We randomly selected and analyzed 44 crosses from the 1965-67 breeding records and 68 crosses from the 1970-7 1 records at seven state- and national-level research centers. For 1974-75, we analyzed 44 crosses made at 10 centers.

We found that 82 percent of the 1965-67 crosses involved at least one semidwarf parent. TN1 was used in 41 percent of the crosses; IR8, in 27 percent; and IRRI rices other than IR8, in 14 percent (see figure). No locally developed semidwarfs were found in the 1965 – 67 sample. The percentage of total crosses that involved semidwarfs increased to 91 percent in 1970 – 71 and leveled off through 1974 – 75. By the early 1970’s, the direct use of TN1 as a parent in crosses had dropped to 10 percent, and to 7 percent by 1974 – 75. The use of IR8 as a parent dropped 1 percent over the first 5 years, then dropped to 17 percent by 1974 – 75. The use of semidwarf materials from other countries increased slightly.

While other IRRI materials were used increasingly by 1974 – 75, locally developed semidwarfs were even more popular. They were used in almost half of the crosses by 1970 – 71 and in 61 percent by 1974 – 75. Fifty-five percent of local semidwarfs used in 1974 – 75 were progenies of IR8 and 39 percent, of TN1 (9 percent involved both) (see figure). Seventy-seven percent of the crosses in 1965 – 67 involved a tall parent, but only 48 percent did in 1974 – 75. The use of intermediate-statured parents declined from 45 percent in 1965 – 67 to 18 percent in 1974 – 75. Seventy-nine percent


of the total parent material was indica in the mid-1960’s; 10 years later, 96 percent was indica. The use of japonicas and ponlais declined over the decade. Fifty-seven percent of the total parents were hybrids in 1965–67, and 74 percent in 1974–75. Thus, we conclude that by the mid-1970's the original stiff-strawed varieties were being phased out of the breeding programs as parents, but that they continued to live on through a wide range of progeny. Rice breeders have incorporated their best genetic traits into newer rices better suited to local conditions.

Objectives of rice breeders in India

Thomas R. Hargrove, associate editor, International Rice Research Institute

To determine the overall objectives of rice breeders, we interviewed rice breeders at 10 agricultural research centers in India. We compiled the genetic traits for which the breeders used each parent

in each of 46 randomly selected crosses made in 1974–75.

Yield potential was cited as a primary breeding objective for making 89 percent of the crosses; fertilizer response was a breeding objective of 80 percent; and resistance to lodging, of 80 percent (see figure). Semidwarfs were almost invariably used as genetic sources of these traits. Grain quality was an objective of 69 percent of the crosses. Seventy- three percent of the times that tall varieties were used, the breeders hoped to transfer a preferred type of grain into the progeny; semidwarfs were used only 49 percent of the time for that. We found that 82 percent of the semidwarfs used for grain quality were locally developed, further indicating that introduced semidwarfs were often crossed with local rices to develop high-yielding varieties with acceptable grain quality. Forty-three percent of the crosses involved resistance to at least one disease, and 37 percent involved insect resistance. Resistance to blast, bacterial blight, and tungro virus were the most frequent disease objectives. Brown planthopper and gall midge

Increased yield potential was the major objective of rice breeders who made 46 randomly selected crosses in 1974-75. Fertilizer response and resistance to lodging also were important among their goals, as war improved grain quality. Ten agricultural experiment stations, India, 1975.


resistance were the most common insect objectives. Drought tolerance was sought in 9% of the crosses; cold tolerance, in 9%; tolerance to waterlogged soils, in 7%; and tolerance to deep water, in 2%. Tall or intermediate-statured parents were used as donors for most of these traits.

Development and spread of high-yielding varieties of rice in Iran

Rice Research Stations, Rasht and Amol, Iran

About 80 percent of Iran's 380,000 ha of rice is grown in the two Caspian littoral provinces of Gilan and Mazandaran, which have sub-Mediterranean (warm temperate) climates with humid summers and mild winters. The ricegrowing season is from mid-April to late September, during which the average maximum temperature is from 18° to 31°C and the minimum is from 8.2° to 20°C.

About 70 percent of the rice area is planted to long, fine-grained varieties of the Sadri type, such as Dumsiah, Dumzard, Dumsorkh, and Moosa Tarom. The Sadri varieties have very good cooking quality by Iranian standards: long, fine kernels that elongate considerably on boiling but do not tend to expand or burst. The cooked rice is tender and remains soft even if kept overnight. The remaining area is devoted to medium- and short- grained varieties known as the Champas. All are indicas and are tall, weak-stemmed, and leafy. Mutual shading and lodging are problems, particularly when the plants are fertilized. Mehr, Firooz, Dumzard 193, Moosa Tarom 110, and Dumsiah 81 are improved Sadri varieties developed by selection from local mixtures. They are not heavy yielders and are susceptible to blast disease. Some of the japonica varieties from Japan, Taiwan, Italy, Egypt, and other countries yielded from 7 to 9 t/ha in the International Rice Adaptation Trials in 1969, but they were acceptable to neither consumers nor farmers because they were short-grained, had poor cooking quality, and lacked seed dormancy (which is essential in Iran, where the harvest season generally coincides with the rainy season).

The high-yielding varieties developed at IRRI have so far failed to perform satisfactorily in northern Iran, probably because of the low temperatures. However, some selections of IR498 and IR533 have yielded from 5 to 6 t/ha. IR5 also performed comparatively better in southern Iran, and efforts are being made to introduce it into that area. Century Patna, an improved variety from the USA, was found to yield higher than local varieties in farmers’ fields. It is tall but stiff-stemmed and yields about 5 t/ha. It has long and fine grains but its cooking quality is poor. Because it yields more and is attractive in the field, farmers in Mazandaran province grow it under the name Misbah. Its area is spreading from year to year. It now occupies about 40,000 ha in that province.

Amol #1 is a semidwarf high-yielding variety developed from a 1965 cross of Tarom Firooz Kande/TN1. Tarom Firooz Kande is a local, tall, low-yielding variety with good eating quality. It was released for cultivation in Mazandaran province in 1973. It has long, slender kernels with acceptable cooking quality and matures about 140 days after sowing. It is more suitable in warmer areas. Sterility is a problem under low temperature in Gilan province. A number of other short-statured advanced lines that are capable of yielding from 5 to 6 t/ha and possess acceptable cooking quality are being tested in yield trials.

A new source of resistance to several diseases and pests of rice

P. S. Shrivastava, rice breeder, Central Rice Research Station, Jawaharlal Nehru Agricultural University, Raipur, M.P., India

Rice breeders are always looking for new sources of resistance to different diseases and insects so that they can incorporate polygenic resistance into new varieties. R-68-1 is a tall variety that was bred at the Central Rice Research Station,

Raipur, M.P., of Jawaharlal Nehru Agricultural University, by crossing Rikku, a Japanese variety, with R4 (Surmatia), a local indica variety. R-68-1 has shown resistant to moderately resistant reaction to bacterial blight and bacterial leaf streak under artificial inoculation tests at Raipur, and to leaf smut, false smut, Sogata, gall fly, and

green leafhopper in field screening trials. It has been extensively used in the crossing program of this station. Several of its derivatives have shown resistant to moderately resistant reactions against different diseases and pests in testing by the National Breeding Nursery and the National Screening Nursery at different sites in India, including Raipur.

Some derivatives of crosses that involve R-68-1 as a parent and that show resistant reaction to different diseases and insects. Central Rice Research Station, Jawaharlal Nehru Agricultural University, Raipur, M. P., India.

Cross Derivative Diseases and combination insects a

R-68-1/CR-10-4050

R-68-1/TN1

R-68-1/Jaya

DGWG/R-68-1

R 2329 R 2330 R 2331 R 2335 R 2338 R 2341 R 2343 R 2386 R 2389

783 R6-2390 R6-2520 R6-2521 R6-2522

R 2356 R 2357 R 2358 R 2359 R 2363 R 2364

R 2325 R 2380 R 2381 R 2384 R4-2517 R4-2518 R4-2519 R4-2528 R4-2529

R30-2549

BB BB, WH BB, FS, WH BB, FS LS BB BB, FS BB, RTV, Sh. B, WH BB, BLS, FS, GLH St. B BB FS BPH BPH, FS

RTV, WH WH BB, BLS, FS WH BB WH

BB BB BB, BLS, LS GM, RTV BB, Blast, FS BB, Blast, FS BB, Blast, LS, FS BB, FS BB, FS, LS

LS, FS

a BB = bacterial blight; BLS = bacterial leaf streak; LS = leaf smut; FS = false smut; RTV = rice tungro virus; Sh.B. = sheath blight; WH = white head; St.B = stem borer; GM = gall midge.


GENETIC EVALUATION AND UTILIZATION

Agronomic characteristics

Shallow water Knee-deep water Transplanting

Semideep water Deep water

Veg. stage Mat. stage Veg. stage Mat. stage Veg. stage Mat. stage Veg. stage Mat. stage Veg. stage Mat. stage Veg. stage Mat. stage Aug. –Sept. Oct.–Nov. Jul.–Sept. Oct.–Nov. Jul. –Sept. Oct. –Nov. June–Sept. Oct. –Dec. June–Sept. Oct.–Dec. May–Sept. Oct.–Dec. 10-60cm 45-15cm 20-90cm 60-15cm 20-110cm 90-25cm 20-120cm 110-25cm 30-160cm 120-60cm More than 160cm

depth depth depth depth depth depth depth depth depth depth depth 2.5–4.5 t/ha 2.5–3.5 t/ha 2.5–3.5 t/ha 2.5–3.0 t/ha 2.5–3.0 t/ha 2.0–3.0 t/ha

Pankaj (M, c, W) NC 678 (M, c, W)

Chakia 59 (L, mc, W) Jalamagna (M, c, W)

OC 1393 (L, mc, W) IR442-2-58 (E, m, W)

Jaladhi 1 (L, mc, R) Jaladhi 2 (M, c, R)

Kalma 222 (M, m, W) Raghusail (M, mc, W) Kumargore (L, c, W) NC 1281 (L, c,W) Patnai 23 (M, mc, W) Tilakkachari (L, c, W) Achra l08/l (L, c, W)

Duration: E = early; M = medium; L = late. Grain quality: m = medium; mc = medium coarse; c = coarse. Kernel color: W = white; R = red.

The extent of adaptation (indicated by arrows) of the rice varieties and their yield potentialities in relation to varying depths and durations of waterlogged situations at vegetative (veg.) and maturing (mat.) stages under direct sown and transplanted conditions. Rice Research Station, Chinsurah, West Bengal, India.

Promising rice varieties for different types of low-lying waterlogged situations

S. K. Datta and B. Banerji, Rice Research Station, Chinsurah, West Bengal, India

Several recommended rice varieties were tested under common water situations – shallow water, knee-deep water, semideep water, and deep water – at the Rice Research Station, Chinsurah, West Bengal, during the monsoon season of 1971 – 72. The varieties were evaluated for suitability to different types of waterlogged areas and to meet farmers’ needs. Eight specially constructed fields were used to study the plants growing at varying depths and varying duration of waterlogged situations. The soil was clay loam with pH of 6.9. No manure was applied.

The accompanying figure names some varieties that show promise for different


low-lying situations, their grain quality and duration characteristics, and their yield potentialities under direct-sown and transplanted conditions. Such information may help rice workers formulate effective recommendations for varietal suitability, choice of grain types, and time of harvest for different low-lying waterlogged situations.

Alternate sources of dwarfism

M. J. Balakrishna Rao, Central Rice Research Institute (CRRI), Cuttack, Orissa, India

Because most of the short-culmed varieties are derived from Dee-geo-woo-gen, scientists at CRRI are investigating possible alternate dwarf gene sources from Japan, China, and Indonesia, and are generating short-culmed lines through mutation. Japonicas are of particular interest among alternate dwarf gene sources.

Scientists at the Central Rice Research institute, Cuttack, India, are using as alternate dwarf gene sources japonica varieties such as Hoyoku an Shiranui (above) and Jikkoku.

Transplanting Direct sowing/transpl. Direct sowing/transpl. Direct sowing Direct sowing

Several stiff-strawed, photoperiod- insensitive, high-yielding varieties have already been developed at CRRI by crossing Japanese varieties such as Jikkoku, Hoyoku, and Shiranui with tall indicas. These lines show strong resistance to blast and fair resistance to bacterial blight under field conditions.

They have thin, erect leaves, late leaf senescence, and high harvest indices. At several testing centers in India, japonica-indica hybrids outyielded existing high-yielding varieties.

and wheat are obtained in Japan and several European countries without

High and stable average yields in rice

adopting dwarf varieties. Efficient plant types suited to different agroclimatic conditions can be developed independent of the dwarf gene. But the process will not be simple, because a constellation of characters must be assembled through hybridization involving several parents with desired characters.


Grain quality Variability in amylose content of rice

C. M. Paule, K. A. Gomez, B. O. Juliano, and W. R. Coffman, International Rice Research Institute

An increasing demand for high-quality rices in both the domestic and foreign markets has brought close cooperation among rice breeders and cereal chemists. Amylose, the linear component of starch in nonwaxy rice, is responsible for the texture of cooked rice and is the chief influence on the eating quality judgments of milled rice. The nonwaxy varieties contain from about 7 to 34 percent amylose of milled rice (dry weight) or from 8 to 37 percent of starch. Rice varieties may be grouped on the basis of their amylose contents into waxy (1–2% amylose), low amylose (8–19%),

intermediate amylose (20–25%), or high amylose (more than 25%). The amylose content of a rice variety may vary by as much as 6 percentage points. Intermediate-amylose varieties remain soft even after cooling and are widely preferred in such countries as the Philippines, Indonesia, Vietnam, Burma, and Pakistan.

Because of the wide variability in amylose content within a variety, screening for intermediate-amylose types in a breeding program presents serious problems. A study was, therefore, undertaken to examine the sources and magnitude of variability due to several nonheritable factors. The total variability was classified into three main groups: that due to the environment or the conditions under which the plant grows;

Amylose content, which is a major factor influencing judgments of eating quality of milled rice, varies widely not only among rices, as above, but even within a variety. The differences in amylose content are reflected in varying tex- tures of the rices when cooked.

that due to the sample plants or the method by which grain samples are obtained; and that due to the measurement technique or the variation involved in the laboratory. Varieties or selections differing in amylose content were selected to gain maximum information on how varieties interact with the various factors studied. The Simplified Amylose Procedure employing the Auto Analyzer Method was used to determine amylose content. The analysis of variance technique was used in most phases of the study.

Amylose content of grain, like protein content, was affected by environment. Temperature was negatively correlated with amylose in the low-amylose rice but showed no distinct trend in either the high- or the intermediate-amylose rices. Nitrogen application tended to reduce the amylose content of rice: split application caused greater reduction than basal application. The large effects of interaction between variety and location indicated that the relative performance of the rices varied from one location to another. The variation in amylose content among panicles of the same hill was larger than that among hills as well as among bulk-samples within a hill. Twenty grains and 100 mg of rice flour were found to be the optimum sample sizes for rice grain and for ground rice, respectively, in the determination of amylose content. Milled rice from a Test Tube Miller gave lower amylose values than did milled rice from a McGill Miller No. 2. The variance component due to samples was consistently much higher than that due to determinations of the same sample. The relative magnitudes of the variations due to runs and due to determinations within samples, on the other hand, were not consistent for all varieties.



Disease resistance

Hybrid lines from two rice crosses, originally intended for other purposes, are being studied as possible new sources of resistance to grassy stunt virus disease. The only source of resistance to grassy stunt known so far is IRRI Acc. 101508 of Oryza nivara. Examining an infected field above (left to right) are IRRI scientists S. H. Ou, plant pathology; G. S. Khush, plant breeding; and K. C. Ling, plant pathology.

Two possible new sources of resistance to grassy stunt virus disease of rice

S. H. Ou, F. L. Nuque, K. C. Ling, and V. Aguiero, Plant Pathology Department,

International Rice Research Institute

In 1973, a very severe outbreak of brown planthoppers and a grassy stunt virus disease of rice occurred in Laguna province, Philippines, including the IRRI farm. Several hybrid lines from two crosses exhibited high levels of resistance to both under field conditions. The two crosses are IR9560 (IR8 3 ///IR8/ Carreon//IR8/Tetep), which was intended to incorporate blast resistance from different sources, and IR4497 (IR24// Zenith/Malagkit Sungsong), which was made to increase the spectrum of resistance to bacterial blight. Several single plants from these crosses were selected and grown separately in pots in the greenhouse. They were artificially inoculated with grassy stunt virus at 2 weeks after sowing in the F 4 generation. Most selections were highly resistant to the disease. The percentage of infection ranged from 0 to 12 percent


for IR9560 lines and from 2 to 9 percent for IR4497 lines. Since only one source of resistance to grassy stunt is known so far, IRRI Acc. 101508 of Oryza nivara, these new sources may be valuable alternate sources in breeding for grassy stunt resistance. All parents of the two crosses are susceptible to grassy stunt. The resistance genes involved in these lines are being investigated.

Pathogenic variability of Xanthomonas oryzae

T. W. Mew and A. G. de la Rosa, Plant Pathology Department, International Rice Research Institute

During the 1975 wet season, 1R30, which carries the dominant gene for bacterial blight resistance, was found susceptible in Iloilo and Davao provinces, Philippines. Pathogenicity studies indicated that the isolates of X. oryzae from these areas attacked IR20 and IR30 in a manner similar to that of the Isabela strain.

However, varieties that carried a recessive gene for resistance were not overcome by these isolates in the greenhouse.

resistance gene), IR20 (carrying Xa 4, a dominant gene for resistance), and IR1545 (carrying xa 5, a recessive gene for resistance) suggested distinct differential interactions. At least four pathogenic groups of the isolates were observed. It is evident that the pathogenic variability of X. oryzae differed not only in virulence but also in pathogenicity. Current efforts are underway to evaluate varieties that will differentiate the Philippine isolates into pathogenic races.

A test of 83 isolates on IR8 (with no

Blast resistance in cold-tolerant boro rim of Uttar Pradesh

J. S. Nanda, R. C. Chaudhary, and O. S. Rana, Department of Plant Breeding, G. B. Pant University of Agriculture and Technology, Pantnagar, Nainital, India

The boro crop of rice is grown in the eastern districts of Uttar Pradesh state near rivers, lakes, and large ponds. Nurseries are sown in November and the crop is harvested around the end of April. During early growth, the crop faces cool temperatures in December and January (as low as 2°C with a monthly av. min. temp. of 10°C). To our knowledge, this rice has not been systematically collected. Therefore the present collection was started in 1972. After purification, 90 distinct types were isolated. The rices were screened against blast disease at Rice Research Station Majhera (29.28°N, 79.32°E and 650 msl), a blast-endemic area, in 1974 and 1975. The material was grown in rod-rows and scored for disease reaction after 1½ months following the method of S. H. Ou (1965). Final grading of the entries was based on highest score value recorded in both years. No entry proved highly resistant (see table). Only 5.6 percent were resistant and 5.6 percent were moderately resistant. Almost 89 percent were in the susceptible classes (88.8%).

The five resistant rices are UPRB-7, UPRB-8, UPRB-31, UPRB-32, and UPRB-33. UPRB-8 has intermediate height and the others are tall. UPRB-7,

Reaction of boro collections to blast disease. G. B. Pant University of Agriculture and Tech- nology, U. P., India.

Collections

(no.) (% of total) Reaction

Highly resistant 0 0.0 Resistant 5 5.6 Mod. resistant 5 5.6 Mod. susceptible 4 4.5 Susceptible 7 7.8 Very susceptible 14 15.6 Highly susceptible 55 60.9

8, and 31 have white kernels and UPRB-32 and 33 have red kernels. UPRB-8 and UPRB-32 have slender grains; UPRB-33 and 8 have short, bold grains. UPRB-31 is also resistant to cold temperature and to bacterial blight; it is being used as a donor parent. All the resistant and moderately resistant collections need to be tested against other stresses.

Varietal reaction to brown spot and narrow leaf spot under natural infection

Suree Sukapanpotharam, rice pathologist, Boon-hong Chongkid, rice pathologist, and Praphas Weerapat, rice breeder, Rice Division, Department of Agriculture, Bangkok, Thailand

Two fungus diseases – brown spot, caused by Helminthosporium oryzae Breda de Hann, and narrow leaf spot, caused by Cercospora oryzae Miyake – were observed in the northeastern, central, and southern ricegrowing areas of Thailand. Chantharasnit and Aroonskul reported that RD1, RD2, and RD3 were resistant to brown spot under glasshouse conditions and artificial inoculation. Many multiple-resistant lines from the cross BKN 6517-63-4-3/RD9 recently exhibited high susceptibility to brown spot at the heading stage. We suspect that brown spot will become a major disease in the future. Therefore, we tested many breeding lines in the seedling stage

leaf spot under natural infection. for reaction to brown spot and narrow

We tested 464 breeding lines from the used as resistant and susceptible checks, intrastation and interstation yield trials respectively. The test rows were in the 1975 wet season at the seedling surrounded by two rows of Hang Yi 71 stage under natural infection at the Kuan to keep high moisture among the plants. Gut Rice Experiment Station and the No fertilizer or other chemicals were Ubolrajthani Rice Experiment Station. applied. The reactions of rice plants to RD1 and Khao Dawk Mali 105 were brown spot and to narrow leaf spot,

Varieties and lines found to be resistant to brown spot and narrow brown leaf spot.

Designation

SPT 6606-100 UBN 6721-5-39-3(1) BKN 6721-11-8-4-1 KKN 6721-5-7-4 SPT 66064-2-1-1 SPT 6606-6-1-1-1 SPT 6606-36-1-1-1 SPT 6012-97 KDML'65 G 4 U-4-351 KDML'65 G 4 U-4-522 KDML'65 G 1 U-45 SKN 24 SKN 48 SKN 15 SKN 49 SPT'58-37-389 SPT'58-37-400 SPT 6207-297 BKN 323-17 492-2-204 KTH'65-G 2 U-31 KTH'65-G 1 U-67 SPRC'70-11-32 SPRC'70-12-45 SPT 6838-2-1-1 SPT 6838-76-2-2-1 SPT 6838-87-2-1-4 SPT 6838-96-1-1-1 SPT 6838-125-1-1-2 SPT 6838-94-1-1-4 SPT 6838-86-2-2-1 BKN 7130-511 SPT 6840-10-2-2-4 SPT 6840-80-2-1-2 SPT 6840-82-2-1-1 SPT 6840-82-2-1-3 SPT 6840-51-2-2-1

Cross Resistance rating a

Brown spot Narrow leaf spot

LT82/Sigadis IR262A/NSPT IR262A/NSPT 2

IR262A/NSPT 2

LT82/Sigadis LT82/Sigadis LT82/Sigadis GR201/LY34 Irr. KDML 105 Irr. KDML 105 Irr. KDML 105 KDML 105/F16216 KDML 105/F16216 KDML 105/F16216 KDML 105/F16216 DML 70 2 /Chinese 345 DML 70 2 /Chinese 345 Pin Gaew Bow 27/JL 11 KTH 17/Ramadja Khao Gaew Irr. KTH 17 Irr. KTH 17 Leuang Hawm Khao Pra Juab SPT 6624-67/NSPT SPT 6624-67/NSPT SPT 662467/NSPT SPT 662467/NSPT SPT 6624-67/NSPT SPT 6624-67/NSPT SPT 662467/NSPT Short Sigadis/KPM 148 NSPT/SPT 6624-67 NSPT/SPT 6624-67 NSPT/SPT 6624-67 NSPT/SPT 6624-67 NSPT/SPT 662467 NPY 70 NSPT

R MR

R R R

MR MR MR MR

R MR MR MR MR MR MR MR

R MR MR MR MR MR MR MR MR MR MR MR MR MR MR MR MR MR MR MR MR MR

MR MR MR MR MR MR MR MR MR MR MR

R MR MR MR MR MR

R MR MR MR R

MR MR MR MR MR MR R

MR R

MR MR R R

MR MR MR MR

a R = resistant, MR = moderately resistant.


based on the number of lesions, were recorded at 45 days after seeding: less than 1% lesions, highly resistant; 1–576 lesions, moderately resistant; 5–25% lesions, intermediate; 25–50% lesions, moderately susceptible; and more than 50% lesions, highly susceptible.

Only 8 percent were resistant to brown spot and 4 percent to narrow leaf spot. The lines that were resistant to both diseases are shown in the accompanying table. RD1 and Khao Dawk Mali 105 were classified as intermediate and moderately susceptible, respectively. Infection of brown spot fungus was severe at both the Kuan Gut and the Ubolrajthani Rice Experiment Stations, but narrow leaf spot infection was severe only at Kuan Gut.

Direct and indirect effect of Udbatta disease on total number of panicles per hill in different paddy cultures N. Shivanandappa, plant pathologist in charge, Rice Research Station, Mandya, and C. H. Govindu, senior professor, Department of Plant Pathology, University of Agricultural Sciences (UAS), Hebbal, Bangalore, India

Udbatta disease caused by Ephelis oryzae Syd. is one of the important paddy diseases in Karnataka. Affected plants show profuse tillering early in plant growth, whitening of young leaves, nonproductive panicles, panicles in the form of cylindrical rods, or a few diseased and healthy panicles in the same clump. Reporting on the direct loss from the disease, Shivanandappa said that wherever the primary tiller was infected, the percentage of infection within the hill ranged from 20 to 95 percent. But when infection took place on the secondary and tertiary tillers, the percentage of diseased panicles varied from 13 to 55 percent. The indirect loss from the disease in terms of reduction in total number of productive panicles in the affected hill is not known. Hence the following study was conducted.

rices were selected and sown in kharif 1974 at Mandya in randomized block


Twenty short- and 20 medium-duration

Effect of Udbatta disease on the total number of panicles per hill. Rice Research Station, Mandya, and Department of Plant Pathology, UAS, Hebbal, Bangalore, India.

Healthy panicles (no.) Panicles Diseased panicles (no.)

Variety or culture

per

incidence healthy diseased hill diseased lost lost Disease Per Per diseased Per Indirectly Total

(%) hill hill (no.) hill

MR 118 MR 263 MR 272 MR 279 MR 297 MR 298 MR 299 MR 300 MR 301 MR 318 IET 1522 IET 1899 IET 1988 IET 2246 IET 2386 IET 2671 IET 2707 IET 2968 IET 31 26 Madhu

MR 44 MR 70 MR 81 MR 249 MR 269 GMR 2 Satya Surya Suhasini Jaya IR20 J.H. 49 IET 1990 IET 199 1 IET 2142 IET 2143 IET 2254 IET 2295 IET 2300 IET 2384

8.25 4.24 4.76 4.54 5.60 5.21 4.96 2.41 4.96 2.44 3.89 2.06 2.73 2.93 2.28 3.94 3.44 4.60 4.99 4.70

6.30 5.06 5.00 4.38 3.84 4.76 3.60 3.53 5.17 4.69 4.18 3.53 4.31 3.26 4.69 3.80 3.87 2.92 6.15 3.87

10.52 12.02 14.08 13.28

8.56 9.60 9.41 8.88

10.41 8.77 9.45

10.26 10.73

8.77 11.25

9.64 10.50 1 1.20 10.85 11.29

14.85 14.26 12.80 14.80 11.60 11.01 11.16 12.36 12.20 11.45 11.73

8.85 11.65 11.58 11.36 13.83 12.46 14.60 11.73 13.55

Shortduration cultures 7.64 9.89 2.25 0.63 2.88 8.33 10.02 1.69 2.00 3.69

10.68 12.12 1.44 1.96 3.40 11.52 12.92 1.40 0.36 1.76 6.45 8.26 1.81 0.30 2.11 7.32 9.21 1.89 0.39 2.28 6.96 8.64 1.68 0.77 2.45 6.12 7.77 1.65 1.11 2.76 7.94 9.83 1.89 0.58 2.47 6.12 8.02 1.90 0.75 2.65 6.04 7.82 1.78 1.63 3.41 6.60 8.29 1.69 1.97 3.66 8.52 10.13 1.61 0.60 2.21 6.37 7.87 1.50 0.90 2.40 8.26 9.86 1.60 1.39 2.99 6.85 8.55 1.70 1.09 2.79 8.30 10.20 1.90 0.30 2.20 7.73 9.53 1.80 1.67 3.47 7.80 9.80 2.00 1.05 3.05 8.42 10.38 1.96 0.91 2.87

Medium-duration cultures

11.96 14.29 2.33 0.56 2.89 11.28 13.34 2.06 0.92 2.98 10.37 12.44 2.07 0.36 2.43 12.70 14.40 1.70 0.40 2.10 9.11 10.99 1.88 0.61 2.49 7.43 9.38 1.95 1.63 3.58 7.78 9.54 1.76 1.62 3.38

10.11 11.86 1.75 0.50 2.25 8.65 10.83 2.18 1.37 3.55 8.46 10.57 2.11 0.88 2.99 9.08 11.14 2.06 0.59 2.65 6.68 8.36 1.68 0.49 2.17 8.60 10.53 1.93 1.12 3.05 8.88 10.83 1.95 0.75 2.91 8.45 10.61 2.16 0.75 2.91

11.41 13.19 1.78 0.64 2.42 9.86 11.79 1.93 0.67 2.60

12.85 14.36 1.51 0.24 1.75 8.36 10.27 1.91 1.46 3.37

10.56 12.39 1.83 1.16 2.99

design with three replications. Twenty- five healthy and diseased hills of each culture were randomly selected in each replication. The healthy and diseased panicles at grain formation in healthy and diseased hills were counted. The number of diseased panicles in diseased hills (direct loss) was obtained by counting the affected panicles in each diseased hill. The indirect loss of panicles was obtained by deducting the total number of panicles (healthy and diseased) in diseased hills from the total number of healthy panicles in healthy

hills. The total loss of panicles was calculated as both direct and indirect loss (see table).

The percentage of disease incidence varied from culture to culture. There was no correlation between the percentage of incidence and the direct or indirect loss of panicles. The range of indirect loss of panicles from culture to culture varied greatly. The number of directly lost panicles per hill ranged from 1.40 to 2.33; that of the indirectly lost ranged from 0.3 to 2.00. Total lost panicles ranged from 1.75 to 3.69.

Screening for resistance to leaf spot

Y. Soepriaman, Sunendar K., Soeparyomo, and L. T. Palmer, Plant Pathology Section, Central Research Institute for Agriculture, LP-3 Cabang Sukamandi, West Java, Indonesia

Nine of 74 selected lines planted in a nursery at Rembang, Central Java, were resistant to brown spot Helminthosporium oryzae and stackburn Alternaria padwickii. These were Siam 1019, IR2071-105-4, IR2071-588-6, IR2031-254-2-3, IR2055-219-1-3, RP 633-680-1-1-1-1, ARC 5793, Balop Merah 910, and Madura Samba.

Lines resistant to narrow brown leaf spot, Cercospora oryzae

Y. Soepriaman, Sunendar K., Soeparyomo, and L. T. Palmer, Plant Pathology Section, Central Research Institute for Agriculture, LP-3 Cabang Sukamandi. West Java, Indonesia

Thirty-two lines from the local collection and 23 lines from the Observational Lines and varieties from Observational Yield Trial and from local collection found to be resistant to narrow brown leaf spot. Sukamandi, Indonesia

Observational Yield Local collection Trial

IR796 C-MR-143-24 S. Hitam Segon IR1514 A-5597-2 Tarak Karo IR1909-1-3-3 Puy IR2031-354-2-3 IR2031-422-3-3 IR2070-78-2-3 IR2070-178-2-3 IR2070-381-1-5-8 Kasih Beranak

Tambu Paya Bokot Munte Puket Garu

IR2070-652-5-4-11 Gadis Kebalsi IR2070-939-3-4-10 Rendah Renumi

IR2071-573-3-3-14 Rampone IR2071-105-9-4 Umbang Katib

IR2071-588-3-5 S. Buyung IR2078-71-2 Saeful Putih IR2688-43-4-3 Lakaton Abang IR2798-88-3 Gadabung Gundill Si 01 b-218-3 Siem Ganol B 1990 Laketu Mangan

B 1990 Sipanci

B 1990 Disi

b-MR-43467-3B Pakui

b-MR-43534-2B R. Jawa

b-MR-43534-2B Raden Rata B 2360-6-4-5 Bakaton Panas B 2360-8-4-5 Lakaton Karamunting B 2932-2-1-4-1-3 Isip

Karang Dukuh Minai

Yield Trial were selected at Sukamandi, susceptible F 3 lines within crosses. The West Java, for resistance to narrow brown plants within each progeny showing leaf spot Cercospora oryzae (see table). false smut were counted and recorded The new IRRI releases — PB26, PB28, for all crosses. Analyses of these data are PB30, PB32, and PB34 — were all rated based on the rating scale system suggested highly susceptible to narrow brown leaf in the “Standard Evaluation Systems

C2 had an incidence of less than 5 spot. for Rice” published by IRRI, 1975.

Reaction of some gall midge crosses to false smut at Mandya, Karnataka, India

percent and was hence, moderately resistant to false smut (Table 1). C1 and C3 had less than 25 percent incidence.

B. S. Naidu. N. Shivanandappa, and S. Kumaraswamy, University of Agricultural Sciences, Hebbal Campus, Bangalore, Karnataka state, India

In kharif 1975, a heavy incidence of false smut Ustilaginoidea virens was recorded on the F 3 progeny of some crosses made for gall midge at the V.C. Farm, Mandya. The disease symptoms were characterized by transformation of the paddy grains to greenish-black spore balls (smut balls) of velvety appearance. The glumes of the spikelets can still be seen on the spore masses. The disease

C4 recorded an incidence of 41.8 percent, and shall be considered susceptible.

The number of F 3 progeny in each cross has been grouped according to the percent incidence of false smut (Table 2).

No F 3 line showed a resistant reaction to false smut. However, some progeny with moderate levels of resistance (1–5% incidence) were recovered in C1 and C2. Most of the F 3 progeny exhibited from 6 to 25 percent disease incidence. In the cross C4, 2 out of 15 F 3 lines studied recorded disease

incidence was severe enough to incidence that exceeded 50 percent, and distinguish susceptible crosses and hence were classified as very susceptible.

Table 1. Incidence of false smut disease (U. virens) in progeny of crosses made for gall midge resistance. University of Agricultural Sciences, Hebbal Campus, Bangalore, Karnataka state, India.

Plants within Line Parents F 3 lines each F 3 line Total plants Incidence

(%) (%) (no.) (no.)

C1 Jaya/W1263 67 80 5360 11.4 C2 W1263/W12787 7 66 462 3.7 C3 Sona/W1263 10 84 840 16.6 C4 Vijaya/W12787 15 84 1260 41.8 ---------------------------------------------------------------------------------------------------------------------------------

Total 99 – 7922 18.4

Table 2. The number of F 3 progeny from crosses for gall midge resistance. University of Agricul- tural Sciences, Hebbal campus, Bangalore, Karnataka state, India.

Incidence Classification Frequency of F 3 progeny (no.) Total Frequency

(%) C1 C2 C3 C4 (no.) (%)

0– 1 R – – 1– 5 MR 12 5 0 0 17 17.2 6–25 HR 46 2 9 3 60 60.6

26–50 S 9 0 1 10 20 20.2 > 50 vs – – – 2 2 2.0

– – – –

---------------------------------------------------------------------------------------------------------------------------------

F 3 total no. 67 7 10 15 99 100.0


This study indicates that derivatives of the cross Vijaya/W12787 are highly susceptible to false smut, while those from W1263/W12787 exhibit a degree of resistance. The other two crosses, Jaya/W1263 and Sona/W1263, have intermediate resistance to false smut.

Yield losses due to sheath blight of rice

S. H. Ou and J. M. Bandong, Plant Pathology Department, International Rice Research Institute

We studied yield losses due to sheath blight on the moderately resistant variety IR26 and the highly susceptible line IR1487-372-1-1 at three levels of disease intensity (10, 20, and 50% hills inoculated) at 0 and 100 kg N/ha during the 1975 dry and wet planting seasons at IRRI.

per unit of disease rating was 2.7 in the plots with 0 N and 2.3 in the plots with 100 kg N/ha. But yield reductions were significant only at the highest level of disease incidence in the plots with higher nitrogen during the dry-season trial. Reductions were insignificant at both N-levels in the wet season. In IR1487 the percent yield reduction per unit of disease rating was 4.4 in the 0 N plots and 4.3 in the 100 kg N/ha

In IR26, the percent yield reduction

IR1487-372-1-1 shows rapidly decreasing yield with increasing intensity of sheath blight disease. Yields of 1R26 demonstrate less sensitivity to the disease.


Sheath blight reduced yields significantly on the susceptible lie IR1487-372-1-1 at all levels of disease intensity and nitrogen fertilizer; yields were significantly reduced on the moderately resistant variety IR26 only at the highest levels of disease intensity and nitrogen. IRRl, 1975.

Hills inoculated (%)

0 10 20 50

0 10 20 50

Yield losses (%) at

0 kg N/ha 100 kg N/ha

Yield a (t/ha) at

0 kg N/ha 100 kg N/ha

– 7.5

12.2 22.7

– 0.4 6.5 8.8

– 8.6

13.8 23.7

IR1487-372-1 (susceptible)

5.7 a 5.2 b 5.0 b 4.4 c

IR26 (moderately resistant) – 2.5 5.1

13.2

6.1 a 6.2 a 5.7 a 5.6 a

5.8 a 5.3 b 5.0 c 4.4 d

7.8 a 7.6 a 7.4 a 6.8 b

a Means followed by a common letter are not statistically different at the 5% level.

plots. The levels of disease incidence at both nitrogen levels were statistically significant. The highest percentage of yield loss was about 13 percent for IR26 and 23 percent for IR1487 (see table).

Correlations between disease rating

and yield losses showed that the susceptible variety was very sensitive to the disease—yields decreased rapidly as disease incidence increased in both the 0 and 100 kg N/ha plots. The moderately resistant variety was less affected by the disease (see figure).

GENETC EVALUATION AND UTlLlZATlON

Insect resistancs Resistance in some rice strains to first-instar larvae of Tryporyza incertulas (Walker) in relation to plant nutrients and anatomical structure of the plants

D. V. Subbarao and A. Perraju, Entomology Department, Agricultural College, Bapatla, Guntun District, Andhra Pradesh. India

The degree of resistance to first-instar larvae of the rice stem borer and the interaction of resistance with certain important plant cell ingredients were studied during 1972–73 in seven rice strains that differ in resistance. To study the possible effects of silica application in inducing stem borer resistance in the rice plant, potassium silicate at 5 g/pot was applied 1) at the time of sowing; 2) during transplanting; and 3) at 7 days after transplanting. The possible effects

on ease of penetration for the larvae and on their survival were also studied. The studies were confined to the first-instar larvae of the rice stem borer on seedlings of Eshwarakora, TN1, W1263, TKM-6, IR20, HR59, and B5580.

There was no uniformity in site of penetration into the plant, larval survival after penetration, or larval ability to cause dead hearts. The uptake of added silica varied among different rices; the variation affected larval survival and growth. The higher silica uptake in IR20 and HR59 fed to the wearing and defacing of the insects’ mandibles and interfered with the boring and feeding capacity of the larvae. Higher silica content was related to higher insect mortality in IR20, Eshwarakora, and TKM-6; silica content was negatively

correlated with larval weight. It was concluded that silica is an important component of resistance. Dead heart incidence varied in the different cultivars; it was highest in B5580 and HR59 and lowest in W1263, TN1, and TKM-6. It was intermediate in Eshwarakora and IR20. The silica content of the plant and the incidence of dead hearts were significantly negatively correlated. The application of silica at sowing was more conducive to its uptake than its application at transplanting 7 days later.

Apparently tissue hardening due to silica in the leaf sheath caused the larvae to leave that part and to bore into the stem to feed on the pith of W1263 and TKM-6. The larvae showed a marked tendency to leave TKM-6 plants, probably because of repellence. This apparent larval reaction was found to be related to plant structure; vascular bundles were arranged closely in TKM-6. The survival and growth of larvae were highest in the susceptible varieties HR59 and B5580, intermediate in W1263, IR20, and TN1, and lowest in

TKM-6 and Eshwarakora. Chemical analysis of major plant constituents indicated that a variety’s degree of resistance is influenced by high content of dry matter, silica, and potassium, and low content of moisture, nitrogen, and sodium.

Biotype 2 brown planthopper in the Philippines

Reeshon Feuer, crop production specialist, International Rice Research Institute outreach project to the Philippines

In October of 1975, IR26, which has the dominant gene Bph-1 for resistance to brown planthopper, was reported to have been attacked by brown planthoppers in Barangay Toril, west of Davao City, Mindanao, southern Philippines. Field investigations confirmed the hopper and grassy stunt virus damage to IR26 and other rices with the dominant gene Bph-1 (IR1561-228-3, IR28, and IR30). Brown

the area since 1973. IR26 was first planthopper attacks had been serious in

grown there in the 1975 dry season.

Rice Brown Planthopper Nursery (IRBPHN) only Ptb 21 and IR2035-255 were not wiped out by grassy stunt virus. Ninety farm trials (each covering 1/33 of a hectare) of IR2071-625-1-252 (recessive gene bph-2 for hopper resistance) came through perfectly in Barangay Toril. IR2071-625-1-252 (which was recently named by the Philippine Seed Board as IR36) provided some 15,400 kg of seed that are resistant to both brown planthopper biotypes 1 and 2. Seed growers harvested an estimated 880,000 kg of IR36 in April 1976.

by brown planthopper throughout the southern Mindanao region where rainfall is uniformly distributed and there are no typhoons to reduce hopper population. The presence of brown planthopper biotype 2 in southern Luzon (south of Manila) was confirmed in September 1975. The Philippine Government is alerting extension workers and rice farmers to the developing situation. The 1976 insecticide and rice variety recommendations have been changed to meet the new menace of biotype 2 of the brown planthopper.

In the trial of the first International

IR26 is reported to have been attacked

Sources of resistance to brown planthopper Nilaparvata lugens

C. Kudagamage, research officer (entomology), Central Rice Breeding Station, Batalagoda, Ibbagamuwa, Sri Lanka

Almost 500 indigenous varieties and foreign introductions were screened in Percent survival of seedlings after infestation with brown planthopper. Central Rice Breeding Station, Batalagoda, Ibbagamuwa, Sri Lanka.

Variety Survival of seedlings a

(%)

Ptb 33 83.7 ARC 6650 78.3 Suduru Samba 76.9 MR 1523 71.2 Sudu Heenati 65.3 TN1 (susceptible check) 8.7

a Av. of three replicates.

the greenhouse in a search for sources of resistance to local biotypes of the brown planthopper Nilaparvata lugens. The varieties were evaluated on the basis of percentage of seedlings that survived after 10 days of infestation by the second- and third-instar nymphs.

The survival of the seedlings of different varieties varied markedly and ranged from 0 to 90 percent. The table indicates the reactions of varieties that demonstrated more than 65 percent survival and which can be considered resistant to the local hopper biotype.

Varietal resistance of rice to the white- tipped nematode Aphelenchoides besseyi

J. S. Park and J. O. Lee, Department of Entomology, Institute of Agricultural Sciences, Office of Rural Development, Suweon, Republic of Korea.

Twenty recommended rice varieties were tested for resistance to the rice white- tipped nematode in pot inoculation trials. Tongil, Early Tongil, Tongil-chal, and Shirogane were found highly resistant. Office of Rural Development, Suweon, Republic of Korea.

Variety Diseased culms (%) Rating a

Early Tongil Tongil Tongil-chal Shirogane Norin Mochi #1 Juckna Paldal Mangyeong Minehikari Akibare Satominori Pungkwang Olchal Jaekeon Suseong Jinheung Palgeum Shin #2 Nongbaek Fukunohana

0 0 0 0

12.1 12.3 15.7 17.9 20.1 20.5 20.7 20.8 22.3 23.1 26.3 27.7 42.2 42.2 43.1 46.6

R R R R MR MR MR MR MS MS MS MS MS MS MS MS S S S S

a R = resistant; MR = moderately resistant; MS = moderately susceptible; S = susceptible.


International Rice Testing Program insect nurseries for 1976

Entomologists met during the 1976 International Rice Research Conference to discuss plans for the international program of screening for resistance to insect pests. They decided that the methodology for the 1975 brown planthopper and gall midge nurseries will remain the same in 1976 except for a few changes in the evaluation procedure and the check varieties, and the addition of new test locations.

A new nursery for stem borer evaluation will be initiated in 1976. Tentative plans were made for testing about 50 lines from six countries in Africa (at the International Institute for Tropical Agriculture), Korea, Thailand, Indonesia, Bangladesh, Sri Lanka, India, Iran, Egypt, and elsewhere.

evaluate nursery sets for stem borer resistance are invited to request the sets directly from the International Rice Testing Program, IRRI.

Scientists who would like to grow and

Resistance of IR2070-4143-9 to rice whorl maggot

Vicente Viajante, research assistant; and Rizal M. Herrera, senior research assistant, International Rice Research Institute

Rice whorl maggot, H. philippina, was once considered a minor pest, but now it may be of major importance in the Philippines and in other ricegrowing countries in Asia. Whorl maggot attacks the rice plant at early stages, up to 40 days after transplanting. The symptoms of damage are whitish discolorations of the leaf margin and small holes on the leaf surface caused by the feeding of the larvae before leaf emergence from the whorl.

Field screening of rice varieties for whorl maggot resistance was initiated at IRRI in 1972. Since then about 20,000 rices have been screened. Several of the varieties were moderately resistant, but most were highly susceptible. The test varieties were planted at a spacing of 25 x 25 cm in a single row.


Those that were damaged least were retested to confirm their resistance. For retesting, the rices were planted in 1- x 5-m plots, replicated four times. Plant reactions to the pest were evaluated at the peak of damage from 25 to 30 days after transplanting, using standard scoring (0–9) by visual observation on a row basis. Among the rices tested, only the line IR2070-414-3-9 (CR94-13/IR20) showed a high level of resistance.

Greenhouse studies of the mechanisms of resistance revealed that resistance is

mostly due to antibiosis. Plant dissection indicated few survivors on the resistant variety; those that survived were smaller than those reared on TN1. Further investigation of the sources of resistance in the field indicated that resistance comes from the parents (R 94-13 and IR20), both of which have moderate resistance. We are attempting to increase the level of resistance by making diallele crosses of moderately resistant parents. To locate additional resistant sources, we are evaluating the world collection.

Yield performance of some gall midge-resistant cultures in field trials in Karnataka, India

Mangalore. Crossing of resistant donors B. S. Naidu, P. S. Ral and B. Jagannath, with semidwarf high yielders has several University of Agricultural Sciences, Hebbal, Bangalore, Karnataka, India potential F4 progeny at Mandya/

Mangalore. The table shows the merits The rice gall midge is a serious pest of the first kharif crop in the coastal districts (South Kanara and North Kanara) of Karnataka. The damage was quite severe in 1974, and yield losses were as high as 25,000 tons in South Kanara alone, where 100,000 ha of rice is cultivated as kharif paddy. The high-yielding varieties Jaya, Sona, IR20, Vani, and Madhu are popular in the State, but they are not resistant to gall midge. In recent years, the pest has damaged crops even in the inland districts. Gall midge incidence was high in the summer of 1975 at Mandya. The number of galls per square meter recorded in a variety trial (49 entries) ranged from 10.2 for RP 268-42-3-2 to 65.6 for RP 545-73-3-5, with a mean of 24.6 ± 1.8.

Since 1970, varieties have been screened for gall midge resistance at

of three resistant cultures identified at Mangalore from 1973 to 1975.

RPW6-13 was released in 1975 as Vikram in Karnataka. Experiments conducted from 1973 to 1975 reveal that RPW6-15 and CR93-4-2 exhibit yields significantly higher than those of Vikram. RPW6-I 5 is practically immune to the insect damage. CR934-2 is by far the best yielder and is also very early. It is superior to Vikram in gall midge resistance, but its grain is coarse. Since coarse grain is desired in the coastal areas (for parboiling), CR93-4-2 should be well accepted, especially in view of its high yield and better resistance.

These cultures have been registered for minikit trials in Karnataka during kharif 1976. Either RPW6-15 or CR93-4-2 is expected to be a good substitute for Vikram for better yield and resistance.

Yield performance of gall-midge-resistant cultures (av. of 3 years, 1973–1975). University of Agricultural Sciences, Hebbal, Bangalore, Karnataka, India.

Culture Parents Yield Duration Galls (t/ha) (days) (no./sq m) Grain type

RPW6-13 IR8/Siam 29 3.6 136 7.09 long, bold RPW6-15 IR8/Siam 29 4.1 133 0.04 long, bold CR93-4-2 CR55-13/IR8 4.5 127 3.83 Jaya 3.8 131 36.72 long, bold

short, bold


Deep water Since high levels of crop management are

Varietal improvement of photosensitiv e not possible during the monsoon period, types for medium-deep area s such varieties should yield better than

M. J. Balakrishna Rao, Central Rice Research Institute (CRRI), Cuttack, Orissa, India

traditional tall varieties now being grown with moderate fertilization and pest control.

For waterlogged areas, highly Much of the riceland in South and Southeast Asia is planted to photoperiod-sensitive varieties of medium to late duration (150–170 days) whose flowering times coincide with the post-monsoon period from mid-October to late November. More than 60 percent of India's riceland is in such varieties. The early, photoperiod-sensitive, high-yielding varieties are not considered suitable for such areas. Badly needed are

productive, photoperiod-sensitive, and nonlodging medium-tall varieties should be developed. Such lines have been bred at CRRI by utilizing Jagannath and Pankaj. Particularly promising are lines from the crosses Pankaj/Jagannath, CR70/Pankaj, and Pankaj/Kada, and from Jagannath natural crosses. These lines yielded from 4 to 6 t/ha with average management, minimum plant protection, and low levels of nitrogen

high-yielding lines that have different (20–40 kg N/ha). Improved late- photosensitive periods, are adapted to maturing types now cultivated in India

Lines from the cross Pankaj/Jagannath made at the Central Rice Research Institute (CRRI),

low light intensity and poor drainage, are Mahsuri, CR 1014, Pankaj, and Cuttack, Orissa state, India, are particularly

and are resistant to insects and diseases. Jagannath. promising.


Temperature tolerance Varietal reactions to high temperature

Shouichi Yoshida, plant physiologist, International Rice Research Institute

Sixty-eight varieties were screened for tolerance to high temperatures under day/night temperature regimes of 35°/27°C in the IRRI phytotron. Interestingly, all varieties identified as tolerant were upland varieties, and six of seven were resistant or moderately resistant to drought under field conditions. The findings suggest that heat and desiccation tolerance (in part) share a common mechanism.

IR8 was more tolerant of high temperature than were the other IRRI varieties tested. Such temperature tolerance may partly explain why IR8 has been successful in regions of Pakistan where high temperatures prevail.

List of high temperature-tolerant and susceptible varieties. IRRI, 1975.

Variety Fertility at high temperature (%)

Tolerant

Agbede Carreon Dular N22 OS 4 PI 215936 Sintiane Diofor IR8

88 90 86 92 86 88 86 78

Susceptible

Basmati-370 BKN 6624-46-2 C4-63G H4 Pelita I/1

4 3 8 2 7

IRRI’s phytotron was used to screen 68 rice varieties for tolerance to high temperatures. Seven upland varieties were identified as tolerant. The phytotron, a gift of the Australian Government, has 32 controlled environment areas; it is used by scientists of various disciplines.


Pest management & control DlSEASES

In vitro isolation of rice tungro virus from cut leaves of rice

A. Kondaiah, V. T. John, and A. P. K. Reddy, All India Coordinated Rice Improvement Project, Rajendranagar, Hyderabad, A.P., India

Repeated tests at AICRIP show that rice tungro virus can be recovered from detached tungro-infected leaves even after 15 days. When nonviruliferous leaf-

hoppers were used to pick up the virus from infected leaves, the infection of detached leaves was similar to that of intact leaves at all ages. The negative transmission to test plants in several replications showed that the insects used carried no virus. Preliminary results are in the table; details will be published elsewhere. The longevity of the virus in vitro in dry tissues is also being studied.

In vitro isolation of tungro virus transmissible from detached infected rice leaves. AICRIP, Hyderabad, India.

Infected plants a (no.) at

0 DS 2 DS 5 DS 10 DS 15 DS Treatment

Insect control 0 0 0 0 0

Healthy control 0 0 0 0 0

Healthy leaf bit 0 0 0 0 0

Infected plants 3.20 2.08 2.40 3.60 3.00 (3–4) (1–4) (1–4) (3–4) (2–4)

(3–4) (1–4) (1–3) (1–2) (1–2) Infected leaf bit 3.60 2.60 2.20 1.40 1.40

Efficacy of Sankel and New Sankel against bacterial blight of rice Xanthomonas oryzae (Uyeda Ishiyama) Dowson in field tests in West Bengal, India

G. G. Mukherjee, A. Santra, and S. K. Mukherjee, Mycology Section, Rice Research Station, Chinsurah, West Bengal, India

a Out of a total of four plants at 20 days after Inoculation. DS = days after storage. Means of five replications. Ranges are in parentheses.

The control of bacterial blight of rice, especially among semidwarf varieties, is one of the most serious problems in ricegrowing countries, including India. Until now, little success has been achieved through chemical applications, although in isolated instances, seed treatments and foliar sprays in the field have considerably reduced disease incidence and enhanced yields. Two new formulations, Sankel and New Sankel, both of


which contain 65 percent nickel dimethyl dithio carbamate, were tested against the disease at the Rice Research Station, Chinsurah, West Bengal. In the monsoon seasons of 1971, 1972, and 1973, 25-day-old seedlings of IR8 transplanted at one seedling/hill were

Disease index of bacterial blight during 1971, 1972, and 1973 (mean of six replicates). Rice Research Station, Chinsurah, West Bengal, India.

Disease index (% damage)

(1971) (1972) (1973) Treatment

Sankel 43.33 1.29 20.20 New Sankel 48.79 2.33 20.50 Control 50.04 1.96 27.95

S.E.m 1.69 3.96 1.00 F ratio 5.04* n.s. 19.07** C.D. 5% 5.32 – 3.14

laid out in a randomized block design with six replications. The nursery bed was sprayed twice with the formulations at a dose of 0.2% mixed with 0.5 cc of ligton liquid sticker for each liter of spray suspension. It was first sprayed at 10 days after seedling emergence and next at 1 day before transplanting. Spraying in the field began about a month after transplanting and continued at 10-day intervals for four spraying. The dose of Sankel and New Sankel used for spraying in the field was 2.22 kg/ha, with the spray suspension mixed with ligton liquid sticker at the rate of 0.5 cc/l. Disease incidence was recorded and a disease index (percent of damage) was calculated after the completion of all the sprays. The 0–4 scale for bacterial blight rating was used on 100 first leaves randomly collected by moving along both diagonals of each plot.

Both Sankel and New Sankel lowered the disease incidence in 1971 and 1973, but no definite indication was obtained in 1972 because disease pressure was low. In 1971, Sankel was significantly superior to New Sankel, but no such difference in their performance was found in 1973. No clear-cut yield differences were observed, probably because many factors other than disease affect yield.

Influence of nitrogen fertilization on the development of bacterial blight

A. Venkata Rao, T. L. Subramanian, K. Chandramani, and K. Tera, Regional Agricultural Research Station, Aduthurai, Tamil Nadu, India

Bacterial blight, incited by Xanthomonas oryzae, is a serious disease in many ricegrowing areas. Its occurrence has intensified with the introduction of

susceptible high-yielding varieties and increased use of nitrogen fertilizer.

a field trial was conducted during the To assess the intensity of bacterial blight,

1975 kuruvai season (July–October) with four levels of nitrogen (0, 50, 100, and 150 kg N/ha). A variety that was highly susceptible to bacterial blight, Karuna (Co. 33), was grown. The intensity of the disease was recorded during the maximum tillering stage, and the total nitrogen content of healthy and diseased leaves was estimated. The disease severity was significantly less with zero nitrogen, and increased with increasing levels of nitrogen. Severe bacterial blight was observed at 150 kg N/ha. The total nitrogen content of infected leaves was reduced more than that of healthy leaves. Increased grain and straw yields were observed in all treatments except the check. However, the reduction in grain and straw yield at the 150 kg N/ha level was due to the severity of the disease.

Efficacy of certain fungicides in the control of bacterial blight of rice

S. Kannaiyan and A. Venkata Rao, Regional Agricultural Research Station, Aduthurai, Tamil Nadu, India

Field trials were conducted with certain fungicides to assess their efficacy in controlling bacterial blight of rice caused by Xanthomonas oryzae. The trials were conducted in randomized block design in two seasons in 1973–74, the kuruvai (June–September) and the thaladi (November–February), using the susceptible varieties Karuna and IR8, respectively. The treatments were 1) Fytolan, 2) T.F. 130 (thiadiazole compound), 3) Vitavax, 4) Cuman EC, 5) Dithane Z-78,6) Hinosan, and 7) untreated control. Three applications were made at 55, 65, and 75 days. Significantly less disease incidence was recorded in all treatments than in the untreated check. The lowest disease incidence in both seasons was obtained with T.F. 130, followed by Cuman EC and Fytolan (copper oxychloride). copper oxychloride was not phytotoxic on the two varieties.

Efficacy of certain fungicides in the control of sheath blight

S. Kannaiyan and N. N. Prasad, Microbiology Laboratory, Faculty of Agriculture, Annamalai University, Annamalainagar, Tamil Nadu, India

Sheath blight of rice incited by Corticium sasakii Shirai Matsumoto is a serious disease in many ricegrowing areas. With the introduction of high-yielding and high-fertility strains of rice, the disease is becoming more common. To study control measures, the fungicides Benlate W.P., Brassicol W.P., Hinosan EC, Kitazin EC, and Dithane D-14 EC were tested at 0.3 and 0.4 levels under pot culture conditions during kuruvai 1975. ADT 31, a variety susceptible to the disease, was raised in cement pots and then sprayed with the fungicides during the maximum tillering stage. The results showed that the systemic fungicide Benlate most effectively checked the disease, followed by Hinosan and Brassicol. Kitazin was also effective in controlling the disease, but it was phytotoxic at the concentrations tested. Dithane D-14 was ineffective against sheath blight, and phytotoxic to rice plants.

Incidence of sheath rot in rice – a potential problem for Sambalpur, Orissa

R. Naik, plant pathologist, Regional Research Station, Chiplima (Sambalpur), Orissa, India

Sheath rot caused by Acrocylindrium oryzae Saw. was observed in high-yielding varieties (HYV) grown in and around the Sambalpur ricegrowing areas in 1974 kharif and rabi and again in 1975 kharif. The intensity of the disease in 1974 rabi was higher than that in the preceding or the succeeding kharif. Sheath rot was widely prevalent in the HW and, to a lesser extent, in local tall varieties in farmers’ fields. The disease was also noticed in local tall varieties in some ricegrowing areas of the adjacent district, Sundargarh, in 1975 kharif. The choking and sheath rot symptoms with discolored grains were more conspicuous in the HW. The table shows rices that are doing well under sheath rot pressure,

Reactions of varieties to sheath rot at Chiplima (Sambalpur), Orissa, India, in the 1975 kharif.

Designation Reaction a/

IR24 R IR26 R CR 44-1 20-1 R RP 825-70-7-1 MR RP 825-71-4-1 R RP 884-81-1 R RP 974-1 12-1-6 R IR1529-RP6801 R IR2071-176-1-2-1 R IR2071-669-3-6-4 MR

R 2410 R R

Jaya MR a / R = resistant; MR = moderately resistant.

IR2071-685-3-5-4 R CR 93-4-2

Widespread occurrence of leaf scald of rice in Indonesia

P. S. Rao, Shagir Sama, and Wasmo Wakman, Lembaga Penelitian Pertanian, South Sulawesi, Indonesia

During the 1976 wet season (December– March), leaf scald disease (caused by Rhynchosporium oryzae) affected more than 1,000 ha of lowland rice in two districts, Gowa and Takalar, of South Sulawesi province. Bakka, a popular local variety, suffered most, but others, including improved varieties, were also affected.

The disease was observed at all plant stages, from seedling to maturity. Panicles of severely affected mature plants were also affected. The most commonly affected stage was maximum tillering. The disease was generally restricted to the tips of the lower leaves. When the spots were few and isolated, typical leaf scald symptoms were noticed. When the spots coalesced and were in an advanced stage, the symptoms resembled those of bacterial blight. Isolations yielded the leaf scald pathogen.

upland rice. It was found in both nitrogen-deficient and fertilized fields, but was more conspicuous in the latter.

Although the disease has previously been noted, this was the first time that large areas were affected in this province. Its present incidence, however, is not alarming. Its spread and incidence would be worth watching in other areas in the future.

The disease was also observed in


Pest management & control INSECTS

Report of the entomology session at the 1976 IRRC

A half-day session at the 1976 International Rice Research Conference was devoted to discussion of the approaches of various Asian countries to integrate the use of insecticides with other control methods, and of means to increase insecticidal efficiency.

The following papers were presented: Integration of insecticides and resistant

varieties by C. H. Cheng, Taiwan; and J. P. Kulshrestha, India.

Application of insecticides based on thresholds of economic damage by J. P. Kulshrestha, India; C. H. Cheng; and V.A. Dyck, International Rice Research Institute.

Placement of insecticides by P. van Halteren, Indonesia; B. Duff, E. A. Heinrichs, International Rice Research Institute; and S. Y. Choi, Republic of Korea.

Effects of insecticides on natural enemies of rice pests by K. Kiritani, Japan; J. P. Kulshrestha; and C. H. Cheng.

Reports on rice pest management programs in various countries by J. P. Kulshrestha; H. A. Custodio, Philippines; I. N. Oka, Indonesia; S. Alam, Bangladesh; and M. B. Kalode, India.

Participants were H. D. Catling, Bangladesh; I. Manwan, Indonesia; S. Tatang, Indonesia; S. Pongprasert, Thailand; Y. Elikewela, Sri Lanka; and R. Feuer, International Rice Research Institute.

The major combination of practices is resistant varieties and judicious application of insecticides. Several countries are using thresholds in the control of the brown planthoppers, stem borers, and rice bugs. The necessity to improve sampling methods and forecasting techniques was discussed. Recent research on the effects of insecticides on natural enemies has made it possible to begin developing a priority list of chemicals for


The root-zone method of application of insecticides, as a method of increasing insecticide efficiency over traditional methods (above), was discussed during a half-day entomology session at the 1976 International Rice Research Con- ference. A major focus of discussion was the approaches of various Asian countries to integrating insecticide use with other control methods.

insect control based on their effects on natural enemies. However, the varied reactions among the different beneficial species make it mandatory that the role and importance of the various natural enemies at each location be determined. The root-zone method of application was discussed as a means of increasing insecticide efficiency. For the first time, we discussed national programs which utilize the pest management concept in their control recommendations. It was encouraging to note that farmers are amenable to the concept of integrated control.

Due to the increasing importance of the brown planthopper, a special session was held. Drs. O. Mochida, Indonesia, and V. A. Dyck, International Rice Research Institute, discussed the bionomics of brown planthopper. Dr. M. D. Pathak, International Rice Research Institute, discussed the current status of resistant varieties.

Seminar on planthoppers and leafhoppers of the rice crop

O. Mochida, IRRI-Central Research Institute for Agriculture (CRIA), and S. Tatang, CRIA, Sukamandi, Indonesia

A seminar on rice planthoppers and leafhoppers was held at the first meeting of the Entomological Society of Indonesia (President, Ir. Soenardi) in Yogyakarta, Indonesia, June 1–3, 1976. It was sponsored by the Faculty of Agriculture of Gadjah Mada University and the Entomological Society. About 200 participants, including plant protection specialists, entomologists, agronomists, breeders, and agricultural spray pilots attended. Thirty-six papers were presented. The participation of many persons in various fields indicated the importance of the brown planthopper in Indonesia. About 290,324 tons of rice was lost to the brown planthopper and to grassy stunt virus in the fiscal year 1974–75.

Survey on integrated control

A discussion was held at the 1976 International Rice Research Conference to explore ways to accelerate the development, testing, and practical application of integrated approaches to insect control. As a starter, communication among entomologists interested in this concept will be promoted so that ideas and experiences can be shared. A survey form has been developed and will be sent to interested entomologists to determine a) the current control recommendations; b) the components lacking or weak in the integrated package; and c) the measures that should be taken to improve the components to make them more usable in the farmers’ fields. All scientists who wish to collaborate are encouraged to write to the Entomology Department, IRRI; we will send the forms to you. We are very anxious to know what insect control methods are being recommended in the rice-producing areas of the world. Your cooperation is appreciated.

Rice & the environment Progress in breeding semidwarf rices that are sensitive to photoperiod

Suvit Pushpavesa, rice breeder, Rice Division, Department of Agriculture, Bangkok, Thailand; and Ben R. Jackson, plant breeder, The Rockefeller Foundation, Bangkok, Thailand

Numerous semidwarf varieties that are insensitive to photoperiod have been developed and released throughout the world. In Thailand, a series of locally developed high-yielding varieties (all insensitive) have been well accepted by farmers in areas under good irrigation in the dry season. But at least 80 percent of the riceland is planted under rainfed conditions in the monsoon season. Most of these areas are planted to tall traditional varieties that are sensitive to photoperiod. Thai scientists have sought to combine the semidwarf and intermediate plant types with sensitivity to photoperiod, as well as with elongation ability for semideep water. This might

encourage wider use of the semidwarfs and increase yields in unirrigated areas.

Selection began in 1970 from the crosses Niaw San Pah Tawng 2 /IR262 and Puang Nahk 16/Pankhari//C4-63. Both Niaw San Pah Tawng and Puang Nahk 16 are strongly sensitive to photoperiod in Thailand. Some of these new photoperiod-sensitive lines were first tested for yield in a preliminary trial in 1974. They were subsequently entered in multilocational yield tests in the 1975 wet season (see table). The fertilizer response of two new photoperiod- sensitive hybrid lines is compared with that of the traditional, tall, waxy Niaw San Pah Tawng and the nonwaxy Leuang Pratew 123 at four locations (see figure). The data, although somewhat limited, suggest that yields might be increased by transferring photoperiod- sensitive genes to semidwarf rices, and by heavy fertilization.

Yield and some agronomic characters of semidwarf and intermediate-height glutinous and nonglutinous lines that are sensitive to photoperiod, and of a tall traditional variety.

Yield (t/ha) Designation Origin 1974 1975 Flowering Ht Panicles

date (cm) (no./hill) Av. Range

BKN 6801- 5 3-3

BKN 6721- 1 1-8-3

BKN 6721- 5-39-l(1)

NSPT

BKN 6721- 2-38-3

BKN 6819- 36-3-1

IR1060-90-2-1

NM S-4

Glutinous (9 locations) LT/IR8//W1252/// 3.5 3.0 1.6–4.9

NSPT

NSPT 2 /IR262 2.2 3.6 1.9–4.9

NSPT 2 /IR262 3.3 3.5 1.7–4.7

Niaw San Pah 3.3 2.0–4.8 Tawng

Nonglutinous (6 locations) NSPT 2 /IR262 3.4 4.8 3.0–5.7

PN 16/PKR//C4-63 4.1 4.8 3.1–6.6

Wag Wag 3 //IR8 3.5 4.1 2.1–5.2

Nahng Mon S-4 3.5 4.2 3.5–4.9

Oct. 14 97 11

Oct. 23 134 10

Oct. 17 136 10

Oct. 23 164 8

Oct. 18 165 10

Oct. 4 114 11

Oct. 10 112 15

Oct. 21 177 9

Nitrogen response of hybrid lines and traditional tall varieties grown at four fertilizer levels at one northern, one northeastern, and two central plains rice experiments stations (data courtesy of C. Kanareugsa and rice experiment station personnel), Thailand.

Announcement — new report

George W. Robertson, P. Ag., agrometeorologist

Rice and Weather—G. W. Robertson. 1975. Technical Note No. 144 of the World Meteorological Organization, Geneva, Switzerland. 40 p.

This report briefly covers such topics as rice cultivation; growth and development; environmental requirements including water, photoperiod, temperature, solar energy, wind, and atmospheric vapor pressure; forecasting the yield of paddy rice; irrigation; climatic zonation for rice; and bioclimatic conditions in rice-producing areas of the world. A section on references and suggested reading lists more than 120 relevant articles.

Although the article was prepared as a general source of information for meteorologists, agricultural climatologists, and crop geographers, agronomists and others working more closely with rice may find useful material here.


Soil & crop management Applied rice research program in northeast Brazil

Kenneth C. Ellis, Consortium for International Development, Cochabamba, Bolivia, and L. D. Haws, International Rice Research Institute

Local rice varieties and cultural practices were compared with new varieties and methods under rainfed upland conditions during the 1974 rainy season at three locations in Maranhao and Piaui states, northeastern Brazil. Each plot was 100 sq m (10 m × 10 m); we harvested 64 sq m (8 m × 8 m) for yield data. At two locations, the rice seed was broadcast; at one location, it was planted in rows. Herbicides (Machete and Stam F-34) were used to control weeds. No insecticides were used except at one location where infestation of ear head bugs was severe.

Results (see table) indicated that: 1) the broadcast method of seeding rainfed upland rice was highly successful; 2) herbicides gave excellent weed control and were cheaper than hand weeding;

3) the semidwarf varieties IR8 and conditions; 4) the use of fertilizers on the CICA-4 yielded significantly more than tall local variety Dourado Agulha was local varieties grown under similar not profitable. Cost of major inputs, and returns per hectare for rainfed upland rice in Maranhao and Piaui states, Brazil.

Costs and returns ($/ha) for

Seed Fertilizers Pesticides Total Gross Net inputs income return

At Piripiri

IR8 9.33 139.00 36.00 185.00 877.00 692.00 CICA-4 9.33 86.00 36.00 131.00 585.00 454.00 D. Agulha 9.33 86.00 36.00 131.00 328.00 19 7.00 D. Agulha 9.33 00.00 36.00 45.00 328.00 283.00

At Teresina

IR8 14.00 56.00 36.00 106.00 889.00 783.00 CICA-4 14.00 38.00 36.00 87.00 561.00 474.00 D. Agulha 14.00 38.00 36.00 87.00 202.00 11 5.00 D. Agulha 14.00 00 .00 36.00 50.00 203.00 153.00

At Santa Ines

IR8 14.00 56.00 25.00 95.00 636.00 541.00 CICA-4 14.00 38.00 25.00 77.00 546.00 469.00 Sagrimao 14.00 38.00 25.00 77.00 416.00 339.00 Sagrimao 14.00 00.00 25.00 39.00 220.00 181.00

Analysis of yield components in ricefields in the Punjab, India

S. S. Saini and G. S. Brar, Punjab Agricultural University Regional Rice Research Station, Kapurthala, Punjab, India

The production of food grains in the Punjab - one of the smaller states of India - more than trebled from 1965 to 1975. During this period, rice production increased about five times (from 292,000 to 1,445,000 tons) and yields increased from 1.0 to 2.6 t/ha. The increases were mostly due to the rapid spread of the high-yielding varieties IR8 and Jaya. The varieties now cover more than 90 percent of the rice area. Although these rices can yield more than 10 t/ha under Punjab conditions, average yield is stabilized at 4 t/ha.


Table 1. Analysis of yield components and yield in 47 rice fields in the Punjab during kharif 1975.

Character

Values from survey of 47 fields Optimum value

to obtain Mean value Range Samples with opti- 100 quintal mum or higher per hectare value

(no.) (%)

Hills (no./sq m) Ear-bearing tillers

Ear-bearing tillers

Non-ear bearing tillers

Nonear bearing tillers

Grains/panicle (no.) Fully ripened grains (%) 1,000-grain wt (g) Grain weight (g/sq m) Grain yield (ql/ha)

(no./sq m)

(no./hill)

(no./sq m)

(%)

33

363

11

–

– 103 85 30

1000 100

22

139

6.3

13

9.3

82.19 28.1

507.3

110

50.73

12 – 41

70 – 280

2.9– 11.8

3 – 40

2.9– 36.4 77 – 214 57.2– 96.8 24.0– 32.0

22.0– 98.6 220 – 986

4

–

1

–

– 21 22 16 – –

8.5

–

2.1

–

44.7 46.8 34.2

–

–

To obtain yields of 10 t/ha, we need good management that will enable a square meter of IR8 and Jaya to produce about 363 productive tillers from 33 hills; each tiller should bear 103 fully ripe grains weighing 30 g/1,000 grains. A survey covering a 500-km route across 10 important ricegrowing districts was undertaken during kharif 1975 to assess the efficiency of farmers’ management practices to produce yield components. Forty-seven ricefields were studied and analysis of the situation in them compared to optimum requirements is

summarized in the table. The rice growers failed to establish

the optimum number of hills in the field or to produce the required number of ears. The percentage of nonproductive tillers (9.3%) was high. The number of grains per panicle, the percentage of fully ripened grains, and their 1,000-grain weight were optimum in 44.7, 46.8, and 34.2 percent of the cases, respectively. That condition might be due to lower plant population and to a low number of ears per hill. The yield in the fields ranged from 2.2 to 9.9 t/ha, averaging

5.1 t/ha — about half of the yield potential of IR8 and Jaya.

To further increase yield, it is essential that farmers establish the required number of hills in the field (the main limiting factor) and to use good management to obtain optimum magnitudes of the yield components. A regular survey of these factors at district level should be undertaken every year to enable extension workers to formulate sound and better recommendations for farmers.

Rice-based cropping systems White grub control in an upland ricecorn cropping pattern

R. F. Apostol and J. A. Litsinger, Cropping Systems Program, International Rice Research Institute

Farmers say that the white grub Leucopholis irrorata (Chev.) Scarabaeidae is the principal insect pest of rice and corn in upland areas of Batangas province, Luzon, Philippines. They particularly notice the grubs feeding on the roots of corn seedlings, causing the plants to wilt and eventually die. In certain years, the white grub also damages rice that is planted before corn. Knowledge of the white grub’s life cycle provides clues to its control.

White grub has one generation per year beginning at the onset of the rainy season in late April. Adult beetles become active and lay eggs in the wet soil when land preparation ends and rice planting begins (see figure). Corn is planted after rice in October when the third-instar larva is predominant. White grubs are usually noticed at this time. Almost without exception, farmers tolerate the damage. Soil insecticide generally is not used because high rates (2 – 4 kg a.i./ha) are needed and the cost is high.

decreased if insecticides should be applied against the first-instar larvae during the rice crop. In a series of trials, several insecticides were tested on both the rice

We thought that rates could be and corn crops. When incorporated into the soil of the rice crop during normal weed cultivation, lindane at 1 kg a.i./ha provided 100 percent control of the early

Population dynamics of the adult and three larval instars of white grub Leucopholis irrorata (Chev.). In a cropping pattern of upland rice followed by corn, cropping systems scientists found that the grubs were most effectively controlled by low applications of a soil insecticide during weeding of the rice crop when they were small and easy to kill. Batangas province, Philippines, 1975.

instar. Only 48 and 65 percent control resulted from lindane at 1 and 4 kg a.i./ha, respectively, applied against the third-instar in the corn crop.


Performance of sorghum varieties in uncultivated lowland paddy

A. A. Gomez and A. A. Evangelista, Department of Agronomy, University of the Philippines at Los Baños, Philippines

In rainfed and partially irrigated rice areas, where water is limiting during the dry months, a logical cropping sequence is to grow rice during the rainy months and to follow it with drought-resistant upland crops during the dry months. Therefore, we tested the performance of 16 high-yielding sorghum varieties in uncultivated lowland puddled soil. By foregoing cultivation we avoided the difficult task of pulverizing a poorly structured soil. We were also able to plant immediately after the rice harvest and, most important, to use the substantial residual soil moisture for the growth of a second crop.

In spite of waterlogging at the early vegetative stage, four varieties – CS 100, CS 107, D 67-1, and D 674 – yielded higher than 4.0 t/ha (see table). These yields compare favorably with yields under normal upland culture.

Performance of 16 promising sorghum varieties grown in uncultivated lowland paddy soil. Uni- versity of the Philippines at Los Baños (UPLB), Philippines, 1975–76 dry season.

Sorghum yield Blooming ht Plant

(t/ha) days (cm) variety

C 67-4 CS 100 CS 107 D 67-1 CS 108 CS 102 CS 106 CS 99 CS 105 CS 103 COSOR 3 IS 2940 139024 CS 104 498003 BPI SOR 1

Cv (%) Mean

LSD .05

4.71 62 153 4.66 66 134 4.23 67 129 4.04 64 157 3.71 63 132 3.42 61 137 3.42 61 147 3.42 62 138 3.33 62 126 3.28 65 125 3.23 65 145 3.04 64 171 2.95 60 142 2.90 67 121 2.42 59 141 1.66 62 151

3.40 63.12 140.56 18.00 2.60 6.00 1.06 2.85 14.31

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