Impact of drought on morphological, physiological and nutrient use efficiency of elite cacao genotypes from Bahia-Brazil, Tarapoto-Peru and Puerto Rico-USA.

IMPACT OF DROUGHT ON MORPHOLOGICAL, PHYSIOLOGICAL AND NUTRIENT USE EFFICIENCY OF

ELITE CACAO GENOTYPES FROM BAHIA-BRAZIL, TARAPOTO-PERU AND PUERTO RICO-USA.

Virupax Baligar1, Alex-Alan Almeida2, Dario Ahnert2, Enrique Arvalo-Gardini3, Ricardo Goenaga4, Zhenli He5, Marshall

Elson1

1USDA-ARS-Beltsville Agricultural Research Center, Beltsville, MD, USA.

2State University of Santa Cruz (UESC), Ilhus, BA, Brazil.3Instituto de Cultivos Tropicales (ICT), Tarapoto, Per,

4USDA-ARS Tropical Agricultural Research Station, Mayaguez, PR, USA.

5 Univ. of Florida-IFAS, Indian River Research and Education Center, Fort Pierce, FL, USA.

2017 International Symposium on Cocoa Research (ISCR), Lima, Peru, 13-17 November 2017.

0

500

1000

1500

2000

2500

1996 2000 2004 2008 2011 2016

Pre

cip

itat

ion

(m

m)

Years

Ilheus Bahia Brazil

Huila Colombia

RAINFALL SELECTED CONTRIESSan Martin Peru

Cacao Genotypes:

From Puerto Rico, USA: TARS -14 (Hybrid, tolerant to soil acidity complexes) and

Amelonado (Forastero, intolerant to acid soil complexes)

From Brazil, Bahia, Ilheus: ICS 9 (Trinitario hybrid, resistant to drought),

EET 103 (Forastero, moderately tolerant to drought)

CC 40 (Hybrid susceptible to drought).

36 Genotypes

From ICT, Peru 57 National and Inter National Clones

METHODS

For 64 days, plants were grown in a growth chamber at 30C with -33 kPa soil moisture.

On 65th day, plants were divided into two groups:

Control - Plants grown at -33 kPa soil moisture content for duration of experiment

Drought - Water withheld until the leaf stomatal conductance was less than 10% of control plants, determined by an SC-1 Leaf Porometer (Decagon Devices, Pullman, WA).

Growth and Morphology:

Dry Weights, Stem Diameter, Leaf Area, Root Length

Physiological traits:

Net photosynthesis rate

Leaf Chlorophyll: Chl a and Chl b

Total Water Use Efficiency (WUETOTAL ):

Nutrient Use Efficiency:

Nutrient Use Efficiency For N, P, K, Ca, Mg:

Drought Tolerance Index:DTI = [(Shoot +root DB at drought )/[(Shoot +root DB at field capacity)] x 100.

Drought Effects on Growth Parameters:

Significant intra-specific differences observed for growth parameters.

Drought reduced total dry weight (shoot +root) and leaf area

Drought increased root length and decreased stem diameter.

0

50

100

150

Pe

rce

nt

of

Co

ntr

ol Drought on Dry Weight

Control

Drought

1A

0500

100015002000

Leaf

Are

a (c

m2) Drought on Leaf Area

Control

Drought

0.00

5.00

10.00

Ste

m D

iam

ete

r (m

m) Drought on Stem Diameter

Control

Drought

02000400060008000

Ro

ot

Len

gth

(cm

)

Drought on Root Length

Control

Drought

1C

1B

1D

DTI in wild and national and international cacao clones at ICT, Peru

Drought tolerance index (DTI):

33 accessions - intolerant to drought,

21 accessions - moderately tolerant to drought

3 accessions (H10, ICT 1087, CA 14) - tolerant to drought.

Drought Effects on Physiological Parameters:

Intra-specific differences were observed for physiological parameters

Drought significantly reduced PN, Chl a/b and NAR.

Drought increased WUE.

0.000.501.001.502.00

Pn

(m

ol/

m2/s

) Drought on Photosynthesis

Control

Drought

0.00

2.00

4.00

6.00

Ch

l a/b

rat

io

Drought on Chl a/b

Control

Drought

2B

0.010.020.030.040.0

WU

E (g

sh

oo

t/g

tran

s)

Drought on WUE

Control

Drought

0.00

2.00

4.00

6.00

NA

R (

g cm

-2d

-1)(

*10

-4) Drought on NAR

Control

Drought

2D

2A

2C

Drought Effects on Macro-Nutrient Use Efficiency (UE)

0.0

20.0

40.0

60.0N

UE

(g s

ho

ot/

g N

) Drought on N Use

Control

Drought

0

1000

2000

3000

P U

E (g

sh

oo

t/g

P) Drought on P Use

Control

Drought

3B

0.0

50.0

100.0

150.0

K U

E (g

sh

oo

t/g

K) Drought on K Use

Control

Drought

3C

0

100

200

300

Ca

UE

(g s

ho

ot/

g C

a)

Drought on Ca NUE

Control

Drought

3D

0100200300400

Mg

UE

(g s

ho

ot/

g M

g)

Drought on Mg NUE

Control

Drought

3A

3E

Drought induced intra-specific

differences for Macro-nutrient UE

In all the genotypes, UE for N, P

and K increased and Ca and Mg

decreased with drought.

Drought Induced Intra-specific differences in nutrient

use efficiency (NUE) of 36 cacao genotypes from

Ilheus, Bahia, Brazil

0

500

1000

1500

2000

2500

N P K Ca Mg

NU

E (g

sh

oo

t /

g n

utr

ien

t)

Control

Drought

CONCLUSIONS

Drought Induced intra-specific variations for:

Growth/morphology: leaf, stem, and root parameters Physiology: photosynthesis, Chl a/b, water use efficiency, NAR Nutrient use efficiency: N, P, K, Ca, and Mg.

Reliable and Stable plant growth traits (morphology, physiology and nutrient use efficiency) will facilitate identification of cacao genotypes tolerant to drought.

Drought tolerant genotypes are useful in crop improvement programs to breed superior cultivars for drought stressed ecosystems.

Drought tolerant genotypes are useful as rootstock or as scion for establishment of new plantations or rejuvenation of old plantations in drought prone areas

Abiotic Stress-Drought

Greenhouse methods developed are useful to identify drought stress tolerant cacao genotypes

FUTURE CHALLENGE

Inter-disciplinary and Multi-institutes (National/International) Approaches are Required in Devising Strategies at Multi-scalar levels to Mitigate Effects of Drought to Achieve Sustainable High Yielding Cacao Production

Highly Collaborative Multi-Institute and Multi-Disciplinary International Research

Brazil (UESC, CEPLAC, EMBRAPA, UENF)

Peru (ICT, UNALM)

USDA-TARS, PR

Univ. of FL- IRREC, TREC

Univ. of Reading UK

I.R.R.E.C.Indian River Research and Education Center

http://trec.ifas.ufl.edu/