dissecting water-saving traits in pulses

Michel E. Ghanem, Hélène Marrou, Shiv Kumar, Vincent Vadez, Thomas R. Sinclair

Dissecting water-saving traits in pulses

Crop Physiology LaboratoryICARDA – Rabat Platform

m.ghanem@cgiar.org

Sensitive Tolerant

No major water extraction differences in sensitive and tolerant chickpea

Yield and water use

Zaman-Allah et al. 2011 JXB

21 28 35 42 49 56 63 70 77 84 91 980123456789

Days after sowing

Wat

er u

sed

(kg

pl-1

)

Sensitive

Tolerant

Low early vigorLow leaf Gs

Tolerant: less WU at vegetative stage, more water left for reproduction and grain filling

Yield and water use

Zaman-Allah et al. 2011 JXB

Vegetative Reprod/ Grain fill

CHICKPEA

A plant that has: enough water for grain filling no more water after grain filling

Hypotheses: Looking for new sources of water Save/manage water

Focus on traits affecting plant water budget

What is a drought tolerant plant ?

Vapor Pressure Deficit (VPD; kPa)Tran

spira

tion

rate

(g c

m-2 h

-

1 )0 2 4

0

1

VPD

Basic research on “Building block” of Water Use (WU)

FTSW0.00.20.40.60.81.0

Nor

mal

ized

tran

spira

tion

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Stage IStage II

Stage III

FTSW

Limited transpiration rate under elevated midday vapor pressure deficit (i.e., low

relative humidity)

Water conservation traits

Sinclair et al., 2005, FPB

6 9 12 15 180.0

0.5

1.0

1.5

2.0

2.5

3.0

< 0.6 mm h-1

< 0.4 mm h-1

VPD

0.0

0.2

0.4

0.6

0.8

1.0

Tr

Time

Vapo

r Pre

ssur

e De

ficit

(kPa

) Transpiration Rate (mm

h-1)

Exploratory studies (modeling): simulation of relative grain yield (sorghum)

Yield gain in 75 % of the cases

What would be the impact of limited transpiration under high VPD trait for soybean production in Africa?

Base line scenario Scenario with improved

variety

• Change value of 1 parameter :• VPD thereshold : 4 1.8 KPa

7

Soltani et Sinclair, 2012

Using crop modeling

8H. Marrou, Montpellier Supagro

What would be the impact of limited transpiration under high VPD trait for soybean production in Africa?

Modeling 50 different years allows risk assessmentSinclair, Marrou et al., 2014, GFS

(g/m2)

Using crop modeling

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.50 1.00 1.50 2.00 2.50 3.00 3.50

VPD (kPa)

H77/2 833-2PRLT-2/89-33

Tran

spir

atio

n (g

cm

-2 h

-1)

Kholova et al 2010 – J. Exp. Bot

Transpiration response to VPD in pearl millet:

Terminal droughtSensitive (VPD-insensitive)

Terminal droughtTolerant (VPD-sensitive)

Water conservation traits

2 mechanisms of water saving: • Low TR at low VPD• Further restriction of TR at high VPD

VPD response in pulses

• Common bean• Chickpea• Peanut• Lentil• Soybean

FTSW0.00.20.40.60.81.0

Nor

mal

ized

tran

spira

tion

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Stage IStage II

Stage III

Plants don’t suffer stress until >60% soil water is depleted

How plants manage water when there is water is critical

Basic response of plant exposed to water deficit

Conserving water by early stomata closure in soil drying cycle in lentil

NTR

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4 FLIP 2009-55L

JL1

FTSW

0,00,20,40,60,81,0

NTR

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

Ghanem, et al. unpublished

Conserving water by early stomata closure in soil drying cycle in lentil

Sensitive

Tolerant

Water conservation traits

• Tolerant line have higher FTSW threshold for transpiration decline under water deficit

FTSW response in pulses

• Common bean• Chickpea• Peanut• Lentil• Soybean (no variation yet found !)• Cowpea

• Two traits have been extensively explored for expression and genetic variability

• VPD• FTSW

• Breeding is now underway based on these results for physiologically-targeted drought traits

Summary

• Professor Thomas R. Sinclair North Carolina State University - USA

• Dr. Vincent Vadez

• Dr. Hélène Marrou UMR SYSTEM-Montpellier SupAgro - France

International Crops Research Institute for the Semi-Arid Tropics - India