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Michel E. Ghanem, Hélène Marrou, Shiv Kumar, Vincent Vadez, Thomas R. Sinclair
Dissecting water-saving traits in pulses
Crop Physiology LaboratoryICARDA – Rabat Platform
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