3rd Africa Rice Congress Theme 2: Intensification and diversification Mini symposium: determinants of agricultural productivity in Africa’s rice-based systems Author: Dingkuhn et al.

1. GRiSP
Integrating Physiology, Crop
Modeling and Genetics
to Tackle Thermal
Stresses in
Rice:
The RIDEV Approach
Michael Dingkuhn (IRRI/CIRAD), Julie Mae
Pasuquin (IRRI), Cecile Julia (CIRAD), Richard
Pasco (IRRI), Jean-Christophe Soulie (CIRAD)
funded by GIZ, AfricaRice, CCAFS and CIRAD
Context of GRiSP Global Rice Phenotyping
Network

2. GRiSP Rationale
 Thermal adaptation is fundamental for agro-ecological fit
 Temperature governs rice phenology and spikelet fertility
 Climate change is changing thermal environments
 Accuracy of crop models is still poor re: thermal effects
 We need…
 Better predictive tools to map climate change impact
 Better understanding of adaptive traits: Physiology &
Genetics

3. GRiSP
History: The 1990s research at WARDA
Thermal constraints to irrigated rice in Senegal
Effect of sowing date on crop duration and sterility
Days to flowering
• Thermal and photoperiod effects on phenology
• Chilling causes spikelet sterility
% sterility
Sowing date
Sowing date
% sterility
Tw(min) at booting
1995 development of RIDEV predicting phenology and thermal
sterility as risk analysis and decision aide for cropping calendars

4. New study on rice phenology and sterility
GRiSP
responses to T
(Thesis of Cecile Julia & ongoing CIRAD/IRRI/CCAFS project)
 Emphasis on microclimate


NEW 
NEW 
Meristem T => phenology
Floodwater T => chilling stress at microspore stage
Panicle T => heat stress at anthesis
Time of day of anthesis (TOA)
 RIDEV v.2 to characterize genetic diversity

5. Philippines - Hot and dry season 2009
36
32
28
24
20
16
12
8
01/03
32
28
24
20
16
12
11/03
21/03
31/03
10/04
20/04
8
10/05
30/04
20/05
Senegal - Cold and dry season 2010
44
40
36
36
Temperature (°C)
Phenology
TOA
Panicle transp. cooling
19/06
France - Temperate Summer 2009
40
Temperature (°C)
Traits observed
5
4
3
2
1
0
44
09/06
VPD (KPa)
4 environments
30/05
Date
Date
DS Philippines
HDS Senegal
CDS Senegal
Temp. summer France
VPD (KPa)
36
5
4
3
2
1
0
40
Temperature (°C)
Temperature (°C)
IR64
IR72
Sahel108
Chomrong
(N22 failed)
44
40
4 genotypes
44
5
4
3
2
1
0
VPD (KPa)
Scope of study:
Senegal - Hot and dry season 2010
VPD (KPa)
GRiSP
5
4
3
2
1
0
32
28
24
20
16
32
28
24
20
16
12
12
8
15/01 25/01 04/02 14/02 24/02 06/03 16/03 26/03
Date
8
01/08
Tair Max
Tair Min
Twater max
Twater min
11/08
21/08
31/08
Date
10/09
20/09
30/09

6. GRiSP
Results
Time of day of anthesis (TOA)
shows adaptive plasticity
Warm nights advance TOA =>
Escape from midday heat
Humid days advance TOA =>
Escape from heat caused by absence
of transpiration cooling
Mean air temp (min) during last 7d before anthesis (oC)

7. GRiSP
Panicle temperature: IR imagery in the field
Pan2
Pan1
Flagleaf4
Flagleaf1
Flagleaf2
Flagleaf3
Leaf5
Pan3
Pan4
ca. 4900 IR observations on in-situ panicle T
Microclimate recording
% sterility observed at maturity

8. Relative humidity or vapor pressure deficit is the
main determinant of Ta-Tp difference
GRiSP
14
Senegal cool-dry
season
Senegal hot-dry
season
France summer
12
14
10
TD (observed) [°C]
c
Example: Senegal cool-dry season
12
TD=Ta-Tp (°C)
10
y = 1.45x - 0.99
R² = 0.79
1:1
8
6
4
2
0
-2
8
-4
-4
6
-2
0
2
4
6
8
TD (predicted) [°C]
10
12
14
Model prediction (sim:obs)
4
Panicle cooler
than air
2
0
Panicle warmer
than air
-2
-4
0
1
Humid
2
3
4
VPD (kPa)
5
6
Arid
7

9. GRiSP The panicle is warmest not in the hottest, but in the
most humid environment
(b)
Air and Panicle Temperature at TOA (calculated)
32
Temperature (°C)
30
28
26
24
22
PHIL_DS
Phils
SEN_HS
Sen.-hot
Site
SEN_CS
Sen.-cool
FR_HS
France

10. Temperature induced spikelet sterility
Chomrong
100
IR64
S108
IR72
(c)
90
80
Sterility (%)
GRiSP
70
Disaggregate observed
sterility into its components
 Incomplete panicle exertion
 Chilling at microspore stage
 Heat at anthesis (at TOA)
60
50
40
30
20
10
0
Phils
PHIL_DS Sen.-hot
SEN_HS Sen.-cool
SEN_CS
Site
France
FR_HS

11. Incomplete panicle exertion
GRiSP
 occurred in cold-night environments
 explained some of observed sterility
Chomrong
Panicle exsertion (%)
160
IR64
S108
IR72
Last grain
Neck node
(b)
140
120
100
Sterile
fraction of
panicle
caused by
non-exertion
80
60
40
PHIL_DS
Phils
SEN_HS
SEN_CS
Sen.-hot
Sen.-cool
Site
FR_HS
France

12. GRiSP 2. Chilling effect at microspore
stage on sterility
(Tmeristem = Twater)
100
Phil-ds
Sen-cs
90
Sen-hs
Fr-hs
Sterility (%)
80
70
60
50
40
Chomron
30
20
10
0
12
14
16
18
20
22
24
26
28
T water (min) at microspore stage (°C)
3. Heat effect at flowering
stage on sterility (Tp at TOA)

13. GRiSP
Conclusions from experimental study
Rice has highly effective adaptations to thermal stresses:
 Avoidance
 Transpiration cooling of panicle
 Good panicle exertion (long peduncle)
 Escape
 Time of day of anthesis (TOA) and its adaptive plasticity
 Tolerance
 To cold, as shown for cv. Chomrong
 Heat tolerant check cv. N22 failed (seed problems)
Heat stress more likely in warm-humid than hot-dry climates!

14. GRiSP A new modeling tool RIDEV V.2
 Simulator of…
 Phenology incl. microclimate & photoperiod effects
 G and E effects on TOA
 Sterility caused by…
 Chilling effects on microsporogenesis (water Tmin)
 Chilling effects on panicle exertion (air Tmin)
 Heat effects on pollination (Tpanicle at TOA)
 Prediction (forward mode)
 Climate change impact mapping, plant type optimization
 Agronomy (crop calendar; optimization)
 Heuristic parameterization of genotypes (reverse mode)
 Phenomics (extraction of genotypic parameter values
from experimental data)

15. GRiSP
Outlook
Use of RIDEV for Phenomics/GWAS

Indica GWAS panel (>200 acc., ORYTAGE project)

Field-phenotyped for phenology and sterility in 12 environments:
 6 sowing dates in Senegal
 3 altitudes x 2 years in Madagascar

Extraction of genotypic response parameters across
environments (Heuristics):
 Cardinal temperatures Tb and To
 Thermal duration of phenological phases
 Photoperiod-sensitivity
 Chilling sensitivity of microsporogenesis
 Chilling sensitivity of panicle exertion
 Heat sensitivity of anthesis

Association study using GBS and 700K Oryza SNP chip

16. GRiSP
Thank you
Merci
Salamat po