Screening Crops for Tolerance to Abiotic Stresses

A member of CGIAR consortium www.iita.org
PHENOTYPING FOR TOLERANCE TO ABIOTIC
STRESSES IN YAM, MAIZE, BANANA AND COWPEA
Workshop on Implementation of IITA’s
Genetic Improvement Strategy
IITA-HQ, Ibadan Nouhoun Belko
09 September 2015 Postdoc Cowpea Agro-Physio

Climate change will increase intensify & frequency of drought

Global low soil P availability is a primary constraint to life on earth
Dominance of red and light-gray colors, indicating soil
P deficiency for the growth of many cultivated species
Importance of P availability as a primary limitation to
agricultural productivity in terrestrial environments
(from Jaramillo-Velastagui, J. Lynch 2011).

N balance deficiency – Issue of accessibility & affordability in SSA

Soil Fertility
Yield
Traditional genotypes lodge at
high fertility
But no yield gain at
low fertility (*)
Can we develop genotypes
with superior yield at all
fertility levels?
Benefit from 20th century
green revolution
Potential Benefit from 21st
century green revolution
Dwarf genotypes
respond to high fertility

Objectives: Know environment, Understand mechanisms, high genetic gain
Hypothesis: Mine available nutrients, Tap water, Save water, Secure reproduction
Approaches: Direct (yield) and Indirect (root - shoot phenes important for specific stress)
Water Phosphorus
5%
18%
11%
23%
10cm
20cm
30cm
4ppm
2ppm
0.5ppm
0.25ppm
40cm
Stomata response differences to
VPD relate to plant hydraulics

Setting up Screening Protocol for N and K
Use Efficiency in Yam
SELECT PARENTS
- NUE Trials, Uromi
- Performance in Low Fertility
Environment, Mokwa
Genotype parents
Using SSR/SNP Markers
Generate
Populations
Phenotype two Populations
In Low N and K Plots
and NUE Trials (field and SH)
Genotype Populations
Using polymorphic
SSR/SNP Markers
Find Marker - Trait
Association for NUE
of N and K or other agronomic traits
Validate Favourable
Markers/QTL (s) using other
populations generated with the
selected parents
A. Lopez-Montes and R. Bhattacharjee

Screening Maize for Tolerance to Drought
S. K. Meseka and A. Menkir
Drought tolerance: Ikenne, Forestry Zone
Field experiments: irrigated & non-irrigated Blocks
 Planting during the second week of November
Sprinkler irrigation system supply 20mm/week
Drought stress imposed from 35 DAP until harvest
Agronomic traits measured
Results from 2000 to 2015
Genetic bases of tolerance to drought understood
2000+ improved lines developed & shared in WCA
NARS & seed companies released varieties/hybrids
Farmers adopted improved drought tolerant materials

Screening Maize for Tolerance Drought & Heat
Drought & heat tolerance: Kadawa, Kano State
 Field experiments: only one block used
 Planting during second week of February
 Gravity irrigation (furrow) every four days
 Irrigation stop in April for 21d then ok once a week
 Agronomic traits measured
 Genetic bases of tolerance not well understood
 400+ varieties/ hybrids & 1500 inbred lines screened
 New inbred lines tolerant to drought and heat stress
with high grain yield identified
Month
Temperature Co
RHMax Min
February 34 21 16
March 39 26 13
April 42 28 15.5
May 40 27 17
June 35 24 21.8

High N Low N
Low N site development
Selection & depletion of nitrogen
Planting high population density
Removal of all crop residues
Low N block (20 kg N/ha)
High N (90 kg N/ha)
Screening Maize for Tolerance to low N
Low nitrogen tolerance: Mokwa, Niger State
 Inbred lines combined tolerance to Low N/Drought
 Non-additive genetic effects for grain yield provided
basis for the exploitation of heterosis
 Hybrids combining high grain yield with tolerance to
drought/low N developed and disseminated to NARS
 Genetic bases of inheritance understood
 Several low N efficient maize lines developed and
disseminated to NARS
 NARS in WCA released several improved low N
efficient varieties/ hybrids

 Drought stress research conducted in forestry zone with
incidence of rainfall at flowering/grain filling stages
 Lack of modern high throughput phenotyping tools &
plant growth facilities for screening large populations
 Limited knowledge of genetic bases of combined drought
and heat stress tolerance in maize plants
 Absence of fully irrigated block for comparison in screening
for tolerance to combined drought & heat
 Traits measured did not include the Plant Root System –
relevant indirect trait in water & nutrient uptake
 Measurement of most Physiological Traits are time
consuming and not practical with large breeding populations
CHALLENGES AND RESOURCE NEEDS

High throughput
genotyping
Environmental data
Field drought evaluation site +
Root phenotyping in Mokwa
Greenhouse drought
evaluation, modern tools,
collaboration with CERAAS
Marker trait association
Marker assisted selection
OPPORTUNITIES AND WAY FORWARD
Initiation breeding for
tolerance to flood and
soil acidity/salinity with
climate change

Musa Phenotypic Response to Drought in 4 Env.
Prof. Swennen Rony and collaborators

Williams
Cachaco
Lep Chang Kut
Osmotic stress during in vitro growth

Green-house screening for leaf area and
transpiration efficiency response to drought
Leafareaafter18weeksTranspirationefficiency

4 varieties
Pahang (AA)
Guyod (AA)
Cachaco (ABB)
Nakitengwa (AAAh)
2 water treatments
Irrigation
No irrigation
10 replicates
Field screening for pseudostem height and leaf
area response to drought between 10 - 40 DAIS

Field high throughput phenotyping for Gs and
ΔT response to drought
Evolution of ΔT across daytime
Transp ~ evapo cooling
Detected by IR imaging
Stress
Optimal
CONCLUSION AND WAY FORWARD
- Screening tools use in breeding program
- The B & A genomes sources of resistance
- AA genome screening with LIPI partners
- Segregating populations: QTLs 800 seeds
- Sequencing all hybrids

Screening for tolerance to low soil P and rock P
use efficiency in Cowpea
K. Suzuki, C. Fatokun, O. Boukar
Pot trials for comparison of shoot growth response to different P applications
 Genotype with 28 entries
 P application with 3 levels
(0 and 30 mg P/kg of KH2PO4 and 90 mg P/kg of Togolese Rock P)
In a split plot design with 2 replications
N uptake
(g/pot)
Shoot dry
weight at 8
WAS (g/pot)
Chlorophyll
content at 5 WAP
Chlorophyll
content at 7 WAP
Plant height at
5 WAP (cm)
Plant height at
7 WAP (cm)
Nodule
number
Nodule dry
weight (g/pot)
Root dry
weight (g/pot)
P uptake (g/pot) 0.888** 0.817** 0.342** 0.232ns 0.308** 0.219ns 0.548** 0.098ns -0.056ns
N uptake (g/pot) 0.845** 0.299** 0.221ns 0.388** 0.319** 0.541** 0.137ns 0.045ns
Shoot dryweight at
8 WAS (g/pot)
0.283ns 0.348** 0.490** 0.327** 0.575** 0.021ns 0.011ns
Shoot dry weight at 8 WAP has significant correlation with P and N uptake.

Variations in shoot growth response to low soil P
and rock P in Cowpea
Shoot DW under 90 mg P/kg Rock P
Shoot DW under 0 mg P/kg KH2PO4
Decrease in shoot biomass in 90 mg P/kg
Rock P relative to 30 mg P/kg KH2PO4
Decrease in shoot biomass in 0 mg
P/kg relative to 30 mg P/kg KH2PO4
Based on their shoot biomass
production under both 0 mg P/kg
KH2PO4 and 90 mg P/kg Rock P:
 Iron Bean, IT87D-941-1, IT90K-
284-2, IT95K-1543 and IT97K-499-
38 were consistently low P tolerant
and rock P efficient lines
 Tvu-7778, Sanzi and IT97K-499-35
were the most low P sensitive and
rock P un-efficient lines

Pot trials for evaluation of optimum dose of rock P for cowpea production
 Selected lines: Iron bean, IT97K-499-38, IT87D-941-1, Dan Ila and IT97K-499-35
 Rock P application with 5 levels: 0, 30, 60, 90 and 120 mg P/kg
In a split plot design with 10 replications
Genotypic difference in shoot growth response
to different doses of rock P application
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
0 30 60 90 120
a
a a
a
Iron bean at 4 WAP
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
0 30 60 90 120
aba
aa
bb
IT97K-499-35 at 4 WAP
ShootDW(g/plant)

Genotypic difference in grain yield and nodule
number under different doses of rock P
Rock P application (mg P/kg)
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
0 30 60 90 120
Grainyield(g/plant)
a
ab ab
aIron Bean
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
0 30 60 90 120
abab
aa
bb
IT97K-499-35
0
10
20
30
40
50
60
70
0 30 60 90 120
Nodulenumber(-)
Iron Bean
0
10
20
30
40
50
60
70
0 30 60 90 120
Rock P application (mg P/kg) Rock P application (mg P/kg)
Grainyield(g/plant)Nodulenumber(-)
IT97K-499-35
 60+ mg/kg of rock P appear to be optimum for
cowpea shoot production
 30+ mg/kg of rock P allow significant increase
in grain yield in rock P efficient lines
 No clear pattern of rock P applications effects
on nodules number across genotypes
 Iron Bean and IT97K-499-35 are potential
parents contrasting for tolerance to low P and
rock P use efficiency and could therefore be
used in cowpea breeding program.

Effects of plant genotype roots and rock P
applications on rhizosphere soil pH
4.60
4.70
4.80
4.90
5.00
5.10
5.20
5.30
5.40
5.50
5.60 IT97K-499-38
Ironbean
IT97K-499-35
DanIla
IT87D-941-1
no-plant
RhizospheresoilpH
Cowpea lines
a a
b
c
a
a
4.8
4.9
4.9
5.0
5.0
5.1
5.1
5.2
5.2
5.3
5.3
0 30 60 90 120
RhizospheresoilpH
Rock Papplication amounts (mg P/kg)
ab
ab
ab
b
a
 P uptake by cowpea roots decreases pH in rhizosphere soil
 Rhizosphere soil pH increases with increase in rock P applications
WAY FORWARD
 Elucidate P uptake mechanisms in cowpea
 Elucidate mechanisms of improved rock P solubility & uptake

Dry Seed Weight (g/plant)
Stressed plants: 0 to 15.4 g/plant
Non-stressed plants: 1.5 to 58.4 g/plant
Number of days to flowering
Drought escape strategy:
Flowering time reduction under stress
Field screening for drought tolerance and high
yield potential in cowpea germplasm
C. Fatokun, O. Boukar, S. Muranaka
Fatokun et al. 2012_Plant Gen. Res. 10:171-176

Field screening for drought tolerance and high
yield potential in cowpea germplasm

HT Phenotyping cowpea mini core germplasm
collection for adaptation to drought and low P
N. Belko, O. Boukar, C. Fatokun et al.
Screen-house trials for assessing variability in drought-avoidance shoot traits
among the cowpea mini core collection in IITA-Kano: Oct 2014 – March 2015
 370 lines + 10 checks under non-limiting water condition in 3 replications
 Gravimetric measurement of whole plant canopy transpiration, leaf temperature, leaf
cholorophyll content, leaf area development and shoot-root biomasses

Extent of phenotypic variations in plant TR,
SPAD-CMR, CTD and LA in cowpea

Field trials for assessing differences in growth and yield performance under well-
watered and water-stressed conditions in Minjibir station: March-July 2015
 348 lines + 12 checks under 2 water regimes in 3 replications
 Plant phenology (days to flowering and maturity), yield components (fodder, pod and
grain), visual scoring for (i) Striga emergence, (ii) insect leaf damages and (iii) leaf
senescence under drought, and SPAD-CMR and NDVI data on selected genotypes
 On-going post-harvest activities and data processing
Field screening for tolerance to drought in
cowpea mini core germplasm collection

2600 2800 3000 3200 3400
60080010001200140016001800
Non-stressed grain yield (kg/ha)
Drought-stressedgrainyield(kg/ha)
58-53
58-57
IAR8/7-4-5-3
Iron-Clay
IT00K-901-6
IT83D-442
IT89KD-288
IT90K-284-2
IT93K-503-1
IT95K-1090-2
IT95K-1095-4
IT96D-610
IT97K-207-15
IT97K-556-6
IT97K-819-132
IT98K-128-2IT98K-205-8
IT98K-317-2
IT98K-428-3
IT98K-498-1
IT98K-698-2
IT99K-124-5
KVX-396
KVX403
KVX-421-25
KVX-525
MougneN’diambour
Petite-n-grn
Suvita 2
Repeat of the field yield based evaluation under WW & WS in Minjibir: Sept-Dec 2015
Integration of partitioning / grain filling parameters and drought tolerance indices
Beebe et al. 2013_Field Crops Res. 148:24–33 Belko et al. 2014_Crop Science 54:1-9

Field and image based phenotying of root traits
for adaptation to drought and low phosphorus
Field and lab trials for evaluating genotypic differences root system architecture
and anatomy at the ARBC Willcox-AZ with PSU partners: July-Sept 2015
 Fifty lines planted in single row plot under WW conditions in 5 reps
 5 plants per plot excavated and visually scored for root traits (Shovelomics: angle,
number, density, diameter) and root samples taken for cross section anatomy analysis
 5 seedlings per line for analysis of root hairs density and length using DIRT & ImageJ

Research plan for genetic improvement (high genetic gain):
1. Identification of plant traits conferring tolerance to drought and adaptation to low P
2. Dissecting traits interactions (trade-off, synergism) and plasticity/stability
3. Parameterization - Modeling the effect of traits across env. and stress scenarios
Opportunities and future:
• Penn State University and ARBC/G Howard Buffet Foundation and ICRISAT for
high throughput phenotyping of relevant root and shoot traits for adaptation to
drought and low fertility
• Institute of Meteorology and Climate Research (IMK-IFU-KIT) Germany, WASCAL
Burkina Faso, and Depart. Crop Sci in North Carolina State Univ for modeling to
develop guidelines for farming options in response to climate variability
Challenges and resource required:
Field and lab research facilities (irrigation, drought and low P screening sites, striga
pression, lysimetric system, rain-out shelter, screen-houses, lab space with specific
equipment etc.) and human resources (technicians and students).
Opportunities and Way forward
Challenges and resource needs

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Screening Crops for Tolerance to Abiotic Stresses

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