Name of speaker : Patel Satishkumar
Reg. no. : 04-1313-2010
Major advisor : Dr. J.A. Patel
Date : 14/03/2012
Time : 1600 hrs
Mechanism of Drought Tolerance
Case studies on Drought Tolerance
Variability and Correlation
Future thrust 2
Botanical Name: Synonyms: Pennisetum glaucum (L.) R. Br.
Pennisetum typhoides (Burm. F.) Stapf. and Hubbard
Pennisetum typhoideum Rich.,
Pennisetum americanum L. Leeke
Common Names:- Bajra, Bulrush millet, Spiked millet, Cat tail millet
Family: - Poeaceae Sub family: Panicoideae Tribe: Paniceae
Origin :- Sahel zone of West Africa
Chromosome No.: 2n=14
Uses:- Feed: Fodder, Fuel, Fencing,
Cross pollinated Crop Spices due to its protogynous flowering nature
Annual C4 crop species.
Stable diet for the vast majority of poor farmers
Table:-1 Area, Production And Productivity (2010-11)
India 8.75 8.89 1015
Gujarat 0.92 1.31 1365
Source: Directorate of Economics and Statistics, Department of Agriculture and Cooperation.
State wise Bajra production (2010-11)
Uttar Pradesh 1.39 1638
Haryana 0.93 1593
Gujarat 0.92 1365
Maharashtra 0.77 741
Madhya Pradesh 0.25 1495
Karnataka 0.15 502
Tamil Nadu 0.08 1513
Andhra Pradesh 0.05 1178
Source: Directorate of Economics and Statistics, Department of Agriculture and Cooperation.
Drought is event which implies the absence of a period
of time, long enough to cause moisture-depletion in soil
and water deficit with decrease of water potential in
Drought is highly heterogenous in time, space, degree
of stress, growth stage and time of stress exposure, and
it is unpredictable.
Types of Drought
• Meteorological Drought:- It is related to deficiencies in
rainfall compared to the average mean seasonal rainfall in
• Agricultural Drought:- Deficit rainfall over cropped
areas during their growth cycle can destroy crop or lead
to poor crop yields.
• Hydrological Drought:- It is a deficiency in surface and
sub-surface water supply. It is measured as stream flows
and also as lake, reservoir and groundwater levels.
Drought affected area in the world
The major bajra growing countries are Senegal, Mali, Niger, Nigeria, Sudan and India.
1.3 Billions people are under drought-prone areas (India/Africa)
Source: www.milletindia.org Source : http://www.mapsofindia.com
Major Bajra Growing Regions of India
States affected by Drought
Bajra is a major cereals in northwestern zone as it represents approximately 25 % of the total
acreage of the crop in the country.
The chronically drought-prone areas around 33 % -receive less than 750 mm of rainfall, while
35 % classified as “drought-prone ” receive rainfall of 750-1,125 mm (in India). 9
About 36% of the land area constitutes arid and semi arid zones, arid and
semi arid areas are more prone to drought.
Drought leads to reduction in both yield and quality of economic product in
crop plants. It has adverse effect on plant growth and development.
Drought damages chloroplasts and lowers photosynthetic output.
There is an increase in proline level in the leaves of plants which are
subjected to all stresses.
Drought resistance is a genetically controlled physiological property of plant
Breeding for drought tolerance is a major objective in arid and semiarid
regions of the world due to inadequate precipitation, shortage of irrigation
water and high water demand for crop evapotranspiration in such climates
Main features of drought
• Drought resistance : Ability of a plant to live, grow and yield
satisfactorily with limited water supply or under periodic water
• Drought escape : Ability of plant to mature before water stress
becomes a serious limiting factor.
• Drought avoidance: Ability of a plant to withstand water deficit as
measured by degree and duration of low plant water potential.
water savers-closing of stomata
water spenders- extract more water from soil
• Drought tolerance: Ability of a plant to recover from a dry period
by producing new leaves from buds, and those were able to survive the
Gupta et al., 1986
Symptoms of Drought
• Reduced leaf area
• Early senescence of older leaves
• Effect on flowering, largely delay in flowering (Cause abscission
• Water stress directly affects cellular processes, membrane structures
and structure of macromolecules.
• Cause severe embolism formation in the xylem vessels.
Morphological traits Physiological factors
Higher rate of photosynthesis
Lower rate of transpiration
Higher leaf turgidity
Higher osmotic concentration
Stomatal characters :-
Shrunken type, small size, less number per unit
area, rapid closing nature
Leaf character:- Waxy leaves, small
thick leaves, hairiness
Root characters:- Root length, root
density, R/S ratio
Growth habit:- Indeterminate
ABA content in Leaf
Drought avoiding plant must maintain
High water potential
Thick and highly impermeable cuticle
Closure of stomata
More waxier leaves
Higher root -shoot ratio
Measurement of drought tolerance
1. Change in growth patterns
2. Change in seed production
3. Electrolyte leakage from leaf
4. Leaf wilting
5. Relative leaf water content
6. Change in the transcriptome
in pearl millet References
Grain and stover yield
Ibrahim et al. (1985), Kumari S (1988).
Bidinger et al. (1987, 2007), Singh and
Singh (1995), van Oosterom et al (1996),
Nepolean et al. (2006), Yadav et al.
(I999a,b, 2002, 2003. 2004) Serraj et al.
ABA accumulation Henson et al. (1981). Henson (1983).
Henson et al. (1983). Henson(1984)
Water potential Henson (1982)
Osmotic potential Henson (1982)
Osmolytes Patil et al. (2005), Kholova et al. (2008)
Antioxidative enzymes Patil et al. (2005), Kholova et al. (2008)
Ibrahim et al. (1985), Ashraf et al. (2001)
Ibrahim et al. (1985), Squire (1979), Black
and Squire (1979), Henson et al. (1981),
Henson (1984), Kholova et al. (2008, 2010
Canopy temperature Singh and Kanemasu (1983)
The selection criteria primarily based on morphological characters could be
selection of parents as well as desirable segregants followed by hybridization.
During selection, characters have high heritabilities and high correlation with
yield under stress across the environments.
Grain yield under stress conditions is usually the primary traits for
A suitable secondary traits should have (Edmeades et al. 2001).
1) Genetically association with grain yield under drought,
2) High heritability,
3) Stable and feasible to measure,
4) Lack of association with yield loss under ideal growing conditions.
Screening methods for Drought
tolerance in Pearl millet
In Laboratory method to identify genotypic difference in germinability, osmotic
solutions like polyethylene glycol (PEG) is used.
The osmotic effect of drought are known to be comparable to true drought effects
The field is uniformly irrigated with overhead system using perforated pipes.
Also used sprinkler method.
The percentage of seedling that emerge is computed.
Line source irrigation method
Table 2 :-Effect of osmotic stress on seedling traits of pearl millet genotype during drought induced by PEG in
ICRISAT (A. P.) Govindaraj et al. (2010) 22
Genotype Germination % Root length
Dry mass of
Normal Stress Normal Stress Normal Stress Normal Stress Normal Stress
X7 99.5 98.0 10.89 6.53 17.90 10.71 0.058 0.074 1781.3 1049.6
X6 97.0 96.0 10.23 6.17 17.48 10.65 0.070 0.080 1695.6 1022.4
Co7 98.3 95.5 9.28 5.58 16.17 9.03 0.073 0.094 1589.5 862.4
WC-C75 99.8 98.3 11.18 4.64 18.43 7.75 0.093 0.101 1839.3 761.8
T 0.636** 0.650** 0.755** 0.0065** 72.133**
V 0.900** 0.919 (NS) 1.068** 0.0092* 102.002 (NS)
T X V 1.272
1.300* 1.510** 0.0131 (NS) 144.268 (NS)
Table 3 :- Germination and physiological parameters under normal (N) and
induced stress (PEG) (S) treatments (T) in pearl millet cultivars (V)
Vijayalakhsmi et al. (2000)
Plants/m Tillers/m Effective
154 5.0 15.9 8.1 24.2 30.4 9.45 2101 -
T2, Rain out
149 4.8 17.5 6.2 22.2 28.8 9.27 1852 11.80
T3, Rainout during
tillering stage 144 4.8 11.8 5.8 20.4 26.3 8.89 1629 22.50
T4, Rainout during
139 5.2 11.6 6.3 21.2 27.8 8.67 1707 18.80
T5, Rainout during
152 4.7 16.2 5.8 20.5 28.2 7.75 1970 6.20
CD (P < 0.05 %) NS NS 2.23 0.30 0.78 NS 0.25 - -
Table 4:-Average growth and yield attributes of pearl millet as affected by different
Agra (U.P.) Prakash et al. (2008) 24
WW (36 %) MS(21 %) SS (9 %)
Ethiopia Yalew and Yemane (2011)
WW (36 %) MS(21 %) SS (9 %)
Fig. 2 Response of pearl millet cultivars (Dadda and Shella ) to post-flowering
WW= Well Water
MS= Moderately Stress
SW= Severely Stress
WW (36 %) MS(21 %) SS (9 %)
Yalew and Yemane (2011)Ethiopia
Fig.3 Potential quantum yield of two cultivars of Pearl millet subjected to
three soil moisture levels.
WW= Well Water (36 %)
MS= Moderately Stress ( 21 %)
SW= Severely Stress ( 9 %)
Fig 4:-Water Conserving mechanisms with the terminal drought tolerance of
Kholova et al. ( 2010)ICRISAT (A.P.)
Lines of pearl millet used in crosses to developed genetic
1 H 77/833-2 Elite male parent of grain hybrids in
north-western India, Susceptible to
downy mildew but with seedling
thermotolerance, high tillering capacity
2 PRLT 2/89-33 Inbred 33 in ICRISAT potential R- line
Trail conducted in 1989; derived by
selfing in the ICRISAT bold seeded Early
Composite, low tillering, large seeds,
drought tolerant which is largely based
on lniadi landrace germplasm from West
Fig. 9:- Strategy for development of Genetic linkage map to identify
QTLs linked to traits
Yadav et al. 2010ICRISAT
Fig:-10 Genetic map
Genetic map of a pearl millet population that segregates for drought tolerance showing the distribution
of molecular marker on the different linkage group. The highlighted regions indicate parts of the
genome controlling grain yield, and its components, during drought stress.
for Grain yield
Genetic Background References
LG2 Up to 32 % H 77/833-2 x PRTL 2/89-33 Yadav et al., 1999,2002
LG 3 & 4 11.6-17.3 % ICMB 841 x 863 B Bidinger et al., 2007
LG 5 14.8 % ICMB 841 x 863 B Yadav et al., 2004
LG 6 & 1 QTL has Pleiotropic to
H 77/833-2 x PRTL 2/833 Yadav et al., 2010
Table:- 15 QTLs associated with drought tolerance of grain yield
Fig:-11 Marker Assisted Backcross Breeding for Drought Tolerance
Fig. 12:- Fine mapping population or High Resolution Cross
Yadav et al. 2010
Objective of HRC
1. To fine map the DT-QTL interval
on LG 2
2. To Pyramid this DT-QTL with
the Downy-mildew resistance
QTLs on LG 1 & 4
Table 16:-Comparison of the DT-QTL based and Field performance-
QTL topcross Hybrids Field topcross hybrids LSD (P=0.05)
Flowering (d) 39.1 41.3 0.19
Biomass (g /m2) 777 845 15.6
Harvest Index (%) 49.6 45.9 0.55
Grain Yield (g/m2) 381 393 7.7
Flowering (d) 41.1 43.5 0.15
Biomass (g /m2) 581 619 11.4
Harvest Index (%) 41.7 38.3 0.60
Grain Yield (g/m2) 245 239 5.6
Flowering (d) 35.1 38.1 0.12
Biomass (g /m2) 537 562 7.9
Harvest Index (%) 49.5 43.8 0.5
Grain Yield (g/m2) 268 255 5.1
Serraj et al.(2005)ICRISAT 53
Fig. 13:-Marker Assisted Selection
1. Marker-assisted selection. Genetic composition at the drought tolerance QTL
( to constitute a MAS TCP)
2. Phenotypic selection. Field performance (best 16) in the drought trials used to
identify QTLs (to constitute a phenotype TCP)
3. A Random control. A random sample from within the mapping population
(to constitute a random TCP).
Bidinger et al. (2005)ICRISAT
The mapped progeny were phenotyped as testcross hybrids
rather than as the skeleton-mapped F2 plants.
• To restore heterotic vigour to partially inbred mapping progeny that might
otherwise be too weak for effective screening under stress conditions
• To reduced variation in flowering time among the test units, in order to
focus the mapping on specific drought tolerance traits rather than traits or
responses associated with variation on capacity for drought escape
• To have test units that approximate the genetic structure of the F1 hybrids
grown by farmers rather than partially inbred F3 or F4 lines.
Framework of an integrated strategy for genetic enhancement of crop grain yield
(GY) and its components under water-limited conditions at ICRISAT.
TR=total plant water transpired; TE=transpiration efficiency; HI= harvest index.
Breeding under optimum (water-stress free)
Breeding under actual drought condition
Breeding under artificially created
Incorporation of drought tolerance
1. Introduction (PRLT 2/89-33, lniadi landrace germplasm from West Africa.)
2. Interspecific and intergeneric hybridization
Three way cross (Gene pyramiding)
3. Pedigree selection
4. Back cross breeding
5. Mutation breeding
6. Ideotype breeding : Breeding activity aimed at producing
new genotypes with novel morpho-physiological features that fit a
pre-defined architecture thought to be advantageous based on
experimental physiology and/or modelling.
7. Marker assisted breeding
8. Marker-assisted backcrossing (MABC): Repeated
backcrossing of the F1’s to reconstitute the
recipient genome without losing the desirable
9. Tissue culture (in vitro Screening by using PEG
10.Development of Transgenic
• There is no single major gene, which has a remarkable effect on
the drought tolerance
• Drought tolerance is an environmental and developmental stage
• Drought reduces nutrients uptake, and is associated with
temperature stress and at higher elevation with cold. This
associations make the breeding programme more complicated.
• Most of the physiological and metabolic processes are affected by
water deficits: cell growth, stomatal regulation, photosynthesis,
• Large number of genes regulated up- or down- by drought
• Large genetic populations and replicates are required
• Even drought component traits are often complex and difficult to
• Tillering stage (30-45 DAS) is most susceptible to drought; wherein 23-25
% of yield reductions occurres, followed by drought at grain filling and
• The osmotic (PEG 6000) stress at the seedling stage is the most suitable
method for drought tolerance screening owing to their significant
relationship with declining the germination percentage, root and shoot length.
• Selection for seedling traits conferring drought tolerance such as root
length, root weight and root shoot ratio will be useful for identifying
genotypes with drought tolerance capacity.
• Post-flowering drought stress is one of the most important
environmental factors reducing the grain yield and yield stability of pearl
millet and increasing the incidence of crop failure in dryland production
• Marker Assisted Selection is the most appropriate method to improve
drought tolerance genotype. 65
• Consolidation of yield grains through multiple resistance
to various abiotic and biotic stresses.
• To develop a plant ideotype by restructuring the
morphological attributes these can withstand drought
• Need to saturate QTL areas to increase the efficiency
• Pyramiding with other QTLs
• In pearl millet, it need to be tested whether high leaf ABA
content and the lower Tr are linked or not.
• Need to develop Transgenic for Drought Tolerance,
though difficult because of polygenic inheritance.