1. //o
Name of speaker : Patel Satishkumar
Reg. no. : 04-1313-2010
Major advisor : Dr. J.A. Patel
Date : 14/03/2012
Time : 1600 hrs
2. Introduction
Mechanism of Drought Tolerance
Screening Methods
Case studies on Drought Tolerance
Physiological
Variability and Correlation
Biochemical
Biotechnological Studies
Breeding approaches
Achievements
Limitations
Conclusion
Future thrust 2
3. INTRODUCTION
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
3
4. Table:-1 Area, Production And Productivity (2010-11)
Area
(million
hectare)
Production
(million tonns)
Productivity
(kg /hectare)
India 8.75 8.89 1015
Gujarat 0.92 1.31 1365
Source: Directorate of Economics and Statistics, Department of Agriculture and Cooperation.
4
5. State wise Bajra production (2010-11)
Rajasthan
31%
Uttar
Pradesh
22%
Haryana
14%
Gujarat
13%
MH
12%
MP
4%
Karnataka
2%
Tamil
Nadu
1%
Andhra
Pradesh
1%
State
Production
(Million Tonnes)
Productivity
(kg/ha)
Rajasthan
2.03 394
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.
5
6. Drought
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
plant tissues.
Drought is highly heterogenous in time, space, degree
of stress, growth stage and time of stress exposure, and
it is unpredictable.
6
7. Types of Drought
• Meteorological Drought:- It is related to deficiencies in
rainfall compared to the average mean seasonal rainfall in
an area.
• 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.
7
8. 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)
8
9. Source: www.milletindia.org Source : http://www.mapsofindia.com
Major Bajra Growing Regions of India
Severely Affected
Moderately Affected
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
10. 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
species.
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
10
11. • Drought resistance : Ability of a plant to live, grow and yield
satisfactorily with limited water supply or under periodic water
deficits.
• 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
dry spell.
Gupta et al., 1986
11
12. Symptoms of Drought
• Reduced leaf area
• Early senescence of older leaves
• Effect on flowering, largely delay in flowering (Cause abscission
of flowers.)
Injury Mechanism
• Water stress directly affects cellular processes, membrane structures
and structure of macromolecules.
• Cause severe embolism formation in the xylem vessels.
12
13. Morphological traits Physiological factors
Higher rate of photosynthesis
Lower rate of transpiration
Higher leaf turgidity
Higher osmotic concentration
Earliness
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
Biochemical factors
Proline content
ABA content in Leaf
13
14. Drought avoiding plant must maintain
High water potential
Thick and highly impermeable cuticle
Closure of stomata
More waxier leaves
Higher root -shoot ratio
14
15. Measurement of drought tolerance
1. Change in growth patterns
2. Change in seed production
3. Electrolyte leakage from leaf
segments
4. Leaf wilting
5. Relative leaf water content
6. Change in the transcriptome
Traits investigated
in pearl millet References
Grain and stover yield
and quality
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.
(2005)
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)
Photosynthetic
pigments
Ibrahim et al. (1985), Ashraf et al. (2001)
Transpiration related
traits
Ibrahim et al. (1985), Squire (1979), Black
and Squire (1979), Henson et al. (1981),
Henson (1984), Kholova et al. (2008, 2010
a, b.c)
Canopy temperature Singh and Kanemasu (1983)
15
18. Screening Criteria
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
selection.
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.
18
20. Laboratory method
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
Field method:
The field is uniformly irrigated with overhead system using perforated pipes.
Also used sprinkler method.
The percentage of seedling that emerge is computed.
Tested Material
Tested Material
Line source irrigation method
Increasewaterstress
Water
Source/chennel
20
22. Table 2 :-Effect of osmotic stress on seedling traits of pearl millet genotype during drought induced by PEG in
Vitro condition.
ICRISAT (A. P.) Govindaraj et al. (2010) 22
23. Genotype Germination % Root length
(cm)
Seedling height
(cm)
Dry mass of
seedling (g)
Vigor index
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
CD
(P<0.05 %)
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
(NS)
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)
Coimbatore (T.N.)
23
24. Treatment Plant
height
(cm)
Plants/m Tillers/m Effective
tillers/m
Length
of ear
(cm)
Weight
of ear
(g)
1000
Grain
weight
(g)
Average
Yield
(kg/ha)
Percent
Reduction
T1, control
154 5.0 15.9 8.1 24.2 30.4 9.45 2101 -
T2, Rain out
during crop
establishment
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
earing and
flowering stage
139 5.2 11.6 6.3 21.2 27.8 8.67 1707 18.80
T5, Rainout during
grain-filling and
maturity stage
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
treatments
Agra (U.P.) Prakash et al. (2008) 24
25. 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
drought stress.
WW= Well Water
MS= Moderately Stress
SW= Severely Stress
WW (36 %) MS(21 %) SS (9 %)
25
26. 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 %)
Dadda
Shella
26
38. Fig 4:-Water Conserving mechanisms with the terminal drought tolerance of
pearl millet
Kholova et al. ( 2010)ICRISAT (A.P.)
Drought Tolerant
PRTL 2/89-33
863B-P2
Drought Sensitive
H 77/833-2
ICMB-841-P3
38
44. Table 14:- Correlation analysis between enzymatic activities and pigments contents
and ratios under well water and water stress condition.
Water stress
Chlorophyll a Chlorophyll b Carotenoids Chl a/Chl b Chl/Car
APX (Ascorbic peroxidase)
APX 2 ns ns ns ns 0.9344*
APX 4 ns ns ns ns 0.9037*/0.9881*
APX 8 ns ns -0.9104* ns ns
APX 9 ns ns ns ns 0.8929*
SOD (Superoxide dismutase)
Mn-SOD2 ns ns ns ns 0.969**
Mn-SOD3 ns ns ns ns 0.9516*
CAT (Catalse)
CAT1 ns ns ns ns 0.9439*
CAT2 ns ns ns ns 0.8911*
Well-watered
Chlorophyll a Chlorophyll b Carotenoids Chl a/Chl b Chl/Car
APX (Ascorbic peroxidase)
APX5 ns ns ns ns -0.8821*
APX 6 ns ns ns ns -0.8972*
APX Sum ns ns ns ns -0.9417*
Kholova et al. ( 2011)ICRISAT (A.P) 44
45. Fig. 8:- Gene networks involved in drought stress response and
tolerance
Function in stress tolerance Signal transduction and gene expression
Shinozaki and Shinozaki (2007)Japan
45
47. Lines of pearl millet used in crosses to developed genetic
maps
Lines Characteristics
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
and earliness
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
Africa.
47
48. Fig. 9:- Strategy for development of Genetic linkage map to identify
QTLs linked to traits
Yadav et al. 2010ICRISAT
48
49. 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.
49
50. Linkage
Group
(QTL on)
Drought Response
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
decreased panicle
number
H 77/833-2 x PRTL 2/833 Yadav et al., 2010
Table:- 15 QTLs associated with drought tolerance of grain yield
50
52. 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
52ICRISAT
53. Table 16:-Comparison of the DT-QTL based and Field performance-
based Hybrids.
Moisture Environment
Crop Trait
QTL topcross Hybrids Field topcross hybrids LSD (P=0.05)
Non- Stress
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
Terminal Stress
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
Line Source
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
54. 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
54
56. 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
(Inbreeding depression)
• 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.
56
57. 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.
57
58. Breeding Approaches
Breeding under optimum (water-stress free)
condition
Breeding under actual drought condition
Breeding under artificially created
environment
Incorporation of drought tolerance
58
59. 1. Introduction (PRLT 2/89-33, lniadi landrace germplasm from West Africa.)
2. Interspecific and intergeneric hybridization
Single backcross
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.
Breeding Methods
59
60. 7. Marker assisted breeding
8. Marker-assisted backcrossing (MABC): Repeated
backcrossing of the F1’s to reconstitute the
recipient genome without losing the desirable
gene.
9. Tissue culture (in vitro Screening by using PEG
6000)
10.Development of Transgenic
60
64. Limitations
• There is no single major gene, which has a remarkable effect on
the drought tolerance
• Drought tolerance is an environmental and developmental stage
specific character
• 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,
translocation, etc.
• 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
screen
64
65. Conclusion
• Tillering stage (30-45 DAS) is most susceptible to drought; wherein 23-25
% of yield reductions occurres, followed by drought at grain filling and
maturity stage.
• 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
environments
• Marker Assisted Selection is the most appropriate method to improve
drought tolerance genotype. 65
66. Future thrust
• 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
conditions.
• 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.
66