67
//o Breeding for drought tolerance in pearl millet (Pennisetum glaucum (L.) R. Br.) Name of speaker : Patel Satishkumar Reg. no. : 04-1313-2010 Major advisor : Dr. J.A. Patel Date : 14/03/2012 Time : 1600 hrs

Breeding for Drought tolerance in Pearl Millet

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Page 1: Breeding for Drought tolerance in Pearl Millet

//o

Breeding for drought tolerance in pearl millet (Pennisetum glaucum (L.) R. Br.)

Name of speaker : Patel Satishkumar Reg. no. : 04-1313-2010 Major advisor : Dr. J.A. Patel Date : 14/03/2012 Time : 1600 hrs

Page 2: Breeding for Drought tolerance in Pearl Millet

Content 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

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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

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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.    

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State wise Bajra production (2010-11)

Rajasthan31%

Uttar Pradesh21%

Haryana14%

Gujarat13%

MH12%

MP4%

Karnataka2%Tamil Nadu

1%Andhra Pradesh

1%

StateProduction

(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.    

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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.

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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.

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Page 8: Breeding for Drought tolerance in Pearl Millet

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)

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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

Page 10: Breeding for Drought tolerance in Pearl Millet

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

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Page 11: Breeding for Drought tolerance in Pearl Millet

Terms of Drought

• 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

Page 12: Breeding for Drought tolerance in Pearl Millet

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.

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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

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Drought avoiding plant must maintain

High water potential

Higher root -shoot ratio

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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

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Drought Tolerance

Physiological processes

Expression Profiling

Reverse Genetics

Allele Mining for natural Variation

MAS/Transformation

Map Based Cloning

Forward Cloning

Forward Genetics

Comparative mapping

Fig. 1 Drought tolerance improvement tools and processes

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Screening Criteria

17

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Screening CriteriaThe 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

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Screening methods for Drought tolerance in Pearl millet

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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

Incr

ease

wat

er s

tres

s

Water Source/chennel

20

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Case Studies

21

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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

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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.)

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Treatment Plant height (cm)

Plants/m Tillers/m Effective tillers/m

Length of ear (cm)

Weight of ear (g)

1000Grain weight (g)

Average Yield(kg/ha)

PercentReduction

T1, control154 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

Page 25: Breeding for Drought tolerance in Pearl Millet

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 WaterMS= Moderately Stress SW= Severely Stress

WW (36 %) MS(21 %) SS (9 %)25

Page 26: Breeding for Drought tolerance in Pearl Millet

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

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Table 5:- Grain yield and physiological parameters as influenced by terminal moisture stress in B-line and inbreds

Pearl millet lines

Days to flower

Grain yield(kg/ha)

Harvest index

Threshing Relative Water content (%)

Drought susceptibilityIndex

81B 70.8 136.1 4.7 22.0 74.9 1.196 + 0.06

218B 65.7 234.4 8.7 28.4 63.4 1.259 + 0.12

89111B 59.3 263.3 11.2 26.0 77.4 1.104 + 0.12

95444B 58.7 628.9 22.4 47.7 74.2 0.812 + 0.06

J-108 57.8 648.9 18.2 40.0 72.0 0.846 + 0.10

J-998 62.8 353.3 9.3 29.7 69.0 1.057 + 0.04

J-2290 68.0 375.0 8.2 31.7 75.7 1.099 + 0.09

J-2296 59.2 376.7 15.4 37.7 75.0 0.880 + 0.08

J-2340 58.8 806.7 18.1 44.4 77.8 0.761 + 0.18

LSD (P=0.05)

4.7 304.2 5.2 13.5 6.5 -

CV % 3.9 39.7 36.4 19.0 7.1 -

Joshi et al. (2005)Jamnagar (Gujarat) 27

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Table 6:- Physiological parameters in pearl millet hybrids as influenced by high temperature and receding soil moisture at seedling stage

Entries/Hybrids

Root Dry mass (mg/plant)

Shoot dry mass(mg/plant)

Total Dry Mass(mg/plant)

Root/shoot ratio(dry wt. basis)

Survival (%) at 19-22DALI*

Leaf elongation Rate (cm/day) index at 15 DALI*

Chlorophyll Stability

GHB-558 26.3 30.9 57.1 0.9 44.9 0.35 0.111 + 0.016

GHB-559 29.5 26.4 55.7 1.2 68.4 0.48 0.079 + 0.007

GHB-316 26.9 25.9 52.8 1.1 61.3 0.47 0.096 + 0.019

GHB-526 38.7 37.4 76.1 1.1 76.4 0.59 0.053 + 0.016

GHB-538 32.8 34.9 67.8 1.0 72.9 0.55 0.058 + 0.014

LSD (P=0.05)

NS 5.3 NS NS 16.4 0.09 -

CV (%) 10.5 15.1 10.8 17.9 9.1 17.3 -

* DALI – Days after last Irrigation, NS- Non significant

Joshi et al. (2005)Jamnagar (Gujarat) 28

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Variability and correlation studies for

drought tolerance

29

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Character GCV % PCV % h2 (B.S.) % Genetic

AdvanceGA % of Mean

E % 12.83 13.52 90.1 20.783 25.09

FSL 12.21 12.85 90.3 2.806 23.89

FRL 12.57 13.65 98.7 4.987 25.73

FSW 16.32 16.60 96.6 0.02 33.05

FRW 21.36 21.91 95.0 0.015 42.87

DSW 22.48 23.14 94.4 0.002 44.99

DRW 24.99 25.32 97.4 0.002 50.79

R/S 22.87 24.03 90.6 0.203 44.83

Table 7:- Estimates on GCV, PCV, heritability in broad sense(h2 B.S.), Genetic advance as percentage of mean (GA %) of seedling traits in 63 pearl millet genotypes

Coimbatore (T.N.) Arulselvi and Selvi (2009)

E %=Emergence %, EI= Emergence index, ERI= Emergence rate, FSL=Fresh Shoot Length, FRL= Fresh Root Length, FSW=Fresh Shoot Weight, FSL= Fresh Root Weight, DSW= Dry Shoot Weight, DRW= Dry Root Weight.

30

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Table 8:-Character contribution towards genetic divergence

Sr. No. Character Contribution (%)

1 Emergence % 4.86

2 Fresh Shoot Length 2.66

3 Fresh Root Length 39.63

4 Fresh Shoot Weight 26.73

5 Fresh Root Weight 2.05

6 Dry Shoot Weight 7.32

7 Dry Root Weight 16.28

8 Root/Shoot 0.36

Coimbatore (T.N.) Arulselvi and Selvi (2009) 31

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Source df E % EI ERI FSL FRL FSW FRW DSW DRW R/S

Replications 1 6.2222 0.002 0.000007 0.0287 0.0229 0.00001 0.000059 0.000002 0.000001 0.0178

Genotypes 62 238.3574** 0.0069 0.000027 4.3309** 11.9518** 0.000201** 0.000107** 0.000002** 0.000001** 0.0226**

Error 62 12.4158 0.0035 0.000014 0.2211 0.0778 0.000003 0.000003 0.0000001 0.0000001 0.0011

SE 2.4717 0.0414 0.0027 0.3298 0.1956 0.0013 0.0012 0.0002 0.0001 0.0234

CD @ 5% 4.9409 0.0828 0.0053 0.6593 0.3911 0.0026 0.0023 0.0004 0.0001 0.0468

Mean 82.8254 1.0956 0.0139 11.7437 19.3833 0.0609 0.0338 0.0047 0.0021 0.4528

Table 9:- Mean Square from analysis of variance for seedling traits conferring drought tolerance in pearl millet genotypes.

** Significant at 0.01 probability level

Coimbatore (T.N.) Arulselvi and Selvi (2009)

E %=Emergence %, EI= Emergence index, ERI= Emergence rate, FSL=Fresh Shoot Length, FRL= Fresh

Root Length, FSW=Fresh Shoot Weight, FSL= Fresh Root Weight, DSW= Dry Shoot Weight, DRW= Dry

Root Weight.

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Traits FSL FRL FSW FRW DSW DRW R/S

E %0.2782 0.4332** 0.4555** 0.5009** 0.4479** 0.3204** -0.0508

FSL 0.4688** 0.7518** 0.5672** 0.5909** 0.5542** 0.0606

FRL 0.5536** 0.4769** 0.5793** 0.5411** 0.0506

FSW 0.7682** 0.8105** 0.6978** -0.0060

FRW 0.5633** 0.8800** 0.4457**

DSW0.5176** -0.3404**

DRW 0.6158**

Table 10:- Simple Correlation coefficients Between seedling traits (conferring Drought Tolerance ) among 63 pearl millet genotypes.

Arulselvi and Selvi (2009) Coimbatore (T.N.) ** Significant at 0.01 probability level

E %=Emergence %, EI= Emergence index, ERI= Emergence rate, FSL=Fresh Shoot Length, FRL= Fresh Root Length, FSW=Fresh Shoot Weight, FSL= Fresh Root Weight, DSW= Dry ShootWeight, DRW= Dry Root Weight.

33

Page 34: Breeding for Drought tolerance in Pearl Millet

Table 11:-Means and F ratios of genotypes for growth and yield components measured in the irrigated control (c) and drought stress (s) treatments.

Characters 1988 (34 Genotypes) 1989 (34 Genotypes) 1990 (32 Genotype)

Treatment Means F ratio Means F ratio Means F ratio

Time to flowering (days) Control 64 5.80** 66 5.92** 67 11.90**

Stress 62 5.40** 65 5.99** 68 15.60**

Biomass (g m-2) Control 621 3.02** 858 1.79** 662 2.49**

Stress 437 2.49** 585 3.28** 598 2.76**

Stover (g m-2) Control 398 3.29** 482 1.91** 431 6.50**

Stress 300 4.38** 359 4.57** 423 3.91**

Panicle (g m-2) Control 223 2.54** 378 1.77** 230 0.97

Stress 137 2.05** 228 2.19** 175 1.41

Grain yield (g m-2) Control 156 2.30** 271 1.66** 158 1.07

Stress 83 2.48** 140 2.64** 121 0.78

Panicle No. m m-2 Control 9.8 1.58* 11.5 3.61** 10.3 1.50*

Stress 8.2 1.47 10.0 2.33** 8.4 1.51*

Panicle yield (g) Control 16.2 4.02** 23.7 3.81** 15.0 2.46**

Stress 9.8 3.00** 13.7 3.23** 14.2 0.72

No. Grains panicle-1 Control 2440 4.47** 3090 3.75** 2260 1.96**

Stress 1840 1.90** 2300 3.16** 2330 0.72

Grain mass (g 100-1) Control 0.67 10.39** 0.77 3.96** 0.66 5.90**

Stress 0.53 7.30** 0.53 2.86** 0.61 2.55**

No. Grains m-2 (*103) Control 2.306 3.34** 35.3 1.93** 23.5 1.16

Stress 15.4 1.88** 23.3 2.43** 19.6 0.81

Harvest index Control 25.4 4.04** 32.0 3.20** 23.0 2.01**

Stress 18.6 4.38** 24.0 3.81** 20.0 0.65

Threshing Percentage Control 70 3.61** 71 1.90** 67 2.30**

Stress 58 3.44** 60 3.76** 69 0.61

Sadore Peter (1992) 34

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CharactersCorrelation Coefficients

Flowering DRI1988 1989 1990 1988 1989 1990

Time to flowering (days) --- ----- --- -0.07 0.07 -0.02Biomass (G m-2) 0.53** 0.47** 0.56** 0.56** 0.59** 0.20Stover (G m-2) 0.76** 0.63** 0.77** 0.26. 0.37** 0.06Panicle (G m-2) -0.31 -0.21 -0.35* 0.73** 0.74** 0.31Grain yield (G m-2) -0.46** -0.35* -0.28 0.69** 0.71** 083**Panicle No. M-2 -0.55** -0.47** -066** 050** 0.11 0.10Panicle yield (g) -0.29 -0.16 0.06 0.62** 0.78** 0.88**No. Grains per panicle 0.13 0.22 0.04 0.55** 0.63** 0.92**Grain mass (G) -0.47** -0.57** 0.04 0.28 0.36* -0.01No. Grains m-2 (x103) -0.22 -0.08 -0.28 0.65** 0.62** 0.85**Harvest index -0.74** -069** -044* 0.44* 0.25 0.82**Threshing % -0.60** -057** -0.09 0.48**

0.44*0.44* 0.91**

Table 12 :- Correlations of yield parameters in the drought stress treatment to time to flowering under drought stress and Drought Response Index.

** P<0.01 * P<0.05Peter (1992)Sadore 35

Page 36: Breeding for Drought tolerance in Pearl Millet

CharacterDays to 50

per cent Flowering

Days to Maturity

Ear head

length(cm)

Ear headgirth(cm)

No. of produc-

tive tillers

per plant

Ear head

weight per

plant (g)

Total biomass

accumulation per

plant (g)

Grain yield per plant (g)

Harvest index

Panicle harvest index

Test weight

(g)

Root length

per plant (cm0

Proline content

(µ g g-1 f. w.)

Drought response index (DRI)

Days to 50 % Flowering 1.00

Days toMaturity 0.14** 1.00

Ear head length -0.22** -0.07 1.00

Ear headGirth -0.06 0.07 0.07 1.00

No of Productive tillers per plant

-0.06 0.04 0.03 -0.18** 1.00

Ear head weight per plant

-0.08 -0.08 -0.01 -0.16** 0.13* 1.00

Total biomass accumulation per plant

-0.05 -0.08 -0.10 -0.06 0.20** 0.24** 1.00

Grain Yield per plant -0.06 -0.12 0.13* -0.20** 0.44** 0.48** 0.19** 1.00

Harvestindex -0.18** -0.15** 0.27** -0.08 0.22** 0.11 -0.26** 0.65** 1.00

Panicle harvest index -0.14** -0.08 0.16** -0.08 0.39** -0.21** 0.03 0.74** 0.66** 1.00

Test weight -0.14** -0.15** 0.14** -0.12 0.23** 0.13* 0.09 0.59** 0.42** 0.55** 1.00

Root length per plant -0.00 0.03 0.17** 0.11 0.21** 0.04 0.09 0.35** 0.26** 0.36** 0.33** 1.00

Proline Content 0.04 -0.00 0.04 -0.09 0.36** 0.10 0.13* 0.49** 0.31** 0.45** 0.50** 0.37** 1.00

Drought response index -0.01 0.00 -0.11 -0.30** 0.35** 0.53** 0.01 0.74** 0.28** 0.41** 0.30** 0.17** 0.35** 1.00

Table 13:-Phenotypic correlation coefficient for different characters under terminal drought condition in pearl millet.

*, ** Significant at 5 and 1 percent level of probability, respectively

AAU (Anand) Patil and Jadeja (2005) 36

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Transpiration Rate

37

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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-P2Drought Sensitive H 77/833-2 ICMB-841-P3

38

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ABA content in Leaf

39

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Fig. 5:- ABA content in pearl millet test cross hybrids (Drought Tolerant Drought Sensitive) in well-water (WW) and water stress (WS) condition

Vegetative Stage Reproductive Stage

NIL-QTLs Drought Tolerant PRTL 2/89-33 863B-P2Drought Sensitive H 77/833-2 ICMB-841-P3

Kholova et al. ( 2010)ICRISAT (A.P.) 40

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Drought Tolerance QTL under salt stress

41

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02468

10121416

843A X H 77/833-2 (Drought

sensitive parent)

843A X 01029 (QTL-NIL)

843A X PRTL 2/89-33 (Drought tolerant parent)

pH 8.5

pH 9.0

pH 9.4

L

eaf

Na

(mg/

g d

ry w

t.)

FIG. 6:- Na+ accumulation in the leaves of drought- sensitive and drought-tolerant parents, at three Alkalinity levels.

Sharma et al. (2010)CSSRI (Karnal) 42

Page 43: Breeding for Drought tolerance in Pearl Millet

Lea

f N

a (m

g/g

dry

wt.

)

0

5

10

15

20

25

843A X H77/833-2 (Drought Sensitive parent)

843A X 01029 (QTL-NIL)

834A X PRTL 2/89-33

(Drought tolerant parent)

EC 2 ds/m

EC 9 ds/m

EC 12 ds/m

FIG. 7:- Na+ accumulation in the leaves of drought- sensitive and drought-tolerant parents, at three salinity levels.

CSSRI (Karnal) Sharma et al. (2010)43

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Table 14:- Correlation analysis between enzymatic activities and pigments contents and ratios under well water and water stress condition.

Water stressChlorophyll 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 nsAPX 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-wateredChlorophyll 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

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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

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Breeding Strategies46

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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.

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Fig. 9:- Strategy for development of Genetic linkage map to identify QTLs linked to traits

Yadav et al. 2010ICRISAT48

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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.

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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

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Fig:-11 Marker Assisted Backcross Breeding for Drought Tolerance

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Fig. 12:- Fine mapping population or High Resolution Cross

Yadav et al. 2010

Objective of HRC1. 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

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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

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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)ICRISAT54

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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.

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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.

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Breeding Approaches

Breeding under optimum (water-stress free) condition

Breeding under actual drought condition Breeding under artificially created

environment

Incorporation of drought tolerance

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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 selection4. Back cross breeding5. Mutation breeding6. 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

C

onve

ntio

nal m

etho

ds

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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

N

on-C

onve

ntio

nal m

etho

ds

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Achievements

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Table:-17 Recommended drought-tolerant/drought-avoiding hybrids/varieties of pearl millet in India

State Hybrids Varieties

Maharashtra Nandi 35,Saburi, PAC 903PPC 6, HC 20, JBV 2, ICTP 8203, ICMV 221, AIMP 92901

Tamil Nadu GHB 558, CoH (Cu)8, X7 Co7, ICMV 221, ICMV 155

Andhra Pradesh PB 106, GHB 558 AIMP 92901, ASP-1, ICTP 8203

Karnataka PB 106, GHB 558 ICMV 221, ICTP 8203

RajasthanHHB 67, RBH 121, GHB 538, PB 180 CZP 9802, Raj 171

GujaratGHB 577, GHB 526, PB 172, PB 112, ICMB 356 JBV 2, HC 20

HaryanaHHB 67, GHB 538, HHB 117, ICMB 356 CZP 9802

ICRISAT REPORT (2007) 62

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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

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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.

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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.

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