MORPHO-PHYSIOLOGICAL CHANGES AND VARIABLE YIELD OF WHEAT GENOTYPES UNDER MOISTURE STRESS CONDITIONS

MORPHO-PHYSIOLOGICAL

CHANGES AND VARIABLE

YIELD OF WHEAT

GENOTYPES

UNDER MOISTURE

STRESS CONDITIONS

R.S. YADA V, GAY ADIN AND A.K. JAISWAL

Department of Crop Physiology, C.S. Azad University of Agriculture &Technology, Kanpur - 208 002 Received on 3 Feb, 2001, Revised on 16 Oct., 2001

SUMMARY

A pot experiment was conducted with eight varieties of wheat grown under normal irrigation (60% ASW) and moisture stress (30% ASW) conditions, to study the effects of different soil moisture regimes on flag leaf area, relative water content (RWC), water potential (at anthesis &milk stages) and grain yield. Flag leaf area, RWC, leaf water potential and grain yield decreased significantly under soil water stress conditions, compared to normally irrigated control. Genotypes K 8027, C 306 and K 65 showed more grain yield/plant than UP 2003, K 8708, HD 2329, HUW 206 and HUW 234 under 30% available soil water conditions. K 8027 may ultimately prove to be outstanding variety under moisture stress situation since it was able to produce the highest flag leaf area, higher leafturgidity, plant water status, grain weight/main ear, grain yield/plant and harvest index. It was also observed that anthesis stage was more sensitive than milk stage.

Key words: Available soil water, flag leaf area, grain yield, leaf water potential, relative water content, wheat.

INTRODUCTION

Drought resistance is the result of numerous morphological, anatomical and physiological characters, both constitutive as well as inducible which interact with maintenance of growth and development process under edaphic and climatic conditions (Steponkus elal. 1980).

Soil moisture stress results in loss of turgor, leading to decrease in stomatal conductivity, photosynthesis and gra~ yield of sorghum (Sullivan and Ross 1979). Differential response of soil water stress at different stages on physiological parameters and yield performance has been reported in rice (Krishnayya and MUl1hy 1991) and wheat (Saxena et al. 1996, Yadav and Mathur 1996, Raneet al.200 1). It was, therefore, considered worthwhi Ie to examine influence ofsoil moisture stress conditions on certain physiological attributes in wheat genotypes.

MATERIALS AND METHODS

The experiment was conducted in rabi seasons of 1992-93 with eight wheat (Triticumaestivum L.)varieties

390

viz., C 306, HD 2329, HUW 206, HUW 234, K 65, K 8027, K 8708 and UP 2003 under pot culture conditions in wire net house. The experimental pots were covered with polythene sheets to protect from rains. Completely factorial randomized block design was adopted. Sowing was done in cement pots (28x25x35cm) containing 8 kg mixture of soil and farm yard manure (4:1). The hole of pots was sealed with cement to ensure retention of water. Fertilizers were applied at the rate of 0.56g urea, 0.35g diammonium-phosphate and O.27g muriate of potash to each pot for the requirement ofNPK @80, 40 and 40kg!

ha, respectively. The phosphatic and potassic fertilizers were applied at the time of sowing while halfamount of urea was applied prior to sowing and remaining half amount was given at 40-45 days from sowing.

The field capacity, moisture holding capacity and pennanent wilting percentage of soil were 21.6, 42.8 and 4.6 per cent, respectively. After the emergence of the seedlings, one uniform plant population was maintained in each pot and other interculture operations were carried out from time to time as per normal recommendations.

EFFECT OF MOISTURE STRESS ON WHEAT GENOTYPES

Pots were divided into two sets. The first set was normalIy irrigated (control) when soil moisture was depleted to 60% available soil water (ASW); second was subjected to 30% ASW. Watering of pots was controlled by Soil Moisture Meter Model DM 33 (Elico Private Limited -Hyderabad-India). Each treatment was replicated twenty times. The first observation was recorded on 85-90 days old plants (Anthesis) and the second on 105-110 days old plants (milky stage), under all the soil moisture treatments, on flag leaf area, relative water content (R We) and leaf water potential. Flag leaf area was measured by automatic leaf area meter. Relative water content of 2nd leaf from top was determined and calculated by using the method of Barrs and Weatherley (1962) and water potential of same leaf was measured by pressure bomb technique, using a Model 3005 Plant Water Status Console (Soil Moisture Equipment Corporation, U.S.A.). Observations were also recorded on grain yield and its attributing characters at the time of harvest. All the data recorded were statistically analysed (Cochran and Cox 1963).

RESULTS AND DISCUSSION

The wheat genotypes showed considerable variation in growth, water relations and grain yield performance under moisture stress conditions. The photosynthetic surface oftlag leaf area (Table 1), at anthesis, was lower under moisture stress (30% ASW) as compared to normally irrigated (60% ASW) controls. Highest reduction in leaf area was observed in genotypes UP 2003 and K 8708 under 30% ASW, whereas, minimum reduction was noticed in K 8027 and C 306. Present study reveals that soil water stress at anthesis and milk stages, showed least reduction in relative water content (R WC) in K 8027, C 306 and K 65 while greater reduction in R

we

Leaf water potential (Table I) at anthesis and milk stages, was lower under 30% ASW as compared to 60% ASW, there being greater reduction at milk stage. Under dry conditions, genotypes K 8027, C 306 and K 65 showed considerably higher leaf water potential than other varieties. So far as reduction in leaf water potential is concerned, genotype K 8027 showed lowest reduction

IndianJ Plant Physiol..Vol. 6. No.4. (N.S.) pp. 390-394 (Oct.-Dec.. 2001)

in leaf water potential under moisture stress, while the reduction was more pronounced in varieties UP 2003 and HUW 206. It was closely fo 1I0wed by HD 2329 (anthesis) and HUW 234 (milky stage). Higher leaf turgidity and water status in wheat genotypes K 8027, C 306 and K 65 under soil moisture stress conditions, thus, appear to be the result of maintenance of the turgor in their leaves. The genotypic variability in RWC, water potential and their mutual association under soil water stress have been reported earlier in rice (Sairam and Dube 1984)and wheat (Uprety and Sirohi 1985, }i:IHafidet al. 1998, Rane et al.

2001).

All the genotypes produced significantly higher grain yield/plant in normally irrigated control than moisture stress conditions (Table 2). Genotypes UP 2003, HUW 206, K 8708, HD 2329 and HUW 234 showed higher grain yield/plant under control (60% ASW). These genotypes showed maximum reduction in grain yield under moisture stress situation as compared to other genotypes K 8027, C 306 and K 65. However, varietiesK 8027, C 306 and K 65 yielded highest under 30% ASW, possibly because of speedy transport of photosynthates towards grains as judged by increase in harvest index and also had least reduction in grain yield/plant in comparison to normally irrigated control.

On mean basis, under 60% ASW, all genotypes produced comparatively higher dry weight/main ear, number of grains and grain weight/ main ear, grains and grain weight/plant and thousand grain weight than 30% ASW conditions and showed significant reduction under moisture stress. Under control conditions, genotype UP 2003, HUW 206 and K 8708 showed highest dry weight/ main ear, grain weight/main ear and grain weight/plant, whereas, K 8027, C 306 and K 65, responded better under 30% ASW situation.

Reduction in grain yield/plant under soil moisture stress might be due to its harmful effect on pollination, as numberof grains/plant and size of grains were significantly reduced. Highest test weight was pronounced by genotypes, HD 2329 and K 65 under both moisture regimes.

Table 1. Effect of soil moisture stress on flag leaf area, relative water content and water potential at different growth stages of wheat genotypes

Flag leaf area (cm2)

Genotypes Anthesis

Control Stress

I. III

(RWC%)

Anthesis

Control Stress

II III

Milky stage

Control Stress

11 III

Water potential (-MPa)

Anthesis Milky stage

Control Stress Control Stress

I. ~ I. ~

C 306 22.9 15.1 (34) 71.1

HD 2329 24.1 12.5 (48) 73.2 55.7 54.3

(22) 55.5 47.4 (26) 41.4 43.9

(15) -0.96 -1.18 (19) -1.26 -1.68 (25) (29) -0.80 -1.24 (35) -1.24 -I. 78 (30)

HUW 206 29.1 13.2 (55) 74.0 56.3 (24) 59.6 43.9 (26) -0.90 -1.49 (40) -1.18 -1.94 (39)

HUW23425.9 12.1 (53) 76.3 (26) 63.3 44.3 ,(30) -1.02 -1.52 (33) -1.24 -1.96 (37)

K65 K 8027 K 8708

32.1 14.0 (56) 68.1 20.9 15.9 (24) 70.9 27.8 11.2 (60) 74.1

56.1 54.5 58.1 56.2

(20) 55.6 46.4 (18) 55.8 48.3 (24) 59.8 44.8

(17) -1.00 -1.18 (15) -1.38 -1.70 (19) (13) -0.98 -1.12 (13) -1.24 -1.66 (25) (25) -1.04 -1.36 (24) -1.20 -1.80 (33)

UP 2003 30.9 10.1 (67) 77.0 55.8 (28) 64.2 42.1 (34) -0.86 -1.40 (39) -1.14 -1.90 (40)

Mean 26.7 13.0 (50) 73.1 55.9 (23) 59.4 45.1 (24) -0.95 -1.31 (27) -1.24 -1.80 (31)

'r' with yield

0.484 0.891** 0786* 0.425 0.306 0.912** 0.514 0.771* 0.814* 0.803*

CD at 5%P

Treatment 0.59

Var. 1.19

Var. X Treatment 1.69

0.64 1.23 1.67

0.82 1.61 2.15

0.034 0.069 0.102

0.042 0.084 0.124

II=60% ASW ( normal irrigation), I"=30% (soil moisture stress), ASW =Available soil water, *=Significant at 5%, * *=Significant

at I%, values in parenthesis indicate per cent reduction over control

''tn the present investigation, all the genotypes showed differential response to soil water stress. Genotypes K 8627, C 306 and K 65, identified as drought tolerant, had higher flag leaf area, RWC and leaf water potential (lower negative value), with minimum reduction in yield parameters and yielded best under 30% ASW, as compared to other genotypes UP2003, K 8708, Hp2329, HUW 234 and HUW 206. Under 30% ASW conditions, lowest reduction in leaf water potential at anthesis stage, was more important than at milk stage. This may possibly be due to increase in relative water content of leaves at

IndianJ. Plant Physiol.,Vol. 6, No.4, (N.S.) pp. 390-394 (Oct.-Dec., 2001)

anthesis than at milk stage which ultimately resulted in maximum leafturgidity in wheat varieties enable them to maintain physiological function.

Highly significant and positive correlation in grain yield of wheat varieties under water stress with flag leaf area, relative water content in leaf at milk stage, water potential at anthesis, biological yield/plant (0.98) at harvest, grain weighton main shoot ear, number of grains/ plant and harvest index and lack of any such association with relative water content at anthesis, number of grains

EFFECT OF MOISTURE STRESS ON WHEAT GENOTYPES

Table 2. Effect of soil moisture stress on yield attributes of wheat genotypes

Geno- Dry weight main Grains/main Grain weight/ Grains/plant toOO-grain Grain weight/ Harvest index

types ear (g) ear main ear(g) weight (g) plant (g) (%)

Control Stress Control Stress Control Stress Control Stress Control Stress Control Stress Control Stress

I. III 11 III I. III I. III II III I. III II III

II = 60%ASW (normal irrigation), I" = 30% (soil moisture stress), ASW = Available soil water, * = Significant at 5%,* *=Signi ficant at 1%

0.762* 0.690 0.852** 0.981 ** 0.842** 0.905** 0.390 0.428

Indian} Plant Physiol.,Vol. 6, No.4, (N.S.) pp. 390-394 (Oct.-Dec., 2001)

0.52 N.S. 1.47

5.1 41.4 36.4

3.3 44.3 31.4

3.6 44.6 32.4

3.3 45.6 31.7

4.3 41.4 36.1

5.3 39.5 38.4

3.4 43.7 31.8

3.4 47.7 30.9

4.0 43.5 36.6

0.864** 0.967**

0.13 0.26 0.37 0.61

1.22 1.73

EIHafid, R., Smith, D.H., Karrou. M. and Samir, K. (1998). Physiological responses of spring durum wheat cultivars to early-season drought in a Mediterranean environment. Ann. Bot. 81: 363-370.

Kumar, P., Dubey, S.D. and Chauhan, V.S. (1998). Relationship among yield and some physiological characteristics in wheat.

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Rane, J. Maheshwari, M. and Nagarajan, S. (200 I). Effect of pre-anthesis water stress on growth, photosynthesis and yield ofSIX

wheat cultivars differing in drought tolerance. Indian J Plant Physiol. 6: 53-60

393 Krishnayya, G.R. and Murthy, K.S. (1991). Influence of different

levels of soil moisture stress on physiological parameters of upland rice cultivars. Indian J Plant Physiol. 34: 387-391. 4.97

9.95 14.07

3.52 1.96 242 126 42.0 39.0 10.4

3.72 1".35 250 72 46.0 42.9 12.1

3.91 1.32 362 100 35.0 33.0 12.9

3.87 1.33 311 95 38.0 34.0 11.4

3.51 1.75 222 103 44.0 42.7 10.4

3.50 1.97 242 132 42.1 39.3 10.5

3.88 1.36 302 98 40.0 32.0 12.4

3.92 1.30 351 94 40.3 35.0 14.4

3.73 1.54 285 103 41.0 37.2 11.8

0.125 N.S. 0.352 1.099

1.442 1.715 2.30 45.0 35.3 2.25 43.0 35.7

2.10 44.0 34.0 2.00 41.7 31.7 2.15 47.0 31.7

2.2b 41.6 31.0

2.05 40.3 30.7

Barrs, H.D. and Weatherley, P.E. (1962). A re-examination of the relative turgidity technique for estimating water deficits in leaves. Aust. J. BioI. Sci. 15: 413-428.

REFERENCES

UP 2003 5.802.15 52.7 33.0

Mean 5.21 2.15 44.4 32.9

Chochran, W.G. and Cox, G.M. (1963). Factorial experiments with main effects confounded : Spit-plot Designs. In : (ed.) Experimental Designs, pp. 263-299. Asia Publishing House, Bombay.

C 306 4.15 HD2329 5.50 HUW206 5.75 HUW 234 5.60

K65 5.10

K 8027 4.10 K 8708 5.70

CD at 5%P Treatment 0.121 Var. 0.241 Var. X 0.341 Treatment 'r' with yield

Sairam, R.K. and Dube, S.D. (1984). Effect of moisture stress on nitrate reductase activity in rice in relation to drought tolerance.

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Saxena, H.K., Yadav, R.S. and Mathur, R.K. (1996). Effect of moisture stress on metabolic activity and grain yield in wheat

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1: 303-306.

Steponkus, P.L., Cutler, J.M. and O'Toole, J.C. (1980). Adaptation to water stress in rice In :N.C. Turner, and P.J. Kramer (eds.) Adaptation of Plants to Water and High Temperature Stress, pp 401-418. Wiley, Interscience. New York.

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Sullivan, c.Y. and Ross, W.M. (1979). Selecting for drought and heat resistance in grain sorghum. In:H. Mousell and R.C. Staples (eds.), Stress Physiology in Crop Plants, pp. 343-373. John Wileys &Sons Publishers, New York.

Uprety, D.C. and Sirohi, G.S. (1985). Effect of water stress on photosynthesis and water relations of wheat varieties. Indian 1. Plant Physiol. 28 :107-114.

Yadav, R.S. and Mathur, R.K. (1996). Proline, protein and nitrate reductase activity in wheat(Triticum aestivum L.) under different levels of soil water stress. Proc. Nat. Acad. Sci. India, 66(B) IV: 359-362.