Agronomic, biochemical and physiological responses of some spring wheat (Triticum alstivum L. em thell) cultivars to drought stress at reproductive stage
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Date
1985
Authors
Gokarna Bahadur Gharti-Chhetri
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Abstract
Wheat crops are most likely to experience drought after anthesis under most growing conditions in the humid tropics.
Nine spring wheat cultivars (seven from Nepal and two from the Philippines) grown in pots were exposed to 4, 8, 12 and 16 days of water stress starting at 50% head emergence by withholding water under glass house conditions. The treatments were arranged on a two-factorial in completely Randomized design, replicated four times. Concurrent measurements of leaf water potential (LWP), upper (Ru) and lower leaf surface (R1) stomatal resistances of flag leaf; soil moisture content (SMC) and nitrate reductase activity (NRA) determination were made through a 16-day period after cessation of irrigation. Free proline was determined from the same flag leaves. Grain protein content, yield and its components were also determined.
Highly significant variety x stress duration interaction effect was observed on stomatal resistance (Rs), LWP, NRA, grain weight, harvest index (HI), SMC but it was not significant in number of grains/spike. NL 370, NL 496, NL 292 and Siddhartha exhibited drought avoidance by maintaining relatively higher LWP under water stress. Rs increased more on the lower than in the upper leaf surface under drought stress. Lerma 52, Triveni and Trigo 1 had sharp rise in their Rs even at mild stress in contrast to other varieties which had gradual increase in Rs as the drought progressed. Early maturing cultivars, namely: NL 496, NL 370, Siddartha and NL 292 had higher NRA than late-maturing cultivars under both stressed and non-stressed conditions. NRA decreased with increase in drought duration. Leaf proline and grain protein content increased as the drought progressed. Leaf proline had significant correlation with LWP (r = -0.80**), SMC (r = -0.48**) and Rs (r = 0.56**). Grain protein had strong negative correlation with SMC, LWP, grain filling duration and 100-grain weight. NL 496, NL 370, NL 292 and Trigo 2 had the higher SMC under different drought durations. Drought enhanced maturity and grain filling duration. Early maturing cultivars had longer grain filling duration than late-maturing ones. Drought affected the number of grains/spike and 100-grain weight. Genotypic variability in grain set was noted under water stress. Lerma 52 gave the highest but Siddhartha and NL 292 gave the lowest biological yield under water stress. Trigo 1 and Trigo 2 gave the highest grain yield under non-stress condition while Siddhartha, NL292, NL 370 and NL 495 produced the maximum grain yield and also HI unde stressed conditions. Considering the responses under different drought stress, early maturing namely Siddartha, NL 292, NL 370 and NL 496 are classified as the drought resisant and mid, late-maturing namely: Trigo i, UP 262, Lerma 52 and Triveni as the drought susceptible cultivars.