Responses of Some Bread Wheat (Triticum aestivum L.) Germplasm to Varying Drought Stress Conditions under Rainshelter

摘要

A better understanding of factors limiting and/or regulating grain yield can provide an opportunity to identify and then select for traits that increase the efficiency of water use and yield under drought stress conditions. The main objective of thisstudy was to assess response of some bread wheat genotypes to varying moisture levels in a tropical environment. In two experiments; twelve bread wheat cultivars were evaluated under the rain shelter in the year 2002 at three simulated moisture regimes (210, 240 and 270 mm). Cultivars differed in their response (p<0.001). The differential responses of the cultivars were mainly due to differences in Evapotranspiration Rates (ET), Harvest Index (HI), kernel number and seeds/head (p<0.001). Although earlyseedling vigor and biomass accumulation ensures drought escape, it is affected by early-seedling stage drought because genotypes can't recover later with supply of water. Other traits identified for selection were longer flag leaf and longer growth cycles. The study provides evidence that under moisture stress, adaptive traits contribute significantly to superior performance and during selection, yield potential and adaptive traits need to be combined, because neither alone will provide superior germplasm or explain superior performance. There was sufficient intraspecific variation in these morphological attributes to suggest their use as selection tools.