Physiological Traits and Drought Tolerance Indices in Advanced Genotypes of Bread Wheat (Triticum aestivum L)

TWO FIELD experiments were carried out at Fac. Agric. Edu. Farm, Minia University, Egypt, during the two successive seasons of 2015/2016 and 2016/2017 under irrigation and drought conditions. Thirty nine genotypes of bread wheat were evaluated to estimate physiological traits related to water stress, tolerance indices, and to determine the best drought tolerant genotypes. The combined analysis revealed significant differences for environments, genotypes, years, environments x genotypes and years x genotypes interactions for all studied traits. Under irrigation, three genotypes No. 39, No. 42 and No. 68 were significantly higher than the better parent in excised leaf water retention and grain yield. Under drought stress condition, genotypes No. 13, No. 42 and No. 246 exceeded the better parent in relative water content, leaf water content, specific leaf weight and grain yield. Under normal irrigation, relative water content showed negative and significant (P <= 0.01) correlation with leaf water loss (-0.86), with leaf area (-0.36), and positive correlation with grain yield (P <= 005), while under drought stress, excised leaf water retention showed negative and significant (P <= 0.01) correlation with leaf water loss (-0.85), and negative correlation with both of leaf area (-0.25) and grain yield. Ranking method indicated that genotypes No. 13, No. 296 and No. 379 were the most drought tolerant genotypes, while genotypes No. 1, No. 74, No. 95 and No. 129 were the most sensitive to drought condition.