Assessing Heat Stress Tolerance in Exotic Spring Wheat Genotypes

The present research was conducted at the experimental field of the Southern Wheat and Barley Research Institute, Tandojam, during the rabi season. The experiment consisted of two different sowing dates, namely November 19th (normal) and December 19th (late), using ten advanced bread wheat (Triticum aestivum L.) lines: HTWYT1, HTWYT2, HTWYT3, HTWYT4, HTWYT5, HTWYT6, HTWYT7, HTWYT8, HTWYT9, and Check Sindhu. Analysis of variance for normal sowing revealed significant differences (P < 0.01) among genotypes, treatments, and genotype × treatment interactions for plant height, number of tillers per plant, number of grains per spike, number of spikelets per spike, 1000-grain weight, biological yield per plant, grain yield per plant, relative water content, and chlorophyll content. HTWYT1 recorded the maximum chlorophyll content, while HTWYT9 showed the maximum relative water content. HTWYT8 recorded the maximum number of grains per spike. At the late sowing date (December 19th), HTWYT1 produced short-stature plants with maximum grain yield and 1000-grain weight. HTWYT6, HTWYT5, and HTWYT4 were identified as heat-tolerant genotypes, exhibiting desirable traits except for plant height, chlorophyll content, and biological yield per plant. In contrast, HTWYT1, HTWYT2, HTWYT3, HTWYT7, HTWYT8, and HTWYT9 were found to be heat-susceptible genotypes for most traits, except for a few. Therefore, heat-tolerant genotypes with desirable traits can be used as selection criteria in breeding programs