A 7x7 half diallel cross along with their parental wheat cultivars were evaluated under two sowing dates (19 th Nov. and 17 th Dec.).The results 7 X Giza 168 (HSI 0.58) and Sakha 93 X Giza 168 (HSI 0.60) have recorded the lowest values of heat susceptibility index (HSI), indicating their tolerance to heat stress (late sowing date).

The present study was conducted to evaluate 50 wheat genotypes for their productivity and stability under eight environmental conditions. Wheat genotypes were sown at two planting dates under two nitrogen fertilization treatments during the winter seasons of 2018/2019 and 2019/202. The analysis of variance showed that the mean squares of genotypes, sowing dates, and nitrogen fertilization treatments were significant for the number of spikes/plant, the number of kernels/spike, 1000-kernel weight, and grain yield/plant. The results showed that sowing at the favorable date using 80 kg N/fed increased all studied traits. This study revealed that line numbers 9 and 10 exhibited general adaptability across different environments; hence, these lines are considered promising and could be exploited in breeding programs for wheat improvement.