Abstract
Three commercial wheat cultivars as testers namely, Gemmeiza 11, Sids12 and Sakha 93 and ten lines from CIMMYT were used in a line x tester mating design at the Experimental Farm of Agriculture Faculty, Kafrelsheikh University, Egypt, during the two seasons 2015/16 and 2016/17. Two separate water regimes normal (four irrigations over the planting one) and water stress (only the planting irrigation) were performed. The studied traits were days to heading, plant height, number of spikes plant(-1), number of kernels spike(-1), kernel weight and grain yield plant(-1) in addition to drought susceptibility index. The water stress treatment decreased significantly all the studied traits. The reduction % of grain yield ranged from 0.41 to 22.39 %. The best values of grain yield were recorded by Line 3 and Line 3 x Gemmeiza 11 under both treatments. The most tolerant genotypes for grain yield were Line 2, Line 3 and Line 10, Line 5 x Sakha 93 and Line 7 x Gemmeiza 11. There were large variations among the studied genotypes, parents, crosses, parents vs crosses, lines and lines x testers in most cases. In addition, the interactions of water treatments with all sources of variations were significant for most traits. Line 1 and Line 3 had the best general combining ability, while Line 4 x Sakha 93 and Line 3 x Gemmeiza 11 had the best specific combining ability for grain yield under all conditions. Dominance variances were higher than additive variances for most traits. Lines and the lines x testers interaction brought much variation in the expression of the studied traits. Significantly and positive correlations were observed between grain yield and each of plant(-1) height, No. spikes plant(-1) and 1000-kernel weight under both conditions.