In order to produce new genotypes under stress condition, seven parents of bread wheat (Triticum aestivum , L.) namely; Sakha 94(P1), Giza 168(P2),Sakha 93(P3),Line 6(P4),Sahel 1(P5), Sids 12(P6) and Gemmeiza 10(P7) were crossed at 2010/2011 growing season in a half-diallel pattern at El-Gemmeiza Agric. Res. Station, ARC, Egypt. In 2011/2012 season, the 7 parents along with their 21 F1 crosses were sown in two adjacent experiments under stress and normal irrigation at Bahteem Agric. Res. Station, ARC. Randomized complete blocks design with four replications was used for each experiment.
Results showed that mean squares of genotypes, parents and crosses were highly significant for all studied traits under normal and stress irrigation. The mean squares associated with general and specific combining abilities were found to be highly significant for all traits at both irrigation levels as well as the combining analysis with a few except lines. This indicates that both additive and non-additive gene effects were involved in the inheritance of these traits. The estimates of GCA/SCA were more than unity suggesting the predominance of additive gene effects in determining the performance of plant height, days to heading, days to maturity, No. of spikes/plant, spike length and 100-grain weight. On the other hand, (GCA/SCA) ratio was less than unity for No. of grains/spike and grain yield /plant at stress condition and combining. The interaction between SCA x Irrigation recorded a significant effect for all traits except No. of days to heading, 100-grain weight and grain yield /plant. The ratios of GCA x I x GCA was much smaller than ratios of SCA X I / SCA for the same studied characters indicating that non additive effects were much more influenced by environmental changes than GCA. The crosses (P1xP2), (P1xP5); (P3xP4), (P5xP7); (P4xP6) and (P6xP7) recorded highest mean values for plant height, number of days to heading and maturity. However, the crosses (P1xP3),(P1xP7), (P3xP6) and the cultivars Sakha 94, Giza 168 and Sids 12 were superior grain yield/plant in their genotypes could be used for improving grain yield and other studied traits under normal and stress irrigation.