Combining Ability of Some Bread Wheat Genotypes for yield and its Components under Normal Watering and Water-Stress Conditions

Abstract

A diallel cross set was carried out at the Experimental Farm of Gemmeiza Agriculture Research Station, Agriculture Research Center, (ARC), Egypt, during the two winter seasons of 2017/2018 and 2018/2019 to assess the variations among six wheat genotypes and their new combinations to estimate heterosis, general and specific combining abilities to determine suitable measurements for drought tolerance in wheat genotypes. Genotypes and the resulted crosses mean squares were found to be either significant or highly significant for all the studied traits under normal and stress environments as well as the combined analysis, except for chlorophyll-a under drought. General combining ability and specific combining ability were found to be significant for all the studied characters under both conditions, except plant height for (SCA) under normal condition, chlorophyll-a for GCA under normal and drought as well as combined analysis and SCA under water-stress condition. The GCA/SCA ratios were found to be greater than unity, suggesting that, additive was much larger and more important than non-additive gene effects in the inheritance of these traits. The two parents Line 1 and Line 3 could be considered as excellent parents in breeding programs aimed to release drought tolerance cultivars. P1, P3, P4, P5 and P6 had the lowest drought susceptibility index value and F1 crosses P1xP2, P1xP3, P1xP4, P1xP5, P2xP6and P3xP5would be classified as drought tolerance due to the least reduction in yield under water stress compared to normal condition, such results might be useful for improving drought tolerance in wheat breeding program.