A Comprehensive study of wheat genotypes for combining ability and heritability in drought tolerance

Abstract

A major challenge in wheat cultivation is the negative impact of water scarcity on growth and yield. Therefore, it is crucial to develop wheat varieties with both high productivity and resilience to drought stress to support food production and improve global food security. The study aims to identify general and specific combining abilities and to understand the genetic mechanisms responsible for key traits by employing half-diallel analysis. In the current study, a half-diallel set comprising 10 x 10 wheat genotypes was subjected to crosses in all feasible combinations, excluding reciprocals, under drought stress conditions. Significant mean squares were observed for both General Combining Ability (GCA) and Specific Combining Ability (SCA) components among the 10 parents and 45 F1 progenies across eleven traits. Assessment of variance components (s2g and s2s), narrow-sense heritability (Hn), broad-sense heritability (Hb) and the GCA/SCA ratio allowed for the determination of the relative contributions of additive and non-additive genetic components. High narrow-sense heritability was noted for traits such as days to 75 % flowering, spike length and biological yield, indicating their predominantly additive genetic control. Conversely, the remaining eight traits exhibited low narrow-sense heritability, suggesting their inheritance is primarily governed by non-additive genetic factors, thus indicating the potential benefits of heterosis breeding. Based on GCA effects, P5 demonstrated superior general combining ability across traits, except for biological yield. P1, P3, P8 and P9 exhibited better combining ability for grain yield per plant. Specific cross combinations including P7×P10, P3×P4 and P5×P6 displayed notable specific combining ability and could be leveraged to develop superior pure lines in subsequent breeding endeavors.