Genetic analysis of field and physiological indicators of drought tolerance in bread wheat (Triticum aestivum L.) using diallel mating design

In order to study the inheritance of field, physiological and metabolite indicators of drought tolerance in wheat, an eight-parental diallel cross, excluding reciprocals, was grown in a randomized complete block design (RCBD) with three replications under two different water regimes (irrigated and rainfed). Significant differences were found for yield potential (Y-p), stress yield (Y-s), stress tolerance index (STI), leaf water potential (LWP), relative water content (RWC), water use efficiency (WUE) and evapotranspiration efficiency (ETE). Y-p, RWC and evapotranspiration efficiency (ETE) showed highly significant differences for both general combining ability (GCA) and specific combining ability (SCA), indicating the involvement of both additive and non-additive gene action in their inheritance. Y-s, STI and WUE revealed highly significant differences for SCA, hence non-additive gene action was predominant for these traits. The best general combiners with positive effects, for improvement of Y-p, Y-s, STI, LWP, RWC, WUE and ETE under drought conditions were parents 5, 1, 6, 2, 7, 1 and 2, respectively. The best specific combination with heterobeltiosis over the best parents for improvement of Y-p, Y-s, STI, LWP, RWC, WUE and ETE were crosses 3 x 6, 2 x 4, 2 x 6, 5 x 8, 2 x 6, 2 x 4 and 1 x 7, respectively indicating that parents of these crosses are genetically diverse. High broad-sense heritability observed for all the traits confirmed that all the traits are more genetic, but because of low narrow-sense heritability the rule of additive part was low.