Genetic analysis of grain yield and yield-attributing traits in navy bean (Phaseolus vulgaris L.) under drought and optimal environments

Abstract Knowledge of the genetic basis of navy bean (Phaseolus vulgaris L.) performance under drought stress (DS) is important for planning appropriate breeding and selection strategies in DS environments. Twenty-eight F2 progenies generated from an 8 x 8 half-diallel mating design were evaluated to determine combining ability effects and mode of gene action of grain yield (GYD) and yield attributing traits in navy bean under DS and non-stressed (NS) conditions. The experiments were conducted in two locations in a 6 x 6 square lattice design with two replications during the 2020 dry season. There were significant (p < 0.001; p < 0.05) positive correlations for number of pods per plant (NPPP), number of seeds per plant (NSPP) and 100-seed weight (SW) with GYD under both DS and NS. General and specific combining ability (GCA; SCA) effects were significant (p < 0.05) under both DS and NS for most traits indicating the importance of both additive and non-additive gene effects in the expression of the traits. Parents with best combining ability for most of the studied traits were G1, G7, G6 and G8 under NS, and G3, G4, G7 and G8 under DS. The most promising progenies with high values for GYD and its component traits under DS were G2 X G3, G2 X G8, G4 X G5, G4 X G8, and G6 X G8. Good general and specific combiners with high significant positive effects under DS should be used further in breeding for moisture stress tolerance.