Genetic analysis of yield and physiological traits in soybean [Glycine max (L.) Merr.] under drought stress

The present investigation on soybean [Glycine max (L.) Merr.] was conducted at the Post Graduate Research Farm, Mahatma Phule Krishi Vidyapeeth (MPKV), Rahuri, during the academic years 2023–25. Under drought conditions, P1 flowered and matured significantly earlier, F1 showed superior yield traits, P2 and F1 excelled in plant height (PH) and number of pods per cluster (NPC), while F2 and F3 displayed only intermediate performance across traits. P1 generally performed best for earliness and chlorophyll content (CC), P2 for leaf area (LA) and relative water content (RWC) related traits and F1 consistently excelled in canopy temperature depression (CTD) and harvest index (HI). F2 and F3 showed mostly average or desirable leaf senescence performance, depending on the cross. All four crosses showed additive gene action for flowering and maturity, while Crosses I, II and III showed the same pattern for number of pods per plant (NPP) and Cross I alone for PH. Dominance and dominance × dominance effects were expressed for multiple traits across crosses, with Cross I showing them for 3 traits, Cross II for four, Cross III for four and Cross IV for six yield traits. Duplicate epistasis was observed for seed index (SI) (Crosses I and IV), DF (Crosses II and III) and NPP (Crosses II and IV). However, complementary epistasis was observed for maturity (Crosses I and IV), PH (Crosses II and IV) and NPP and yield per plant (YPP) (Cross III).