Genotype × environment interaction studies in monoecious and gynoecious bitter gourd (Momordica charantia L.) genotypes for stability using multi-model based approach

Bitter gourd is an important cucurbitaceous crop grown in the summer and rainy seasons. However, its improvement requires genotypes with high yield and stability across the seasons. We evaluated 22 (gynoecious and monoecious) lines across four environments (spring-summer and rainy seasons over 2 years) for number of fruits per plant (NFP), fruit length (FL), fruit circumference (FC), fruit weight (FW), and yield per plant (YP), with the goal of determining the genotype-by-environment interaction (GEI) for yield and yield-contributing traits. Analysis of variance indicated a highly significant variation among the genotypes, environments, and GEI for all the traits under study. The environmental influence on yield accounted for 70.38% of the total variation. The presence of a strong environmental effect on complex traits such as yield indicates a substantial difference among different growing seasons. AMMI, WAASBY/ASV, and YSI all identified broadly stable genotypes; G3, G5, and G8 (notably high NFP), with G8 and G7 combining stability and high YP. Best performers included G16, G19, and G7 for FL; G9, G2, and G11 for FC; and G13, G16, and G21 for FW, with G12 expressing the most FW. GGE biplots identified two mega-environments; E2 and E3, which were the most discriminative for NFP and YP, respectively, with environment-specific "winners" allowing for targeted deployment. BLUPs and BLUEs were consistent across environments, with G20, G8, and G7 consistently leading in YP. The high-yield group (BLUP ≥ 1.79 kg: G14, G20, G9, G5, G6, G4, G8, G7) outperformed the grand mean. These findings support a need for a dual breeding strategy to advance broadly adapted, high-YP lines (G20, G8, G7, and G3, G5) for wide release and hybrid production, while exploiting specific adaptation for market-defining traits (FC and FW) using E2/E3 as primary selection sites. Integrating stability indices with BLUPs accelerates genetic gain and makes gynoecious lines more suitable for hybrid seed production.