Genotype-by-environment interactions for fruit yield and related traits in selected hybrids of bottle gourd ( <i>Lagenaria siceraria</i> )

Abstract Bottle gourd [ Lagenaria siceraria (Mol.) Standl.] is a multi-purpose cucurbit crop cultivated globally. The crop in sub-Saharan Africa (SSA) shows considerable genetic diversity and resilience to drought and heat stress. However, smallholder farmers use low-yielding unimproved landrace varieties due to a lack of investment support and breeding efforts to develop and release best-performing and widely adapted hybrid varieties with desirable product profiles. Therefore, the objective of this study was to determine the genotype-by-environment interactions (GEI) for fruit yield and related traits among newly developed bottle gourd hybrids to guide variety recommendation and registration. Eight preliminarily selected F 1 hybrids and four checks were evaluated in five contrasting environments of varying moisture conditions using a randomized complete block design with three replications. Data were collected on days to 50% male flowering (DTMF) and female flowering (DTFF), total number of fruits per hectare (TNFH) and fruit yield per hectare (FYPH) and subjected to analysis of variance, additive main effects and multiplicative interaction (AMMI) and genotype plus genotype-by-environment (GGE) biplot models. The AMMI model revealed significant (p ≤ 0.001) effects of genotype (G), environment (E) and GEI for the studied traits. The AMMI model explained a higher (96.30%) variation for TNFH, of which G, E and GEI effects explained 49.88, 24.21 and 22.21% of the total variation, respectively. The model ascribed variations of 12.36, 73.16 and 11.41% for FYPH attributable to the G, E and GEI effects, in that order. The GGE biplot model explained 94.53 and 96.56% variations for TFYPH and FYPH, respectively. The hybrids BG-58 × BG-80, BG-80 × GC, BG-27 × BG-52 and BG-52 × BG-58 attained high and stable FYPH under water-limited conditions. The hybrids BG-52 × BG-58, BG-58 × BG-80 and BG-52 × BG-79 recorded high FYPH under irrigated conditions. The identified hybrids are recommended for registration and commercialization for cultivation under rainfed and irrigated conditions in South Africa and similar agroecologies.