Multi-environment evaluation identifies high-yielding and stable winged bean (Psophocarpus tetragonolobus (L.) DC.) accessions for sub-Saharan Africa

Abstract

The improvement of winged bean offers great importance for food and nutritional security in sub-Saharan Africa under climate change, yet limited information exists on the genetic variability and seed yield stability of available germplasm under multi-environment conditions. Therefore, the identification of high-yielding and stable accessions with broad adaptation has become a major objective in winged bean improvement programs. This study evaluated 110 winged bean accessions for 21 agronomic and yield-related traits across six environments in Nigeria during the 2022 and 2023 cropping seasons using an alpha lattice design in three replicates. Data were subjected to combined analysis of variance, estimation of genetic variability parameters, phenotypic and genotypic correlation, additive main effects and multiplicative interaction (AMMI), and accession × environment interaction (GGE) biplot analyses. Highly significant differences ( p  < 0.001) were observed among accessions and environments for all traits, and the accession × environment interaction was significant ( p  < 0.05) for all traits except hundred seed weight. Total seed weight exhibited moderate genotypic and phenotypic coefficients of variation, while total pod weight, seed weight per plant and number of seeds per plant combined low genotypic coefficients of variation with moderate broad-sense heritability and moderate genetic advance, indicating scope for improvement through selection. Highly significant positive correlations were observed among pod and seed yield-related traits. Stability analysis of the 20 best- and 10 poorest-performing accessions partitioned 75.28% of the total variation to the environment, 15.94% to the accession × environment interaction and 8.78% to accessions, confirming that the environment strongly influenced seed yield expression in winged bean. Both AMMI and GGE biplot analyses consistently identified TPt-270 (G70) as the highest-yielding accession, closely followed by TPt-198 (G31), while TPt-187 (G29) was identified as the accession closest to the ideal genotype. TPt-198 was additionally ranked among the early-flowering accessions. In addition, both GGE biplot analysis and AMMI identified ENV3 (Ibadan 2023) and ENV4 (Ikenne 2023) as the ideal environment. Together, TPt-270, TPt-198 and TPt-187 represent the most promising accessions identified in this study and are recommended as elite parental lines for winged bean improvement programmes targeting superior seed yield.