Boosting soybean adaptation in Africa through multi-trait selection in multi-environment trials

Soybean breeding in Africa is constrained by environmental heterogeneity and strong genotype-by-environment (G×E) interaction, which limits the identification of high-performing and stable genotypes. We evaluated 145 soybean genotypes across 24 environments in seven African countries for grain yield (GY), number of days to maturity (NDM), 100-grain weight (W100), oil content (OIL), and protein content (PROT). Likelihood ratio tests indicated significant genotype, environment, and G×E effects for all traits. GY ranged from 1.404 to 3.391 kg ha⁻¹, with variation in maturity and grain composition associated with altitude and cropping season. Genetic correlations revealed important trade-offs, including positive associations among GY, NDM, and W100, and antagonism between OIL and PROT. Multi-trait selection with 10% intensity identified 14 genotypes closest to the ideotype, with expected gains of 15.7% in GY and favorable responses in the other traits. These findings demonstrate the effectiveness of multi-trait, multi-environment strategies for soybean improvement in Africa.

Keywords:
Glycine max (L.) Merr.; selection index; genotype × environment interaction; multi-environment trials