Effects of genotype, environment and their interaction on protein and amino acid contents in soybeans

Soybean [Glycine max (L.) Merr.] is an important source of protein and oil. Genotype, environment and the interaction of genotype x environment influence the protein composition in soybean seeds. The main objectives of this study were to i) study the influence of genotype, environment and their interaction on soybean protein and amino acid contents; ii) evaluate the stability of soybean genotype across various environments, with a focus on soybeans grown in a northern latitude; and iii) identify the correlation between crude protein and critical amino acid value (CAAV). Twenty-three soybean genotypes were grown at four locations in Manitoba, Canada for two years (2018 and 2019). Soybean seeds were analyzed for protein and amino acids (nine essential amino acids and cysteine). The effects of genotype, environment and genotype x environment interaction on all traits were significant (P < 0.05). Genotype and environments explained the main part of variation for all traits. G13 and G15 cultivars performed better in favorable environments (bi > 1), and G22 cultivar showed greater resistance to environmental change. Protein and amino acids responded differently to various environments, but the optimal environments for greater soybean protein and amino acid remains to be established. The CAAV had a negative linear relationship with protein content in soybean (k = -0.17). This work expands our knowledge of the factors impacting the protein quality of soybeans grown in northern latitudes.