Unravelling the environmental drivers determining the residual fraction of soybean seed

Abstract

There are threemain components of soybean (Glycine max (L.) Merr.) seeds: protein,oil, and residual. The residual fraction includes soluble and insoluble carbohydrates,lignin, and minerals. Among soluble carbohydrates, the presence of raffinose familyof oligosaccharides (RFOs) has poor nutritional value (i.e., raffinose and stachyose),and the inability of monogastric animals to digest them limits the potential useof soybean meal for food and feed applications. Our objective was to understandhow different environmental conditions impact soybean seed quality, particularlythe concentration of the residual fraction and its components. Nine commercialgenotypes from three maturity groups were sown on early and late dates. The concentrationof insoluble carbohydrates + lignin was positively associated with seedweight (r = 0.67) and negatively associated with the mean temperature during theseed-filling period (R5–R7; r = −0.61). Within soluble carbohydrates, RFOs werenegatively influenced by the mean temperature at the beginning of the seed-fillingperiod (R5–R6; r = −0.37), while sucrose concentration showed the opposite effect(r = 0.43). In contrast, precipitation exhibited a positive correlation with RFOs,whereas sucrose displayed a negative correlation (r = 0.38 and r = −0.42). Thisstudy showed that the decrease in protein concentration was related to the increasein the residual fraction of the seeds, and higher temperatures during seed-fillingperiod impacted the residual composition of the seeds, specifically by reducing RFOconcentration.