Phenological Development, Environmental Effects, and Selection of Soybean Lines from Crosses with Contrasting Relative Maturity Groups

Soybean is the main oilseed crop cultivated worldwide and is important for human and animal nutrition. The duration of flowering, reproductive period, and maturity is determined by genetic factors and influenced by environmental variables such as temperature, photoperiod, precipitation, soil type, and crop management, affecting yield and regional adaptation. However, gaps remain regarding the interaction between relative maturity groups (RMG) and the environment. Therefore, this study aimed to characterize the behavior of soybean populations and the environmental effect on the phenological cycle of the crop. Two populations were developed from biparental crosses with a narrow range in RMG among the parental cultivars. The E2 population originated from BMX Potência RR (RMG 6.7) × BMX Energia RR (RMG 5.3), and E3 from BRS 245 RR (RMG 7.3) × BRS 278 RR (RMG 9.4). The populations were evaluated over four growing seasons in an augmented block design, and traits were analyzed using mixed models with environmental covariates. Higher temperatures and lower precipitation were associated with shorter phenological periods, whereas higher precipitation and lower temperatures were associated with longer periods. Earlier lines were more environmentally sensitive, whereas later lines showed greater phenological stability.