Contribution of weather variables to genotype × environment interaction in soybean

Abstract

Plant breeders are often faced with the problem of genotype × environment (GE) interaction. The use of weather variables to explain GE interaction may help breeders understand the cause and nature of the interaction. Therefore, the objective of this investigation was to determine the contribution of covariates (environmental index, rainfall, minimum and maximum temperature, and relative humidity) to GE interaction. Four Group-V, eight Group-VI, and four Group-VII soybean ( Glycine max (L.) Merr.) cultivars grown in 12 (Group V) and 15 (Groups VI and VII) environments were used. Genotype × environment interaction was significant and partitioned into σ i 2 components assignable to each genotype and into s i 2 components following use of a covariate. Environmental index contributed the most to the GE sums of squares in groups V and VI cultivars. Rainfall was the most important weather variable in removing heterogeneity from the GE sums of squares. We concluded that there were differences due to maturity group in the amount of heterogeneity accounted for by environmental index, and that cultivars in Groups V and VI were differentially affected more by differential fertility and/or cultural practices than by the weather factors.