Genotype ✕ Environment Interaction and Stability Analysis of Protein and Oil in Grain Sorghum

Testing newly developed cultivars in different environments is important for evaluating stability of performance and range of adaptation. The objective of this study was to determine genotype ✕ environment (GE) interaction and stability of grain sorghum [Sorghum bicolor (L.) Moench] hybrids and lines for protein and oil, and effect of different environments on association of yield traits with protein and oil. Forty-six hybrids and five lines of sorghum were evaluated at five locations across Nebraska and Kansas in 1978 and 1979. Hybrids and lines showed significant interaction with environments. The relative magnitudes of interaction variance components viz., genotype ✕ year (), genotype ✕ location (), and genotype year ✕ location () indicated that the relative performance of genotypes (hybrids and lines) for protein was more inconsistent across years than across locations. The opposite was true for oil. The results of stability analyses revealed that most of the high-protein and highoil hybrids were more responsive to less favorable environments. Lines generally were more responsive to less favorablenvironments for protein and to more favorable environments for oil. The proteinyield correlation varied among environments. At three locations, this correlation was significantly negative, but at another location characterized as a low yielding environment with slow accumulation of growing degree days and delayed maturity, correlation of protein with yield, seed number, and seed weight was significantly positive. The oil-yield relationship was positive at three locations. The results suggest that stability of high-protein and high-oil sorghum genotypes should be considered in breeding programs. Concurrent selection for high-protein and high-yield genotypes may be possible in less favorable environments where full yield potential of sorghum genotypes is generally not attained.