Stability analysis for soybean (Glycine max (l.) Merrill) Cultivars in Eastern South Dakota Environments

Crop yield is complex trait which is influenced by many factors such as environment conditions, genotypes, and genotype-by-environment (GE) interactions. Crop yield is also impacted by its component traits. It is important to identify cultivars with wide range of adaptation across various environments or specific adaptation in areas of interest. In this study, we grew 15 soybean cultivars provided by four seed companies at six locations of Eastern South Dakota in 2011 and 2012. A randomized block design was used in each environment. Yield (ton/ha), protein content (%), oil content (%) and other agronomic traits including yield component traits were measured. The data sets were analyzed by various statistical methods such as correlation, mixed linear model approaches, stability methods, and conditional approach to determine stability of these soybean cultivars and factors associated with yield stability. A differential environment specific phenotypic correlation effect was found which could have conferred variable stability to different genotypes/cultivars. A significant GE interaction was reported for seed yield, protein content % and oil content % indicating cultivars performed unparallely to different environments for respective traits. GE interaction accounted for 6.2%, 5.7% and 3.8% of total phenotypic variance for seed yield, protein content% and oil content %, respectively in 2011, while it was 1.2%, 3.2%, and 1.8 % in 2012. All these three traits were mainly affected by both environment and genotype in both years. Environmental variance component comprised a major portion to total phenotypic variation. Most yield components and other agronomic traits, however, were not significant for GE interaction among environments. A high conditional ratio of yield components due to environmental effect was found in both years. AMMI 1 biplot and AMMI 2 biplot were used to find the general or specific adaptation of soybean genotypes/cultivars to given locations. In 2011, cultivars HEFTY H15Y12 and HEFTY H19Y12 were widely adapted for grain yield, while HEFTY H17Y12 and NORTHSTAR 1257R2 were found to perform best in all locations in 2012. Conditional AMMI helped to find out the factors responsible for change in yield stability. Plant height was found to be important for seed yield in North East while it was not important for seed yield in Warner/Bath