Factor analysis and environmental stratification in the assessment of grain sorghum adaptability and stability

The environmental stratification studies are crucial when releasing hybrids for different growing regions. An outstanding performance of a genotype in one environment does not qualify it for indication to all environments, due the occurrence of GxE interaction. Environmental stratification aim the breeders to form groups of environments that minimize GxE interaction. The purpose of this work was to evaluate the use of factor analysis in preliminary environmental stratification assisting at the recommendation of grain sorghum cultivars. Twenty-five hybrids were evaluated, using a randomized block design, in 12 locations during the 2015/16 season. Initially, the individual analysis of the experiments was carried out and later the joint analysis, aiming to examine the existence of G×E interaction. The means of the hybrids in the individual analyses were used to obtain the correlation matrix between pairs of environments. The factorization of this matrix was also carried out via factor analysis in order to group together the environments that most correlated with respect to the hybrids performance. Thus, differential performance between hybrids was observed through individual analyses for all the environments, with the exception of Sete Lagoas and Teresina. The joint analysis revealed the existence of a significant G×E interaction, that is, a differential behavior of the hybrids in relation to the evaluated environments. Based on the criterion of the analysis of the proportion of explained variance, it was found that six factors captured an accumulated variation of 86.29%, and the average communality observed was of 0.86. Considering the geographic and edaphoclimatic variables in the cultivation period, a pattern was not observed among the grouped places, but it is noteworthy that the grouping of places is a function of the performance of the evaluated genotypes, which can be similar even under different conditions. Given the results presented, factor analysis proved to be a tool with potential to perform environmental stratification and assist in the recommendation of grain sorghum cultivars for different regions.