Environment Stratification in the Evaluation of Corn Hybrids in Southern Brazil

The implementation of a network of maize trials is an onerous task, so breeding programs seek to eliminate redundant environments, remaining only contrasting ones. The objective was to perform the homogeneous environment grouping by studying the G×E interaction through different environmental stratification methods, as well as to compare the efficiency of these methods. Four methods were used- environmental dissimilarity (Djj); Decomposition of the genotype × environment interaction (G×E) into simple and complex parts by Cruz and Castoldi; Pearson correlation coefficient; and factor analysis. Twenty-five single-cross corn hybrids and three commercial cultivars were tested in eight cultivation environments in a randomized complete block design with three replicates in the evaluation of grain yield. Quedas do Iguaçu and Cascavel can be reduced into only one test environment by methods of factor analysis and Pearson correlation. The environments of Pato Branco and Ampére are grouped by two of the four methods employed. However, Clevelândia, Londrina, and Coxilha do not group with other environments in three of the four methods, and Itapiranga in two of the four methods. Cruz and Castoldi’s method and stratification by factor analysis are more rigorous in grouping criteria.