Comparison of clustering methods for study of genetic dissimilarity in soybean genotypes

Abstract

This study aimed to compare clustering methods based on the dissimilarity measures and get information on genetic diversity in twelve soybean genotypes. The experiment was conducted at the State University of Mato Grosso do Sul - Unit Aquidauna. The genotypes were grown in a randomized complete block design with four replications. The following quantitative traits were measured: Plant height, first pod insertion height, number of branches and pods, mass of hundred grains and grain yield. It were evaluated the clustering methods Ward, complete linkage, median, mean linkage within group and mean linkage between groups using as dissimilarity measures the mean standardized Euclidean distance (D) and the Mahalanobis’s generalized distance (D²). The diagnosis of multicollinearity revealed adequacy of data to the proposed study. Clustering based on standardized mean Euclidean distance is distinct from those formed based on the Mahalanobis’s generalized distance, being this measure most recommended to quantify the genetic diversity in soybean genotypes based on morphological traits because it presents higher values cophenetic correlation coefficient (CCC) for all clustering methods. The mean linkage between groups’s hierarchical method formed concordant groups for D and D², being recommended for these dissimilarity measures. According to both methods, the cross between the genotypes CD238 with SYN3358 and CD238 with Potencia can generate hybrids with high heterotic effect due to different numbers of loci in which the dominance effects are evident. Key words: Dissimilarity measures, genetic divergence, Glycine max, quantitative descriptors.