Genetic variability among common black bean (Phaseolus vulgaris L.,) accessions in southern Brazil

Abstract

To obtain superior genotypes, the use of natural genetic variability is essential, aiming to select parents that will make future crossings blocks. Therefore, the aim of this study was to determine the genetic variability and dissimilarity using multivariate analyzes in common black bean accessions native to southern Brazil. The experiment was conducted in the 2014/2015 in Frederico Westphalen – RS. The experimental design was augmented blocks (RCBD) with four repetitions (totally 149 treatments), in which 147 black common bean accessions were evaluated. Two commercial cultivars were used as witnesses: BRS Esplendor and BRS Supremo. The phenotypic traits such as days to flowering, plant height at flowering, days to maturity, plant height at maturity, insertion of the first pod, number of pods per plant, number of seeds per pod, mass of seeds per pod, number of branches, mass of seeds per plant, seed length, seed width, seed flattening, seed brightness, presence of halo, color of the halo were measured. The distributions of phenotypic frequencies indicate genetic variability among the 149 genotypes of common black bean. The Tocher optimization method presents the formation of eight groups of genotypes. The dendrogram formed by the standardized Euclidean distance was efficient in the stratification of the accessions for their genetic distance. The relative contribution evaluated by Singh method shows that the characters days to flowering and seed brightness are those that best discriminate the genotypes. The multivariate techniques of Tocher optimization and the standardized Euclidean distance show similar responses, proving to be viable tools for the choice of parents in a breeding program.