Morphological and Agronomic Variability between Seven Local Cowpea Genotypes in Acre, Brazil

Local varieties of cowpea are promising for breeding programs, as they harbor an important source of genetic variability. The objective of this study was to estimate the genetic variability among cowpea genotypes based on morphological and agronomic descriptors. The experiment was carried out in a randomized complete block design with three replications in the experimental field at Universidade Federal do Acre, in Rio Branco, Acre, Brazil. The experimental unit consisted of six lines of 5.0 m, with a spacing of 0.80 m x 0.50 m, with the four central lines used in the evaluations of 21 characters. The treatments consisted of seven local cowpea genotypes. The Mahalanobis generalized distances (D2) were calculated and used in the Tocher and UPGMA clusters. Principal component analysis, relative contribution of traits and analysis of variance were also performed. Manteiguinha and Mudubim de Rama were the most dissimilar genotypes, while Ceará Mercado and Baiano were the most similar. The main component of greater explanation illustrated the separation of genotypes into two groups, with the union between Manteiguinha and Manteigão forming one group and the other genotypes forming the other group. The traits grain yield, number of grains per pod and grain mass of fifty pods were the main determinants in the quantification of genetic divergence. The combination of the Manteiguinha with Mudubim de Rama genotypes is the most suitable for obtaining promising segregating populations.