Recursos genéticos de Vigna Unguiculata: variabilidade genética e potencial de uso no melhoramento genético

Abstract

Cowpea [Vigna unguiculata (L.) Walp. ] is a culture rich in protein and other nutrients and for its rusticity represents staple food for the low-income populations of northeastern Brazil. Culture has its success based on breeding programs aimed at selecting the most divergent genotypes. Genetic divergence studies are of great importance as they provide estimates for the identification of high genetic value parents who, when crossed, increase the chances of selecting superior genotypes. Given the context, the objective of this study was to analyze the variability and genetic divergence of cowpea accessions of the UFC Active Germplasm Bank (BAG), using morphoagronomic characters and multivariate analyzes. The experiment was carried out at the Federal University of Ceará, using as treatments 76 accessions of the UFC BAG. The accessions were sown in rows of five meters with 0.5 m distance between plants, totaling 10 plants per access. To characterize the accessions, 19 descriptors were used, which were converted into multi-categorical variables, thus obtaining estimates of the genetic distances between the accessions. Phenology and production traits were also evaluated. Based on the frequency distribution of the accessions in the different phenotypic classes of each descriptor, the Shannon and Weaver (H ') index was estimated. After standardization of the variables, genetic distance estimates and dendrogram estimation were based on Euclidean distance squares and Ward's agglomerative method. Another dendrogram was also obtained using only the descriptors selected based on the entropy level (H '). Based on the entropy level, the descriptors flower color, central leaflet shape, pod position, pod color, seed coat color, seed brightness, initial flowering, 100 grain weight and reaction to virus diseases can be used. to analyze genetic variability among cowpea accessions. Crossings between 23 (CE-102) and 1 (CE-07) or 5 (CE-030) are indicated, as CE-102 is the earliest access among the studied, but has Number of Pods per Plant and Low Plant Production, which would be complemented by the high NVP and P / Pl characteristics of the CE-07 and CE-30 accessions, and they are in distinct groups in the dendrogram, which confirms the genetic divergence between them.