Caracterização morfológica, seleção de descritores e diversidade genética entre acessos de mangueira do banco ativo de Germoplasma da Embrapa Semiárido

Abstract

The aim of this work was to perform the genetic diversity analysis among the active germplasm bank of mango accesses from Embrapa Semiarid which was performed through morphological characterization, another goal was to select descriptors for later use in the characterization of the accesses. We used 53 accesses for the first chapter and 41 for the others. A total of 53 descriptors were applied, the list of descriptors was given by the Ministry of Agriculture, Livestock and Supply in 2011. The application of the descriptors was performed by only one person to reduce the difference in personal judgment. For the characterization of the accesses, a simple percentage was used. The selection of qualitative descriptors occurred through the Shannon entropy level and the quantitative descriptors through the direct selection method, proposed by Jolliffe and the multicollinearity diagnosis. The clustering analysis was obtained using the UPGMA method, using the complement of the similarity coefficient for the qualitative descriptors, the Euclidean distance for the quantitative descriptors and the Gower distance for the quantitative and qualitative descriptors separated and together. In the characterization of the accesses, genetic variability was observed for the descriptors applied, mainly in those related to the coloring of the fruits. It was observed a low variability in the accesses for the descriptors: growth habit of the main branches, space between the secondary veins of the limbus, length of the petiole and presence of neck in the fruit. The selection of descriptors allowed to exclude those that contributed little to the total variation, in the selection of qualitative descriptors were excluded 19.45% corresponding to the descriptors habit of growth of the main branches, space between the secondary veins of the limb, rippling of the edge of the limbus, presence of neck in the fruit, proximal protuberance of the stylus scar, point in the stylus scar, shape in the lateral view of the seed. For the quantitative descriptors, 17.65% were excluded, which is equivalent to fruit length, limb width and inflorescence diameter. The selected descriptors were applied in the analysis of genetic divergence, allowing to observe distinct genotypes that could be considered as new options for use in controlled crossings, allowing the diversification of the orchards of the crop, besides the characterization of the accesses allowed to detect genetic variability for the descriptors applied, thus reaching the conclusion of the morphological characterization of the active germplasm bank from Embrapa Semiarid.