Characterization of a segregating population of passion fruit with resistance to Cowpea aphid-borne mosaic virus through morpho-agronomic descriptors
In passion-fruit breeding programs, characterizing genotypes developed through morpho-agronomic descriptors helps quantify genetic diversity and identify individuals with desirable qualities. We examined the discriminatory ability of passion-fruit descriptors and determined their relative importance in the characterization of 91 genotypes from a breeding program for resistance to Cowpea aphid-borne mosaic virus. Twenty-four quantitative and 14 multi-category qualitative descriptors related to plant, leaf, flower, and fruit characteristics were used. The quantitative descriptors were subjected to correlation and principal-component analyses and selected based on direct selection and the Singh method. The traits were used to obtain a distance matrix, based on Gower’s algorithm, and a comparative clustering between the dendrograms for the morpho-agronomic variables was obtained using the unweighted pair group method with arithmetic mean procedure. Based on the principal components method, the traits that most contributed to genetic variability were number of seeds (23.241%), petiole length (19.438%), and petal width (10.440%). In its turn by the Singh method, the traits androgynophore length (6.68%), followed by flower length (5.47%), area under the disease progress curve (5.27%), and peduncle length (5.17%) were those which most contributed to the differentiation of genotypes. Although seven descriptors (leaf length, bract width, corona long filament length, sepal length, fruit width, fruit mass, and mass of fruit pulp) showed little contribution to the characterization of genotypes, their discard is not suggested, as they significantly contribute to the discrimination of genetic divergence in the population. Comparative analysis between the dendrogram containing all descriptors and the dendrogram containing only flower, leaf, or fruit descriptors evidenced the need for using a large number of descriptors in the characterization of genetic diversity in Passiflora. The use of all 38 descriptors increased the efficiency in the discrimination of groups.