Characterization of the genetic structure of a cupuassu tree population collected in primary forest

Abstract

The evaluation of the genetic dissimilarity of access is a fundamental step in a genetic improvement program, allowing the direction of actions and supporting decision making that will define the program success. This study aimed to determine the most informative variables to analyze the diversity of the Active Germplasm Bank (BAG - Cupuassu) - Nova Ipixuna Collection, through the morphological characterization of leaves, flowers and fruits. For this purpose, 20 clonal access from fragments of primary forest in the municipality of Nova Ipixuna, Pará, were characterized for floral, leaf and fruit characters. In all, 34 characters were measured. The access were designed in randomized complete blocks with three useful plants per plot and five replications. The characters had their genetic variances and correlations analyzed. These two procedures were used to discard characters. Dissimilarity was estimated using the generalized Mahalanobis distance, which were used for clustering via UPGMA (Unweighted Pair Group Method using Arithmetic averages). In general, the traits have high heritability and a high coefficient of genetic variation. Correlations were more pronounced between characters belonging to the same group. Such analyzes allowed the discarding of 11 variables, leaving 23 for the calculation of dissimilarity. The grouping determined the formation of six groups, which did not depend on the place of collection. Therefore, the presence of genetic variability among access is verified, accrediting them for use in the breeding program.