Genetic Dissimilarity for Resistance to Foliar Diseases Associated With the Agronomic Potential in Maize

Abstract

In the present study the objective was to evaluate the genetic diversity among families of maize siblings for resistance to foliar diseases associated with their agronomic potential, identifying groups of families that can be used as sources of resistance in maize crop. The experiments were conducted in the experimental area of the Federal University of Goiás at the Jataí Regional Unit, in Jataí, GO, Brazil, constituted by 182 half-sibling families of maize and two commercial hybrids as a control. The 182 half-sibling families were divided into three experiments with 60, 60 and 62 families, respectively. The experimental design used was randomized blocks, with three replicates. Eight quantitative characters and 4 foliar diseases were evaluated. The multivariate analysis technique was used to measure the genetic divergence for the four foliar diseases represented by the generalized Mahalanobis distance. Based on the genetic dissimilarity matrix, the dendrogram was constructed using the clustering method of the average distance between groups (Unweighted Pair Group Method with Arithmetic Mean - UPGMA). After defining the groups, univariate analysis of variance was performed in order to evaluate the effects of the groups on each character studied. Comparisons were made between the means of the groups, using the Tukey test (p <0.05). White spot (32.53%) was the disease that most contributed to the total divergence between families. Group 10 stood out among the others as a source of resistance to the disease complex associated with yield. The genetic variability of families for foliar disease complex reveals potential for future studies facing pyramiding genes.

Mixed Modeling in Genetic Divergence Study of Elite Popcorn Hybrids (Zea mays var. everta)

“…This cut-off point proved to be efficient to evaluate the phenotypic association among landraces and to determine clusters of popcorn genotypes in a work developed by Cheim et al [44]. Studies on diversity in the genus Zea based on morpho-agronomic variables have been successfully performed to form clusters based on the UPGMA methodology [41,[45][46][47][48]. The cophenetic correlation coefficient of 0.70 demonstrated a good consistency of the clustering pattern, and it is such to estimate a linear correlation between the distance matrix elements and the elements of the cophenetic matrix.…”