Abstract
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.
Highlights
In the perspective that involves the production chain, numerous factors contribute to reducing the yield of maize (Zea mays L.), such as problems with weeds, inadequate management, pests and diseases
This study aimed to evaluate genetic diversity based on the morpho-agronomic characterization of 182 half-sibling families of maize, through the use of multivariate techniques, and indicate groups with greater potential for resistance associated with the main foliar diseases and grain yield
By the analysis of variance, significant differences were observed between the half-sibling families of maize evaluated, which reveal the existence of genetic variability for quantitative characters and for foliar diseases caused by P. polysora, P. ananatis, E. turcicum and C. zeae-maydis (Table 1)
Summary
In the perspective that involves the production chain, numerous factors contribute to reducing the yield of maize (Zea mays L.), such as problems with weeds, inadequate management, pests and diseases. Foliar diseases have caused serious economic damage in crops, leading to reductions of up to 30% in grain yield (CUNHA et al, 2020). In Brazil, the foliar diseases considered most relevant and affecting grain yield and quality are common rust (Puccinia sorghi), polysora rust (Puccinia polysora Underw); turcicum blight (Exserohilum turcicum), phaeosphaeria leaf spot or white spot (Pantoea ananatis), and gray leaf spot (Cercospora zeae-maydis) (WORDELL FILHO et al, 2016). These diseases, which are expressed under certain favorable edaphoclimatic conditions, can cause epidemics in the field and partially or totally compromise grain yield. It is necessary to know the genetic variability available, as well as the type of control and inheritance of the characters involved, to identify sources of resistance to foliar diseases
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