Selection of popcorn hybrids resistant to southern corn leaf blight grown in distinct N availability

Abstract

Although resistance to diseases is genetically controlled, the environment has a strong influence on the reaction of plants to pathogens. Thus, the selection of superior genotypes in plant breeding programs can be more efficient the more intrinsically the environmental factors that influence the trait of interest are considered. This study aimed to investigate the adaptive genetic capacity of popcorn maize plants in relation to the occurrence of southern corn leaf blight (SCLB) in contrasting environments regarding nitrogen availability. Gene effects were estimated based on the implementation of a full diallel without reciprocals from which 28 hybrids were obtained. These hybrids, together with their parents, were evaluated in four environments in relation to SCLB reaction. The studied characteristics were area under the disease progress curve, estimated for severity and incidence. The experimental design was a 6 × 6 square lattice with three replications. Significant effects were found on the interactions between genotype, general combining ability, and specific combining ability × environment, demonstrating severe implications of soil nitrogen concentration on the performance of parent lines and hybrids. Dominant gene effects prevailed in the expression of resistance to SCLB. Considering the need for an environmentally and economically sustainable awareness in the control of this disease, it is of interest to take advantage of the heterotic effect contained in the combination L77 × P7, which stood out in relation to the other hybrids for the evaluated environments.