Resistance of popcorn hybrid (Zea mays) to multiple diseases and correlation between leaf disease intensity and agronomic traits

Grain yield and popcorn quality losses have become more common due to attacks by pathogens responsible for leaf diseases. Genetic resistance is the main control measure, as it is applicable in large areas and uses reduced costs and less environmental impact, compared to chemical control. In this context, the purpose was to select popcorn hybrids that meet resistance to Exserohilum turcicum, Bipolaris maydis, and Puccinia polysora and to have high levels of popping expansion and grain yield. We took into account two growing seasons (summer harvest - October 2014 to January 2015 - and winter harvest- April to July 2015). Twenty-eight hybrids from the complete diallel cross scheme were evaluated, among eight inbred lines (P8, P1, L55, L61, L70, L76, L77 and L88). For this purpose, we used a randomized block design with four replicates in two growing seasons. The traits investigated were the incidence of P. polysora (IPP), B. maydis (IBM), and E. turcicum (IET); severity of P. polysora (SPP), B. maydis (SBM), and E. turcicum (SET); grain yield (GY); and popping expansion (PE). Data from the experiments were submitted to the principal component analysis (PCA) through the R software. Results showed that the traits IET and IPP in the summer harvest, and IET and SET, in the winter harvest, were the most significant in the select of hybrids. The P8 x L76 and L70 x P8 hybrids were selected for summer harvest and the L77 x L61 hybrid, for winter harvest