Combining ability of popcorn lines for resistance to the fungus Puccinia polysora (Pucciniaceae)
The selection of southern rust-resistant genotypes caused by Puccinia polysora (Pucciniaceae) is considered an efficient way to control this disease, which causes high crop losses in popcorn. To help choose adequate cultivars, we examined the combining ability of lines and the agronomic performance of popcorn hybrids for rust resistance. Eight S7 popcorn lines were used, which were crossed in a complete diallel mating scheme, resulting in 56 hybrids. The disease incidence on the whole plant (INC), severity on a leaf of the main ear (SEV), grain yield (GY), popping expansion (PE) and volume of expanded popcorn per hectare (PV) were evaluated. Analysis of variance was performed and the means were grouped by the Scott-Knott algorithm. The analysis diallel was performed by the method of Griffing, using the Diallel I method. The hybrids L76xP8, P8xL70, L77xP8, P8xP1 and L55xL76 stood out with a GY of >3000 kg.ha-1 and PE of >30 mL.g-1. For the traits GY and VP, the non-additive effects were predominant, and the heterosis effects high. For the trait expression of INC, SEV and PE, the additive effects were more relevant. The estimates of general combining ability of lines L70, L61, P1 and L76 were negative for INC and SEV. For commercial cultivation, L77xL76, L76xP1, L77xL70, L76xL70, L70xL76 and L77xP1 are recommended, in view of their excellent agronomic performance and superior resistance to rust.