Evaluation of maize hybrids tolerant to phaeosphaeria leaf spot, gray leaf spot and common rust and yield

Abstract

The objectives of this study were to identify maize hybrids which have high grain yield and resistance to Phaeosphaeria leaf spot, gray leaf spot and common rust, as well as to estimate the most efficient period for measuring the reaction of the hybrids to the pathogens. Two experiments were set up in Lavras, MG, Brazil, assessing 30 hybrids in the season of 2011/2012. The experimental design was a 6 x 5 lattice arrangement with three replications. Grain yield was evaluated and five assessments of disease severity were performed at ten-day intervals as of 60 days after maize emergence. After that, the area under the disease progress curve (AUDPC) and the Spearman correlations between the diseases and the various assessment periods for each disease were estimated. It was found that the hybrids GNZ9626 PRO and GNZ9501 PRO have high grain yield and a satisfactory level of resistance to Phaeosphaeria leaf spot, gray leaf and common rust, and that assessment of the level of resistance to these diseases should be performed in the period from 80 to 100 days after plant emergence, which provides results similar to AUDPC.