Reaction of popcorn germplasm to polysora rust under field conditions and natural inoculation

Abstract

Polysora rust, caused by Puccinia polysora, is one of the most economically important foliar diseases of maize, and the use of resistant genotypes is the most efficient and economically appropriate measure to control this disease. In popcorn, damage caused by this disease is equivalent to that found in common maize. However, studies on the identification of sources of resistance in popcorn are much more scarce. This study aimed to evaluate the reaction of popcorn genotypes regarding polysora rust resistance. For this purpose, 37 temperate and tropical popcorn genotypes were evaluated in randomized block experiments with four replicates in two crop seasons, in Campos dos Goytacazes, RJ, Brazil. Disease intensity was estimated by quantifying incidence and severity using a diagrammatic scale, based on the plant and the leaf immediately below the first ear. We found that incidence can efficiently replace severity at low epidemic levels, facilitating field diagnostics. Also, we observed genetic variability for traits related to polysora rust resistance. The landraces PARA 172, ARZM 05083 and the line L80 are recommended to integrate breeding populations for Puccinia polysora resistance as they may carry favorable alleles for disease control.