GRAIN YIELD AND RESISTANCE TO LEAF BLIGHT (Exserohilum turcicum) OF FERTILE AND ADROSTERILE MAIZE HYBRIDS.

Abstract

Maize (Zea mays L.) growers in Mexico face the problem of buying expensive seed of the hybrids they cultivate. An option to reduce seed price is androsterility in the formation of the hybrids. This characteristic, however, is associated with phytosanitary problems, such as leaf, or northern, blight (Exserohilum turcicum), a pathogen present in Mexico. Therefore, it is necessary to control its distribution with materials that are resistant to the disease and produce higher grain yield. The hypothesis of this study was that androfertile and androsterile hybrids have the same level of resistance to blight and that the androsterile are higher-yielding than androfertile. In this study yield and resistance to northern blight was evaluated in five experimental maize hybrids in their fertile and androsterile versions and compared with five hybrids of normal fertility that are widely used in the study region. The experimental design was complete randomized blocks with two inoculation treatments, three replications per treatment, and the experimental unit was one row 5 m long by 0.80 m wide. The research was conducted during the spring-summer 2016 growing cycle in the High Valleys of Central Mexico in Cuautitlán and Texcoco, Estado de Mexico. Mean grain yield (8.0 Mg ha-1 ) showed that phenotypical expression of the hybrids was outstanding. The commercial genotypes Cimarrón, Aspros 823, P3368W and Tsiri Puma, and the experimental material H3 in its fertile version were outstanding for their grain yield. The last hybrid exhibited contrasts in resistance to northern blight. The hybrids with normal fertility produced higher grain yield. Resistance to leaf blight did not depend on androsterility since both genotypes, androsterile and fertile, had similar resistance.