A PROPOSAL FOR DEVELOPING A YELLOW MAIZE HETEROTIC PATTERN FOR THE TRANSITION ZONE OF MÉXICO. I. METHOD AND POPULATIONS DEVELOPMENT

Abstract

Maize (Zea mays L.) commercial hybrids for the Mexican transition zone (1900 to 2200 m, altitude) have been developed by combining subtropical x High Valleys germplasm created independently in each zone. However, there is not a combined breeding strategy specific for the transition zone. The objectives of this research were: a) to present a crop breeding strategy for integrating a yellow grain maize heterotic pattern for the transition zone of Mexico, and b) to describe the maize population development for integrating an heterotic pattern for this zone. For the first objective, the strategy includes both breeding methodology and types of hybrids to be generated. For the second objective, diallel crosses among tropical and temperate yellow maize populations were evaluated in six locations of the West-Central region of México. White-grain progenitors were converted to yellow-grain types, and yield trials involving yellow-grain commercial hybrids and yellow-grain half sib families obtained by crosses with high valleys and transition germplasm were established at Tepatitlán, Jal. It was concluded that the proposed methodology for integrating heterotic patterns and improved varieties for the transition zone of México has technically more advantages than the actual method used in the Maize Program at INIFAP. It was confirmed that temperate maize germplasm could contribute importantly in both grain yield and earliness for the transition zone, thus this germplasm was used for the conversion of white-grain line “LPC1A-9R-11”to yellow-grain. Selected half sib families used to integrate “INIFAP-Amarillo Dentado-3” population had similar maturity but more tolerance to lodging and healthy ears than landrace Amarillo Zamorano, the best yellow native maize in the region.