COMPARISON OF TYPES OF MAIZE VARIETIES DEVELOPED BY INIFAP IN THE CENTRAL-WESTERN PART OF MEXICO

Abstract

The INIFAP maize (Zea mays L.) breeding program for the central-western part of México developed elite lines to make new experimental varieties of different types. The new varieties: synthetic varieties, double cross, three-way, and single cross hybrids, formed with late and intermediate elite germplasm, were compared for yield to commercial hybrids as controls. The varieties were evaluated in a total of 71 experiments established in subtropical and tropical environments of that region in 1990 an 1991. Combined analyses of variance were performed by years considering all the environments, as well as the subtropical and tropical environments. No significant differences for yield were found when double, three-way, and single cross hybrids were compared; however, single crosses had larger mean squares (variance) than the other two types of hybrids. Experimental varieties outyielded the commercial ones by 10 % and the hybrids to synthetic varieties by the same percentage. Most of the interactions between the hybrids and the environment were significant, which confirms environmental specificity for each type of hybrid. Also, the importance of heterosis was clear for all hybrids when lines of the two maturity groups and different genetic background were crossed. Subtropical environments were 19 % more productive than tropical ones, and were more promising for utilizing single cross hybrids in the spring-summer season.