USE OF MEXICAN CORN RACES IN A PROGRAM GENETIC IMPROVEMENT

Abstract

The purpose of this study was to evaluate the General (GCA) and Specific Combining Ability (SCA) of several races of maize (Zea mays L.), and three testers, as well as to detect races that could be used to improve the regional varieties. Samples of 20 races of maize with good performance at Iguala, Gro., and other regions of Mexico were crossed to three testers known to Guerrero producers. The tes­ters were VS-521, well adapted to the warm region; VS-373, from the semi-warm region; and line D 7501- 471 derived from the hybrid B-670 which has wide adaptation. The varietal hybrids were evaluated in the 1984 rainy season, in two contrasting enviromen­ ts, one with AwO, and the other one with (A) Cw₂ cli mate. The North Carolina genetic design ll was  used,
with testers as females and racial collections as males. There were highly significant differences for locatíons and GCA of females and males. Significant differences at the 7% probability level, for the SCA effects at Iguala and across sites were also detec­ted. The best testers were D 7501-471 and VS-521 and the maize races that had the largest GCA effects were Motozinteco, Onaveño, Celaya, Raton and Tuxpeño.