Abstract

Twenty-four lines at the S5 inbreeding level were crossed with two testers (CML 247 and CML 254) to produce test crosses. The resulting hybrids were evaluated in San Andrés Tuxtla, and Ignacio de la Llave, where major environmental differences are found in temperature, precipitation, and average height above sea level. Results showed that general combining ability (GCA) and specific combining ability (SCA) were significant. Three variables were significant sources of variation in the first case: bad ear cover (BEC), roUen ears (RE), and grain yield (GY); while for hybrid combinations (line x tester), only two variables were significant: BEC and GY. Significant ACE values separated the lines by varialbe evaluated, but the most interesting variable was GY. In general, the best test crosses were superior to their commercial controls. Hybrid 12 had the highest GY, ranking 1 (Tester 1), producing 8973 kg/ha; and hybrid 4 had the lowest GY, ranking 24 (Tester 1), yielding 5480 kg/ha. Hybrids combined with Tester 2 had a lower performance: the highest GY - ranking as 1 - was hybrid 3- which produced 7972 kg/ha; and hybrid 20 showed the lowest GY, producing 3553 kg/ha, occupying the lowest position in the ranking. It was also noted that the lines x tester with the best SCA for GY resulted in higher values in at least one of the other three variables evaluated.