COMBINING ABILITY OF INBRED LINES FOR MAIZE (Zea mays L.) SINGLE CROSS HYBRID PRODUCTION UNDER IRRIGATION

Abstract

Given that maize (Zea mays L.) displays broad genetic diversity, as part of a breeding program, knowledge of the components of genetic variation is necessary to optimize strategies for their use. Combining ability, maternal effects, type of genetic effects of the crosses and their genetic potential were studied through evaluation of simple mating combinations between 10 lines (S-6-S-8) to produce single-cross hybrids, under irrigation, in Tecamac and Montecillo, of the Estado de Mexico and in Mixquiahuala, of the State of Hidalgo, in the High Valleys of Central Mexico. The experimental design was a simple 10x10 lattice. Genetic analysis was performed with model I of Griffing Method I. Average grain yield (5.6 t ha(-1)) showed that phenotypical expression of the lines was outstanding. General combining ability of lines L5, L6, L8, L10 and L9 stood out, although there were contrasts in grain yield. Genetic expression of grain yield for the outstanding crosses in the study was based on two possibilities: 1) that the cross was formed by both high general combining ability (GCA) lines, in which case the effects of specific combining ability (SCA) may or may not be high, and 2) that the cross was achieved with at least one high GCA line whose SCA effects are high. Based on the number of outstanding crosses, the foremost lines that conformed these crosses were L10, L9, L8 and L6. Line L10 was part of almost 50 \% of all the crosses (10) and in all cases they functioned as female or as male parental lines. The genetic structure of the crosses showed contrasts, which means that there is a possibility of using some specific genotypes as single-cross hybrids, open pollinated varieties, or incorporated into a recurrent selection scheme to take advantage of additive effects.