YIELD OF EXOTIC MAIZE LINES IRRADIATED WITH GAMMA RAYS AND OF SINGLE CROSS HYBRIDS

Abstract

The development of maize hybrids (Zea mays L.) with high yield for the Mexican highlands is necessary to face the increasing demand for grain. In genetic improvement, this activity has additional attractiveness when parental lines come from exotic germplasm. In order to determine the per se potential performance of exotic maize lines irradiated with Co⁶⁰ and simple hybrids generated with them, 53 progenitor lines derived from 10 highly homozygous high yielding lines, along with six single crosses and two commercial hybrids as checks were evaluated. The evaluation was carried out in 2015 in three environments: Montecillo, Chapingo and Tecamac, State of Mexico, under a randomized complete blocks design with three replications. The experimental unit consisted of plots with two 6-m long rows, 80 cm between rows and 40 cm between plants. The traits measured were days to male flowering (DFM); plant and ear height (AP, AM) in cm, grain yield (t ha- 1) (RG); ear length and ear diameter (LMz, DMz) in cm; number of kernel rows per ear (NHM); number of grains per row (NGH). There was significance between environments, genotypes, and genotype × environment interaction for all the evaluated traits. RG of the 10 best lines exceeded 3.4 t ha^-1, which shows their potential as parents of single cross hybrids. The crosses 99 × 107, 107 × 206 and 106 × 180 were the most early-maturing with yields of 8.432, 8.432 and 8.276 t ha^-1, respectively, and statistically different from the check hybrids HS-2 (9.421 t ha^-1) and H-40 (8.913 t ha^-1). The most productive lines could represent an advantage in the production of low cost hybrid seed of those single crosses with high productive potential.