Heterosis and combining ability of tropical maize populations

Estimation of genetic parameters using diallel crosses experiments aids to objective decision making in plant breeding programs. The objectives of this study were to estimate heterosis, the general combining ability (GCA) of eight tropical maize populations, and the specific combining ability (SCA) of 28 crosses. The populations evaluated were: population 21, 22, 23, 25, 32, 43, 49 and the commercial variety VS 536. The Griffing method 2 design was utilized to estimate GCA and SCA effects, on a complete randomized block design with two replications, at two planting dates. The diallel analysis showed significant differences (p <=.01 and p <= 0.05) among planting dates (PD) of evaluation, crosses (C), GCA, PD x C and PD x SCA interactions. Populations 23 and 43 showed the highest GCA (p <= 0.01), and the crosses VS 536 x Pob 32, Pob 22 x Pob 43, Pob 25 x Pob 49 y Pob 43 x Pob 49 showed the highest SCA effects (p <= 0.01). Both high parent positive heterosis were observed for the crosses Pob 25 x Pob 49, Pob 43 x Pob 49 and Pob 22 x Pob 43. Populations 23 and 43 revealed potential to be used in tropical maize breeding programs.