Genetic components of maize heterotical contrasting tropical and subtropical populations.

Abstract

A diallelic cross between 16 tropical and subtropical populations was formed at Iguala, Gro., in the winter nursery 2002 - 2003. Crosses and parents were evaluated during the 2003 growing season at INIFAP Bajio Experimental Station, in Celaya, Gto, Mexico. The objective was to identify the best populations to support the heterotic structure in our breeding program and as sources to derived new inbred lines. Data were analyzed using the Gardner and Eberhart model, in which variance components can be separated to estimate additive and nonadditive genetic effects. Results showed that despite the heterotic response involved in the formation of the populations, the “tropical x subtropical” heterotic pattern was expressed in specific combinations such PABG T x Sint “B” IG and Sint PABG I ACG x Sint “A” IG, with grain yields of 12.5 and 12.4 t/ha respectively. These crosses presented maximum values of specific heterosis which can be used for developing high-yielding hybrids through reciprocal recurrent selection. Tropical population Sint “A” IG presented the highest varietal effect, and because of its good adaptation in the subtropic is considered an outstanding germplasm to be incorporated in the Bajio Maize Breeding Program. The best value of varietal heterosis, which is an indicator of General Combining Ability, was observed in PABG I GH “A” synthetic which can be used as tester. More detailed analysis will permit to take advantage of the germplasm involved to benefit maize breeding programs.