Phenotipic relationships and heterosis among commercial hybrids and exotic germplasm of maize in Jalisco, México [Relaciones fenotópicas y heterosis entre híbridos comerciales y germoplasma exótico de maíz en Jalisco, México]

Maize (Zea mays L.) breeding programs in central-western México have been using adapted genetic materials, mainly commercial hybrids, improved populations, and exotic materials introduced from other areas. In this study, phenotypic and genotypic relationships among adapted and exotic populations were measured to define the best way to use these materials in breeding programs. Multivariate analysis techniques (Biplot analysis) and cluster analysis applied to adapted and exotic materials and their crosses, were used with regard to agronomic traits and ear yield components. It was confirmed that grain yield is still the most important variable in the characterization of genetic materials, in combination with lodging, ear quality and descriptive variables of the maturity cycle (days to tassel and silking flowering). Cluster analysis, clearly separated the adapted from the exotic materials, with the exception of some of the high yielding exotic crosses ('Pob49 x P-3394', and 'Pob32 x P-3394'), which involved exotic materials with sub-tropical and tropical germplasm in their pedigree ('Pob32 x SynB73' and 'Pob49 x Pob32'), and crosses that possibly involved temperate materials ('A-7573 x P-3066'). In crosses of adapted x exotic materials, the combinations with 'SynB73' and 'P-3394' were located in the opposite group from the crosses with 'SynMo17' and 'Blanco de Ocho', while in the intermediate group predominated crosses with 'Pob49' and 'Pob32'