Heterotic groups based on yield-specific combining ability data and phylogenetic relationship determined by RAPD markers for 28 tropical maize open pollinated varieties

Twenty eight maize open pollinated varieties (OPVs) were crossed in a diall el scheme and the 378 F-1's were evaluated in 10 environments in Brazil. Ba sed on yield-specific combining ability data (SCA), these varieties were cl assified in four heterotic groups. The consistence of the proposed heteroti c groups was confirmed comparing intra- and inter-group F-1 values and midp arent heterosis. Superior OPVs combinations for use as a source of inbreds in hybrid breeding programs were determined. RAPD markers were used to geno type these varieties. A UPGMA dendogram, based on marker data from 50 prime rs and 178 polymorphic bands, was obtained. Phylogeny obtained with RAPD ma rkers agreed with known pedigree data. Dent germplasm tended to group separ ately from flint germplasm. Multidimensional Scaling Analysis on marker dat a and morphological data showed a higher degree of genetic divergence among the dent germplasm than among the flint germplasm used in this study. Corr elation between RAPD marker estimated genetic distance and SCA for yield wa s low and positive (r = 0.16(**)).