METHODS TO EVALUATE THE GENETIC MAIZE DIV ERGENCE AND ITS RELATION WITH THE DIALLELIC CROSSINGS

The utilization of the multivariate techniques to estimate the genetic divergence was evaluated to help maize (Zea mays L.) breeders to iden tify promising materials to obtain hybrids or populations with large g enetic variability. With this purpose, twenty eight populations, with different origins were evaluated in a competition assay with the gener ations S-0 and S-1, and in hybrid combinations on a diallel crossing s ystem. Beyond these populations, seven testers were used, that were ev aluated in a simple lattice 21 x 21 in Sete Lagoas, MG, Brazil. Measur ements were made in the S-0 generation based in sixteen traits, and mu ltivariate analysis was performed on this data. Later, divergence was evaluated with the multivariate distance (generalized Mahalanobis). It should be noticed that: multivariate evaluation of genetic divergence before any crossing would avoid many crosses to be made, reducing the cost and increasing the precision of experiments; genetic divergence was small and due to the variety BAIII-TUSON and BR 136 related to the others. This fact was responsible to the small variation on the estim ates of the combining ability and heterosis.