Heterosis and combining ability in crosses between two groups of open-pollinated maize populations

The rapid expansion of corn in Brazil indicates the need to explore new sources of germplasm. Thus, the wider use of local germplasm, and the introduction of exotic ones seem to be an advisable strategy to achieve higher levels of yield and adaptability. The objective of this work was to generate information about the potential of two groups of populations (NAP – exotic; HG – local) and their heterotic pattern in hybrid combinations for the synthesis of new populations. Populations and hybrids were evaluated in complete randomized block designs with four replications, in two locations, and three yield traits were studied (GY – grain yield, EY – ear yield, SW – specific weight). The basic strategy was the selection of one HG population as base for the incorporation of each exotic population. The expectedyield gain of the best combinations varied from 1 to 22%. Average heterosis for grain yield was 34.5%