Twelve long-eared and twelve thick-eared lines were identified for this purpose. Single crosses were evaluated using a 12 x 12 simple lattice design with four replications in five environments during 1995. General combining ability (GCA) and Specific combining ability (SCA) estimates for grain yield were ca1culated using line x tester analysis. Line 4 (Pop.21xPop.43) registered the highest GCA value (0,58 t/ha) among long-eared lines; while in the group of thick-eared lines the highest GCA values (0,48 t/ha) corresponded to line 19 (Pop.25). The highest yield (8,35 t/ha) and SCA effect of (0,61 t/ha) was produced by cross 4 x 22 (Pop.21xPop.43) x (Pop.32). Results showed that it is important to consider the use of lines with different traits and their heterotic pattern to develop hybrids maximizing Fl performance.