The main objectives of this investigation were to evaluate half–sib family selection for improving grain yield and earliness, estimate the genetic components of variance and heritability and calculate the expected and actual gain from selection after one cycle of reciprocal recurrent selection. Results showed that additive genetic variance (σ²_A) for days to 50% silking, ear length, no. of rows/ear, no. of kernels/row and 100-kernel weight for half-sib families of Pop. B was higher than those of half- sib families of Pop. A. Dominance variance (σ²_D) had the important role in the inheritance of ear diameter and grain yield in the two populations. Results indicated that Pop A had accumulate genetic variance (σ²_G) more than Pop B for plant height, ear length, rows/ear, kernels/row, 100-kernel weight and grain yield. The average degree of dominance (ā), indicated the presence of over dominance in Pop. A for ear height, ear length, ear diameter, 100-kernel weight and grain yield and partial dominance for no. of rows/ear. In Pop. B, the over-dominance was observed for plant height and grain yield and partial dominance for 100-kernel weight. Heritability estimates in broad and narrow sense for grain yield in Pop. A were 54.74 and 15.37%, respectively, while it was 64.28 and 8.21% in Pop B. Expected gain for grain yield (kg/plot) was 22.07% and 20.70% and actual gain was 4.14% and 4.49% for Pop. A and Pop. B, respectively.