Six flue-cured cultivars of Nicotiana tabacum L., 15 possible $F_1$ hybrids and 15 $F_2$ populations among them, and 15 haploid populations of $F_1$ hybrids and 6 haploid from parents, were evaluated. The variances of general combining ability were predominant for all characters studied in $F_1$ hybrid and $F_2$ population, and in haploid populations of $F_1$ hybrids except leaf width, value and reducing sugar. There were significant correlations between generations in variances and ranks of parental GCA effects estimated from general combining ability analysis of $F_1,;F_2$ and haploid generation of $F_1$ hybrids for yield, stem height, days to flower. leaves per plant, value and total alkaloids.