Heterosis and Combining Ability in Diallel Crosses of Burley Tobacco, <i>Nicotiana tabacum</i> L.¹

Abstract

Twelve burley cultivars of N. tabacum L., the 66 possible F 1 hybrids among them, and the 66 F 2 populations were evaluated during 1966‐69. Comparisons of the F 1 hybrids with the parents indicated that heterosis values were small but significant for several characters. Two hybrids, ‘Ky 10’ × ‘Burley 37’ and Ky 10 × Experimental line 42, yielded more cured leaf than Ky 10, the highest yielding variety in the test. Percentages of inbreeding depression obtained from comparisons of the F l and F 2 generations in 1969 were also small, but they were significant for some characters. Estimates of variances for general combining ability were significant for all seven characters studied. Specific combining ability variances were significant for days to flower, leaf width, and yield.