Quantitative genetic studies in flue-cured tobacco (Nicotiana tabacum). I. Agronomic characters

Abstract

A five parent diallel cross in flue-cured tobacco (Nicotiana tabacum L.) was grown over a 2-year period at the Delhi Research Station. Griffing's (1956) and Hayman's (1954) analyses indicated that general combining ability explained a high proportion of the variability of most of the agronomic characters, suggesting that additive gene action was the major component in determining the expression of these characters. This was substantiated by high narrow-sense heritability estimates. Specific combining ability components were small suggesting that dominance, if any, played a minor role. The WrVr graphic analysis of Hayman indicated a general lack of nonallelic interaction. Phenotypic, genotypic, and additive genetic correlations explained covariation among pairs of characteristics in an almost analogous manner. Implications of the genetic nature of variation in terms of practical utilization by the breeder are discussed.