Quantitative genetic studies in flue-cured tobacco (Nicotiana tabacum). III. Inheritance of phenolic constituents

Abstract

Genetic analyses of major phenolic constituents of flue-cured tobacco (Nicotiana tabacum L.), utilizing Griffing's method II model II and Hayman's Wr–Vr graphic analysis on a five-parent diallel set excluding reciprocals, were conducted in a replicated randomized block design over a 2-year period at the Delhi Research Station. The ANOVA for general and specific combining ability and Wr–Vr graphic analysis indicated genetic control for these phenolics. Additive genetic variance was the predominant contributor in the expression of chlorogenic acid and its isomers, scopoletin, scopolin, and rutin; dominance where present was in the partial dominance range. The role of nonallelic interaction was negligible for all variables except scopoletin and rutin. Tannins consisting of chlorogenic acid and its isomers were under dominant gene control, while the coumarins, scopoletin, and scopolin, and the flavonoid rutin were under recessive gene control. A considerable degree of positive pleiotropic effect was exhibited by all phenolic constituents except scopoletin where negative correlations were prevalent. Breeding procedure and choice of parents are discussed in manipulating pheolics.Key words: quantitative genetics, tobacco, Nicotiana, phenolics.