An investigation of gene action on different traits of tobacco under irrigated and drought stress environment
A diallel cross involving five Virginian tobacco genotypes were evaluated to determine the genetic behavior of tobacco genotypes across the environments. The experimental material was planted under irrigated as well as drought stress conditions. The data collected on yield and related traits revealed highly significant differences among genotypes under both sowing conditions. Graphical analysis showed that additive action of genes for dry leaf yield and leaf area index under irrigated conditions changed to over dominance under drought. However, it was also found that gene action for length of leaf, width of leaf and number of leaves remained the same over the environments. It was also observed that parental genotypes shifted their positions in the graphs from recessive to dominant or the midway or vice versa, showing different genetic constitution for the same trait in response to environmental change. Genotypes displaying similar constitution under both sowing conditions showed that they contain stable genes expression for those particular characters and may prove useful in future breeding strategies.
Key words: Diallel, drought stress, environment, genetic action, tobacco.