Generation mean analysis of some Physiological Traits Contributing to heat Tolerance in Upland Cotton (Gossypium Hirsutum L.)

Various physiological parameters help out the plant to overcome the adverse effect of thermal stress. To understand the genetic base of these traits, the current study is a step ahead. The objective of this research was to estimate the gene actions that are responsible for survival of plant under heat stress condition. Six generations (P1, P2, F1, F2, BC1 and BC2) of three crosses were developed by crossing among six cotton genotypes and evaluated at the Central Cotton Research Institute, Multan Farm. The experiment was done in randomized complete blocks besign in three replications under normal and heat stress conditions. The mean of data of all six generations of three crosses were recorded keeping in view the support from literature. Additive, dominance and epistatic genetic effects were operating in controlling the phenotypic expressions of most of the traits contributing to heat stress tolerance. Heterobeltosis for relative water content was observed only in on cross under heat stress condition with the value of 1.39 while the excised leaf water loss did not showed. heterobeltosis under both conditions.