Abstract
Responses of 80 genotypes/lines of Gossypium hirsutum were examined at seedling stage under water stressed and non-stressed conditions in glasshouse. Plant growth was measured as longest root and shoot after 45 days. Genotypic differences for indices of drought tolerance were statistically significant. Based upon the differences and similarities, four tolerant i.e., 149F, B-557, DPL-26, BOU 1724-3 and 4 susceptible namely FH-1000, NF-801-2, CIM-446 and H-499 genotypes/lines were crossed in all possible combinations. The responses of 64 families were examined under water stress and non-stressed (control) conditions at seedling stage. Seedlings were allowed to grow for 45 days. Root lengths of all the families were measured under the two conditions. indices of drought tolerance (relative root length) were analyzed following Hayman-Jinks approach. Regression coefficient (b=1.0 +/- 0.15) and analysis of variance of (W-r+V-r) and (W-r-V-r) provided no evidence of the presence of epistasis and the genetic model was found fully adequate for analyzing the data. The results revealed that both additive and non-additive genes affected variation for drought tolerance, but the influence of additive gene was more pronounced. High estimates of h(ns)(2), 0.82 and mode of gene action suggest that it is possible to improve drought tolerance in G. hirsuitum by single plant selection in later segregating generations. (C) 2011 Friends Science Publishers