Identification of Traits Associated with Drought Tolerance in Cotton (Gossypium hirsutum L.)

The cotton genotypes viz; NDLH-1935, NDLH-1943, NDLH-1949, NDLH-1976, NDLH-1979, NDLH-2019, Sivanandi and NDLH-2005-4 recorded comparatively higher mean values for primary root length, shoot length, shoot dry weight, root dry weight, relative water content and root/shoot ratio both under controlled and moisture-stress conditions out of 30 genotypes studied under greenhouse conditions at seedling stage during kharif, 2022-23 at RARS, Nandyal. Low to moderate range of phenotypic coefficients variability (9.54 to 25.22 and 14.16 to 24.67), higher heritability (93.00 to 98.30 and 96.30 to 99.80) coupled with higher genetic advance over mean (18.29 to 51.07 and 28.22 to 50.31) registered under controlled and moisture-stress conditions, respectively revealed the importance of additive gene action for all the characters studied. Primary root length had positive and significant phenotypic and genotypic associations with shoot length (0.3105** and 0.3211**), root dry weight (0.3294** and 0.3332**) and root/ shoot ratio (0.3688 **and 0.3753**) under controlled conditions while the same character showed either non significant or significant negative correlations (0.0355 and 0.0342, -0.0830 and -0.0702 and 0.2126** and-0.2230**) under moisture stress conditions. Shoot length showed non significant associations with all the characters studied under both the conditions. The phenotypic associations between shoot dry weight and root dry weight (0.7168** and 0.5431**) and root dry weight with root/ shoot ratio (0.8115** and 0.5515**) were significant and positive association at phenotypic level under controlled and moisture-stress conditions, respectively. Relative water content had non significant associations whereas root/ shoot ratio showed positive and significant associations with primary root length and non significant associations with all other characters under both the conditions. Based on mean values, heritability and genetic advance for primary root length, shoot dry weight, root dry weight and root/shoot ratio under both controlled and moisture stress conditions, the above characters may be considered as important parameters while selecting genotypes for improving drought tolerance ability in upland cotton.