PHENOTYPIC ASSOCIATIONS, REGRESSION COEFFICIENTS AND HERITABILITY ESTIMATES FOR QUANTITATIVE AND FIBER QUALITY TRAITS IN UPLAND COTTON GENOTYPES
A field trial was carried out at the experimental area of the Department of Plant Breeding and Genetics, Sindh Agriculture University Tandojam during 2014, to determine the correlations, regression and heritability estimates for quantitative and fiber quality traits in upland cotton genotypes. The experiment was laid out in RCBD (Randomized Complete Block Design) with four replications. The material was consisted of eight varieties viz. CRIS-134, AA-802, Neelum-121, CIM-598, MNH-886, FH-113, BT-142 and CRIS-342. The observations were recorded on eight plant traits. The ANOVA revealed that there is a significant difference for all the traits except for seed index. Based on mean performance, variety CRIS-342 produced desirable medium taller plants, ginned maximum lint%, formed more sympodia plant-1, set higher bolls plant-1, measured longer fiber and produced higher yield plant-1, yet next good performing genotype was FH-113. However, bigger bolls were weighed by Neelum-121. The phenotypic correlations and regression results revealed significantly positive associations of sympodial branches plant-1 with number of bolls plant-1 (r=0.931**) and the r2 revealed that approximately 86.67% of variability in bolls plant-1 was attributable to its relationship with sympodia plant-1. The number of bolls plant-1 revealed positive association with yield (r=0.985**) and the r2 revealed that 97.02% of variation in seed-cotton yield was attributable to its correlation with bolls plant-1. On the contrary, number of bolls plant-1 demonstrated highly significant but negative correlation with boll weight (r=-0.803**), yet r2 suggested that 64.48% of variability in boll weight occurred owing to its relationship with bolls plant-1. The present findings suggested that raising bolls plant-1 caused a significant decrease in boll weight. Results generally pointed out that sympodial branches plant-1, bolls plant-1 and lint% were considered to obtain higher seed-cotton yield. Higher heritability estimates ranging from 36.69 to 99.50% revealed that most of the traits studied were under genetic control, most likely by additive genes, hence significant improvement can be expected through hybridization and selection from segregating populations.