Assessment of genetic variability, heritability and association of plant attributes with lint yield and fiber quality in advanced lines of cotton (Gossypium hirsutum L.)

Information on genetic variability and heritability of plant attributes and their correlation with lint yield and fiber quality is important for planning breeding and selection strategies for prediction of genetic gains in cotton breeding programs. For these purpose, a field experiment was carried out using randomized complete block design with four replications in 2016 and 2017 at Hashem-Abad cotton research station, Gorgan, Iran.  Variability and heritability and genetic improvement for sixteen quantitative and qualitative traits were evaluated in 40 cotton genotypes including; 31 recombinant inbred lines (F7) and nine parental genotypes.in. The analyisis of variance as well as phenotypic, genotypic and environmental variances revealed high variation among cotton genotypes.  Cotton genotpeswere grouped in three distinct classes using cluster analysis. In general, phenotypic coefficient of variation (PCV) estimates were higher than genotypic coefficients of variation (GCV) for all the studied attributes, implying the environment effect on the studied traits. The highest PCV and GCV were estimated for seed cotton yield, sympodial and monopodial branch numbers. High heritability and genetic improvement was observed in lint percentage (76.7% and 15.2%, respectively), boll number (72.6% and 23.5%, respectively), boll weight (67.9% and 19.7%, respectively) and sympodial number (56.8% and 79.3%, respectively), indicating the effect of additive gene action and favorable response of these traits to selection. Also, the above mentioned traits had significant positive correlation with seed cotton yield and reaffirmed to be the main cotton yield components. The results indicated that selection for boll number per plant, boll weight, lint percentage and sympodial branch number per plant are desirable selection indices for indirect selection for lint yield and fiber quality improvement of cotton at early generations.