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A study was carried out at Cotton Research Institute, AARI, Faisalabad Pakistan during the year 2013 to determine the cause and effect of some morphological traits viz. number of leaves per plant, number of sympodial branches per plant, number of bolls per plant and plant height on seed yield per plant in upland cotton. Seventy two cotton genotypes at F5 generation were sown in a RCBD with three replications. The results indicated that number of leaves (0.2334), sympodial branches (0.4859) and number of bolls per plant (0.3722) had exerted positive and significant to highly significant correlation at genotypic level with seed cotton yield per plant. The data also revealed that number of leaves showed positive and highly significant correlation with sympodial branches (0.3427"") plant height (0.6924"") and bolls per plant (0.4238""). Number of leaves, bolls per plant and sympodial branches showed positive direct effect on seed-cotton yield per plant. Direct effect of sympodial branches on cotton yield was very high and positive. However, number of leaves showed positive indirect effect via sympodial branches, bolls per plant and plant height. Similarly sympodial branches had shown positive indirect effect on seed yield per plant via number of leaves and bolls per plant. Direct effect of number of leaves on seed-cotton yield per plant was low while indirect effect via number of bolls per plant was positive. The number of bolls per plant also showed positive indirect effect via number of leaves, sympodial branches and plant height but effect of plant height on cotton yield was negative via number of bolls and sympodial branches. The results conclude that sympodial branches per plant influenced the cotton yield per plant to greater extent. Hence selection based on this trait may lead to development of genotypes having high seed cotton yield potential. [ABSTRACT FROM AUTHOR]

Upland cotton is the most economically important fibre crop. The human-mediated selection has resulted in modern upland cultivars with higher yield and better fibre quality. However, changes in genome structure resulted from human-mediated selection are poorly understood. Comparative population genomics offers us tools to dissect the genetic history of domestication and helps to understand the genome-wide effects of human-mediated selection. Hereby, we report a comprehensive assessment of Gossypium hirsutum landraces, obsolete cultivars and modern cultivars based on high throughput genome-wide sequencing of the core set of genotypes. As a result of the genome-wide scan, we identified 93 differential regions and 311 selection sweeps associated with domestication and improvement. Furthermore, we performed genome-wide association studies to identify traits associated with the differential regions and selection sweeps. Our study provides a genetic basis to understand the domestication process in Chinese cotton cultivars. It also provides a comprehensive insight into changes in genome structure due to selection and improvement during the last century. We also identified multiple genome-wide associations (GWAS associations) for fibre yield, quality and other morphological characteristics. [ABSTRACT FROM AUTHOR]

Genetic potential of 20 cotton (Gossypium hirsutum L.) varieties was evaluated against different levels of salinity stress under green house conditions in the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad during 2011-12. Plants were grown in polythene bags in CRD with three replications. Four NaCl concentrations (0, 100, 150 and 200 mM) were applied to the genotypes after one week of emergence of seedlings. Data on root length, shoot length, root fresh weight, shoot fresh weight, root dry weight, shoot dry weight and fresh seedling weight were recorded. The results clearly indicated varying growth potential of seedlings of all varieties under low and high saline conditions. Based upon absolute data, varieties NIAB-78, MNH-554, and CIM-448 proved to be more tolerant than MS-94, RH-112 and MNH-147. Estimates of broad sense heritability appeared to be high under low and high salinity suggesting that salinity tolerance in cotton genetically controlled. Superiority in salt tolerance of NIAB-78, MNH-554 and CIM-448 may be attributed to low uptake of Na+ and greater K+/Na+ ratio. [ABSTRACT FROM AUTHOR]