DISPARITY IN GROWTH, YIELD AND FIBER QUALITY OF COTTON GENOTYPES GROWN UNDER DEFICIENT AND ADEQUATE LEVELS OF BORON
Balanced boron (B) supply is essential for growth, yield and fiber quality of cotton crop. The wide disparity in genotypic response and narrow range between B deficient and toxic levels in soil makes it difficult to achieve the quality cotton production. A field study was conducted during Kharif season 2013 to compare ten cotton genotypes of Pakistan for their production and quality traits by growing under B deficient and B adequate conditions. Treatments for B rates i.e. B deficient (control) and B adequate (2.0 kg B ha-1) were applied in main plots and ten cotton genotypes were grown in sub-plots arranged in split plot design with three repetitions. Boron application produced variable effects on growth, yield and fiber quality of cotton genotypes, but the degree of effects was varied from genotype to genotype. Adequate application of B significantly enhanced plant height (8.4%), sympodia per plant (6.4%), bolls per plant (10.0%), boll weight (8.6%), seed-cotton yield (18.7%), leaf B content (14.1%), lint production (5.2%) and reduced the microniare value by 7.1% of all genotypes. Cotton genotypes significantly varied among each other in all the growth, yield and quality traits, except fiber length under both B regimes. Genotype CIM-589 produced the maximum bolls per plant, the highest seed-cotton yield per plant and retained the highest B in its leaves under both B conditions. The best fiber quality was produced by IR-NIBGE 1524 with longest fibers under B deficiency condition. Our findings confirm that the adequate level of B nutrition had pronounced effects on various growth and yield associated traits as compared to fiber quality traits of cotton genotypes.