Effect of benzyl amino purine and gibberallic acid on yield and fiber quality of cotton

The effect of foliar application of two plant growth regulators (PGRs) viz. benzyl amino purine (BAP) and gibberallic acid (GA₃) was studied on yield components and fiber quality of two cultivars, LH 1556 and LHH 144, of Gossypium hirsutum and one cultivar LD 694 of G. arboreum. Foliar application of BAP (50 mg 1⁻¹)was given at 65 days after sowing (DAS) and GA₃ (50 mg 1⁻¹)at 85 and 105 DAS. In combined application, BAP was applied at 65 or 85 DAS and GA₃ at 85 DAS. Foliar application of BAP and GA₃, individually as well as in combination, had significant positive effect on leaf production. BAP application resulted into increased total leaf area in LH 1556 and LD 694 and improved boll retention in the three cultivars. In sets treated with BAP, more boll setting was recorded as compared to untreated control. Heavier bolls were produced when BAP was applied at vegetative stage and GA₃ was applied at anthesis stage. Fiber quality parameters were also significantly affected by application of growth hormones. BAP increased span length in the three genotypes but GA₃ had no marked effect. Coarseness of fibers was increased in GA₃ treated plots of LD 694 but it increased to lesser extent in LH 1556. BAP application increased bundle strength whereas response of GA₃ application was variable.