Effect of Potassium and Zinc on Growth, Yield, Quality Parameters and Nutrient Uptake by Bt Cotton

A field experiment was conducted during 2009-11 to 2011-12, on medium black calcareous soil (Typic Ustocrepts) with hybrid Bt cotton (NH 44) using seven levels of K₂O (0, 120, 150, and 180 kg ha^-1 and each in split application, 1/2 at basal and 1/2 at 45 DAS) and two levels of ZnSO₄ (0, and 50 kg ha^-1) at Cotton Research Station Junagadh Agricultural University, Junagadh. The results showed that the significantly higher average seed cotton (2313 kg ha^-1) and stalk (3208 kg ha^-1) yield were recorded with split application of potassium @150 kg ha^-1 (1/2 at basal and 1/2 at 30 DAS) and basal application of potassium @150 kg ha^-1, respectively. Whereas the significantly higher average seed cotton yield (2307 kg ha^-1) and stalk yield (3165 kg ha^-1) were recorded with application of ZnSO₄ @ 50 kg ha^-1. The interaction effect of K₁₈₀ × Zn₅₀ was also found significant on seed cotton yield (2496 kg ha^-1). The significantly higher values of bolls per plant (51.5), five boll weight (23.6g.), oil content (20.88 %), SFI (12.68), sympodial (12.07) and monopodial (2.75) branches per plant and plant height (108.5 cm) were observed with the basal application of potassium @ 150 kg ha^-1 (K₃). Maximum uptakes of K and Zn by seed cotton as well as stalk were recorded under application of 180 kg K₂O and 50 kg ZnSO₄ ha^-1, respectively.