Effect of Different Levels of Nitrogen, Phosphorus and Potassium on Growth, Yield and Quality of Bt Cotton

A field experiment was conducted at Cotton Research Sub-Station, S. D. Agricultural University, Khedbhrahma (Gujarat) in randomized block design (factorial) during the kharif season of 2005-06. Three levels each of N (160, 200 and 240 kg ha^-1), P₂O₅ (0, 20 and 40 kg ha^-1) and K₂O (0, 40 and 80 kg ha^-1) were tried. Total 27 treatment combinations were replicated three times. The results indicated that Bt cotton crop fertilizing at 240 kg N ha^-1 significantly increased yield attributes viz., plant height, sympodial branches per plant, No. of bolls per plant, No. of seeds per boll and boll weight as well as seed cotton yield, quality and nutrient uptake. Fertilizing Bt cotton at 40 kg P₂O₅ kg ha^-1 numerically increased yield attributes and seed cotton yield of 2427 kg ha^-1 which was at par with 20 kg P₂O₅ ha^-1. An application of 80 kg K₂O ha^-1 significantly increased yield attributes viz., plan height, sympodial branches per plant, number of bolls per plant, boll weight and seed cotton and stalk yield. However, this level was at par with 40 kg K₂O ha^-1 in yield attributes, seed cotton and stalk yield. Application of 80 kg K₂O ha^-1 removed higher N (53.48 kg ha^-1) and K (50.46 kg ha^-1) which was statistically at par with 40 kg K₂O ha^-1. Among all treatment combination numerically highest seed cotton yield (2641 kg ha^-1) and maximum net realization of Rs. 38704 ha^-1 was recorded under treatment 240 kg N ha^-1 + 20 kg P₂O₅ kg ha^-1 + 40 kg K₂O ha^-1 (N₃P₁K₁). Thus, the results of present study indicated that potential production and profit from Bt cotton crop can be secured by fertilizing the crop with 240 kg N ha^-1, 20 kg P₂O₅ kg ha^-1, and 40 kg K₂O ha^-1 under irrigated condition.