Effect of soil and foliar application of nutrients on yield and nutrient concentration in BT cotton

The field experiments were conducted on Bt cotton hybrids (RCH 134 and RCH 317) at 18 locations in five districts of Punjab namely Mansa (5), Bathinda (5), Mukatsar (2), Faridkot (4) and Moga (2) to determine their nutrient requirements. Treatment consisted of recommended dose of nutrients along with additional nutrients applied as soil and foliar application. When the soils were grouped into low, medium and high category with respect to available potassium, it was observed that cotton responded to soil application of potassium (60 kg K₂O ha⁻¹) on soils testing low and medium in available potassium and no response to soil application was observed on soils testing high in available potassium. The benefit cost (BC) ratio of soil applied potassium was 5.2:1.0. The foliar application of potassium nitrate increased the yield of seed cotton irrespective of the soil status and soil applied potassic fertilizers. On an average, the benefit cost (BC) ratio of about 10.5:1.0 was obtained with the foliar application of potassium nitrate. The soil as well as foliar applied nutrients had significant effect on the number of sympodial branches and bolls weight. On an average, N, P and K content in cotton leaves varied from 0.88 to 1.45%, 0.23 to 0.43% and 0.91 to 1.28%, respectively, under different treatments.