Response of rainfed cotton (Gossypium hirsutum) to foliar application of potassium

Field studies were conducted (2002–03 to 2004–05) in Nagpur, Maharashtra under rainfed conditions to evaluate the response of upland cotton (Gossypium hirsutum L.) to foliar application of potassium (K). Treatments included a control (without K), soil application, soil application along with one foliar spray of K at either early boll or peak boll and two sprays at early and peak boll stages. Averaged across years, yield of the K applied plots were similar (0.97 to 1.07 tonne/ha) and were significantly greater than the control (0.81 tonne/ha). Yield differences were owing to more bolls in the K applied (40.8 to 53.3/m²) than control plots (33.6/m²). Year x treatment interaction was highly significant. In 2002–03 and 2004–05, rainfall was lesser than average and the K applied plots had significantly greater seed cotton yield (0.84 to 1.30 tonne/ha) than the control (0.71 to 0.75 tonne/ha). In 2004–05, treatment with 2 foliar sprays produced 392 kg/ha more seed cotton than soil application and was significantly superior to 1 spray. Total K uptake was greater in the K applied plots (61.3 to 68.8 kg/ha) than the control (39.1 kg/ha). Regardless of treatments, K balance (input - uptake) was negative (−37.1 to -43.8 kg/ha). In general, K application did not impact fibre quality. It was found that K application may be advantageous in years with low rainfall.