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 tonnetha) and were significantly greater than the control (0.81 tonnetha). Yield differ- ences were owing to more bolls in the K applied (40.8 to 53.3/m2) than control plots (33.6/m2). Year x treatment in- teraction 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 tonnetha) than the control (0.71 to 0.75 tonnetha). In 2004-05, treatment with 2 foliar sprays produced 392 kgtha more seed cotton than soil application and was sig- nificantly superior to 1 spray. Total K uptake was greater in the K applied plots (61.3 to 68.8 kgtha) than the con- trol (39.1 kglha). Regardless of treatments, K balance (input - uptake) was negative (-37.1 to -43.8 kgtha). In gen- eral, K application did not impact fibre quality. It was found that K application may be advantageous in years with low rainfall.