Optimizing Potassium Application Timing and Rates for Enhanced Cotton (Gossypium hirsutum L.) Productivity in a Wheat-Cotton Cropping System, Punjab, Pakistan

Abstract

Cotton (Gossypium hirsutum L.) is an important cash crop in Pakistan, yet its yield is constrained by a range of biotic and abiotic stress factors. Imbalanced fertilizer use is a key abiotic factor reducing yield, while potassium (K) is an essential macronutrient that regulates photosynthesis, water balance, fiber quality, and boll development. To assess the effect of K management, a two-year field study was carried out during the Kharif seasons of 2020 and 2021 using a randomized complete block design with three replications. Four treatments were tested: T1, 93.75 kg ha⁻¹ in two splits (½ at sowing + ½ at flowering); T2, 93.75 kg ha⁻¹ in three splits (⅓ at sowing + ⅓ at flowering + ⅓ at boll formation); T3, 125 kg ha⁻¹ in two splits (½ at sowing + ½ at flowering); and T4, 125 kg ha⁻¹ in three splits (⅓ at sowing + ⅓ at flowering + ⅓ at boll formation). Results showed that T4 significantly improved yield and yield components, recording seed cotton yield of 2,431 kg ha⁻¹, 22.8 bolls plant⁻¹, and boll weight of 3.15 g. Treatment T3 performed similarly, producing 2,367 kg ha⁻¹ yield, 21.2 bolls plant⁻¹, and 2.86 g boll weight. The lowest performance was noted in T1, with yield (2,132 kg ha⁻¹), 19.2 bolls plant⁻¹, and 2.58 g boll weight. The study concludes that applying 125 kg K ha⁻¹ in three splits at sowing, flowering, and boll formation is the most effective strategy to enhance cotton productivity.