Application of Potassium along with Nitrogen under Varied Moisture Regimes Improves Performance and Nitrogen-Use Efficiency of High- and Low-Potassium Efficiency Cotton Cultivars
Muhammad Naeem Akhtar, Tanveer Ul Haq, Fiaz Ahmad, Muhammad Imran, Wazir Ahmed, Abdul Ghaffar, Muhammad Rafiq Shahid, Muhammad Hamzah Saleem, Huda Alshaya, Mohammad K. Okla, Shafaqat Ali
Abstract
Low nitrogen-use efficiency (NUE) is a serious issue for cotton production and environmental sustainability in arid climates. A pot study was conducted to evaluate the effect of K nutrition on NUE and performance of low- and high-K-efficiency cotton cultivars under two moisture regimes. Treatments included two soil moisture levels—i.e., normal irrigation, 100% available water content (AWC); reduced irrigation, 50% AWC—three levels of nitrogen (N)—i.e., 0, 375, and 750 mg N pot−1—and two K levels, i.e., 0 and 208 mg K pot−1. Results reveal that 208 mg K pot−1 application with nitrogen significantly enhanced the N-use efficiency, growth, and yield attributes of both cotton cultivars compared with sole N fertilization. Similarly, the combined application of NK @ 375 N + 208 K mg pot−1 caused up to 83% increase in NUE under AWC50% and AWC100%, as compared with NK control (0 N + 0 K). Compared with the control, imposed low-moisture stress caused a decrease of 13.9% in stomatal conductance (gs), 2.5% in transpiration rate (E), and 6.5% in net photosynthetic rate (PN), respectively. The physiological water use efficiency (PN/E) decreased by 13.2% under AWC50%. Applied NK @ 375 N:208 K, mg pot−1 caused 27.39 and 27.56% improvement in the PN/E in HKE and LKE cultivars under AWC50%, respectively. The HKE cultivar, i.e., CIM-554, maintained the highest gs and PN than FH-901, that was low-K-efficiency cultivar. The study suggests that varietal selection and adequate K fertilization have the prospects to improve NUE and save considerable quantities of fertilizer and irrigation water in cotton production under arid environments.