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Equal potassium-nitrogen ratio regulated the nitrogen metabolism and yield of high-density late-planted cotton (Gossypium hirsutum L.) in Yangtze River valley of China

Ali, Saif, Hafeez, Abdul, Ma, Xiaolei, Tung, Shahbaz Atta, Chattha, Muhammad Sohaib, Shah, Adnan Noor, Luo, Dan, Ahmad, Shoaib, Liu, Jiahao, Yang, Guozheng
Industrial crops and products 2019 v.129 pp. 231-241
Gossypium hirsutum, alanine transaminase, biochemical pathways, chlorophyll, cotton, fertilizer application, free amino acids, glutamate-ammonia ligase, leaf area, leaves, lint yield, nitrate nitrogen, nitrate reductase, nitrite reductase, nitrogen, nitrogen metabolism, potassium, potassium fertilizers, protein content, river valleys, China, Yangtze River
Potassium (K) plays a pivotal role in physiological and biochemical processes and is indispensable for efficient production of cotton. The optimal K fertilization ratio relative to reduced nitrogen (N) rate for efficient N metabolism and yield formation in late planted high-density cotton remain to be understood. In the field, three K ratios relative to N [K1 (K2O: N = 0.8: 1), K2 (K2O: N = 1: 1), and K3 (K2O: N = 1.2: 1)] were applied in a randomized complete block design, in 2016 and 2017. Results revealed that increasing the K fertilization ratio exerted a significant effect on leaf area, fresh and dry weight of functional leaf, chlorophyll content, and N metabolism, as well as yield and yield indices in both cropping years. Higher lint yield was obtained with the application of K2 and K3 rather than K1. Similarly, K2 and K3 treatments evidently improved the activity of N metabolizing enzymes such as NR (nitrate reductase), NiR (nitrite reductase), GS (glutamine synthetase), GOGAT (glutamate synthase), GPT (glutamic-pyruvic transaminase), and GOT (glutamic oxaloacetic transaminase). Moreover, leaf nitrogen, nitrate-N, free amino acids, and soluble protein contents were efficiently balanced in K2 and K3 treatments over K1. The findings of this study suggest that the application of K ratio must be equivalent to N to achieve an acceptable yield and profitable return in late-planted high-density cotton.