Abstract
Nitrogen and sulphur are fundamental macronutrients for the production of sunflower crop. Nitrogen is required consistently in larger amounts for sunflower production while common urea has more losses due to high solubility. On the other hand, sulphur application increases oil contents and availability of other essential nutrients (N, P, and K). Therefore, combined application of polymer coated urea with sulphur fertilization might be a promising option which can increase achene yield, oil contents, and nitrogen use efficiency (NUE). However, no particular studies have been conducted to explore the main and interactive effects of polymer coated urea and sulphur fertilization on growth, physiology, yield, oil contents, and NUE under arid field conditions. Hence, the current field experiment consisted of two nitrogen fertilizers [polymer coated urea (PCU) and common urea (CU)] and three sulphur fertilizer rates [S-0 (0), S-1 (30) and S-2 (60) kg ha(-1))] in a split-plot arrangement under randomized complete block design (RCBD) during spring season of 2019 and 2020. Experimental results revealed that growth, physiology, yield, oil contents, and NUE of sunflower crop were significantly improved with the application of nitrogen fertilizers, sulphur fertilizer rates, and their interaction. Meanwhile, NUE, achene yield and oil contents were increased by 16.0-17.2%, 16.5-17.0%, and 2.96-3.19% respectively with the application of PCU compared with CU. Furthermore, NUE, achene yield and oil contents were also increased by 12.8-13.3%, 13.1-13.7%, and 10.7-10.9%, respectively, due to sulphur fertilization of 60 kg ha(-1) compared with no sulphur application. Similarly, NUE, achene yield, and oil contents were increased by 32.9-39.5%, 31.7-32.6%, and 13.1-13.2% respectively with the application of PCU in combination with sulphur fertilization of 60 kg ha(-1)compared with CU x S-0,S- which also evidenced a clear and positive interaction between nitrogen and sulphur. Conclusively, PCU (130 kg ha(-1)) in combination with sulphur fertilization of 60 kg ha(-1) is promising option for obtaining higher achene yield, oil contents, and NUE for sunflower crop under arid environment, and hence, it might be a good agronomic adaptation strategy for sustainable production of sunflower.