Polymer‐Coated Urea Application Could Produce More Grain Yield in “Super” Rice

Core Ideas Polymer‐coated urea could increase both grain yield and nitrogen use efficiency in rice production, particularly in super rice.Larger sink size, more productive tillers and deeper root distribution are important agronomic performances in super rice.Higher plant activities are important physiological traits in super rice. Extensive economic reforms have resulted in a significant decrease in the involvement of rural labor force in rice (Oryza sativa L.) production in China. One of the most effective ways in minimizing the use of labor in field management while maintaining or even increasing grain yield is by using polymer‐coated urea (PCU) instead of conventional urea (CU). This study investigated whether super rice (SR) cultivars could exhibit better yield performance and nitrogen use efficiency (NUE) under PCU application than non‐super rice (NSR) cultivars. Two representative SR cultivars and two representative NSR cultivars were field grown. Three treatments, no nitrogen application (0N), CU application, and PCU application, were conducted, the application N rate of CU and PCU were both 200 kg N ha−1. Compared to NSR cultivars, SR cultivars had larger sink size, more productive tillers, larger root biomass and deeper root distribution, higher root oxidation activity at mid‐ and late grain‐filling period, greater aboveground biomass production at mid‐ and late growth stages, and greater nonstructural carbohydrate (NSC) accumulation in the stem and more nonstructural carbohydrate per spikelet (NPS) at anthesis under PCU. Polymer‐coated urea increased grain yield and agronomic NUE by 11.6 and 5.5% in SR cultivars and 4.8 and 2.2% in NSR cultivars, respectively. We conclude that using PCU could increase both grain yield and NUE in rice production, especially in SR cultivars. Improved agronomic and physiological performance contributes to an increase in grain yield and NUE in SR cultivars under PCU.