Advance of rice fertilizer-nitrogen use efficiency

Fertilizers can become a source of pollution when they are used in excess. Reducing application rate of fertilizer-nitrogen use and increasing efficiency of fertilizer-nitrogen use for irrigate rice is an important task for the agricultural scientists. In this paper, research advances on relationship between efficiency of fertilizer-nitrogen use and the application method of fertilizer-nitrogen use, rice genotype differences, root growth, matter accumulation, physiological metabolism, plant characteristics were reviewed. Rice variety with stronger root system was in favor of raising the absorptive capacity of soil nitrogen; Stronger tillering ability, higher grain-leaf ratio at full heading stage, dry matter accumulation after heading stage, seed-setting rate, grain weight, yield and harvest index of cultivars resulted in higher nitrogen use efficiency. Its physiology characteristics were characterized by higher activities of nitrate reductase, glutamate synthase and the activity of RuBP carboxylase. Ways of increasing fertilizer-nitrogen use efficiency (i.e. balancing between N and P, K, improving method of fertilizer-nitrogen and water management, and applying accurately fertilizer-nitrogen), were also discussed. At last, research hotspots regarding N losses reduction and N use efficiency enhancement were put forward.