Effects of nitrogen application on nitrogen use efficiency, grain yields and qualities of rice under different water regimes

Effects of nitrogen application on nitrogen use efficiency, yields and qualities of rice under different water regimes were studied using a rice cultivar, Liangyoupeijiu, in a field study. The cultivar was grown under traditional flooding (W1), alternate wetting and drying irrigation (W2), and raised-bed irrigation (W3) at four N rates (N 0-270 kg/hm2 in 90 kg increments, expressed as F0, F1, F2 and F3). Compare to W1, total nitrogen accumulation (TNA) and nitrogen recovery efficiency (NRE) under W2 and W3 are increased by 18.5%, 94.6％ and 22.1％, 62.4％, respectively, and rice yields are increased by 2.5％ and 9.1％. Compared to F1 fertilizer (N 90 kg/hm2) treatment, nitrogen agronomic efficiency (NAE) and nitrogen recovery efficiency(NRE) of the F2 (N 180 kg/hm2) treatment are increased by 73.9％ and 36.2％, and the average yield of F2 is increased by 48.9% than F0 treatment. The above results indicate there are significant effects of interaction between water and nitrogen on rice chalky percentage and protein content.