Effects of Nitrogen Amount on Yield and Nutrient Absorption of Cold Land Japonica Rice under the Condition of Straw Returning

Effects of nitrogen amount on yield and nutrient absorption of cold land japonica rice under the condition of straw returning were studied using cold land rice variety Dong Nong 428 as experimental material. The results showed that: with the improvement of nitrogen amount, the plant dry matter accumulation of tillering stage, heading stage, grain filling stage and maturity stage all took on obvious increasing trend. The yield and effective spikes increased first then reduced, the highest yield and effective panicles per plant was 7983.33 kg·hm-2and 17.7 per plant, in treatment with nitrogen amount of 133 kg·hm2, Differences of plant N, P and K accumulation of each treatment in tillering stage were not obvious and showed single peak curve change in heading stage and obvious increasing trend in grain filling stage and maturity stage. The straw returning increased effective spikes, but had no effects on yield, spike weight, total shriveled rate and 1000-grain weight. The straw returning also had no effects on N, P and K accumulation in tillering and heading stage, and could inhibit N, P and K accumulation in grain filling stage.