低温后追氮对寒地水稻产量及氮效率的影响

采用小区试验,水稻返青后冷水处理7 d,研究水稻前期低温后追氮对水稻生长、干物质与养分积累、产量及氮效率影响。结果表明,低温抑制水稻分蘖,水稻生育期延迟约3 d,降低水稻有效穗数、干物质积累、氮积累量及产量。低温后施氮促进分蘖恢复并对生育期影响较小,但过量施氮反而延长生育期约6 d。施氮促进水稻产量恢复,追施40 kg N·hm~(-2)即可使水稻产量恢复至常温水平,大穗型品种主要增加穗粒数与结实率,穗数型品种主要是穗数恢复。追施80 kg N·hm~(-2)产量达到常温水平,但PFP显著降低。低温后施氮2周对干物质积累影响较小,施氮后5周干物重恢复速度增加,至成熟期增加供氮处理干物重已恢复至正常水平。低温后施氮促进水稻氮代谢,增加氮积累量与硝酸还原酶活性。综上所述,低温后适量施氮可促进水稻生长及产量恢复,此试验条件下追施40 kg N·hm~(-2)即可,追施氮量过高导致生育期延期,降低氮效率。

Effect of nitrogen application after low temperature on rice yield and nitrogen use efficiency in cold area

A plot experiment was conducted to investigate the effects of different nitrogen levels on rice growth,dry matter and nutrient accumulation,yield and nitrogen use efficiency after cold water treatment for 7 d after tuming green.The results showed that low temperature suppressed rice tillering,delayed the growth period of rice by about 3 d and decreased the number of effective panicles,dry matter and nitrogen accumulation and rice yield.The application of nitrogen after low temperature promoted the recovery of tillering and had little impact on rice growth period.However,excessive nitrogen application delayed the growth period about 6 d.Results also showed that nitrogen application promoted the recovery of rice yield,and application of 40 kg N· hm-2 restored rice yield to normal temperature.For large-spike type rice variety,the application of nitrogen increased the number of panicles and 1000-grain weight.For quantitative spike type rice,the application of nitrogen facilitated the recovery of panicles.Although the application of 80 kg N·hm-2 recovered rice yield to normal temperature level,PFP was significantly reduced.The application of nitrogen had little impact on dry matter accumulation two weeks after fertilization.However,the dry matter recovered rapidly five weeks after the application of nitrogen and retumed to normal levels at the mature stage.The application of nitrogen after low temperature promoted nitrogen metabolism in rice,and increased nitrogen accumulation and nitrate reductase activity.In conclusion,applying proper amount of nitrogen after low temperature could promote the recovery of rice growth and yield,and 40 kg N· hm-2 was suitable for this experiment.While,excessive amount of nitrogen resulted in rice growth delay and reduced nitrogen use efficiency.