基蘖肥与穗肥氮比例对双季稻产量和碳氮比的影响

试验研究了基蘖肥与穗肥氮比例对双季早、晚稻产量,干物质积累量,氮素积累量和碳氮比的影响。结果表明，当总施氮量为N 225 kg/hm2时，基蘖肥与穗肥氮比例7∶3处理的产量最高，其次为6∶4、8∶2处理，均比当地习惯施肥法（10∶0）高产。同时，当基蘖肥占总施氮量60%70%时，双季早、晚稻具有较高的干物质积累量、氮素积累量、氮素当季利用率、氮素农艺效率，群体的碳氮代谢也比较协调。早稻孕穗期叶片可用性糖（可溶性总糖＋淀粉）含量17%18%，碳氮比5055，晚稻孕穗期叶片可用性糖含量19%21%，碳氮比5060，这可能是基蘖肥与穗肥氮比例为7∶3和6∶4时双季水稻高产的生理基础。综合双季早、晚稻产量、氮素利用率及碳氮比值，穗肥施氮量占总施氮量的适宜比例为30%-40%。

Effects of nitrogen application on yield and C/N of double-cropping rice

The experiment was conducted to study effects of different ratios of basic and tillering, and panicle nitrogen fertilization on yield, dry matter accumulation, nitrogen accumulation and the ratio of carbon and nitrogen of double cropping rice. The results show that when the total nitrogen rate is N 225 kg/ha, the yield is the highest under the treatment which the ratio of basic and tillering nitrogen amount to panicle nitrogen amount is about 7∶3, the followings are the treatments of ratios of 6∶4 and 8∶2, which are all higher than that of the conventional nitrogen application pattern (10∶0). When the ratio of basic and tillering nitrogen application to total nitrogen application amount is from 60% to 70% of double cropping rice, the dry matter accumulation, nitrogen accumulation, nitrogen utilization efficiency, N-agronomy efficiency are all increased under the ratio of 7∶3, the carbon metabolism and nitrogen metabolism are also in a good coordination. The usable carbohydrate including soluble sugars and starch of early rice leaf at booting stage is 17%-18%, C/N is 50-55, and the usable carbohydrate of late rice is 19%-21% and C/N is 50-60These would be the physiological base of getting higher rice yield when the ratios are 7∶3 and 6∶4In all, synthesizing the yield, nitrogen utilization efficiency and C/N of double cropping rice, the ratio of nitrogen application at the panicle stage of rice to total nitrogen application amount is from 30% to 40%.