增密减氮对东北水稻产量、氮肥利用效率及温室效应的影响

水稻生产正向资源节约和环境友好的方向转型，常规高产稻作技术亟待创新.本研究以粳稻辽星1号为试材，在2012、2013年研究密度增加、基蘖肥减少、穗肥稳定的“增密减氮”栽培模式对东北水稻产量和氮肥利用效率及温室效应的影响.结果表明： 与常规高产栽培模式相比，在基本苗增加33.3%和基蘖肥施氮量减少20.0%的条件下，氮肥农学效率和氮肥偏生产力两年平均分别提高49.6%(P<0.05)和20.4%(P<0.05)，单位面积和单位产量的温室效应两年平均分别下降9.9%和12.7%(P<0.05).虽然水稻有效穗数和总生物量下降，但结实率和收获指数提高，所以产量基本稳定甚至提高.增密减氮降低了土壤NH₄⁺-N和NO₃^--N浓度，提高了氮素回收效率.表明适度增密减氮可兼顾水稻高产、氮肥高效利用和温室气体减排.

Effects of increased planting density with reduced nitrogen fertilizer application on rice yield,N use efficiency and greenhouse gas emission in Northeast China.

The traditional rice growing practice has to change to save resource and protect environment, and it’s necessary to develop new technology in rice cultivation. Therefore, a two year field experiment of Japonica rice (Liaoxing 1) was conducted in Northeast China in 2012 and 2013 to investigate the integrated effects of dense planting with less basal nitrogen (N) and unchanged top dressing N (IR)on rice yield, N use efficiency (NUE)and greenhouse gas emissions. Compared with traditional practice (CK), we increased the rice seedling density by 33.3% and reduced the basal N rate by 20%. The results showed that the average N agronomy efficiency and partial factor productivity were improved by 49.6% (P<0.05)and 20.4% (P<0.05), respectively, while the area and yield scaled greenhouse gas emissions were reduced by 9.9% and 12.7% (P<0.05), respectively. Although IR cropping mode decreased panicle number and biomass production, it significantly enhanced rice seed setting rate and harvest index, resulting in an unchanged or even higher yield. NH₄⁺-N and NO₃^--N concentrations in rice rhizosphere soil were reduced, resulting in an increment of N recovery efficiency. Generally, proper dense planting with less basal N application could be a good approach for the trade off between rice yield, NUE and greenhouse gas emission.