水稻氮肥精确后移及其机理

以早熟晚粳品种武运粳7号、武香粳14、常优1号为供试材料，通过搁田后一次性追肥试验来精确确定高产高效的氮肥后移施用叶龄期；在此基础之上，对氮肥精确后移施用模式进行了研究，并探讨了其高产高效机理。结果表明: (1)倒四、倒三叶是早熟晚粳稻最利于高产高效的追肥叶龄期。从产量构成因素看，倒四、倒三叶追肥群体穗数足、穗型大，群体颖花量高，且结实率与千粒重均可稳定在正常水平；从群体生长发育来看，倒四、倒三叶追肥群体茎蘖消长平缓，高峰苗适中，成穗率高(80%左右)，生育中、后期氮肥累积量大，适宜叶面积指数高，群体光合势强，干物质积累多，最终产量高，氮素当季利用率亦高。(2)较之常规施氮模式，氮肥精确后移模式产量显著高，氮素当季利用率、生理利用率、施氮增产力以及表观生产力均显著高，百公斤籽粒需氮量则略低，在大面积生产上应用表现显著增产增效。其高产高效机理为，既能巩固穗数，又能有效控制无效(低效)分蘖，获取高成穗率，形成足量的群体有效穗数；既能攻取大穗，又能防止群体叶面积过度增长，于生育中期形成较高且适宜的叶面积指数与配置良好的冠层结构，具有较高粒叶比，使抽穗期群体干物质数量足且质量优；既能提高抽穗后群体干物质积累量，又能协调群体茎鞘物质输出与运转，以强源畅流促进群体库容的有效充实。

Precise Postponing Nitrogen Application and Its Mechanism in Rice

Leaf ages of nitrogen application for high yield and apparent nitrogen recovery efficiency were specified through applying nitrogen fertilizer once in middle stage of growth and development using early-maturing and late japonica rice-Wuyunjing 7, Wuxiangjing 14, Changyou 1 as materials. Based on this, we studied precise postponing nitrogen application and its mechanism. Results showed that leaf ages of nitrogen application to high yield and apparent nitrogen recovery efficiency were 3rd leaf and fourth leaf...