以粳稻品种武香粳9和籼稻品种H97-322为材料，在基础地力和穗肥施氮相同的条件下，研究了氮素基、蘖肥不同施用水平对水稻氮素吸收利用的影响。结果表明：（1）各处理水稻相对吸氮速率随生育进程而降低，其降低速度随氮素基、蘖肥占总施氮量比重增大而加快。增施氮素基、蘖肥，增加了拔节前吸氮量，但抑制了拔节后吸氮，尤其是显著增加了有效分蘖临界叶龄期至拔节期阶段吸氮量，显著降低了抽穗期至成熟期阶段吸氮量；增施氮素基、蘖肥，虽然有利于拔节前氮素基、蘖肥利用率的提高，但不利于整个生育期的氮素基、蘖肥利用率和总氮肥利用率的提高。（2）氮素基、蘖肥用量适宜，相对吸氮速率平稳减小，各生育阶段吸氮比例协调，氮素利用率和产谷效率协同提高是高产的重要条件。研究还表明目前一般的氮素基、蘖肥用量存在偏高现象。

以5种水稻控蘖剂为供试材料，研究结果表明：5种控蘖剂均能有效抑制水稻分蘖发生，其中控蘖剂B抑蘖能力最强；施药时期影响控蘖剂的抑蘖效果，施药越早抑蘖效果越强；控蘖剂靶标蘖位与施药时叶龄关系密切，主茎5叶期施药，受抑制蘖位主要为Ⅳ和，主茎Ⅴ叶期施药，受抑制蘖位主要为Ⅶ和Ⅷ；无效分蘖期喷施控蘖剂能减少大田无效分蘖的发生，降低群体的高峰苗数，增加氮素吸收量，提高氮素利用效率、茎蘖成穗率和产量。

采用去穗与疏花方式调节库大小，研究了对水稻不同叶位叶片氮代谢的影响。去穗或疏花后，已完成发育的源叶片，尤其是顶4叶，蛋白质合成重新旺盛，蛋白氮含量提高，出现了类似于生长库的氮代谢特征。水稻叶片的酸性转化酶活力可反映其蛋白质合成能力，据此可判断叶片是属于氮素供应源还是氮素接受库。研究证实下位叶的氮代谢对植株缺氮的反应比上位叶敏感，顶4叶酸性转化酶活力低是植株从土壤中吸收的氮素不能满足生长库氮需求的一种指示。

以迟熟中粳稻武香粳9号为材料，研究了基本苗和施氮量对水稻氮素吸收与利用的影响。结果表明，施氮量增加，水稻吸氮量增多，但营养器官的氮转运率、氮收获指数和产各效率显著下降；基本苗增加，水稻吸氮量也增多，而营养器官的氮转运率、氮收获指数、氮素产谷效率和氮肥利用率则明显提高。因此，适当增加基本苗是提高水稻氮素利用效率、减少施氮量的有效方法。研究还发现，在8.5t•hm-2以上的高产条件下，100kg稻谷需氮量和氮肥利用率基本稳定，每生产100kg稻谷需氮量约为2.1kg，氮肥利用率在42%左右。

Proteins and carbohydrates in developing rice panicles were analyzed to see whether these parameters control spikelet number in rice. Two rice cultivars and 2 levels of nitrogen topdressing were used to obtain panicles with different numbers of spikelets. A japonica rice cultivar, Nipponbare, with topdressing (H) had 1.8 times more spikelets per panicle than that without topdressing (L). Moreover, the number of spikelets per panicle in an indica rice cultivar, Takanari, without topdressing was 2.7 times larger than that in Nipponbare-L. Panicles with more spikelets (LP) in Nipponbare-H and Takanari-L showed slower growth than those with few spikelets (SP) in Nippanbare-L in an early stage. LP, however, increased markedly in size thereafter, eventually exceeding SP, in length and fresh weight. Soluble protein content was higher in LP than SP in an early stage, but this difference was hardly detected in a late stage. No clear difference was observed in sugars or starch between LP and SP. Analysis of soluble and insoluble proteins by SDS-polyacrylamide gel electrophoresis showed that bands corresponding to insoluble proteins with a molecular weight about 42 kDa were present at higher intensities in LP than in SP. These results suggest that the spikelet number in rice is controlled by the soluble protein content in an early stage and insoluble proteins with a molecular weight of 42 kDa during panicle development, but not by the carbohydrates in developing panicles.