以杂交稻天优998为材料，设置稻草覆盖还田和无稻草还田2种处理和4种氮肥处理，并进行了连续2年的田间试验。稻草覆盖还田可以显著提高晚稻产量，4个施氮处理表现一致。在产量构成因素中，有效穗数对产量的贡献最大。稻草覆盖还田促进水稻分蘖，最高茎蘖数和分蘖成穗率协同提高，最终使有效穗数显著增加。稻草还田增强群体物质生产能力，叶面积指数和叶片叶绿素含量 （SPAD值）提高，最终提高了地上部干物质量。稻谷产量与不同时期的叶片叶绿素含量、地上部干物质量及茎蘖数呈极显著正相关。在稻草覆盖还田的情况下，增加前期施氮量对稻谷产量没有显著影响。

Two field experiments were conducted during late seasons of 2006-2007 at Baiyun Experimental Station of Guangdong Academy of Agricultural Sciences, Guangzhou, China. Tianyou 998, a hybrid rice, was arranged in split plot design experiments with straw mulching as main factor and N treatment as split factor with four replications. There were two levels of straw management and four N treatments. Straw mulching resulted in significant increase in grain yield at all N treatments. No significant differences were found in grain yield between three N treatments with the same total N input but different distribution among key growth stages. Path analysis showed that panicle number per m2 had the biggest direct effect on grain yield. Both maximum tiller number per m2 and productive tiller percentage were greater in straw mulching treatment compared to those in zerostraw mulching treatment. Straw mulching significantly improved dry matter production of rice plants. Leaf area index, chlorophyll content (SPAD value), and dry matter accumulation were significantly higher in straw mulching treatments at key growth stages. Grain yield was positively and significantly related with tiller number per plant, chlorophyll content of leaves, and dry matter production. Applying more N at early stage had no significant effect on grain yield, indicating that additional N at early stage was not necessary under straw mulching.