以丰优998和培杂77为材料，在盆栽条件下，在抽穗后进行遮光处理，研究施氮量、光照对水稻干物质积累量和产量的影响，探讨水稻抽穗后光氮互作的定量关系。结果表明，以处理期间的日均辐射量作为光照强度指标，在一定光照强度条件下，干物质积累量和产量与施氮量呈抛物线关系；在一定施氮水平下，干物质积累量和产量随着光照强度的提高而直线增加；水稻干物质积累量和产量由施氮量（X1）和光照辐射量（X2）共同决定，其定量关系可用Y=a0+a1X12+a2X1X2表示；根据这一定量关系，可求得最适施氮量（Nopt）与光照辐射量（X2）的定量关系为Nopt = b0+b1X2，表明在本试验条件下，最适施氮量随处理期间光照日均辐射量的增加而直线增加。

Pot culture experiments were conducted using two hybrid rice varieties with the method of shading to control the light intensity after heading. The effects of light intensity and nitrogen application and their interactive effect on the biomass production and grain yield of rice were investigated to explore the quantitative relation of interactive effect of post-anthesis light and nitrogen on rice. The result indicated that the effects of light intensity （X2, KJ/m2/d） and N application （X1,g/kg soil） on rice biomass and grain yield were mathematically represented by the following equation: Y=a0+a1X12+a2X1X2. A quadratic multinomial equation could be used to describe the correlation between N application and rice biomass. Moreover, a linear model could be used to describe the correlation between light intensity and biomass. The optimum N rate could be estimated by the light intensity after heading: Nopt = b0+b1X2. The optimum of N fertilizer was influenced lineally by light intensity or the average solar radiation per day during the treatment period, under the study condition.