密度和追肥时期对重穗型高产冬小麦的群体发展 ,冠层辐射和光合特性有明显的调节效应。随着密度增加 ,开花前的叶面积指数 (L AI)、群体净光合速率 (NCP)、群体叶源量 (CL SC)提高 ,但生育后期衰减较快 ;密度过高导致群体透光率下降 ,消光系数增加 ,单茎受光量降低 ,冠层光环境恶化 ,后期旗叶的羧化效率降低 ;密度过低则导致生育前期漏光损失较多。在采取适宜密度的基础上 ,推迟追肥时期 ,可改善小麦生育后期群体的光环境和光合特性 ,有效地协调重穗型小麦的源库关系 ,提高籽粒产量和光能利用率 Density and top dressing period had significant regulation effects on population development, canopy radiation and photosynthetic characteristics of heavy-ear type and high-yield winter wheat. With increasing density, leaf area index (L AI), net photosynthetic rate (NCP) and CL SC increased before flowering, but decayed quickly during late growth stage. , The extinction coefficient increased, the light intensity of single stem decreased, the light environment of canopy deteriorated, and the carboxylation efficiency of flag leaf decreased in the late stage. The low density led to more light leakage loss in pre-birth stage. On the basis of appropriate density, postponing the top-dressing period can improve the light environment and photosynthetic characteristics of wheat at the later growth stage, effectively coordinate the relationship between source and sink of the heavy-panicle type wheat, and improve the grain yield and light energy utilization rate