Abstract: Two indexes,semi-extinction depth(D_s) and canopy light intensity(CLI) were introduced to analyze the effects of panicle type and row spacing on light distribution of rice canopy.Leaf angle was the main factor to determine light distribution at the booting stage.Generally,the smaller the leaf angle was,the better the light distributed.At the full-heading stage the light distribution was mainly attributed to the panicle.Curved panicle cultivars caused much shade so as to affect light distribution.Light distribution was also influenced by the panicle at the grain filling stage.For any cultivars,the more the row spacing was,the better the light distribution was throughout the growth period.At different stages,light distribution changed significantly for the same cultivar and row spacing.In general,light distributions at booting stage were better than those at the full-heading stage,and improved at the grain filling stage.But the rules were various for the different cultivars.

Key words: panicle type, row spacing, rice, semi-extinction depth, canopy light intensity

摘要： 提出了量化指标半消光深度（Ds）和冠层照光度（CLI）两个概念。利用这两项指标对不同行距下不同穗型水稻冠层的受光态势进行了比较研究，结果表明：在孕穗期，叶角是决定不同品种之间光分布差异的主要因素。一般叶角越小，冠层受光越优越。在齐穗期穗子成为影响冠层光分布的主要因素，并以弯穗型品种穗子遮光强烈而对冠层内光分布影响较大。灌浆期穗型的变化仍然是影响冠层光分布的主要因素：弯曲穗型由于穗子严重弯曲，上部受光良好，但下部并不比其他穗型优越。无论什么品种，在整个生育时期行距越宽，冠层受光越好。相同品种相同行距在不同生育时期光分布有明显变化，一般是在孕穗期光照条件比齐穗期优越，到灌浆期光照条件又有所改善。但不同品种变化规律不尽一致。

关键词: 穗型, 行距, 水稻, 半消光深度, 冠层照光度