水稻不同穗型群体冠层光分布的比较研究

根据颈穗弯曲度将水稻划分为直立、半直立和弯曲三种穗型，并将弯曲穗型进一步分为穗弯曲型和颈穗弯曲型。穗型主要影响群体中上部的光分布。直立穗型群体中上部光照条件好，光的分布比较均匀；半直立和弯曲穗型群体穗位以下的光照条件远不如直立穗型群体。不同穗型群体下部光分布的差异不大。弯曲穗型在一定程度上降低了穗在群体中的相对位置，有利于上层叶片的光合作用，因而可能优于半直立穗型。穗型也是影响消光系数的重要因素之一，在比较不同穗型品种的冠层特征时，以消光系数作为综合指标有一定局限性。此外，还讨论了株形与光能利用的关系和直立穗型的利弊。

COMPARATIVE STUDY ON LIGHT DISTRIBUTION IN RICE CANOPIES WITH DIFFERENT PANICLE TYPES

According to the curvature of panicle neck, rice varieties can be divided into three types: erect, semi-erect and curved. The curved types can be further divided into panicle curved type and neck-panicle curved type. The effect of panicle morphology on light distribution in cawopy was conspicuous, and occurred mainly in the middle and top layers of the canopy. In the canopy of population of erect panicle type, the light distribution was more uniform in the upper layer. the light distribution below the panicle layer in the population of semi-erect and curved panicle types was less adequate than that in the population of erect panicle type. The light distribution in lower parts of different panicle type canopies varied slightly. The rolatively lower position of panicle in canopies of rice with curved pani(?) is favourable to photosynthesis of upper leaves. In this respect, the e(?)rved panicltype may be better than the semi-erect panicle type. Panicle type is also one of the important factors which affects the extinction coefficient. Therefore, it has some limitation to use extinction coefficient as a comprehensive index for comparing and analyzing the canopy characteristics of rice cultivars with different panicle types.