大豆不同群体叶面积与光强垂直分布初步分析

THE PREMARILY ANALYSIS ON DISTRIBUTION OF LEAF AREA AND INTENSITY OF ILLUMINATION AT DIFFERENT COLONY OF SOYBEAN IN VERTICAL DIRECTION

亚有限类型和无限类型大豆品种（品系）叶面积指数（ＬＡＩ）在结荚期均达到最大值，至鼓粒期亚有限类型回落明显，无限类型仍维持较高值。结荚或鼓粒期ＬＡＩ分布为下层比例最低，亚有限类型上层比例大、无限类型中层比例大。开花期光照分布主要集中于上层、中层较弱、下层更弱，亚有限类型冠层上部光强低于无限类型。按叶片自然生长姿态将冠层分成上、中、下三部分，ＬＡＩ累加值自上而下递增，冠层中光分布依次衰减。叶面积大小是制约冠层中光分布的重要原因，但不是唯一原因，株型收敛程度、株高、叶型、结荚习性等都和群体冠层内透光性有密切关系。根据不同品种类型，合理摆布群体，将适当的群体ＬＡＩ与冠层内良好的透光环境统一起来，是大豆稳产高产的重要保证。

LAI of semi-determinate and indeterminate varieties(strains) reached the highest in podding period,and decreased distinctly in pod-filling stage for semi-determinate varieties(strains) while decreased less for indeterminate ones. The rate of LAI in podding or pob-filling Period was the lowest at the part of bottom for both semi-determinate and indeterminate varieties (strains), it was the highest at the top part for semi-deter-minate ones as well as at the middle part for indeterminate ones. Illumination distributed mostly at the top, less in the middle and least at the bottom for both semi-determinate and indeterminate varieties(strains), and illumination is lower for semi-determinate ones than for indeterminate ones at the top of the canopy. The LAI accumulative naturally distributed on the 3 layers of the canopy increased downwards and accom-panted by the reduction of illumination in the canopy. Leaf area is an important but not the only factor to affect the distribution of illumination of the canopy, the characteristics of convergence of plant type, habit of growth, plant height, leaf types, etc. ware also related with the permeability of illumination closely in the canopy. In accordance with different types of varieties,suitable plant population and a suitable combination of LAI with proper light Penetration in the canopy is important for raisins yield of soybean steadily.