通过几何模拟 ,从理论上分析了北半球夏半年不同行向水稻遮荫宽度在不同纬度、不同季节的日变化 ,结果表明 :中、低纬度地区东西行向遮荫宽度较小 ,有利于群体充分利用光能 ,而高纬度地区则以南北行向有较大优势。此外 ,还讨论了行向、行距与光能利用的关系。 By means of geometric simulation, the diurnal variation of shade width at different latitudes and seasons in different rows of rice in the Northern Hemisphere in summer was analyzed theoretically. The results show that the shading width of east-west row in middle and low latitudes is small, Use of light energy, while the high latitudes in the north-south direction to have a greater advantage. In addition, the relationship between line direction, line spacing and light energy utilization is also discussed.