遮阴对地枫皮幼苗生长和生物量分配的影响

为了解光照强度对地枫皮(Illicium difengpi)幼苗生长和生物量分配的影响，对不同等级幼苗在不同遮阴处理下的形态和生物量变化进行了研究。结果表明，遮阴处理下幼苗的株高、冠宽和平均单叶面积均显著高于对照，同时比叶面积均随光强增大而显著降低。除I级苗50%遮阴处理外，全光处理下各等级幼苗的根长均显著高于遮阴处理。随着光照强度的增加,各等级幼苗的根生物量比与根冠比显著增加，叶生物量比显著减少；不同等级幼苗对强光和弱光环境均表现出较强的适应性,但以50%遮阴处理的总生物量最大，全光和85%遮阴处理均较小。遮阴处理的幼苗个体大小与其初始大小呈正相关，其中II级苗与I级苗差别较小，III级苗生长较差。在人工育苗条件下I级苗数量不到10%，较差的种苗质量叠加喀斯特山顶恶劣环境，可能是导致野外幼苗更新限制的重要原因。因此在野外回归和人工栽培过程中宜选用I、II级种苗，光强控制在透光率50%为宜。

Effect of Shading on Growth and Biomass Allocation of Illicium difengpi Seedlings

In order to understand the effect of light intensity on the growth and biomass allocation of Illicium difengpi seedlings, the changes in morphological characteristics and biomass of seedlings at different classes were studied under different shading treatments. The results showed that the plant height, crown width and mean leaf area of seedlings under shading were significantly higher than those under control, while the specific leaf area decreased significantly with increasing of light intensity. The root length of seedlings with different classes under full light were significantly higher than those under shading, except for 50% shading of I-class seedlings. With increasing of light intensity, the root biomass ratio and root to crown ratio of seedlings at all classes increased significantly, and the leaf biomass ratio decreased significantly; seedlings at different classes showed strong adaptability to both high and low light environments, but the total biomass was the biggest under 50% shading, and smaller under full light and 85% shading. The size of seedlings under shading was positively correlated with their initial size, while the difference between II-and I-class seedlings was small, and the growth of III-class seedlings was poor. The number of I-class seedlings was less than 10% under artificial nursery conditions, and the poor seedling quality superimposed on the harsh environment of karst summits might be an important reason for the limitation of its field seedling regeneration. Therefore, it was advisable to use first and secondary seedlings in field regression and artificial cultivation, and to control the light intensity at about 50% light transmission.