黄山花楸幼苗对遮荫的形态、解剖和光合生理响应

Morphological,Anatomical,Photosynthetic and Physiological Responses of Sorbus amabilis Seedlings Under Different Shade Environments

在遮荫强度为0、67%、76%、92%4种处理下,研究1年生黄山花楸(Sorbus amabilis)幼苗对遮荫的形态、解剖和光合生理响应。结果表明:遮荫使幼苗高生长、叶面积增加,地径、主根长减少,造成高径比和比叶面积升高;遮荫改变了幼苗的生物量积累和分配方式,67%和76%的遮荫促进生物量积累,而92%的遮荫则产生抑制作用,遮荫下生物量分配向地上部分倾斜,根生物量比降低,茎、叶生物量比及冠根比升高;随光照强度的减弱,叶片逐渐变薄,栅栏组织与海绵组织比值降低,叶绿素质量分数增加;几种处理的净光合速率日变化均为单峰型,遮荫使日平均净光合速率和蒸腾速率降低。试验表明遮荫诱发了黄山花楸幼苗的形态和光合生理适应机制,适度遮荫可以提升苗木质量。

An experiment was conducted to study the morphological, anatomical, photosynthetic and physiological responses of one-year-old Sorbus amabilis seedlings under four shade levels （0, 67% , 76% , and 92% ）. Results showed that the shade treatments produced plants with greater seedling height, leaf area, height-diameter ratio and specific leaf area, and less stem diameter and main root length. Shading treatments led to an altered biomass accumulation and a change in alloca- tion patterns. Biomass accumulation increased in the shading treatments of 67% and 76% ; however it decreased in the shading treatment of 92%. All shading treatments resulted in more photosynthetic products to transfer to above-ground parts, an increase in shoot to root ratio due to the increase of stem and leaf mass ratlo, and a decrease in root mass ratio. Leaf thickness and ratio of the thickness of palisade parenchyma to spongy decreased, and chlorophyll content increased in all the shading treatments compared with the control. The diurnal variation of leaf net photosynthetic rate of S. amabilis seedlings under different shading treatments could be described with unimodal curve. The daily mean net photosynthetic rate and transpiration rate decreased after shading. Shading stimulated the morphological and physiological adaptation mechanisms in S. amabilis seedlings, and moderate shading could improve plant quality during the nursery period.