【摘要】 研究了生长在不同光条件下的长柄双花木幼苗叶片含水量、质膜相对透性、光合色素含量及光合速率的变化.结果表明,组织含水量、自由水含量及渗透势均以3层遮荫处理最高,并有随遮荫程度的减少而下降的趋势.幼苗的净光合速率在晴天表现为双峰型日变化特征,且在自然光照下的幼苗"午休"现象更为明显.分析表明,长柄双花木幼苗为喜荫类型,而其分布地人为形成的裸露地不能为其提供足够的荫蔽环境,致使居群更新能力不强,这可能是导致长柄双花木分布地逐渐缩小而濒危的原因之一.更多还原

【Abstract】 Under different illumination, the changes of water contents, cell membrane’s relative penetration ability, photothetic pogment contents, and net photosynthesis of the endangered plant--Disanthus cercidifolius Maxim.var.longipes H.T. Chang are studied in this paper. The results show that, the seedlings under threelayer shading (Ⅲ) is the highest in tissue water contents, free water contents and penetration, the second is that under twolayer shading (Ⅱ), next is onelayer shading(Ⅰ), and the full sunlight is the lowest. But the bound water contents and cell membranes relative penetration ability is on the contrary. With shading layers descending, photothetic pogment content is descending. The net photosynthesis of seedlings is a "towtop" daily change in sunnyday, and the "noon break" of seedlings is obviously. Seedlings under threelayer shading are lower in earlier stage, then grow up and exceed the others. The results of analysis show that the Disanthus cercidifolius Maxim. var. longipes H.T. Chang seedling is a shadytype one, but the artificial uncovered area cannot provide enough shading for the seedling, so the turnover rate of the populations is low. That would be one of the important reasons lead the area of Disanthus cercidifolius Maxim.var. longipes H.T. Chang distirbuting to reduce and to endanger.更多还原