遮荫对刺五加生长和光合特性日变化影响的研究

Effects of Shading on Growth and Photosynthetic Characteristics of Eleutherococcus Senticosus

在透光率为100%、60%、20%三种光照条件下,对两年生刺五加的生长和光合特性进行研究。结果表明刺五加移栽苗当年的茎粗、冠幅和叶面积的生长均表现为透光率60%>100%>20%,株高生长随透光率的增加而增加。刺五加的净光合速率在100%光照条件下为双峰曲线,上午10:00达到最高峰,之后即急剧下降,16:00出现次峰,表明自然光照条件下刺五加有明显"午休"现象,遮荫处理的净光合速率日变化规律均为单峰曲线,在12:00出现高峰,比全光照条件下延迟两小时,在全光照条件下刺五加有灼伤现象,因此在人工栽培刺五加的过程中可以进行林下栽植,以得到适当的遮荫,利于其生长。

An experiment was conducted to study the growth and photosynthetic characteristics of biennial Eleutherococcus senticosus under three shading levels （100%, 60% and 20% of full light）. The results indicated that the diameter increments of stem, crown and leaves of 1-year-old transplants reduced with light intensity changing from 60%, 100% to 20%. However, height increment of the transplants rises with light intensity increasing. The daily variation of net photosynthetic rate presents a bimodal curve under 100% of full light condition. The peak occurred at about 10：00 a.m, then dropped sharply. The second peak occurred at about 15：00 p.m. The variation trend of the curve showed that Eleutherococcus senticosus had obviously ＂nap＂phenomenon under natural sunlight. While under other light intensity conditions, the daily variation of net photosynthetic rate presents a unimodal curve. The peak occurred at about 12：00 a：m later than that under full light intensity condition. All these indicated that Eleutherococcus senticosus was scorched under full light condition. Therefore, Eleutherococcus senticosos could be planted under low forest coverage in order to obtain appropriate shade whidh is good for the growth of it.