连香树幼苗对光照强度的响应

Response to Light Intensity of Cercidiphyllum japonicum Seedlings

摘要:

为了解不同光照强度对连香树(Cercidiphyllum japonicum)幼苗生长的影响，分别在10% (L₁)、25% (L₂)、100% (L₃)、110% (L₄)和125% (L₅)自然光照强度下处理1 a生连香树幼苗，对其形态和生理适应能力进行研究。结果表明，随光照强度的增加，株高增长量、生物量、叶长、叶宽、叶面积均呈现先升后降的趋势且都在L₂达到最高值；比叶面积、叶片含水量、根冠比持续下降，基径增长量则持续上升。L₁和L₂处理的过氧化物酶活性保持在较高水平且显著高于L₄和L₅处理，丙二醛含量则相反；随处理时间的增加，L₂处理的超氧化物歧化酶活性先升后降，L₁处理的持续上升且高于L₃、L₄、L₅处理, 总叶绿素、叶绿素a和叶绿素b含量随处理时间增加而降低，且光照越强，含量越低。因此，连香树幼苗在遮荫和强光环境下均能生长，以25%自然光照强度更适宜。

Abstract:

In order to understand the effects of light intensity on growth of Cercidiphyllum japonicum seedlings, one-year-old seedlings were grown under 10% (L₁), 25% (L₂), 100% (L₃), 110% (L₄), and 125% (L₅) natural light intensity, and the adaptive ability in morphology and physiology of seedlings was studied. The results showed that the increase of plant height, biomass, leaf length, leaf width, and leaf area increased at first and then decreased with the increase of light intensity, and all of them reached the highest under L₂. The specific leaf area, leaf water content, and root shoot ratio continued to decrease, while the base diameter increased continuously. The peroxidase activity under L₁ and L₂ was significantly higher than that under L₄ and L₅, while the changes in malondialdehyde content was the opposite. With the increase of treatment time, the superoxide dismutase activity under L₂ increased at first and then decreased, which under L₁ continued to increase and was higher than that under L₃, L₄ and L₅. The contents of total chlorophyll, chlorophyll a and chlorophyll b decreased with the treatment time, and the stronger the light, the lower the content. Therefore, Cercidiphyllum japonicum seedlings could grow under both shade and strong light, and 25% natural light intensity was more suitable.