摘要
在不同光照强度处理下(100%、50%和5%自然光强),测定了濒危植物银缕梅幼苗叶片光合生理及其相应的形态指标,以探讨银缕梅幼苗叶片光合功能执行及叶形态建成在不同光照条件下的响应趋势。结果表明:银缕梅幼苗最大净光合速率(Pn,max)、光饱和点(LSP)和光补偿点(LCP)随着光强下降而显著降低,表明当年生新叶在一定程度上能够利用低强度光。全光强下银缕梅幼苗虽然具有较高的净光合速率,但其非光化学猝灭系数(NPQ)同样显著高于弱光下的幼苗,表明在幼苗建成阶段其强光利用能力较低,需要通过增加热耗散以散发过剩的光能。50%光强下的银缕梅幼苗叶片的比叶面积(SLA)显著高于5%及100%光强下幼苗叶片的SLA,并且单株产叶数显著增加,说明在中等遮荫条件下银缕梅幼苗可进行有效的光合功能执行,并在形态建成方面表现出积极的响应。5%光强下银缕梅幼苗的SLA最低,但单位面积及单位干质量的叶绿素含量均显著高于50%与全光照下幼苗的相应指标。银缕梅幼苗在光合功能执行以及叶形态建成等方面对低光环境所表现出的适应策略,较好地解释了自然种群中幼树(幼苗)个体占据绝对优势的现象。但作为典型的阳生性树种,生长后期的光资源限制则可能导致植株处于"光饥饿"的压制状态,严重限制其种群更新。光环境的改善将直接促使幼树(幼苗)从光制约状态释放出来,以利于银缕梅种群的顺利更新。
Parrotia subaequalis,an endangered species endemic to eastern China,is in the first-class national list of key conservative plant. We investigated the adaptation of its seedlings to different light availabilities created by different layers of black nylon net over the nursery site. The treatment of light availabilities included three levels,l00 % ,50 % and 5 % of natural illumination,we measured photosynthesis-related parameters and growth characteristics of seedling leaves under these three light environments. Results showed that the maximal rate of photosynthesis,light compensation point and light saturation point of leaves decreased under the low light environment in the summer growing season,which implicated that seedlings of P. subaequalis could adapt to low light intensity to a certain extent. Although the leaves have the highest Pn,max under the full daylight,their non-photochemical quenching coefficient were significantly higher than that in 5 % and 50 % natural illumination,which showed the leaves of seedlings could not use high intensity light and dissipated part of absorbed light energy in the form of heat. Saplings in 50 % natural illumination had the greater adaptive response than that in 5 % and 100 % natural illumination,which had significantly higher specific leaf area and number of leaves per individual.Chlorophyll content of saplings in 5 % natural illumination was significantly higher than that in 50 % and 100 % natural illumination,which may be one of the most important strategies to adapt to very low light conditions. Performances in photosynthetic physiology and morphological characteristics of saplings’leaves in the low light environment demonstrated their high ability of dark-adaptation. However,as one typical light-demanding tree species,there is certain inhibition in growth and biomass accumulation of saplings under low light environment in the later stage,which may contribute to the limitation of population regeneration. Improving light conditions by human intervention,such as selective removal and cutting of shrubs may contribute to individual establishment and population regeneration of P. subaequalis.
出处
《南京林业大学学报（自然科学版）》
CAS
CSCD
北大核心
2010年第3期83-88,共6页
Journal of Nanjing Forestry University：Natural Sciences Edition
基金
江苏省林业生态工程重点实验室开放研究课题
关键词
银缕梅
光合作用
光适应
Parrotia subaequalis
photosynthesis
light adaptation
