生长环境光强对夏蜡梅子叶显微形态结构和光合参数的影响

Effect of environmental light intensity on the morphological microstructure and photosynthetic parameters in the cotyledons of Calycanthus chinensis

夏蜡梅子叶在一年生幼苗的成苗和生长过程中具有重要作用。为了解夏蜡梅子叶的光适应能力和机制,采用不同层数遮阳网遮光的方式,研究四种生长环境光强(4%、22%、50%和100%全光照)对夏蜡梅子叶显微形态结构和光合参数的影响。结果表明,随着生长环境光强的减弱,夏蜡梅子叶光饱和点(LSP)、光补偿点(LCP)、叶片厚度降低,叶绿素含量升高。在50%全光照下,子叶结构发育完全,细胞排列紧密,维管组织发达,最大净光合速率(Pmax)和暗呼吸速率最高(Rd);而低于22%全光照下子叶趋向于阴生叶结构。因此,夏蜡梅子叶具有较强的耐荫能力。

The cotyledons of Calycanthus chinesis played critical roles in forming annual seedlings. In order to investigate the mechanism of light adaption of C. chinesis cotyledons,different layer adumbral nets were used in this experiment, the light intensity were 4 %, 22%, 50 % and 100 % of full sunlight, respectively. The results indicated that with the increasing of shade, the cotyledons showed lower light saturation point（LSP）, lower light compensation point （LCP）, thinner blade thickness and higher chlorophyll contents. The cotyledons developed fully with the compactness cells and the upgrowth vascular tissues,consequently,the maximal net photosynthetic rate （Pmax） and dark respiration rate （Rd） were highest under 50% full sunlight. When the light intensity was below 22% of full sunlight, the cotyledons trended towards the shade-leaved structure. The present study indicated that the cotyledons of Calycanthus chinensis were tolerant to canopy.