圆柏刺叶和鳞叶的光合功能比较

Comparison of Photosynthetic Function between Needle Leaves and Scale Leaves of Sabina chinensis

异形叶在植物界普遍存在,其中圆柏的刺叶和鳞叶在园林树种中最为典型。为了分析圆柏刺叶与鳞叶更替的作用和意义,本文系统比较了这两种圆柏异形叶的光合功能。结果显示,两种类型叶片的含水量没有显著差异。刺叶的光合作用光反应活性和净光合速率均高于鳞叶,可溶性糖含量也显著大于鳞叶。刺叶的高光合效率与其较高的蛋白质含量、叶绿素含量以及较大的单位面积反应中心密度(RCs/CSo)及质体醌库(Sm)有关,其较大的气孔导度也有助于光合作用的进行。但与鳞叶相比,刺叶的蒸腾速率较高,水分利用效率相对较低。因此,多年生圆柏仍保留部分幼年期的刺叶对其生长发育是有利的,刺叶与鳞叶更替则有助于圆柏适应干旱环境。

Heteromorphic leaves are ubiquitous in the plant kingdom,among which the needle leaves and scale leaves of Sabina chinensis are the most typical.In order to analyze the role and significance of the replacement of needle leaves and scale leaves on S.chinensis trees,the photosynthetic functions of two heteromorphic leaves of S.chinensis were systematically compared.The results showed that there was no significant difference in water content between the two types of leaves.The photoreaction activity and net photosynthetic rate of needle leaves were higher than that of scale leaves,and the soluble sugar content was also significantly higher than that of scale leaves.The high photosynthetic efficiency of needle leaves was related to its higher protein content and chlorophyll content,larger reaction centers density per cross section(RCs/CSo)and plastid quinone pool(Sm).Larger stomatal conductance also contributed to photosynthesis of needle leaves.But the transpiration rate of needle leaves was higher than scale leaves and their water use efficiency was relatively lower than scale leaves.Therefore,it is beneficial for the growth and development of perennial S.chinensis trees to retain some needle leaves and the replacement of needle leaves and scale leaves is helpful for S.chinensis to adapt to drought environment.