乌拉尔甘草不同部位叶片气孔泌盐与光合气体交换特征

The Salt-secreting and Photosynthetic Gas-exchanging Characteristics of Leaves Stoma at Different Positions on the Stem of Glycyrrhiza uralensis

以野生乌拉尔甘草为研究对象,对其不同部位叶片(上部、中部及下部)的气孔泌盐状况、叶绿素含量、叶片解剖结构、净光合速率以及气孔导度进行比较分析。结果显示:(1)上部叶片气孔未见盐分积累,中部叶片气孔内有少量盐分分泌和累积,下部叶片气孔的泌盐量最大。(2)上部和中部叶片的叶绿素含量显著高于下部叶片。(3)上部叶片叶肉细胞排列最致密,中部叶片次之,下部叶片叶肉细胞排列疏松。(4)不同部位叶片的净光合速率和气孔导度也均存在显著差异,均表现为上部叶片净光合速率最高,中部叶片次之,下部叶片净光合速率最低。研究认为,野生乌拉尔甘草上部叶片的气孔在植物生长过程中主要进行光合气体交换,几乎不分泌盐;下部衰老叶片的光合能力最弱,其气孔主要负责将体内多余的盐分排出体外,以维持植株体内的离子平衡,保证乌拉尔甘草新陈代谢的正常进行;不同部位的叶片分工协作,在气孔的气体交换和泌盐这两种利益冲突的行为之间实现了巧妙的权衡,是乌拉尔甘草对高盐环境的一种适应策略。

Wild Glycyrrhiza uralensis as the research material,we compared stoma-salt-secreting condition,leaves anatomical structure and net photosynthetic rate（Pn）,stomatal conductance（Gs）among different leaves of G.uralensis.The results showed that：（1）compared with the upper and middle leaves＇stomata,the lower leaves＇stomata were of the strongest salt secretion ability,secondly were the middle leaves＇stomata.There were no salt accumulation at the upper leaves＇stomata.（2）The upper and middle leaves＇chlorophyll content were significantly higher than that of lower leaves.（3）The upper leaves＇mesophyll cells arranged the densest,the middle leaves taken second place,and the lower leaves＇mesophyll cells arranged loose;（4）The leaves＇net photosynthetic rate and stomatal conductance in the upper leaves were the highest,and those in the lower leaves were the lowest.The stomatal conductance also appears the same pattern.We concluded that the upper leaves＇stoma are mainly used for gas-exchanging of photosynthetic in the main process of plant growth,hardly secret salt,and the lower of senescen leaves＇photosyn-thetic capacity is weak,the stoma is mainly responsible for put the excess salt out of the body,in order to maintain ion balance,to ensure normal metabolism of G.uralensis.So the division of labor and collaboration of different parts of the leaves achieve a clever trade-off between the two interest-conflicting behaviors：stomatal salt-secreting and photosynthetic gas exchange,which is an adaptation strategy of G.uralensis to the high salt environment.