【摘要】 用CO₂分析。含酸量和PEP羧化酶活性测定的方法对长药景天（Sedum spectabile）光合型进行研究,其成熟叶浇水时表现为C₃型,干旱条件下转变成CAM型,但极度的干旱又使其CAM活性降低。浇水植株的幼叶PEP羧化酶活性和含酸量低,成熟叶较高。但在干旱过程中,幼叶酶活性和含酸量的增加比成熟叶更为显著,表明幼叶对水分胁迫更敏感。水分胁迫中,叶最大PEP羧化酶活性和最大含酸量在植株由下而上各叶位转移。更多还原

【Abstract】 With methods of CO₂ exchange analyse, acid content and phosphoenolpyruvate carboxylase activity determination, the photosynthetic type was studied in Sedum spectabile, a widely distributed plant in China. The mature leaves in well watered plants were of C₃-type, shift from C₃ to CAM could been occurred by drought treatment. But, the CAM activity decreased under extreme drought. In well watered plants, phosphoenolpyruvate carboxylase activity and acid content were lower in young leaves than that in mature leaves. However, the increases of them were greater in young leaves under water stress and showed that young leaves were more sensitive to drought treatment. The transfer of the highest phosphoenolpyruvate carboxylase activity and acid content in plants occurred from base to apex during trought treatment period.更多还原