镉离子对茶叶光合机构及性能的影响

Effect of Cadmium Ions on Photosynthetic Structure and Its Functions of Tea Leaves

对水培在镉污染下的茶叶光合机构进行连续观察和光合性能测定。结果表明镉离子(0.5 mmol/L)伤害茶苗叶片叶绿体超微结构。在毒害初期,表现为基粒减少,排列不规则,类囊体减少,垛叠紧密度下降;而后,叶绿体逐渐变圆并与质膜分离,类囊体腔膨胀,垛叠疏松;到后期叶绿体结构更加混乱,类囊体大幅度降解,有些叶绿体外膜局部破裂,基质外泄。随Cd2+处理时间的延长,茶叶叶绿素含量减少,叶绿素a/b值下降 ,叶绿素荧光动力学参数Fv/Fo和Fv/Fm值降低。镉离子对光合作用有多方面影响,而且对细胞的毒害具有明显的累积效应。

Tea plant was cultivated in Hoagland nutrient solution containing 0.5 mmol/L Cd2+ for 8 days. Tea leaves lost their green color gradually with the change in the ultrastructure of the chloroplast . At the early stage, there was a slight decrease in the number of granum thylakoids. Then, the thylakoids piled up loosely, and chloroplasts rounded off to different extents. At the late stage , the structure of the chloroplast related to thylakoid became unclear, while the thylakoid system was disintegrated abnormally with a few single bent and swell thylakoids, and some ruptured envelope of chloroplast. Cadmium ions significantly inhibited the photosynthesis activity and led to the decline in the chlorophyll content and chlorophyll a/b ratio. Further more the photochemical efficiency of PSII(Fv/Fm)and the potential activity of PSII(Fv/Fo)decreased in different degrees with increasing Cd2+ stress . The pollution duration resulted in the damage of photosynthetic structure in tea leaf cells.