茶树叶片光合作用的光抑制及其恢复研究

Photoinhibition and Recovery of Photosynthesisin Leaves of Camellia sinensis

以茶树的连体和离体叶片为研究材料,测定了茶树在自然光强和模拟光强下的光合特征和叶绿素荧光参数。结果表明:连体叶片经午间强光处理后,净光合速率(Pn)、表观量子效率(AQY)和光系统 (PS )的光化学效率(Fv/Fm)降低,说明茶树发生了光抑制,而当光强达到光饱和点时,Fv/Fm和PS 潜在活性(Fv/Fo)就降低,且其降低幅度随着光强的增加而增加,说明自然条件下,茶树比较容易发生光抑制,离体叶片的光抑制程度随着强光照射时间的延长而加重,但是它们在光强减弱或在弱光下恢复2～4h,其值接近正常值,说明仅强光逆境引起的光抑制是可逆的;茶树光合作用的光抑制程度不仅具有品种差异性,而且随叶龄而异,即幼叶比老叶更易发生光抑制。

Photosynthetic characteristics and chlorophyll fluorescence parameters were determined in tea plant leaves and its disks in natural and simulated light.The results showed that net photosynthetic rate (Pn), apparent quantum yield(AQY),and photochemical efficiency of PSⅡ(Fv/Fm) of tea plant leaves decreased after exposed to midday high irradiance, indicating that photoinhibition occurred.Once light intensity was near to light saturation point Fv/Fm and potential efficiency of PSⅡdeclined, and the extent of reduction increased with the light intensity increased,which testified that photoinhibition of tea plant happens easily. However, the value of Fv/Fm were close to the level observed in the morning, recovering for 2～4 h in weak light after photoinhibition, it indicated that photoinhibition only induced by high light is reversible. The extent of photoinhibition varied with varieties and leaf age in tea plant.