黄金梨和鸭梨叶片光合作用的光抑制及其恢复的比较研究

 以黄金梨和鸭梨的连体和离体叶片为研究材料, 在自然光强和模拟光强下测定光合作用和叶绿素荧光参数。结果表明: 黄金梨和鸭梨连体叶片经午间强光处理后, 净光合速率( P_n) 、表观量子效率(AQY) 和光系统Ⅱ ( PSⅡ) 的光化学效率(F_v /F_m ) 降低, 初始荧光( F_o ) 升高, 且其降低或升高的幅度随着光强的增强而加大, 说明强光胁迫使叶片发生了光抑制; 黄金梨和鸭梨离体叶片的光抑制程度均随着强光照射时间的延长而加重, 但是在光强减弱或在弱光下恢复2～4 h, 均可基本恢复到正常值, 说明仅强光引起的光抑制是可逆的; 对DTT处理的叶片进行强光处理, 其F_v/F_m比未吸入DTT的叶片低, F_o比对照高, 说明依靠叶黄素循环进行热耗散是梨树叶片防御强光破坏光合机构的重要途径之一; 黄金梨对强光胁迫的忍耐能力和恢复能力较鸭梨弱, 说明梨树光抑制程度品种间有差异。

Photoinhibition and Recovery of Photosynthesis in Pear Leaves

Photosynthesis and chlorophyll fluorescence parameters are measured onWhangkeumbae and Yali pear leaves and their 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 ) decreased and minimal initial fluorescence ( F_o ) was imp roved after being exposed to midday high irradiance, indicating that photoinhibition of Whangkeumbae pear and Yali pear occurred. However, photoinhibition was only induced by high light and could be recovered after 2-4 hours of low light, it indicated that photoinhibition only induced by high light is reversible. Photochemical efficiency of PSⅡ (F_v/F_m ) decreased and minimal initial fluorescence (F_o) was imp roved after being exposed to DTT, which indicate that Xanthophyll cycle was the major protective mechanism to prevent from the deteriorating effects of strong light in the pear leaves; The capacity ofpatience and recovery of Yali on strong light stress was stronger than that ofWhankgeumbae, indicating that the extent of photoinhibition varied with varieties in pear.