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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(Pn)、表观量子效率(AQY)和光系统Ⅱ(PSⅡ)的光化学效率(Fv/Fm)降低,初始荧光(Fo)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2～4h,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Fv/Fm比未吸入DTT的叶片低,Fo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。
The photosynthesis and chlorophyll fluorescence parameters were measured under the conditions of natural light intensity and simulated light intensity using the Siamese and Pear Siamese and in vitro leaves as the research materials. The results showed that net photosynthetic rate (Pn), apparent quantum yield (AQY) and photochemical efficiency (Fv / Fm) of photosystem Ⅱ (PS Ⅱ) decreased after the midday light treatment. The initial fluorescence (Fo) increased, and the amplitude of decrease or increase increased with the increase of light intensity, which indicated that light stress inhibited leaf photosynthesis. The duration of intense light irradiation was aggravated, but the light intensity returned to normal after 2 ~ 4h recovery in low light, indicating that light-induced light suppression was reversible. For DTT-treated leaves, The results showed that Fv / Fm was lower than that of non-inhaled DTT and Fo was higher than that of control, indicating that heat dissipation by lutein cycle was one of the most important ways to prevent photosynthetic apparatus from damaging leaf light by pear leaves. The tolerance and recovery ability of glare stress was weaker than that of pear, which indicated that there were some differences among varieties of pear tree.