不同浓度臭氧处理对‘赤霞珠’葡萄叶片光系统Ⅱ功能的影响

Effects of Different Concentrations of Ozone Stress on Photosynthetic System Ⅱ in Vitis vinifera cv. ‘Cabernet Sauvignon'

探讨O3处理对‘赤霞珠’葡萄叶片光系统功能Ⅱ（PSⅡ）的伤害机制及O3胁迫发生阈值。以一年生‘赤霞珠’为试材,设置不同O3浓度（25、40、55、80和105 n L·L-1）,测定叶片叶绿素含量、气体交换和叶绿素荧光参数,分析不同O3浓度处理对葡萄叶片PSII活性的影响。结果表明,随着O3浓度升高,叶片净光合速率（Pn）、气孔导度（Gs）、PSII的实际光化学效率（ΦPSII）、光下最大光化学效率（Fv’/Fm’）、捕获光能用于QA以后的电子传递的概率（ΨEo）、单位面积有活性反应中心的数量（RC/CSm）均呈下降趋势;PSII激发压（1-qP）、K点的相对可变荧光（Wk）、慢相荧光淬灭（qI）呈现上升趋势;在低O3浓度条件下（25~55n L·L-1）,Pn的下降主要是由于气孔限制引起的,O3浓度达到并超过80 n L·L-1时,叶绿素含量显著降低,非气孔限制占主导因素,PSII功能开始受到抑制;浓度达到105 n L·L-1时叶片出现较明显的表观伤害症状,电子供体侧伤害程度大于受体侧。实验结果说明,葡萄叶片可以在短时间内（8 h）忍受一定浓度（不超过55 n L·L-1）的O3胁迫,O3浓度达到或超过80 n L·L-1时,PSII功能受到较严重的抑制。

The effects of 03 treatments on the operation of photosynthetic apparatus were investigated to reveal the mechanism of inhibition of photosynthetic system Ⅱ （PSII）. One-year-old ＇Cabernet Sauvignon＇ grapevines were treated with different 03 concentrations （25, 40, 55, 80 and 105 nL·L-1）. Chlorophyll concentration, gas exchange and chlorophyll a fluorescence parameters were simultaneously analyzed to investigate the effects of different 03 concentrations on the PSII function. The results showed net photosynthetic rate （Pn）, stomatal con- ductance （Gs）, actual PSⅡ efficiency （Фpsu）, electron transport rate （ETR）, density of RCs （RC/CSm） and the probability that a trapped exciton moves an electron into the electron transport chain beyond QA （ψEo） continually decreased with the increase of PSII excitation pressure （1-qP）, slowly-relaxing quenching （q/） and relative vari- able fluorescence intensity at K-step （Wk）. Under the low 03 concentrations （25-55 nL·L-1）, the decrease of Pn was due mainly to stomatal limitation. When the 03 concentration reached 80 nL·L-1, chlorophyll concentration decreased significantly, the non-stomatal limitation played dominant role in decline of photosynthesis and PSII function began being inhibited, the treated leaves even showed obvious injury symptoms and the damage de- gree of the donor side was more sever than that of the acceptor side under treatment of 105 nL·L-1. The experi- ments showed that grape leaves could cope with certain 03 concentration （less than 55 nL·L-1） within 8 h, how- ever, over the concentration of 80 nL·L-1 resulted in serious photoinhibition of PSII.