不同温度/光照组合对‘赤霞珠’葡萄叶片光系统Ⅱ功能的影响

Effects of Different Temperature and Light Treatments on Photosynthetic System Ⅱ in Vitis vinifera L.cv.Cabernet Sauvignon

【目的】探讨温度与光照交叉处理对‘赤霞珠’葡萄叶片光系统功能的伤害机制。【方法】以一年生‘赤霞珠’为试材,设置不同温度(28、34、37、40℃)与光强(800、1600μmol.m-2.s-1)组合,测定叶片气体交换和叶绿素荧光参数,分析不同温度和光强处理对葡萄叶片PSⅡ活性的影响。【结果】无论高光强还是适宜光强下,随着处理温度升高,叶片净光合速率(Pn)、气孔导度(Gs)、PSⅡ的实际光化学效率(ΦPSⅡ)、电子传递速率(ETR)、光合性能指数(PIABS)、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/CS)均呈下降趋势;PSⅡ激发压(1-qP)、非光化学淬灭系数(NPQ)、相对荧光曲线的初始斜率(Mo)呈现上升趋势;在适宜光强条件下,28—34℃内,叶片PSⅡ的RC/CS以及受体侧未发生显著变化,Pn的下降主要是由于气孔限制引起的,温度达到和超过37℃时,PSⅡ反应中心和受体侧开始出现伤害,叶黄素循环在植物光破坏防御过程中作用增加;在高光照条件下,高光强/28℃时的Pn已降至适光/34℃时的水平,PIABS已低于适光/40℃时的水平,适宜温度范围内(28—34℃),PSⅡ电子受体侧已受到伤害,温度超过37℃时,反应中心和电子受体侧出现更加严重的伤害,叶黄素循环受到抑制,最大光化学效率明显降低。【结论】适宜光强时,温度达到或超过37℃时,PSⅡ受到伤害,发生较严重的光抑制;强光胁迫在28℃时对PSⅡ功能造成伤害,随着温度的升高,伤害显著加剧,说明强光胁迫比高温胁迫更易造成PSⅡ功能的伤害。

【Objective】The combined effects of different temperature and light treatments on the operation of photosynthetic apparatus were investigated to reveal the mechanism of inhibition of photosynthesis.【Method】One-year-old Cabernet Sauvignon grapevines were treated with different temperatures（28,34,37 and 40℃）combined with two kinds of light intensities（800,1600 μmol？m-2？s-1）.Gas exchange and chlorophyll a fluorescence parameters were simultaneously analyzed to investigate the effects of different treatments on the PSII function【Result】Despite the treated light intensities,as temperature increased,net photosynthetic rate（Pn）,stomatal conductance（Gs）,actual PSⅡ efficiency（ΦPSII）,electron transport rate（ETR）,performance index（PIABS）,density of RCs（RC/CS） and the probability that a trapped exciton moves an electron into the electron transport chain beyond QA（ΨEo） decreased;PSⅡ excitation pressure（1-qP）,non-photochemical quenching（NPQ） and approximated initial slope of the fluorescence transient（Mo） increased.Under the moderate light intensities,the decrease of Pn was due mainly to stomatal limitation during the temperature from 28℃ to 37℃,and the xanthophyll cycle played an increased role to protect photosystem II.Under strong light stress,28℃ treatment decreased Pn to the level of the 40℃ treatment of moderate light intensities,meanwhile PIABS reached a lower level.【Conclusion】Under moderate light intensities,the PSⅡacceptor sides were not injured until the temperature reached 37℃;strong light stress,however,began to injure the PSⅡ acceptor sides from 28℃,when the temperature reached or exceeded 37℃,the density of RCs and the acceptor sides were damaged severely which showed PSⅡcould be more susceptible to strong light than moderate heat temperature.