NaCl胁迫对架豆叶绿素荧光参数的影响

Effects of salt stress on photosynthetic parameters in bean leaves

以架豆(Phaseolus vulgarisL.)为材料,利用叶绿素荧光仪测定了在不同浓度(0,200,400,600,800和1 000 mmol.L-1)NaCl胁迫下架豆叶片光系统Ⅱ(PSⅡ)最大光量子产量Fv/Fm(maximum quantum yield of photosystem Ⅱ)、PSⅡ实际光化学量子产量Y(Ⅱ)(actual photochemical efficiency of PSⅡ in the light)、光化学淬灭系数qP(photochemical quenching)和非光化学淬灭系数qNP(Non-photochemical quenching)等叶绿素荧光参数的变化,讨论了各个参数随NaCl浓度递增的变化规律.实验结果表明,植物Fv/Fm和Y(Ⅱ)随着NaCl胁迫浓度的上升而逐渐下降,表明NaCl胁迫导致了架豆叶片光合作用水平的降低.随着NaCl胁迫浓度的增加,qP值下降,表明NaCl胁迫导致了叶绿体光合机构还原力积累水平的上升.在200,400和600 mmol.L-1浓度胁迫下,qNP水平上升,暗示植物在受到低浓度NaCl胁迫时,植物能够启动非光化学淬灭机制来保护植物的光合机构;但当NaCl浓度为800和1 000 mmo.lL-1时,qNP又发生了一定程度的回落,表明较高水平的NaCl胁迫在一定程度上破坏了非光化学淬灭机制自身保护体系,进而加剧了Fv/Fm和Y(Ⅱ)的下降.

The chlorophyll fluorescence spectrometer PAM2500 is used to measure the chlorophyll fluorescence parameters,such as Fv/Fm（maximum quantum yield of photosystem Ⅱ）,Y（Ⅱ）（actual photochemical efficiency of PSⅡin the light）,qP（photochemical quenching） and qNP（non-photochemical quenching） in bean leaves suffered from different concentrations of NaCl,and then the regulations of these parameters are discussed.The results show that qP significantly decreases under the various concentrations of NaCl,which indicate that the reducing power increasingly accumulates.Similarly,Fv/Fm and Y（Ⅱ） show the same variation trend.This suggests that photosynthesis declines with the change of qP.The results also show that under 200,400 and 600 mmol·L-1 NaCl,qNP level is likely to rise significantly because of the protection system of bean leaves is activated by salt stress.On the contrary,during 800 to 1 000mmol·L-1 NaCl,qNP falls after a rise.This aggravates the decline of Fv/Fm and Y（Ⅱ）.