中文摘要：

用荧光动力学的方法探讨Na2CO3胁迫下星星草幼苗叶片电解质外渗率与PSⅡ光能耗散的关系。结果表明,随着星星草幼苗叶片电解质外渗率的增大,PSⅡ的最大光化学效率（Fv/Fm）和潜在光化学效率（Fv/Fo）呈逐渐减小的趋势。同时,当电解质外渗率小于0.2时,PSⅡ实际光化学效率（ΦPSⅡ）、电子传递速率（ETR）、光化学淬灭系数（qP）、光化学速率（PR）、捕光色素的光能被用于热耗散的相对份额（HD）、热耗散速率（HDR）都随着电解质外渗率的增大而增大;而当电解质外渗率超过0.2时,PSⅡ实际光化学效率（ΦPSⅡ）、电子传递速率（ETR）、光化学淬灭系数（qP）、光化学速率（PR）却随着电解质外渗率的增大而减小。另一方面,电解质外渗率在小于0.15时,非光化学淬灭系数（qNP）一直在增加,但是当电解质外渗率超过0.15时,qNP却减少。本试验结果说明当电解质外渗率在一定范围内,星星草通过增加热耗散以及增加捕光色素吸收的光能被用于热耗散的相对份额（HD）和热耗散速率（HDR）来改善PSⅡ的功能,由此引起的活性氧增加则由体内较高的保护酶来清除,若超过了一定阈值则抑制了PSⅡ的功能,或者说PSⅡ系统可能遭受了不可逆损伤。

英文摘要：

Fluorescence induction kinetics was used to investigate the relationship between electrolyte leakage and light energy dissipation of PSⅡ in the leaves of Puccinellia tenuiflora seedlings under Na2CO3 stress. Themaximal photochemical efficiency of PSⅡ （Fv/Fm） and potential photochemical efficiency （Fv/Fo） decreased as electrolyte leakage increased. Actual photochemical efficiency of PSⅡ in the light （φPSⅡ）, electron transfer rate （ETR）, the photochemical quenching coefficient（qP）, photochemical efficiency （PR）, heat dissipation （HD） and heat dissipation rate （HDR） increased when electrolyte leakage was less than 0. 2. However, φPSⅡ, ETR, qP and PR decreased when electrolyte leakage was more than 0.2. The dividing line for effectual control of P. tenuiflora appeared to be an electrolyte leakage of 0.2. The non-photochemical quenching coefficient（qNP） increased when electrolyte leakage was less than 0. 15, while qNP decreased when electrolyte leak was over 0.15. Thus the inflexion of qNP appeared to be an electrolyte leakage of 0.15, whereas that for φPSⅡ,ETR, qP and PR was 0.2. This could explain the regulation ability of effectual heat dissipation when electrolyte leakage was less than 0.15 and why the ability of heat dissipation reduced when electrolyte leakage was over 0.15. The results showed that P. tenuiflora improved the function of PSⅡ by increased heat dissipation and light energy ahsorbion by light-harvesting pigment, resulting in the augmentation of active oxygen elimina-tion by leakage damage. antioxidant enzyme systems when electrolyte leak was in exceeded this range, the functioning of PSⅡ was inhibited a or certain range. However, the PSⅡ system suffered when electrolyte from irreversible damage.