外源硒对菲胁迫下苍耳光合荧光特性的影响

Effect of Exogenous Selenium on Photosynthetic Fluorescence Characteristics of Xanthium sibiricum Patrin ex Widder under Phenanthrene Stress

为了探究硒元素缓解土壤中多环芳烃污染对陆生植物苍耳（Xanthium sibiricum Patrin ex Widder）的胁迫作用,选择菲作多环芳烃代表物,通过盆栽实验,研究了土壤中不同菲污染浓度（0,20,80,320mg·kg^-1）对苍耳的生长、叶绿素含量、光合参数及叶绿素荧光参数的影响,以及外源性施加硒（0.5mg·kg^-1）对上述胁迫效应的缓解作用.结果显示,硒能显著缓解高浓度（320mg·kg^-1）菲胁迫下苍耳生物量的减少（p〈0.05）,同时缓解各浓度菲胁迫下叶片中叶绿素含量的降低;硒还能缓解植物在菲胁迫下净光合速率、气孔导度、胞间CO2浓度的降低,减缓叶片PSⅡ最大光化学效率、PSⅡ实际光能转化效率、光化学淬灭系数的下降和非光化学淬灭系数的上升.研究表明,土壤中外源性添加硒能保护菲胁迫下苍耳的光合机构,改善其光合功能.

In this study,pot-culture experiments were carried out to assess the effects of selenium（0.5 mg·kg-1 soil）on the growth and photosynthetic fluorescence characteristics of Xanthium sibiricum Patrin ex Widder after exposed to phenanthrene,apolycyclic aromatic hydrocarbons pollutant,at levels of 0,20,80,and 320 mg·kg-1 soil.Response variables including plant growth,chlorophyll content,photosynthetic parameters and chlorophyll fluorescence parameters were tested.Meanwhile,the alleviation of exogenously applied of selenium（0.5 mg·kg^-1）on the above stress effects were also tested.The biomass of Xanthium sibiricum Patrin ex Widder reduces significantly at the highest exposure level to phenanthrene（320 mg·kg^-1）,while the application of selenium（0.5 mg·kg^-1）to the soil significantly alleviats these reduction（p〈0.05）.Selenium also alleviats the decrease of chlorophyll content in leaves under different concentrations of phenanthrene stress.Furthermore,selenium can alleviate the decrease of net photosynthetic rate,stomatal conductance and intercellular CO2 concentration under phenanthrene stress,as well as the decrease of the maximum quenching yield of PSⅡ,the quantum yield of PSⅡ,proportion of open PSⅡ and the rise of non-photochemical quenching.The results show that exogenous application of selenium can protect photosynthetic organs and improve photosynthetic function of Xanthium sibiricum Patrin ex Widder under phenanthrene stress.