Photosynthetic fluorescence characteristics of four greening tree species based on leaf scale under different ozone stress levels
Ground-level ozone(O3)is considered as a secondary air pollutant with strong oxidative toxicity to plants,which causes serious damage to plant photosynthetic system and impedes forest carbon sequestration.In this study,based on leaf-scale chlorophyll fluorescence imaging technology,the open-top chambers were used to mea-sure photosynthesis fluorescent parameters and investigate ozone dose-response relationships of four urban greening tree species(Fraxinus chinensis,Platanus orientalis,Robinia pseudoacacia,and Sophora japonica)in Beijing.The results showed that with the increases of O3 concentration,the maximum photon yield of PS Ⅱ reaction center(QYmax),the steady-state light adaptive non-photochemical fluorescence quenching coefficient(NPQLss),the steady-state fluorescence attenuation parameter(Rfd Lss),the actual photochemical quantum efficiency of PS Ⅱreaction center(PhiPS2Lss)and the photostable maximum photon efficiency of PS Ⅱ reaction center(Fv'/Fm')decreased significantly,while the steady-state light adaptive photochemical fluorescence quenching coefficient(qPLss)did not change.Except for RfdLss,there were significant differences in chlorophyll fluorescence parameters among different greening tree species.All the four species showed a significant negative correlation between fluores-cence parameters and the O3 dose index AOT4O(cumulative value of hourly ozone concentration exceeding 40 nmol·mol-1).The chlorophyll fluorescence imaging of the whole leaf reflected the process that the PSⅡ reaction center was gradually damaged with the increases of O3 dose,and the reduction of photosynthetic capacity followed the order from leaf margin to leaf mesophyll to leaf vein.Chlorophyll fluorescence imaging technology could reflect the spatio-temporal response characteristics of plants to O3 stress on leaf scale,with certain application prospect.
ozonedosegreening tree specieschlorophyll fluorescencelinear relationship
万方数据
维普
