Effect of Elevated CO2 Concentration On Four Populus by the Fast Fluorescence Rise OJIP

Increased atmospheric carbon dioxide (CO 2 ) can influence the stability of ecosystems in the world. The chlorophyll fluorescence technique was considered as an effective tool to evaluate the photosynthetic levels on many plant species. In this study, we analyzed the state of PSII on four kinds of populus ( Populus L.) ( populus X, Pop ulusdeltoides × cathayana , Poplus alba ′Berdinensis ′ L, Populus euramerican ′N3016′ × Populus ussuriensis ) under high CO 2 condition. The results show that the PSII performance was negatively influenced by CO 2 stress. High CO 2 stress resulted in down-regulation of Fm, φPo (=Fv/Fm), ψEo, φEo and PItotal in four kinds of populus . And a significant decrease in the P-step level of the fluorescence transients OJIP curves of four populus species after 7 days of treatment was observed. Therefore, a fast decrease of the P-step level indicated there was main change to fluorescence transients. These results indicated that changes of PSII attribute to the degradation of antenna pigment and inhibition of the electron transport at the acceptor side of PSII.