Stress of Different Concentration of Lead on Chlorophyll Fluorescence Properties of Hedera helix

In April 2016, half lignification Hedera helix branches were harvested for cutting in Kunming, Yunnan province. In June of the current year, cuttings were treated by different concentrations of Pb2+ (0 as CK, 50, 200, 400, 800 μmol·L-1). 60 days later, determinations were implemented on chlorophyll content and chlorophyll fluorescence parameter of cuttings. The result showed that compared with the control, seedlings treated by different concentration of lead had significant low content of chlorophyll content, higher chlorophyll a/b. Under 200 and 400 μmol·L-1 of lead stress, minimal fluorescence (F0), non-photo chemical quenching coefficient (qN) of seedlings increased significantly, while yield, photo chemical quenching coefficient (qP), and apparent photosynthetic electron transport rate (ETR) decreased evidently, photochemical efficiency of PSⅡin the light (Fv/Fm) had no evident change. Less than 800 μmol·L-1 of lead stress, F0 and qN increased sharply, and the left index decreased evidently. Correlation analysis demonstrated that chlorophyll a had extreme significant relation with chlorophyll b, as well as qP with ETR, both qP and ETR with yield under any lead stress. The experiment concluded that 50 μmol·L-1 of lead stress could decreased chlorophyll content, but had no evident effect on PSII, 200 and 400 μmol·L-1 of lead stress had effect on PSII, 800 μmol·L-1 of lead stress had great effect.