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The effects of cadmium ions () on the Chl a fluorescence of Ricciocarpos natans were investigated in order to determine whether Chl fluorescence can be used as a biomarker to estimate the physiological responses of plants to cadmium stress. In all plants treated with , the image of Fv/Fm, which represents the maximum photochemical efficiency of PSII, changed as the concentration increased, when treated for 48 h or more. Changes of and images were recognized even at 10 . The Chl a O-J-I-P fluorescence transient was also affected even at 10 . The fluorescence yield decreased considerably in steps J, I and P in plants treated with , although a typical polyphasic rise was observed in non-treated plants. The Chl fluorescence parameters, Fm, Fv/Fo, Sm, SFIabs, PIabs and ETo/CS, decreased as the concentration increased, while the Mo and Kn parameters increased. Peroxidase activity decreased significantly and catalase activity increased as the concentration increased. Because of its sensitivity to Ricciocarpos natans is useful in experiments investigating the responses of plants to cadmium exposure. Several parameters (Fm, Fv/Fo, Sm, SFIabs, PIabs, ETo/CS, Mo and Kn) can be applied to determine quantitatively the physiological states of plants under cadmium stress. |
