Comparison of different physiological parameter responses in Lemna minor and Scenedesmus obliquus exposed to herbicide flumioxazin

The sensitivity of different physiological parameters in Scenedesmus obliquus and Lemna minor exposed to herbicide (flumioxazin) was investigated to indicate the most convenient and sensitive parameter. To assess toxicity of flumioxazin, we used a panel of biomarkers: pigment contents, chlorophyll fluorescence parameters and antioxidative enzyme activities. Algae and duckweed were exposed to 48-h IC50 for growth rate. In L. minor, the sensitivity of the parameters was as follows: Q(N) > Oxygen emission > PhiS(PSH) > Q(P) > Phi(PSII) > CAT, GR > Pigment > APO > Growth. For S. obliquus, this ranking was as follows: CAT > Oxygen emission > Q(P) > APO > GR > Pigment > PhiS(PSII) > Growth > Phi(PSH) > Q(N) (from the greatest to the least sensitive). The results demonstrated that the observed toxicity is related not only to interspecific variations but also to the selected parameter. (C) 2004 Elsevier Ltd. All rights reserved.