Use of fluorescence induction kinetics of Lemna minor as a tool for chemical stress evaluation

Abstract

Slow fluorescence induction kinetics have been studied for Lemna minor under exposure to toxic chemicals. The first objective of the study was to find optimal values for condition measurements (dark adaptation time, light intensity, temperature, biomass and CO 2 concentration) to obtain only fluorescence induction due to chemical stress. The second end point was to test three chemical compounds, pentachlorophenol (PCP), simazin wand potassium bichromate. Results of toxicity were expressed as an index derivated from the Lichtentaler Vitality Index. A log-type dose-response curve was obtained for the three chemicals with an I 50 of 1.7 mg·1 −1 for PCP, 2.7 mg·1 −1 for simazin and 45 mg· −1 for potassium bichromate. This index is correlated to the inhibition of growth. The studied signal seems to be a good marker of pertubation of photosynthesis of aquatic plants in respect of the low variability (1–10%), the time scale of the response (1–2 min) and its easiness.