Short-Term Effects of Arsenate-Induced Toxicity on Growth, Chlorophyll and Carotenoid Contents, and Total Content of Phenolic Compounds of Azolla filiculoides

Abstract

This study evaluated the toxic effects of arsenic (As) on the growth, total antioxidant activity, total content of phenolic compounds, and content of photosynthetic pigments of Azolla filiculoides. The aquatic fern was propagated and exposed to Yoshida nutrient solution contaminated with sodium arsenate (Na2HAsO4·7H2O) at six concentrations (5, 10, 20, 30, 60, and 120 μg As mL−1), including the control without As contamination. Azolla cultures were kept under environmental chamber conditions 26°C, 12 h photoperiod and 80% HR for 96 h. Increased As concentrations (>30 μg mL−1) significantly diminished growth of A. filiculoides and the total content of chlorophyll and total phenolic compounds, but significantly enhanced of total carotenoid + xanthophylls content. The concentrations of 5 and 10 μg As mL−1 significantly stimulated the growth of A. filiculoides. This aquatic fern tolerates As concentrations lower than 30 μg mL−1, and its maximum As accumulation (28 μg g−1 dry weight) was achieved when exposed to 60 μg As mL−1, but showing clear symptoms of As toxicity.