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The physiological response of Arundo donax L. to thallium (Tl) accumulation in a simulated wetland
A simulated wetland experiment was employed to investigate the effect of thallium (Tl) accumulation on the growth of Arundo donax L. and its photosynthetic characteristics and antioxidant enzyme activities. Our results showed that Tl accumulated in the order of stems < leaves < roots and gradually increased with increasing Tl concentrations (from 0 to 2.5 µg/L). Relevant Tl applications (from 0.2 to 2.5 µg/L) increased both the rates of photosynthesis (Pn) and transpiration (Tr) and the activities of catalase (CAT) and peroxidase (POD). Tl slightly affected stomatal conductivity (Gs) but had no effect on the relative chlorophyll content (SPAD) or the potential and effective photochemical efficiency of photosystem II. However, intercellular CO2 concentration (Ci) and superoxide dismutase (SOD) decreased in response to increasing Tl concentrations. Although 50 µg/L Tl treatments significantly decreased the SPAD and the potential and effective photochemical efficiency of photosystem II, these treatments had no effects on Pn and Tr. These results suggested that root restriction and oxidative stress were involved in the mechanism of thallium toxicity, but the photosynthetic system of A. donax was not harmed by certain concentrations of Tl, suggesting the strong tolerance of this species to increased Tl pollution.
MF17093 Accepted 20 September 2017
© CSIRO 2017