Influence of some metal chelators and light regimes on bioaccumulation and toxicity of Cd2+ in duckweed (Lemna gibba) |
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Authors: | Emine Polar Rezzan Küçükcezzar |
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Institution: | Çekmece Nuclear Research Centre, P.K. 1 Havaalani, Istanbul, Turkey. |
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Abstract: | A factorial culture experiment was designed to investigate the influence of light regimes and of some metal chelators on the accumulation of cadmium by Lemna gibba L. The plants were grown in a complete nutrient solution containing Cd2+ concentrations ranging from 0 to 27 μ M with or without EDTA, ethylenediamine-N,N'- bis -( o -hydroxyphenylacetic acid) (EDDHA) or salicylic acid. Each experiment was run for eight days in 18 h:6 h light:dark or continuous light. An increase in the Cd2+ concentration in plants and a simultaneous drop in accumulation efficiency (ratio of Cd2+ concentration in plants to the initial Cd2+ concentration in the nutrient solution) with increasing ambient Cd2+ levels was best represented by regression power curves. At the lowest Cd2+ concentration which caused a significant decrease in the relative growth rate of duckweed, there was a decrease in manganese and zinc and an increase in the iron level in the plants. EDDHA and EDTA protected in some cases against the toxic action of cadmium without preventing its uptake by plants. It was thus observed that 9 μ M or higher levels of Cd2+ were toxic to Lemna gibba depending on the chelator and light regime. Duckweed grown in continuous light produced, in general, more dry matter and hence accumulated more cadmium. |
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Keywords: | EDDHA EDTA iron manganese salicylic acid zinc |
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