Document Type : Original Article
Heavy metal contamination of soil, water and air has caused serious environmental hazard in the biosphere due to rapid industrialization and urbanization. A variety of metal binding ligands such as organic acids and amino acids involve in the heavy metal remediation mechanisms by plants. This paper analyses the possible role of amino acid histidine and organic acids, namely, citric, oxalic and fumaric acids to elevate the absorption of Pb and Cd by canola plants. Soaked seeds were placed in plastic dishes of 10cm diameter with a layer of filter paper on bottom and 10 ml aqueous solution of each treatment with certain Pb and Cd and concentration was added. After 72 hours, the content of Cd and Pb in canola seedlings was measured using atomic absorption technique. All data compared using ANOVA test and SPSS (v. 17) and p<0.05. The results showed that oxalic acid and citric acid elevate the accumulation of cadmium in experimental group (plants under Cd treatment with no organic acid exposure). Although all organic acid treatments (including histidine as a mono-carboxylic acid) increase Pb absorption and accumulation by canola plants, Pb accumulation was higher in plants just under Pb treatment with no additional carboxylic acid exposure. Therefore, the possible role of organic acids in heavy metals detoxification and resistance processes by canola plants is suggested for further research.