Heavy Metal Tolerance And Accumulation Characteristics Of Vetiveria Zizanioides

Phytoremediation is an innovative technology that uses plants to remove and/or degrade environmental contaminants such as heavy metals and organic compounds. Plants that possess the ability to accumulate high levels of metals in their biomass are referred to as metal accumulator. Remediation of heavy metal contaminated sites using plants presents a promising alternative to current environmental methodologies. In the hydroponic experiment, the effects of Cd, Zn and Cu on the growth and its accumulation in the vetiver plant were determined. A low level of treatment medium heavy metals slightly stimulated the growth of vetiver. Plant dry biomass and water contents slightly increased with low heavy metal treatments. Toxicity appeared only at the respective highest exposure concentrations of Cd, Zn and Cu treatment.Results showed that exposure to lower heavy metal levels (1 and 7.5 mg/L for Cd and 5 for Zn and Cu, respectively) led to increased chlorophyll contents and root activities, while higher level of Cd treatment caused a significant decrease in these parameters. Malondialdehyde (MDA) contents were found to be significantly enhanced at all heavy metal concentrations.The contents of heavy metals in the plant roots and leaves increased with increasing heavy metal treatment concentration. The most of heavy metals taken up by plant accumulated in the roots (2232 mg Cd/kg, 6528 mg Cu/kg and 2580 mg Zn/kg after 15 d at their highest treatment concentration) , and only a minor amount of Zn and Cu were translocated to shoots (229 mg Cu/kg and 1164 mg Zn/kg). Interestingly, compared to the standard of Cd hyperaccumulation-100 mg kg-1·DW of Cd in shoots, vetiver had no ability to accumulate Cd in this study considering accumulated 93 mg kg-1·DW of Cd in shoots. In view of their fast growth, high biomass, and adequate heavy metal tolerant system, vetiveria zizanioides appear to have great potential for remediation purposes.