3. Results
3.1. Uptake of Pb by vetiver in pot experiment
In the pot experiment, the vetiver grass grew well, and there were no visual signs of phytotoxicity in any of the treatments during the first 6 weeks after transplanting. After the application of EDTA (0.5, 2.5 and 5.0 mmol kg−1 of soil), vetiver seedlings under all different treatments showed no adverse effects, such as wilting, changing colour and necrosis for 14 days. The results showed that vetiver is able to grow in highly contaminated soil, even after EDTA application.
Table 2 depicts the Pb uptake patterns of the vetiver grown in the 500, 2500 and 5000 mg kg−1 Pb amended soils under different EDTA application programmes. In the control group without EDTA treatment, the shoot and root Pb concentrations increased significantly with increasing Pb concentration in the soils, in the shoot from 0.82 to 43.0 mg kg−1 of dry weight, and in the root from 60 to 556 mg kg−1 DW in the soils. Lead in the roots accounted for the majority of the total Pb in the plant. The translocation of Pb from roots to shoots was low (see Table 2).