Tolerance, absorption and accumulation of Ilex rotunda seedlings to lead and cadmium in polluted soil

Objective  This study was aimed to investigate the tolerance of Ilex rotunda, absorptions and accumulations of lead (Pb) and cadmium (Cd) in Pb or Cd polluted soil, and provide a theoretical basis for phytoremediation of Pb or Cd contaminated soil.

Method  A pot experiment was conducted to evaluate the effects of single Pb pollution (500, 1 000 and 1 500 mg·kg⁻¹) and single Cd pollution (10, 25 and 50 mg·kg⁻¹) on growth, root morphology, nutrients and Pb or Cd absorption and accumulation of I. rotunda seedlings.

Result  Compared with the control (non-polluted soil), 500 mg·kg⁻¹ Pb treatment significantly increased the root biomass and root surface area of I. rotunda, and both 500 and 1 000 mg·kg⁻¹ Pb treatments significantly increased shoot diameter and quality index. 1 500 mg·kg⁻¹ Pb treatment significantly reduced the biomass, quality index, and total nitrogen (N) accumulation ofI. rotunda and inhibited root growth, but significantly increased phosphorus (P) contents in root and shoot as well as potassium (K) content in shoot. All Pb addition treatments showed significantly higher total Pb contents and accumulations than those of the control treatment, and 1 500 mg·kg⁻¹ Pb treatment had the highest Pb contents and accumulations in root, shoot and total plant. Compared with the control, Cd treatments had no significant effect on growth, root morphology and nutrient accumulation of I. rotunda, but significantly increased K content in shoot. All Cd treatments significantly increased Cd contents and accumulations in root, shoot and total plant. Root Cd content increased significantly with the increase of Cd concentration, while 50 mg·kg⁻¹ Cd treatment had the highest root Cd content of 6.40 mg·kg⁻¹. The content and accumulation of Pb in root were significantly higher than those in shoot. Cd content in root was also significantly higher than that in shoot. Cd accumulation in root was significantly higher than that in shoot under 50 mg·kg⁻¹ Cd treatment.

Conclusion  I. rotunda is well adapted to single Pb or Cd pollution in soil, and has a strong ability to absorb and accumulate Pb or Cd. I. rotunda can be used as a candidate tree for remediation of Pb or Cd polluted soil.