Nitrogen application to enhance zinc and cadmium uptake by the hyperaccumulator Sedum alfredii.

Two hydroponic culture experiments were conducted in a glasshouse to understand the effect of nitrogen (N) nutrition on growth and the zinc and cadmium (Zn/Cd) uptake by Zn/Cd hyperaccumulator Sedum alfredii.Results showed that both low(≤0.50 mmol·L-1) and excessive(5.00 mmol·L-1) supply of N impaired growth of plant dry matter and reduced plant uptake of Zn and Cd.By contrast,2.50-5.00 mmol·L-1 of N improved plant growth,increased concentrations of Zn(to 12.00 g·kg-1) and Cd (to 2.00 g· kg-1) in the shoots,and enhanced partitioning of Zn and Cd from roots to shoots.Thus,to maximize heavy metal phytoremediation efficacy for Zn/Cd contaminated soils in the field,optimal N fertilization of S.alfredii is required.