Effects of Organic and Inorganic Nitrogen on Growth and Cadmium accumulation of Sedum alfredii Hance

The effects of organic and inorganic nitrogen on plant growth and cadmium absorbability and accumulation in two ecotypes of Sedum alfredii Hance were investigated using hydroponic culture. Compared with the control (T1), the application of inorganic nitrogen (urea) markedly increased the biomass (dry weight) of shoot and root and chlorophyll a, b content of two ecotype Sedum alfredii Hance under both low cadmium(10 μmol·L-1) and high cadmium(100 μmol·L-1) treatments (P0.05). At low cadmium, only Cd concentration in hyperaccumulating ecotype(HE) shoot and non-hyperaccumulating ecotype (NHE) root increased markedly under the treatment with inorganic nitrogen (P0.05). At high cadmium, the application of inorganic nitrogen had no significant effect on the concentration of Cd in two ecotypes of Sedum alfredii Hance (P0.05). While at both low cadmium and high cadmium, compared with the control, the biomass(dry weight) of shoot and root and chlorophyll content of HE declined markedly when applied with organic nitrogen (arginine) (P0.05). At low cadmium, the application of organic nitrogen increased markedly the concentration of Cd in two ecotypes of Sedum alfredii Hance (P0.05), but had no significant effect on concentration of Cd in two ecotypes of Sedum alfredii Hance at high cadmium (P0.05).