Effect of Planting Densities on Yields and Zinc and Cadmium Uptake by Sedum plumbizincicola

A field plot experiment was conducted to study the effects of planting densities on the growth and heavy metals uptake by Sedum plumbizincicola.The results showed that yields of Sedum plumbizincicola were enhanced with the increase of planting density;however,there was no further increase when planting density was too high.With planting density increasing from 1.1×10~5 plants per hm~2 to 4.4×10~5 plants per hm~2,Cd and Zn uptake of aboveground Sedum plumbizincicola increased from 0.208(kg·hm~(-2)) to 0.631(kg·hm~(-2)),from 13.2(kg·hm~(-2)) to 58.7(kg·hm~(-2)),respectively;yet,there was no significant enhancement between the planting density of 4.4×10~5 plants per hm~2 and 1.0×10~6 plants per hm~2.When planting density was 4.4×10~5 plants per hm~2,the Cd and Zn removal rates in contaminated soil were 21.1%,4.60%,respectively.Appropriate planting density would benefit Cd and Zn uptake of aboveground Sedum plumbizincicola,and shorten phytoremediation period.