Zinc accumulation potential and toxicity threshold determined for a metal-accumulating Populus canescens clone in a dose-response study.

The effect of increasing soil Zn concentrations on growth and Zn tissue concentrations of a metal-accumulating aspen clone was examined in a dose-response study. Plants were grown in a soil with a low native Zn content which was spiked with Zn salt solutions and subsequently aged. Plant growth was not affected by NH(4)NO(3)-extractable soil Zn concentrations up to 60 microg Zn g(-1) soil, but it was completely inhibited at extractable concentrations above 90 microg Zn g(-1) soil. From these data an effective concentration of 68.5 microg extractable Zn g(-1) soil was calculated at which plant growth was reduced by 50%. The obtained information on toxicity threshold concentrations, and the relation between plant Zn accumulation and extractable soil Zn concentrations may be used to assess the suitability of the investigated Populus canescens clone for various phytoremediation strategies. The potential risk of metal transfer into food webs associated with P. canescens stands on Zn-polluted sites may also be estimated.