To identify populations with the ability to accumulate heavy metals, a
pproximately 300 accessions pertaining to 30 plant species were grown
for 4 wk in a hydroponic media that approximated the nutrient and heav
y metal composition of a soil contaminated with moderate levels of cad
mium (Cd), copper (Cu), and zinc (Zn), The results indicated that seve
ral Brassica spp, exhibited moderately enhanced Zn and Cd accumulation
, Selected accessions of Brassica juncea (L,) Czern, B. napus L,, and
B, rapa L, were then grown in pots with heavy metal-contaminated soil
to compare the Zn and Cd phytoextraction by these species to that of T
hlaspi caerulescens J. & C, Presl, a known Zn and Cd hyperaccumulator,
and two grass species, Agrostis capillaris L, and Festuca rubra L, Th
e three Brassica spp, were the most effective in removing Zn from the
contaminated soil, primarily because they produced more than 10 times
the shoot biomass produced by T. caerulescens, When the soil was amend
ed with Gro-Power, a commercial soil amendment that improves soil stru
cture and fertility, removal of Zn by plant shoots doubled to more tha
n 30 000 mg Zn pot(-1) (4.5 kg). The results suggest that for phytorem
ediation of metal-polluted soils to be successful, a strategy should b
e considered that combines rapid screening of plant species possessing
the ability to tolerate and accumulate heavy metals with agronomic pr
actices that enhance shoot biomass production and/or increase metal bi
oavailability in the rhizosphere.