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156 T. Vamerali et al.

phytomanagement option with some species and for some trace elements only, but
is probably only effective over a long-term period. Among a narrow range of crops,
we found the Brassicacea fodder radish showed substantial Zn and Cu removals,
whereas management of the most toxic metals, such as As and Pb, still remains
problematic. The much larger variability in shoot metal concentrations of the crops
tested here compared with woody species suggests exploiting the potential of other
herbaceous species, although we believe that more profitable progress could be
achieved with an integrated approach involving genetics, biology, physiology and
especially agronomy, to maximise plant adaptation and growth. In any case,
identification of a pool of plants to be cultivated in association or in rotation is
necessary, in order to cover the soil permanently and reduce possible damage by
parasites. Assisted phytoextraction seems difficult to manage as regards timing and
dosages of the compounds used and frequently reduce biomass yield and metal
removal.
The phytomanagement of sites polluted by pyrite waste may simply involve the
establishment of a vegetation cover with cultivated plants left to reproduce them-
selves or with biomass harvesting and annual sowing. However, besides
phytoextraction, long-term stabilisation of metals in plant roots is an important
issue to consider, in view of the high metal retention at root level, and recent
evaluation at the University of Padova showed that 6 % of tap root biomass in
rapeseed was recalcitrant to degradation after about 18 months from shoot harvest.

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