Zinc tolerance and accumulation in the ferns Polypodium cambricum L. and Pteris vittata L.

Zn uptake and compartmentalisation were studied in two ferns, the European Polypodium cambricum L., a possible Zn tolerant, and the sub-tropical Pteris vittata L., an As accumulator also able to accumulate Zn. Ferns growing in hydroponic systems were exposed to Zn concentrations ranging from non-toxic to lethal doses (0, 50, 125, 250, 500 mg/kg as ZnSO4). After treatments, the following analyses were made: photosynthetic efficiency (Handy PEA), anatomical symptoms (optical and scanning electron microscopy), determination of Zn in fronds, rhizome and roots (atomic emission spectrometry, ICP-AES). Both species showed high bioconcentration and bioaccumulation factors, but low translocation factor, indicating Zn sequestration in the root/rhizome system. P.cambricum was more resistant to Zn, while P.vittata suffered from unrestricted uptake leading to macro- and microscopical damages and plant death. Data suggest that P.cambricum could be suitable for phytostabilisation of Zn-contaminated soils in temperate areas.