engleski

Adaptive response of Poplar (Populus nigra var. italica) after long-term Cd exposure

An outdoor pot experiment was designed to study the changes of growth parameters, accumulation and distribution of Cd in Poplar (Populus nigra var. italica) during a prolonged exposure period (growing period of 17 months including 3 harvest points), allowing the consideration of time effects and long term adaptation to Cd stress. Simultaneously, changes to the antioxidant system in roots and leaves were monitored. It was demonstrated that Poplar could adapt to the Cd contaminated soils after prolonged exposure. Total Cd accumulation in the aerial parts of Poplar, due to high biomass production and acceptable Cd accumulation parameters, implies that the tested Poplar species could be a good candidate for phytoextraction application in Cd soil contents up to 25 mg kg-1 soil while Poplar could be used as phytostabilizator of Cd in heavy polluted soil. Furthermore, the activity of the antioxidant machinery displays both a tissue- and exposure-specific response pattern to different Cd treatments, indicating that strict regulation of the antioxidant defence system is required for the adaptive response of Poplar. In addition, this report highlights the importance of prolonged exposure studies of physiological responses of plants, especially for long life cycle woody species under heavy metal stress, since some misleading conclusions could be reached after shorter time periods.

antioxidative enzymes; cadmium; heavy metal stress; phytoremediation; Populus nigra; prolonged exposure period

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