Purpose. This work was planned for providing a useful screening tool for the selection of Populus alba clones suitable for phytoremediation techniques. To this aim, we investigated variation in arsenic, cadmium, copper and zinc tolerance, accumulation and translocation in three poplar clones through an in vitro screening. Poplars have been widely proposed for phytoremediation, as they are adaptable to grow on contaminated areas and able to accumulate metals. The investigation of possible differences among poplar clones in metal tolerance and accumulation deserves to be deeply studied and exploited for the selection of the more suitable tool for phytoremediation purposes. Methods. In vitro multiplied microshoots of a commercial and two autochthonous Populus alba clones were subcultured on hormone-free WPM medium for one month and then transferred for two weeks onto media containing different concentrations of the metals investigated. At the end of the treatments, plantlets were sampled, weighed and mineralised by wet ashing. Metal concentrations were determined by ICP-OES. Results. For the metal concentration used in the experiments, our clones of Populus alba showed variation in metal tolerance, metal accumulation and content. The fast growing commercial clone, even if rarely showing the highest plant metal concentration, displayed the highest metal content, suggesting biomass production as the key factor in evaluating the phytoextraction capacity of Populus alba clones for the metals studied. Conclusions. Data demonstrated that in vitro screening of cuttings represents a valuable way of assessing the ability of different poplar clones, to take up, tolerate and survive metal stress.
