Morphophysiological responses, heavy metal accumulation and phytoremoval ability in four willow clones exposed to cadmium under hydroponics

Water pollution by heavy metals has become a serious concern in the developing world; thus, the reclamation of this natural resource represents a major environmental challenge. In this context, the development of sustainable technologies such as the phytoremediation is considered a promising opportunity. Salix spp., forest species of the riparian ecosystem, have been suggested as prospective candidates for phytoremediation of contaminated soil and water. In this study four Salix alba L. clones were treated under hydroponics with 50 ?M cadmium sulphate, and the growth responses, photosynthetic performance and metal accumulation in different organs were evaluated in order to assess the Cd tolerance and phytoremoval ability. Significant differences among clones were observed. In particular, a notable capability to extract Cd from the metal-spiked solution and accumulate it in roots and to a lesser extent in above-ground organs was highlighted in clone SS5. Moreover, analysis of morphophysiological traits (biomass production and photosynthetic performance) revealed that this clone was more tolerant to Cd than the other clones. The suitability of the willow clones as a biological tool for the reclamation of Cd-contaminated water is discussed, taking into account the notable Cd phytoremoval ability shown by the S. alba clone SS5.