Differences in uptake and tolerance to cadmium in varieties of Salix integra

Willows (Salix spp.) have been proposed for use in phytoremediation technology. Three varieties of Salix integra in hydroponic experiments for their metal resistance and accumulation were investigated. Plants were exposed for 6 weeks with 0 μmol · L -1, 10 μmnol · L -1, 50 μmol · L -1 CdCl 2, measurements of growth parameters have been combined with Cd concentration in shoots and roots. Plant biomass, metal tolerance and Cd accumulation pattern in shoots and roots varied among varieties. Shoot growth and number of lateral roots were significantly reduced under cadmium treatment, 10 μmol · L -1 and 50 μmol · L -1 CdCl 2 treatments reduced the dry biomass of shoots and roots, Elevated Cd concentration in medium decreased Cd transport from roots to shoots in all varieties. The leaf: root ratios for Cd in all varieties were < 1, but the total amount of Cd in shoot: root were highly significantly > 1, the ratios of total amount of Cd decreased with Cd level in the medium. Tolerance Index (TI root,) of S. integra 'Weishanhu' variety was 0.61-0.82, S. integra 'Dahongtou' variety had a TI root of 0.88, TI root of S. integra 'Yizhibi' was about 0.92-0.93. These results showed that Salix integra has the potential to be used for phytoextration of Cd in moderately contaminated soil.