Abstract: [Objective] To select the clone with maximum Cd²⁺ concentration both in above- and under-ground parts, we have studied characteristics of Cd²⁺ absorption and distribution in 27 willow clones in their roots, bark of cuttings, branches and leaves, which can provide a theoretical basis for phytoremediation of Cd contaminated soil and an experimental basis for further studies of Cd detoxification mechanisms.[Method] A total of 27 willow clones with economic and ornamental value were studied. Different tissues of clones, including roots, branches, leaves and bark of cuttings, were sampled after 6 days of exposure to 40 mg·L^-1 CdCl₂ in hydroponic conditions and the cadmium concentration in these tissues were detected with atomic absorption spectrophotometer, contribution rate of cadmium transportation in different parts were then calculated.[Result] Cd were mainly accumulated in the roots of 27 clones with a range from 1 106.08 mg·kg^-1 to 4 261.46 mg·kg^-1. Specially, S. viminalis had the highest concentration, while clone Q2 was only 25.96% of the former. The Cd concentrations in above-ground part were detected at a range from 38.29 mg·kg^-1 to 207.87 mg·kg^-1, and the clones SH31 and D31 were the highest and the lowest cadmium accumulation respectively. Moreover, SH31 accumulated the most cadmium than other clones in leaf, branch and bark. Though the cadmium transport coefficient in the 27 willow clones was small, SH31 was the largest one with a value of 0.199, significantly higher than other clones, and clone 2465, was only 0.016. There were different contribution rates to Cd transportation in different tissues among different clones. Clones Q43 and SH18 had the biggest contribution to root-shoot transfer in branches, which was 56.3% and 57.2% respectively, while the bark was in dominant position during transportation in other clones, with a maximum accumulation of 88.5% in clone 23 and a minimum of 28.6% in Q43.[Conclusion] Cadmium were mainly enriched in roots in the 27 willow clones, and less cadmium was transferred to shoots. Furthermore, S. viminalis has the largest cadmium concentration in roots, mitigating the damage of Cd to other organs effectively and reducing the cadmium concentration in soil to alleviate the injury to other plants.SH31 accumulated the most cadmium in shoot than other clones, which could reduce the cadmium in soil by several short rotations and by collecting the shoots of SH3.

Key words: willow, Cd, aboveground, underground, root, branch, leaf, bark, beneficiation