Accumulation of cobalt and nickel in tissues of Clethra barbinervis in a metal dosing trial

Aims This study reveals the accumulation properties of Co from viewpoints of the analogy with Ni and also the variation of the other essential micro elements in the Co accumulator tree, Clethra barbinervis . Methods Seedlings of C. barbinervis were grown in single and mixed treatments in the rhizosphere containing Co, Ni, or both at three different concentrations (5, 50, and 500 μM). In roots, stems, and leaves, the concentrations of Cu, Fe, Mn, and Zn, together with Co and Ni, were determined. Results Biomass was reduced in plants treated with 500 μM Ni, but not when treated with Co. The Co concentration in leaves was higher than those in other tissues, and the maximum Co accumulation in leaves was 2012 μg g −1 . Accumulation of Co competed with Zn transport and stimulated Cu transport. Conclusion Our results indicate that C. barbinervis is a Co hyperaccumulator and is more tolerant to Co than to Ni. The Co hyperaccumulation capacity is likely achieved by Zn transport systems involved in root to shoot translocation, and Co accumulation has some competitive and facilitative interactions with the other heavy metals.