Manganese uptake and accumulation in a woody hyperaccumulator, Schima superba

A wide-spread subtropical tree species, Schima superba (Theaceae), occurring in a Mn mine wasteland, was found to contain unusually high Mn content in the leaf tissues. A pot growth experiment with different Mn treatments was conducted to further illustrate its Mn tolerance, accumulation and relocation capacity. Schima saplings grew well and showed no symptoms of Mn toxicity with Mn supply below 60 mmol/l. Total plant biomass decreased with the increase of Mn supply, but Mn contents in tissues increased significantly, and peaked (62 412.3 mg/kg) in stem at 150 mmol/l treatment. Under all treatments, Mn concentrations in the aboveground tissues were constantly greater than those in roots. When the external Mn supply was over 40 mmol/l, the Mn levels in the leaves and stems all exceeded 10 000 mg/kg, the suggested value for Mn hyperaccumulation. Most of the Mn taken from the substrates were transported to the aboveground tissues, e.g. over 86% accumulated in the aboveground parts at 150 mmol/l treatment, These findings confirmed that Schima superba is a Mn hyperaccumulator.