Distribution and variability of silicon, copper and zinc in different bamboo species

With a high growth rate and biomass production, bamboos are frequently used for industrial applications and recently have proven to be useful for wastewater treatment. Bamboos are considered as Si accumulators and there is increasing evidence that silicon may alleviate abiotic stresses such as metal toxicity. The aim of this study was to investigate the extent of metal concentrations and possible correlations with Si concentrations in plants. This study presents, for the first time, reference values for silicon (Si), copper (Cu) and zinc (Zn) concentrations in stems and leaves of various bamboo species grown under the natural pedo-climatic conditions of the island of R,union (Indian Ocean). A broad range of silicon concentrations, from 0 (inferior to detection limit) to 183 mg g(-1) dry matter (DM), were found in stems and leaves. Mean leaf Cu and Zn concentrations were low, i.e. 5.1 mg kg(-1) DM and 15.7 mg kg(-1) DM, respectively. Silicon, Cu and Zn concentrations increased over the following gradient: stem base < stem tip < leaves. Significant differences in Si, Cu and Zn contents (except Zn in the stem) were noted between bamboo species, particularly between monopodial and sympodial bamboo species, which differ in their rhizome morphology. Sympodial bamboos accumulated more Si and Cu than monopodial bamboos, in both stems and leaves, whereas sympodial bamboos accumulated less Zn in leaves than monopodial bamboos. The findings of this study suggest that a genotypic character may be responsible for Si, Cu and Zn accumulation in bamboo.