Influence of root exudates and root activity on the availability of nutrients and other metals in the rhizosphere

摘要

The goal of this study was to investigate the influence of organic root exudates and root activity on nutrient and metal species in the rhizosphere of Lupinus albus and species and ecotypes of the plant genus Thlaspi. Using a modified version of the rhizobox system developed by Dieffenbach et al. (1997), we found that phosphate concentrations were highly variable in the vicinity of roots during the exudation of organic acids by Lupinus albus. In addition, large amounts of metal cations were mobilized in the rhizosphere of Lupinus albus during a burst of exudation. Metal concentrations were closely correlated with citrate. The Zn and Cd hyperaccumulator ecotype Gange of Thtaspi caerulescens investigated in this study strongly bound Zn and Cd to the root surfaces. We hypothesize that strong expression of high-affinity metal transporters by this plant is a key factor involved in Zn and Cd hyperaccumulation by this plant.