Transport Characteristics and Mechanism S of C D by Bidens Pilosa L. R Oot S Under D Ifferent Exogenous Inorganic Ions and Ph Conditions

Abstract

To investigate the effects of exogenous inorganic ions and pHon Cd uptake by Bidens pilosa roots with application of NMT. The results indicated that Cd 2+ influxes at 300 μm from the root tips decreased under Cd treatments with higher concentration Ca 2+ , Mg 2+ , Fe 2+ , SO 4 2 - , Na + or K + , as compared to Cd stress alone. However, Cd treatments with lower concentration of ions had little effect on the net Cd 2+ influxes. Importantly, Cd treatment with 0.05mM Fe 2+ promoted Cd 2+ uptake by B. pilosa roots, and Cd treatments at pH=4.0 markedly increased Cd 2+ influxes in solutions. Results also showed that Cd treatments with higher concentration of ions significantly decreased concentrations of chlorophyll (Chl) a and b in leaves and root vigor of B. pilosa relative to Cd treatments alone while there were no significant differences between Cd treatments with lower concentration ions and Cd treatments alone. A significant increase of root vigor was observed in Cd treatments at pH=4.0, as compared to pH=5.5. Pearson correlation showed that physio-biochemical indicators were significantly positively related to Cd 2+ influxes, with the exception of biomass.

Keywords: cadmium, Bidens pilosa, influxes, root tips, root vigor