Sensitivity of Eucalyptus globulus to red and blue light with different combinations and their influence on its efficacy for contaminated soil phytoremediation.

Abstract

The influence of combined red and blue light on the capacity of Eucalyptus globulus to phytoremediate a metal-polluted soil was evaluated in this study. Five combinations of blue and red light (0%, 10%, 25%, 50% and 100% blue) at the same intensity were used to treat E. globulus, and its biomass generation, metal uptake and water absorption in phytoremediation under different light treatments were assessed. The plant produced significantly more biomass under blue light, regardless of the ratio, than under single red or white light. The highest biomass was generated under the light ratio of B10R90. In addition, light combination influenced the metal concentrations in different plant tissues. The highest concentrations of Cd and Cu in roots appeared under the light ratio of B0. All metals in plant shoots achieved their highest concentrations under the light ratio of B100, except Pb. Comparing with control, red and blue light combined in varying proportions increased the efficiency remove Cd, Pb and Cu by 50.6-65.6, 71.1-88.7 and 28.9-70.6%, respectively,. The leachate volume under blue and red light combinations was 46.7-66.0% less than control with the combination of B10R90 mitigating the most metal loss. Light sources with different spectra combinations can enhance the phytoremediation efficiency of Eucalyptus globulus and alleviate leaching risk at the same time.