The influence of humic substance on Cd accumulation of phytostabilizer Athyrium wardii (Hook.) grown in Cd-contaminated soils

The application of organic amendments into heavy metal contaminated soil is considered as an environmentally friendly technique to promote the potential of phytoremediation. A pot experiment was carried out to evaluate the effect of humic substances on growth, cadmium (Cd) accumulation and phytostabilization potential of the mining ecotype (ME) and the corresponding non-mining ecotype (NME) of Athyrium wardii (Hook.) grown in Cd-contaminated soils. The addition of the humic substances demonstrated great promotion for the growth and Cd uptake of ME. Both plant biomass and Cd concentration significantly increased with the increasing application of the humic substances up to 100 g kg⁻¹, beyond which no significant change of underground part biomass and Cd concentrations in underground part of A. wardii was observed. The maximum Cd concentration in underground part of ME was 180 mg kg⁻¹ when 150 g kg⁻¹ humic substances were applied. The ME showed greater Cd accumulation capability in underground part (0.47–0.68 mg plant⁻¹) than that of NME (0.27–0.45 mg plant⁻¹). Increasing bioaccumulation coefficient (BCF) values of A. wardii was observed with increasing application of the humic substances. The BCF values of ME were higher than those of NME. However, the use of the humic substances exhibited little impact on translocation factors (TFs) of ME, and the TF values of ME were less than NME. Furthermore, the application of the humic substances improved the remediation factors (RFs) of A. wardii. The RF values in underground part of ME ranging from 0.73 to 0.91 % were apparently higher than those of NME. These results indicated that the humic substances can be a potential candidate for enhancing the phytostabilization of A. wardii grown in Cd-contaminated soils.