Effect of an arbuscular mycorrhizal fungus on maize growth and cadmium migration in a sand column

The ecological role of arbuscular mycorrhizal fungi (AMF) on altering cadmium (Cd) migration in polluted soil is still unresolved. The present experiment aimed to clarify whether AMF can reduce Cd loss due to leaching at different Cd concentrations (0, 5, 10, and 15 mg L-1) with maize as a host plant cultured in a sand column. The effects of the arbuscular mycorrhizal fungus Funneliformis mosseae on the root morphology, exudate content, and Cd uptake by maize and Cd loss due to leaching were investigated. The AMF altered the root morphology and exudate content of the maize, resulting in increases in the root length, volume, surface area, tips and branch number and in the contents of soluble sugars, proteins, and amino acids in the root exudates, and the AMF increased maize biomass and Cd uptake by 22.0-31.0%. Moreover, the AMF significantly increased the contents of total and easily extractable glomalin-related soil protein (GRSP), increased Cd adsorption by sand particles and decreased the Cd concentration in the solution at a depth of 20 cm, resulting in a 67.5-97.2% decrease in the Cd loss due to leaching from the sand column. Furthermore, the root exudate content was very significantly positively correlated with Cd adsorption by the sand particles. Root length was significantly positively correlated with Cd uptake by the maize roots, but the average root diameter was very significantly negatively correlated with Cd uptake by maize. Thus, the AMF altered Cd migration by increasing the contents of GRSP and exudates and root morphology, which contributed to reducing the Cd concentration in the solution and Cd loss due to leaching from the sand column. Taken together, these results indicated that AMF serve an ecological function in reducing Cd loss due to leaching from polluted soil.