Cd accumulation characteristics of Salvia tiliifolia and changes of rhizospheric soil enzyme activities and bacterial communities under a Cd concentration gradient

Abstract

This study aimed to explore the phytoremediation potential of Salvia tiliifolia for cadmium (Cd)-contaminated soils and to understand the interactions in soil-Cd-plant systems. We assessed the Cd tolerance and accumulation characteristics of S. tiliifolia grown in soils with 0, 5, 25, and 50 mg kg− 1 Cd for 3 months. We also analysed the changes in physicochemical properties, enzyme activities, and bacterial community composition in the rhizosphere soils of S. tiliifolia. S. tiliifolia could tolerate all Cd concentrations with unchanged biomass. Cd concentrations (21.50–189.50 mg kg− 1) in roots of S. tiliifolia and corresponding bioconcentration factors (3.79–4.30) were much higher than those in shoots, and Cd translocation factors (0.03–0.23) were thereby very low. Rhizosphere pH decreased with increasing concentrations of Cd. Soil pH and rich organic matter may jointly affect the soil available Cd. Ultimately, soil enzyme activities involved in carbon, nitrogen, and phosphorus cycles were affected to varying degrees, and bacterial diversity and richness were slightly influenced by Cd stress. Interestingly, bacterial ABC transporters were induced by Cd stress during this process. S. tiliifolia can be designed as a Cd excluder. The induced soil bacterial ABC transporters may contribute to Cd detoxification and accumulation in both soil microbial communities and S. tiliifolia plants.