Intercropping coupled with inoculation on Cd accumulation in a Sedum alfredii-oilseed rape system under various field conditions

Intercropping of hyperaccumulator and cash crop, as a kind of phytoremediation coupled with agro-production (PCA), is now considered a promising strategy to address the issue of Cd contamination in arable lands. In the present study, hyperaccumulator Sedum alfredii intercropped with oilseed rape ( Brassic juncea L) in three Cd contaminated fields were conducted to explore the effects of intercropping on growth performance and Cd accumulation in plants coupled with application of plant growth promoting endophyte (PGPE) consortium. The results indicated that shoot biomass was increased by intercropping, PGPE inoculation, and superposition treatment with 2.16-25.5 %, 3.79-22.9 %, and 22.2-44.0 % for S. alfredii and 2.30-14.3 %, 16.5-35.1 % and 19.3-50.1 % for oilseed rape across three sites as compared to monoculture. Intercropping and inoculation increased Cd accumulation by 4.65-17.4 % and 7.56-37.0 % for oilseed rape as well as 6.51-47.8 % and 13.2-32.8 % for S. alfredii among three locations, therefore increasing Cd removal efficiency in soil. The combination of intercropping and inoculation effectively increased Cd accumulation by 3.68-46.8 % considering only half the amount of oilseed rape and S. alfredii plants under strip intercropping as compared to the sum of two plants under monoculture. While Cd concentrations in seeds of oilseed rape were in the safe range of 0.04-0.18 mg kg -1 under intercropping or inoculation. These results revealed that synergistic application of intercropping and inoculation represents a viable approach to enhance the Cd phytoextraction efficiency and proposed an integrated technology pattern and sustainable technical assistance for PCA in slightly and moderately Cd contaminated soils, and also provided universal information for mechanisms between intercropping and PGPE inoculum.