Maize intercropping with cadmium-hyperaccumulator plant Solanum nigrum var. humile promotes growth and cadmium uptake of both plant species.

To alleviate the cadmium (Cd) stress in maize, we investigated the effects of intercropping maize with the Cd-hyperaccumulator plant Solanum nigrum var. humile on the growth and Cd uptake of both plant species under Cd stress (5 mg/L). Intercropping maize with S. nigrum var. humile increased the plant height, root length, and biomass in both plant species. Compared with their respective monocultures, intercropped maize showed the increase effects in root and shoot biomass by 13.58% and 8.58%, respectively, while intercropped S. nigrum var. humile exhibited the increases of 13.87% and 12.26%, respectively. Additionally, intercropping enhanced the photosynthetic pigment content, photosynthetic gas exchange parameters, and antioxidant enzyme activities in both plant species. Furthermore, intercropping with S. nigrum var. humile decreased the root Cd content but increased the shoot Cd content and translocation factor in maize. In S. nigrum var. humile, intercropping increased both root and shoot Cd contents, as well as the translocation factor. Thus, intercropping maize with S. nigrum var. humile can promote Cd uptake in aboveground parts of maize, and it may be not suitable for maize production in Cd-contaminated areas.