Effects of living hyperaccumulator plants and their straws on the growth and cadmium accumulation of Cyphomandra betacea seedlings

To determine whether the living hyperaccumulator plants and their straws have the same effects on the growth and heavy metal accumulation of common plants, two pot experiments (intercropping experiment and straw mulch experiment) were conducted to study the effects of living hyperaccumulator plants (Solanum photeinocarpum, Tagetes erecta, Galinsoga parvifiora and Bidens pilosa) and their straws on the growth and cadmium (Cd) accumulation of common plant Cyphomandra betacea seedlings. Intercropping with T. erecta or B. pilosa promoted the growth of C. betacea seedlings compared with the monoculture, while intercropping with S. photeinocarpum or G. parvifiora inhibited that. Intercropping with S. photeinocarpum decreased the Cd contents in the roots and shoots of C. betacea seedlings compared with the monoculture, but intercropping with the other plants did not. In the straw mulch experiment, the straw of S. photeinocarpum or T. erecta promoted the growth of C. betacea seedlings compared with the control, while the straw of G. parvifiora or B. pilosa did not. The straw of S. photeinocarpum or T. erecta decreased the Cd contents in the shoots of C. betacea seedlings, and the straw of G. parvifiora or B. pilosa increased the shoot Cd contents. Thus, intercropping with S. photeinocarpum and applying S. photeinocarpum or T. erecta straw can reduce the Cd uptake of C. betacea.