Effects of selenium–cadmium interactions on soil cadmium forms and the enrichment of selenium and cadmium in rice

Aims

The relationship between selenium (Se) and cadmium (Cd) is a commonly observed phenomenon in nature, making it a hot research topic. Se, an essential trace element for human biology, frequently coexists in soil alongside hazardous heavy metal Cd. The challenging objective of ensuring Se enrichment in crops while minimising the detrimental effects of Cd in Se-rich soils has emerged as a prominent research theme.

Methods

In this study, rice was used as the experimental model to investigate the impact of low (0.2 mg·kg⁻¹), medium (1.0 mg·kg⁻¹) and high (5.0 mg·kg⁻¹) concentrations of Se, as well as low (0.5 mg·kg⁻¹), medium (2.5 mg·kg⁻¹) and high (10.0 mg·kg⁻¹) concentrations of Cd, on the enrichment and distribution of Cd and Se in several parts of rice crops.

Results

The findings demonstrated that the dynamics between different concentrations of Se and low concentrations of Cd considerably reduced Cd enrichment in brown rice, ultimately reaching a state of no Cd enrichment. At medium and high Se concentrations, the higher the Cd concentration, the more pronounced the inhibition of Se enrichment in brown rice. When 0.2 mg·kg⁻¹ Se interacted with 0.5 mg·kg⁻¹ Cd, brown rice fulfilled the standards for being Se-rich, Cd-free and safe for consumption.

Conclusions

Se and Cd exhibited a synergistic effect at low concentrations, whereas revealed an antagonistic effect at medium and high concentrations on Se and Cd enrichment in brown rice.