Influence of Foliar Zinc Application on Cadmium and Zinc Bioaccessibility in Brassica chinensis L.: In Vitro...

Foliar zinc (Zn) application can affect the accumulation and bioaccessibility of cadmium (Cd) and Zn in crops. However, the mechanisms by which foliar Zn application influences Cd and Zn bioaccessibility remain elusive. This study examined the effects of spraying ZnSO₄ and ZnNa₂EDTA on bioaccessibility and chemical forms of Cd and Zn in pakchoi (Brassica chinensis L.) shoots and evaluated human health risks via pakchoi consumption. Spraying ZnSO₄ reduced the concentrations of ethanol-extractable (F_ethanol) and deionized water-extractable (F_d-H2O) Cd, as well as the corresponding bioaccessible Cd concentrations (20.3-66.4%) and attendant health risks of Cd, whereas spraying high-dose ZnNa₂EDTA significantly increased the concentrations of both Cd forms and bioaccessible Cd. Spraying ZnSO₄ and high-dose ZnNa₂EDTA significantly increased the concentrations of Zn in F_ethanol and F_d-H2O and the corresponding bioaccessible Zn concentrations (0.8-8.3-fold). F_ethanol and F_d-H2O were the primary sources of bioaccessible Cd and Zn, contributing more than 59% of the bioaccessible Cd and Zn. These results indicate that foliar Zn application can affect Cd and Zn bioaccessibility in pakchoi mainly by modulating Cd and Zn in F_ethanol and F_d-H2O. These findings provide scientific support for the development of more efficient measures to produce safe and high-quality leafy vegetables from Cd-polluted soils.