Arsenic and Zinc Accumulation in Zinc-Biofortified Wheat under Arsenic-Contaminated Irrigation and Varied Zinc Application Methods

Abstract

Purpose: Arsenic (As) contamination in groundwater and soil affects the quality of plant-based foods, while zinc (Zn) deficiency in agricultural soils leads to global zinc malnutrition. Addressing these issues is both crucial and urgent, especially for wheat production. This study compared Zn application methods for decreasing grain As and increasing grain Zn concentrations in two Zn-biofortified wheat cultivars, Akbar-2019 and Zincol-2016. Methods: The experiment involved growing the cultivars in pots and applying Zn through different methods: control, seed priming with distilled water and 6 mM ZnSO₄ solution, soil application at 0 and 8 mg Zn kg⁻¹, foliar sprays of distilled water and 0.05% Zn (w/v) at booting and heading, and all combinations of these application methods. Throughout the growth period, the pots were irrigated with As-contaminated water (1.0 mg As L⁻¹). Results: Zinc application significantly increased chlorophyll and carotenoid contents, and dry matter yields. Moreover, there was an increase in Zn and phosphorus (P) concentrations in grains, along with a rise in the estimated dietary intake (EDI) of Zn. This was associated with a simultaneous decrease in As concentrations in various plant parts, including grains, and a decrease in the EDI of As. The most significant increase in grain yield and grain Zn accumulation, coupled with the most notable decrease in grain As concentration, was observed with the combined application of Zn through seed priming, soil application, and foliar spray. Conclusion: Soil application and foliar spray of Zn mitigate As contamination in wheat grains under As-contaminated irrigation, while also ensuring agronomic Zn biofortification.