Abstract: Objective: To investigate the effect of combined foliar application of zinc fertilizer and pesticides on the zinc bioavailability in wheat grains and their products. Methods: A two-year field experiment was conducted, with five treatments applied at the anthesis stage [control, Zn, Zn + thiophanate-methyl/cypermethrin (Zn + P1P2), Zn + thiophanate-methyl/propargite (Zn + P1P3), and Zn + cypermethrin/propargite (Zn + P2P3)], and five treatments applied at the milking stage [control, Zn, Zn + imidacloprid/triadimefon (Zn + P4P5), Zn + imidacloprid/carbendazim (Zn + P4P6), and Zn + triadimefon/carbendazim (Zn + P5P6)]. The concentrations of zinc, iron, manganese, and phytic acid (PA) in wheat grains and their products (flour, bran, steamed bread), as well as the quality attributes of steamed bread, were determined. Zinc bioavailability was evaluated using PA/Zn molar ratio and the total daily absorbed zinc (TAZ) model. Results: Compared with the control group, the combined foliar application of Zn with two pesticides at the anthesis stage (Zn + P1P2, Zn + P1P3, Zn + P2P3) or at the milking stage (Zn + P4P5, Zn + P4P6, Zn + P5P6) significantly increased the Zn concentration in wheat grains, flour, bran and steamed bread by 64.41%-94.21%, 54.99%–89.99%, 67.08%–86.67% and 56.31%-84.03%, respectively, but had no significant effect on grain yield or phytic acid content. Meanwhile, the combined application significantly reduced the PA/Zn molar ratio and increased the TAZ value, indicating a marked improvement in Zn bioavailability. Compared with the Zn-alone treatment, the combined application of Zn and pesticides did not significantly affect the Zn concentration or Zn bioavailability in flour, bran or steamed bread, nor were there any significant differences in Zn concentration or bioavailability between the anthesis and milking stage treatments. During the milling of zinc-enriched wheat, the loss rate of PA (89.46%–91.41%) was higher than that of Zn (83.93%–88.13%), resulting in a 1.43-fold higher Zn bioavailability in flour than in grains. During steamed bread making, PA concentration further decreased (68.04%–72.82%) while Zn concentration increased (11.35%–13.69%), leading to a significantly improved Zn bioavailability in steamed bread, which was 3.30 and 4.94-fold higher than that in flour and grains, respectively. In addition, the combined application of Zn and pesticides did not negatively affect the content or bioavailability of Fe and Mn, nor did it affect the quality of steamed bread. Conclusion: The combined foliar application of zinc fertilizer with pesticides commonly used by farmers at the anthesis or grain-filling stage can effectively increase the Zn content and bioavailability in wheat grains and their products (especially steamed bread), providing a practical and feasible approach to improving human zinc nutrition and health.

Key words: wheat; zinc fortification; bioavailability; steamed bread; quality