| To investigate the role of foliar inhibitors in the safe production of wheat under mildly to moderately Cd- and Pb-contaminated soil conditions, a field plot experiment was conducted using the wheat variety Bainong 307 as the experimental material. A Zn-Fe-Mn-Mg mixed foliar inhibitor (A), a silicon-based foliar inhibitor (B), and a zinc-based foliar inhibitor (C) were sprayed at the jointing, booting, and grain-filling stages of wheat, respectively, with water spraying used as the control (CK). This study mainly evaluated the effects of different treatments on wheat yield, Cd and Pb contents in different plant parts, and their translocation, aiming to screen foliar inhibitors that could effectively reduce Cd and Pb contents in wheat grains. The results showed that, compared with the control (CK), all treatments had no significant effect on the theoretical yield of wheat. Compared with the control, the three foliar inhibitors (A, B, and C) significantly reduced Cd and Pb contents in grains (P<0.05), bringing them within the limit values specified in the National Food Safety Standard for Maximum Levels of Contaminants in Foods, with Pb showing a greater reduction than Cd. Specifically, the three treatments reduced grain Cd contents to 0.062, 0.059, and 0.079 mg/kg, with reductions of 49.59%, 52.55%, and 36.39%, respectively. The silicon-based foliar inhibitor (B) showed the greatest reduction, followed by the Zn-Fe-Mn-Mg mixed foliar inhibitor (A) and the zinc-based foliar inhibitor (C). For Pb content, the three treatments reduced grain Pb contents to 0.038, 0.015, and 0.032 mg/kg, with reductions of 61.31%, 84.65%, and 66.91%, respectively. The silicon-based foliar inhibitor (B) performed best, followed by the zinc-based foliar inhibitor (C) and the Zn-Fe-Mn-Mg mixed foliar inhibitor (A). In addition, compared with the control, all treatments significantly reduced the translocation factors of Cd and Pb from glumes, stems, and leaves to grains. Correlation analysis showed that grain Cd content was significantly positively correlated with the grain/leaf translocation factor (TF) (P<0.05). Grain Pb content was extremely significantly positively correlated with stem Pb content (P<0.01) and the grain/glume translocation factor (TF) (P<0.001), significantly positively correlated with the grain/leaf translocation factor (P<0.05), and significantly negatively correlated with the glume/stem translocation factor (P<0.05). In addition, glumes acted as a barrier to the translocation of Cd and Pb to grains. Overall, this study recommends the use of the silicon-based foliar inhibitor as an effective measure to significantly reduce Cd and Pb contents in wheat grains, thereby improving the level of safe wheat production under contaminated soil conditions. |
