Objective  Proper selections of rice varieties, soil conditioners, and foliar blockers to mitigate the ill-affected rice quality and production and soil condition on a Cd-Pb contaminated paddy field were investigated.

Method  In a field experiment, conventional hybrid rice varieties, Yongyou 9, Yongyou 1540, Yongyou 17, Tailiangyoumeisi, Liangyou 1516, Xiliangyoufengsimiao, Gengxiangyoutangsi, Gengxiangyou 703, Zhongzheyou 8, and Zengxiangsilongwangliangyou 889, were planted on Cd-Pb contaminated soils treated with various conditioners and sprayed on plant leaves with different foliar blockers. Grain yield and Cd-Pb in the harvested brown rice of each rice variety as well as in the soils under treatments were recorded. The soil conditioners applied included oyster shell powder, medical stone powder, Yimida soil remediation agent IM-2, Yimida soil conditioner IM-3, ultra-stable mineralized soil remediation new material, and Yangyu soil structure conditioner, and the foliar blockers included Chuge, Linglong silicon, Geili silicon, Liang'anhao, liquid silicon. Effectiveness and feasibility of the combined optimal treatments in reversing the ill-effects of the heavy metal contamination on the farmland were examined.

Result  Significant differences on yield and Cd-Pb in brown rice of the varieties of rice grown on the lots were found. For instance, Yongyou 17 had the highest yield and Tailiangyoumeisi the lowest, but the Cd-Pb contents for all 10 rice cultivars were below the national standards GB 2762-2022, 0.2 mg·kg⁻¹ for Cd and 0.2 mg·kg⁻¹ for Pb. Zengxiangsilongwangliangyou 889, Yongyou 9, Zhongzheyou 8, and Yongyou 17 performed well on yield with low Cd-Pb. The soil conditioners, other than the ultra-stable mineralized soil remediation new material, significantly raised the soil pH and grain yield. Among them, the oyster shell powder, medical stone, Yimida soil conditioner IM-3, and the ultra-stable mineralized soil remediation new material significantly lowered the available Cd-Pb in soil; the oyster shell powder, Yimida soil conditioner IM-3, Yangyu soil structure conditioner, and the ultra-stable mineralized soil remediation new material significantly reduced the Cd in brown rice; and, except Yangyu soil structure conditioner, all others helped to render Pb not detectable in the brown rice. The tested foliar blockers sprayed on rice plants significantly improved the grain yield with reduced Cd in brown rice in the order of: Liang'anhao＞liquid silicon＞Linglong silicon＞Chuge＞Geili silicon. Aside from Liang'anhao, the foliar blockers also decreased the Pb in brown rice to a non-detectable level. In combination, the three methods tried in this study not only effectively decreased the Cd-Pb contents in brown rice and soil but also significantly enhanced the grain yield.

Conclusion Zengxiangsilongwangliangyou 889, Yongyou 9, Zhongzheyou 8, and Yongyou 17 were low in accumulating Cd-Pb and high on yield. The oyster shell powder and Yimida soil conditioner IM-3 were the choice soil conditioners. The liquid silicon or Linglong silicon performed satisfactorily as a foliar blocker. By combining the above-recommended selections for a treatment, an effective reduction in soil Cd-Pb, crop increase on rice, and safety assurance for consumption could be realized.