The application time and soil pH are key to manganese (Mn) bioavailability, which may influence Mn effects on cadmium (Cd) accumulation in rice. Accordingly, this study investigated the effects of Mn application at different stages, alone or with basal liming, on Cd accumulation in rice through pot and field experiments. The results showed that basal Mn application maximally elevated soil dissolved Mn, and increasing Mn accumulation in rice by 140%-367% compared to the control. Additionally, basal or tillering applications had better effects on enhancing iron manganese plaque (IMP) and inhibiting CaCl₂-extractable Cd than later applications. Therefore, basal and tillering Mn reduced brown rice Cd by 24.6% and 18.9% compared to the control, respectively. Liming reduced CaCl₂-extractable Cd by 83.3% compared to the control but inhibited soil dissolved Mn (25.8%-76.6%) and IMP (28.9%-29.7%), resulting in only a 41.7% reduction in brown rice Cd. Liming combined with tillering Mn maximally reduced brown rice Cd by 67.4%, structural equation modeling revealed CaCl₂-extractable Cd and manganese plaque played the greatest positive and negative roles, respectively. Therefore, basal liming and tillering application of Mn is most effective at reducing rice Cd through inhibition of Cd bioavailability and alleviation of IMP reduction.

施用时间和土壤 pH 值是锰 (Mn) 生物有效性的关键，这可能会影响锰对水稻中镉 (Cd) 积累的影响。因此，本研究通过盆栽和田间试验研究了在不同阶段单独或与基础石灰一起施用锰对水稻中镉积累的影响。结果表明，与对照相比，基础施锰最大限度地提高了土壤溶解锰，并使水稻中的锰积累量增加了140%-367%。此外，基部或分蘖施用对增强铁锰斑块（IMP）和抑制CaCl ₂可提取Cd的效果优于后期施用。因此，与对照相比，基础和分蘖 Mn 使糙米 Cd 分别降低了 24.6% 和 18.9%。石灰还原 CaCl ₂- 与对照相比，可提取 Cd 降低了 83.3%，但抑制了土壤溶解 Mn（25.8%-76.6%）和 IMP（28.9%-29.7%），导致糙米 Cd 仅减少 41.7%。石灰联合分蘖锰最大程度降低糙米Cd 67.4%，结构方程模型显示CaCl ₂可提取Cd和锰斑分别发挥最大的正向和负向作用。因此，通过抑制 Cd 生物利用度和减轻 IMP 还原，基础施石灰和分蘖施用 Mn 在降低水稻 Cd 方面最有效。