Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China; Ministry of Education's Key Laboratory of Poyang Lake Wetland and Watershed Research, School of Geography and Environment, Jiangxi Normal University, Nanchang 330022, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
J Hazard Mater. 2021 Aug 5;415:125597. doi: 10.1016/j.jhazmat.2021.125597. Epub 2021 Mar 6.
Manganese (Mn) has the potential to reduce cadmium (Cd) uptake by rice; however, the efficiency depends on its soil availability. Therefore, this study designed a slow-release Mn fertilizer by employing a polyacrylate coating. Pot trials were conducted to study the effects of coated-Mn and uncoated-Mn alone or in combination with lime on the dynamics of soil dissolved-Mn and available Cd, and the transportation of Mn and Cd within rice. The results showed that coated-Mn declined the release of Mn until the 7th day of application; however, it consistently supplied more dissolved-Mn than uncoated-Mn. As a result, coated-Mn induced a greater Cd reduction (45.8%) in brown rice than uncoated-Mn (9.7%). The total Cd of rice and its proportion in brown rice were greatly reduced by coated-Mn, indicating the inhibition of root uptake and interior transport of Cd. Additionally, lime addition prominently increased the soil pH and decreased the CaCl-extractable Cd (90.1-93.9%). However, since lime reduced the soil dissolved-Mn, downregulated the OsHMA3 expression and upregulated the OsNramp5 expression, brown rice Cd was reduced by only 43.0%. The combined addition of lime and coated-Mn alleviated the liming effect on soil Mn and gene expression in roots, thereby reducing brown rice Cd by 71.5%.
锰（Mn）有可能降低水稻对镉（Cd）的吸收，但这取决于其在土壤中的有效性。因此，本研究通过采用聚丙烯酸酯涂层设计了一种缓释 Mn 肥料。通过盆栽试验研究了单独或与石灰一起施用包膜 Mn 和未包膜 Mn 对土壤溶解态 Mn 和有效态 Cd 动态以及 Mn 和 Cd 在水稻体内迁移的影响。结果表明，包膜 Mn 降低了 Mn 的释放速度，直到施用后的第 7 天；然而，它始终比未包膜 Mn 提供更多的溶解态 Mn。因此，包膜 Mn 诱导糙米中 Cd 的还原量（45.8%）比未包膜 Mn（9.7%）更高。包膜 Mn 显著降低了水稻的总 Cd 及其在糙米中的比例，表明其抑制了 Cd 的根吸收和内部运输。此外，石灰的添加显著提高了土壤 pH 值，降低了 CaCl2 可提取的 Cd（90.1-93.9%）。然而，由于石灰降低了土壤溶解态 Mn，下调了 OsHMA3 表达，上调了 OsNramp5 表达，因此糙米 Cd 的减少量仅为 43.0%。石灰和包膜 Mn 的联合添加缓解了石灰对根中土壤 Mn 和基因表达的影响，从而使糙米 Cd 的减少量达到 71.5%。
