富硅稻壳灰对水稻吸收砷的调控作用
Using Si-Rich Husk Ash to Regulation Arsenic Uptake by Rice
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摘要: 通过向土壤中添加富Si稻壳灰提高土壤溶液中Si浓度可以有效抑制水稻对As的吸收. 为了探索富Si稻壳灰对水稻吸收As的内在调控机理开展了大田试验. 大田试验结果表明:富Si稻壳灰的添加使土壤孔隙水中Si浓度较对照组显著增加了866.0%,这为水稻生长提供了充足的Si,使Si在与As的竞争吸收中占据主导作用,同时富Si稻壳灰促进了土壤铁氧化物的沉淀,使孔隙水中As浓度下降了20.3%,这一过程中由于铁氧化物的还原溶解而释放的As重新被固持. 水稻根系铁膜的形成对As的截留作用是抑制As向地上部转运的关键,富Si稻壳灰通过促进通气组织的形成来增加根系氧化能力,使水稻根表铁膜铁浓度(DCB-Fe)较对照组增加了47.3%,使根表铁膜As浓度(DCB-As)较对照组增加了41.0%. 富Si稻壳灰为水稻生长供应的足量Si,通过下调水稻根系中Si转运蛋白Lsi1和Lsi2的表达,从而限制了水稻根系对As(III)的吸收,结果显示富Si稻壳灰使精米中无机As浓度降低了29.1%,低于GB 2762—2017《食品安全国家标准 食品中污染物限量》标准限值. 该研究通过大田试验,从土壤孔隙水、水稻根表铁膜以及Si与As在水稻茎叶和稻米运输中的竞争作用三方面系统论述了低温燃烧条件下制备的富Si稻壳灰对水稻吸收As的调控作用,结果表明以0.2%的施加比例施加富Si稻壳灰有效降低了水稻籽粒 As 含量,为As污染土壤的水稻安全生产利用提供有效的解决途径.Abstract: Adding Si-rich husk ash to increase the Si concentration in soil could effectively inhibit the absorption of As by rice. Field experiments were carried out to explore the regulation mechanism of Si-rich husk ash on As absorption by rice. Field experiment results showed that the addition of Si-ash significantly increased the porewater Si concentration by 866.0% compared with the control, which provided sufficient Si for rice growth and made Si play a dominant role in the competitive absorption of As. Meanwhile, Si-rich husk ash promoted the precipitation of Fe plaque in soil and reduced the concentration of As in porewater by 20.3%. During this process, As released due to reductive dissolution of Fe plaque is re-retained. The formation of Fe plaque in rice roots plays a key role in inhibiting the transport of As to the shoot. Si-rich husk ash increased the root oxidation capacity by promoting the formation of aerated tissue, and the Fe concentration of Fe plaque on the rice root surface (DCB-Fe) increased by 47.3% compared with the control. The concentration of As in root surface Fe plaque (DCB-As) increased by 41.0% compared with the control. Si-rich husk ash provides sufficient Si for rice growth and restricts the absorption of As (III) by rice roots by down-regulating the expression of Si transporter Lsi1 and Lsi2 in rice roots. The results showed that Si-rich husk ash reduced the concentration of inorganic As in white rice by 29.1%, which is lower than the standard limit of GB 2762-2017 "Limit of Contaminants in Food of National Food Safety Standards". Through the field experiment, the study from the soil porewater, Fe plaque, and Si and As in straw and rice transportation system competition effect three aspects discusses the low-temperature combustion under the condition of the preparation of absorption of rice in Si-rich husk ash As a regulation function. The results showed that adding Si-rich husk ash at a ratio of 0.2% could effectively reduce As content in rice grains, providing an effective solution for the safe production and utilization of rice contaminated by As.
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Key words:
- arsenic (As) /
- silicon (Si) /
- rice /
- rice husk ash
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