| 施硼对水稻幼苗吸收和分泌砷的影响 |
| 摘要点击 1594 全文点击 495 投稿时间：2017-12-21 修订日期：2018-01-17 |
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| 中文关键词 三价砷 五价砷 硼 外泌 吸收 水稻 |
| 英文关键词 arsenite arsenate boron efflux uptake rice |
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| 中文摘要 |
| 通过3组水培试验研究了营养液不同供硼（B）浓度和叶面施B对水稻（Oryza sativa L.）幼苗吸收、转运和分泌砷（As）的影响.在10 μmol·L-1三价砷[As（Ⅲ）]或五价砷[As（Ⅴ）]处理下，营养液B浓度没有显著影响水稻体内As（Ⅲ）、As（Ⅴ）和总As的含量、转移系数和根吸收效率.叶面施B使得水稻幼苗地上部的B含量显著增加15.8倍，使得As（Ⅴ）处理条件下的根部As含量和As根吸收效率分别显著降低20.9%和18.0%，As（Ⅲ）处理条件下的根部As含量和As根吸收效率分别降低12.6%和13.8%（P<0.05），而地上部As含量降低不显著（P>0.05）.在As（Ⅴ）处理下，叶面施B使根部B含量显著降低达47.1%，而As（Ⅲ）处理下根部B含量无显著变化.As（Ⅴ）处理下的水稻根部B含量平均比As（Ⅲ）处理高85.3%（P<0.05）.叶面施B后，As（Ⅴ）处理下水稻根部中总As含量和As（Ⅴ）含量均与根部B含量呈显著正相关（P<0.05）.As（Ⅲ）预处理后水稻幼苗根系外泌的As总量比As（Ⅴ）预处理高105.2%.叶面施B使As（Ⅲ）预处理水稻的As外泌量增加14.0%~16.9%（P>0.05），对As（Ⅴ）预处理的水稻As外泌无影响.水稻根部有45.9%~70.7%的As可以在1周内被外排到生长介质中.结果表明，营养液供B浓度为As浓度的4倍时仍不能减少水稻幼苗对As的吸收累积，而叶面施B有助于减少水稻对As的吸收.B通道不是As（Ⅲ）进入水稻根系的主要途径；As（Ⅴ）在水稻中的迁移分配机制可能与B的迁移运输有关. |
| 英文摘要 |
| The impacts of boron (B) root application and foliar spray on arsenic (As) uptake, translocation, and efflux by/in rice seedlings (Oryza sativa L.) were investigated in three hydroponic experiments. The addition of B to culture medium did not alter concentrations of arsenite (As[Ⅲ]), arsenate (As[Ⅴ]), and total As, nor did it alter transfer coefficients or uptake efficiency of As in rice seedlings under either As(Ⅲ) or As(Ⅴ) exposure. Foliar B supply increased shoot B concentrations 15.8-fold, and decreased root As concentrations and As uptake efficiency by 20.9% and 18.0% under As(Ⅴ) treatment, and by 12.6% and 13.8% under As(Ⅲ) treatment, respectively, yet did not significantly decrease shoot As concentrations (P>0.05). Interestingly, foliar B supply reduced root B concentrations by up to 47.1% under exposure to As(Ⅴ) but not As(Ⅲ), and corresponding root B concentrations were 85.3% higher in As(Ⅴ) treatment than in As(Ⅲ) treatment on average (P<0.05). Both total As and As(Ⅴ) concentrations were positively related to B concentration in rice roots under As(Ⅴ) treatment following foliar B supply (P<0.05). Rice seedlings extruded 105.2% more As after As(Ⅲ)-pretreatment than after As(Ⅴ)-pretreatment. Foliar B supply increased the amount of As excreted by As(Ⅲ)-pretreated rice root by 14.0%-16.9% (P>0.05), and had no effect on the As efflux of As(Ⅴ)-pretreatment seedlings. A range of 45.9%-70.7% of root As was excreted to solution during one week. These results indicate that the root application of B at four times the concentration of As can slightly decrease As accumulation by rice, whereas foliar B supply is conducive to a decline in As acquisition by rice roots. It is likely that the B channel is at least not the main pathway for As(Ⅲ) entering into rice roots, and the As(Ⅴ) distribution mechanism in rice plants may be shared with that of B. |
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