【摘要】：重金屬污染土壤的防治是全世界普遍關注的熱點、難點問題之一。近幾十年來,由于采礦、污灌、三廢排放和肥料不合理施用,我國農(nóng)田土壤鎘污染日趨嚴重。目前,其治理的方法有很多,其中關于硅對作物鎘毒害的緩解作用已被國內外學者廣泛認同。前人研究使用的含硅物料多為堿性物質,且含有伴隨離子,而pH和伴隨離子又是影響鎘活性的重要因素,那么含硅物料對作物鎘毒害的緩解是改變土壤pH和伴隨離子引起,還是硅自身的作用就很難確定。因此,本試驗在消除pH和伴隨離子影響的基礎上,采取室內分析和生物試驗相結合的手段,研究鎘脅迫下施硅對兩種水稻逆境和細胞結構、鎘吸收與分配、土壤吸附解吸鎘的影響,以期明確施硅條件下,鎘累積性不同品種水稻對鎘的響應以及硅抑制水稻累積鎘的機制。研究結論如下:1.硅通過影響抗氧化酶活性和游離脯氨酸含量,緩解了膜脂過氧化作用,在相同條件下,"遼星19"體內膜脂質過氧化程度大于"遼粳9"。加硅使葉片細胞結構趨于完整,葉綠體片層排列逐漸整齊、清晰,嗜鋨顆粒逐漸變小、變少;線粒體數(shù)目逐漸增多,雙層膜解體現(xiàn)象得到緩解。2.硅使鎘滯留在水稻根部,減少了向地上部的運輸,有效緩解鎘對水稻的毒害,增加水稻生物量,提高水稻產(chǎn)量,降低糙米中鎘的含量。與單加鎘處理相比,施硅顯著降低兩種水稻稻米中鎘含量(P0.01)。在相同條件下,"遼星19"糙米、莖葉轉移富集能力大于"遼粳9"。3.硅促進了土壤對鎘的吸附,抑制土壤鎘的解吸,其效應隨著加硅量的增加而增大;硅還可降低土壤中酸可提取態(tài)、可還原態(tài)鎘含量,提高土壤中可氧化態(tài)、殘渣態(tài)鎘含量,從而降低了鎘的生物有效性。綜上所述,硅能有效緩解鎘對水稻的毒害,提高水稻產(chǎn)量,降低糙米中鎘含量,在施硅量為100、150 mg/kg時,"遼粳9"糙米中鎘含量達到國家標準;施硅促進土壤對鎘的吸附,加劇解吸的滯后效應,使土壤中的鎘向無效形態(tài)轉化。因此,在鎘中、低污染地區(qū),種植鎘累積性較低的水稻品種,配合施用硅肥,可以實現(xiàn)鎘污染土壤修復和安全利用。
[Abstract]:The prevention and control of heavy metal contaminated soil is one of the hot and difficult problems in the world. In recent decades, because of mining, sewage irrigation, waste discharge and unreasonable application of fertilizer, cadmium pollution of farmland soil in China is becoming more and more serious. At present, there are many ways to control the effects of silicon on crop cadmium toxicity, which has been widely recognized by domestic and foreign scholars. Most of the silicon-containing materials used in previous studies are alkaline materials and accompanied ions, and pH and accompanying ions are important factors affecting cadmium activity, so the mitigation of cadmium toxicity caused by silicon-containing materials is caused by changing soil pH and accompanying ions. The role of silicon itself is hard to determine. Therefore, on the basis of eliminating the effects of pH and accompanying ions, the effects of silicon on the stress, cell structure, absorption and distribution of cadmium in rice under cadmium stress were studied by the combination of laboratory analysis and biological experiments. The effect of soil adsorption and desorption of cadmium in order to clarify the cadmium accumulation of different rice varieties under the condition of silicon application, and the mechanism of silicon inhibiting cadmium accumulation in rice. The conclusions are as follows: 1. Silicon alleviates membrane lipid peroxidation by affecting antioxidant enzyme activity and free proline content. Under the same conditions, the degree of membrane lipid peroxidation in "Liaoxing 19" is greater than that in "Liaojing 9". Adding silicon made the leaf cell structure complete, the chloroplast lamellar arrangement was neat and clear, osmiophilic particles became smaller and less, the number of mitochondria gradually increased, and the phenomenon of double layer membrane disintegration was alleviated. 2. Silicon makes cadmium stay in the root of rice, reduces the transportation to the aboveground, effectively alleviates the toxicity of cadmium to rice, increases the biomass of rice, increases the yield of rice, and reduces the content of cadmium in brown rice. Compared with single cadmium treatment, silicon application significantly decreased the cadmium content in rice (P0.01). Under the same conditions, the enrichment ability of "Liaoxing 19" brown rice was higher than that of "Liaojing 9". Silicon promoted the adsorption of cadmium and inhibited the desorption of cadmium, and the effect increased with the increase of the amount of silicon added. Silicon can also reduce the contents of extractable acid and reductive cadmium in soil and increase the content of oxidizable and residual cadmium in soil, thus reducing the bioavailability of cadmium. To sum up, silicon can effectively alleviate the toxicity of cadmium to rice, increase the yield of rice and reduce the cadmium content in brown rice. When the amount of silicon applied is 100150 mg/kg, the cadmium content in "Liaojing 9" brown rice reaches the national standard. Application of silicon promoted the adsorption of cadmium in soil, aggravated the delayed effect of desorption, and transformed cadmium in soil into invalid form. Therefore, in the middle and low pollution area of cadmium, planting rice varieties with low cadmium accumulation and applying silicon fertilizer can realize the remediation and safe utilization of cadmium contaminated soil.
【學位授予單位】：沈陽農(nóng)業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X53;X173
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本文編號：2407049