本文選題：汞 + 水稻　； 參考：《華東師范大學(xué)》2017年碩士論文

【摘要】：水稻對汞具有一定的積累能力,人類活動(dòng)造成越來越多稻田受到汞污染,使稻米暴露在汞環(huán)境中,影響人類健康。因此,如何管理并利用汞污染稻田,減少水稻地上部的汞積累成為了亟待解決的糧食安全問題。目前對于受到汞污染的水稻田尚未有低成本、高效率的修復(fù)方法,但已有實(shí)驗(yàn)發(fā)現(xiàn)不同品種的水稻對汞的吸收具有很大的差異性,這意味著可以通過合理的選種來降低水稻對汞的積累。但是對于其中的機(jī)理的探索還不夠充分。根系是水稻主要的吸收器官,其構(gòu)型不僅影響了植株對水分和養(yǎng)分的吸收,同時(shí)也對重金屬等污染物的吸收轉(zhuǎn)運(yùn)具有重要影響。當(dāng)環(huán)境條件發(fā)生變化時(shí),水稻的根系會(huì)調(diào)整自身的生長,而由此造成的構(gòu)型變化又會(huì)改變水稻根系的吸收特征。因此,本文以兩種根系結(jié)構(gòu)具有顯著差異性的水稻品種(綠旱1號、武運(yùn)粳21號)作為研究對象,以室內(nèi)培養(yǎng)和統(tǒng)計(jì)分析為主要手段,研究了不同環(huán)境因子(養(yǎng)分供應(yīng)、鐵膜誘導(dǎo)、鎘脅迫)對汞脅迫下水稻根系生長的影響,進(jìn)而探討其對水稻汞積累的影響,從而為農(nóng)業(yè)生態(tài)系統(tǒng)中汞污染的防護(hù)與治理提供理論依據(jù)與實(shí)踐參考。主要研究結(jié)果如下:1、正常條件下,與綠旱1號相比,武運(yùn)粳21號的根系更加發(fā)達(dá)和粗壯,具有更大的根表面積與根體積。在汞脅迫(0.5mg/LHg(Ⅱ)、1mg/LHg(Ⅱ))的條件下,武運(yùn)粳21號的根系表現(xiàn)出較強(qiáng)的穩(wěn)定性,各根系參數(shù)(根長、根表面積、根體積、根直徑、根尖數(shù)、生物量、根冠比)均無顯著變化;綠旱1號的響應(yīng)則比較明顯,與對照組相比,水稻根系在0.5 mg/L Hg(Ⅱ)條件下根冠比顯著提升,在1 mg/LHg(Ⅱ)條件下根尖數(shù)顯著下降。2、與汞脅迫組(0.5mg/LHg(Ⅱ))相比,鎘的加入(0.5mg/LHg(Ⅱ)+0.5mg/L Cd(Ⅱ))可以降低綠旱1號水稻的根冠比,降低了其根系與地上部的汞濃度(根系未濃度從63.35 mg/kg下降到30.74 mg/kg,地上部汞濃度從12.94 mg/kg下降到10.89mg/kg),但是汞的轉(zhuǎn)移系數(shù)卻有所提升(從20.41%升為35.41%)。3、在汞脅迫(0.5mg/LHg(Ⅱ))的條件下,減少氮素的施用可以使武運(yùn)粳21號水稻的根直徑和根體積顯著降低,根系汞濃度有所下降(從160.42mg/kg降低為106.9mg/kg),但是地上部的汞濃度則從11.6mg/kg上升為15.33mg/kg,轉(zhuǎn)移系數(shù)從7.23%上升為14.34%。4、對于供試的兩種水稻,在正常施肥條件下,鐵膜形成均能夠促進(jìn)其根系生長,顯著地提高水稻的根長、根表面積、根尖數(shù)、根生物量及地上部生物量。但是在汞脅迫(0.5 mg/LHg(Ⅱ))的條件下,鐵膜形成對兩種水稻的根系各指標(biāo)(根長、根直徑、根表面積、根體積、根尖數(shù)、生物量、根冠比)的影響不大,但是可以有效降低汞從根系往地上部的轉(zhuǎn)運(yùn)(其中綠旱1號水稻汞的轉(zhuǎn)運(yùn)系數(shù)從20.42%下降到16.33%,武運(yùn)粳21號水稻汞的轉(zhuǎn)運(yùn)系數(shù)從7.23%下降到3.05%)。5、本試驗(yàn)發(fā)現(xiàn),在汞脅迫與養(yǎng)分缺乏的聯(lián)合脅迫條件下,鐵膜的形成依然可以促進(jìn)水稻根系的生長。其中,在減少氮素施用并施加汞脅迫的條件下,鐵膜的形成使綠旱1號水稻的根伸長,根系與地上部的生物量均有顯著提升,根系汞濃度從228.61 mg/kg下降為215.54 mg/kg,地上部汞濃度從9.58 mg/kg下降為5 mg/kg,轉(zhuǎn)運(yùn)系數(shù)從4.19下降為2.32;相同條件下,鐵膜誘導(dǎo)可以顯著提高武運(yùn)粳21號水稻的根長、根表面積、根尖數(shù)及地上部生物量,從而提高了水稻根系的汞濃度(從106.9mg/kg上升為450.93mg/kg),但地上部汞濃度則反而有所減少(從15.33 mg/kg下降到8.37 mg/kg),汞的轉(zhuǎn)移系數(shù)大大下降(從14.34下降到 1.86)。本研究表明,武運(yùn)粳21號比綠旱1號更適合在汞污染的稻田中生長。無論是在營養(yǎng)條件變化,或者是重金屬的脅迫下,其根系的生長都具有較強(qiáng)的穩(wěn)定性。另一方面,在環(huán)境變化時(shí)根系響應(yīng)顯著的綠旱1號水稻可以作為農(nóng)田生態(tài)系統(tǒng)的指示生物。在種植過程中,應(yīng)該重視調(diào)節(jié)肥料中不同的營養(yǎng)元素,從而對汞污染帶來的食品安全問題進(jìn)行風(fēng)險(xiǎn)調(diào)控。
[Abstract]:Rice has a certain accumulation capacity for mercury. Human activities have caused more and more rice fields to be polluted by mercury, which make rice exposed to mercury environment and affect human health. Therefore, how to manage and use mercury to pollute rice fields and reduce the accumulation of mercury in the upper part of rice has become an urgent problem for food safety. There has not been a low cost and efficient repair method in the field, but it has been found that the absorption of mercury in different varieties of rice is very different, which means that the accumulation of mercury can be reduced by reasonable selection. But the exploration of the mechanism is not sufficient. The root system is the main absorption organ of rice and its configuration. It not only affects the absorption of water and nutrients, but also has an important influence on the absorption and transport of heavy metals. When the environmental conditions change, the roots of rice will adjust their own growth, and the resulting configuration changes will change the absorption characteristics of rice roots. Therefore, this paper has two root system structures. The significant difference of rice varieties (green drought 1, Wu Yun Jing 21) as the research object, the effects of different environmental factors (nutrient supply, iron film induction, cadmium stress) on the growth of rice root system under mercury stress were studied by indoor culture and statistical analysis, and the effects on the accumulation of mercury in rice were discussed, thus the agricultural ecosystem was used as an agro ecosystem. The main research results are as follows: 1, under normal conditions, the root surface area and root volume of Wu Yun Jing No. 21 are more developed and stronger than that of green drought 1. Under the condition of mercury stress (0.5mg/LHg (II), 1mg/LHg (II)), the root of Wu Yun Jing 21 is shown. The root length, root surface area, root volume, root diameter, root diameter, root diameter, root diameter, root diameter, root number, root and crown ratio were not significantly changed, and the response of green drought 1 was obvious. Compared with the control group, the root crown ratio of rice root was significantly increased under the condition of 0.5 mg/L Hg (II), and the number of root tips decreased significantly under the condition of 1 mg/LHg (II), and the number of mercury threatened with mercury. Compared to the forced group (0.5mg/LHg (II)), the addition of cadmium (0.5mg/LHg (II) +0.5mg/L Cd (II)) could reduce the root and crown ratio of the green drought 1 rice, and reduce the concentration of the mercury in the root and the upper part of the ground (the root concentration decreased from 63.35 mg/kg to 30.74 mg/kg, and the mercury concentration in the upper part of the ground decreased from 12.94 mg/kg to 10.89mg/kg), but the transfer coefficient of the mercury was raised to some extent. (from 20.41% liter to 35.41%).3, under the condition of mercury stress (0.5mg/LHg (II)), the reduction of nitrogen can significantly reduce the root diameter and root volume of Wu Yun 21 rice, and the concentration of mercury in root is decreased (from 160.42mg/kg to 106.9mg/kg), but the concentration of mercury in the upper part of the ground increases from 11.6mg/kg to 15.33mg/kg, and the transfer coefficient is from 7.23%. Up to 14.34%.4, for the two kinds of rice, the formation of iron membrane can promote the growth of root system under normal fertilization conditions, and significantly increase the root length, root surface area, root tip number, root biomass, root biomass and aboveground biomass. However, under the condition of mercury stress (0.5 mg/LHg (II)), the iron membrane forms the root system of two rice roots (roots). Long, root diameter, root surface area, root volume, root tip number, biomass, and root and crown ratio have little effect, but it can effectively reduce the transport of mercury from root to ground. (the transfer coefficient of mercury in green drought 1 is decreased from 20.42% to 16.33%, and the transfer coefficient of mercury in Wu Yun 21 is decreased from 7.23% to 3.05%).5. Under the condition of combined stress of nutrient deficiency, the formation of iron film can still promote the growth of rice root system. In the condition of reducing nitrogen application and exerting mercury stress, the formation of iron film makes the root of green drought 1 rice root elongate, the biomass of root and the above ground increase significantly, and the concentration of mercury in root is decreased from 228.61 mg/kg to 215.54 mg/ Kg, the mercury concentration in the upper part of the ground decreased from 9.58 mg/kg to 5 mg/kg, and the transport coefficient decreased from 4.19 to 2.32. Under the same condition, the iron film induction could significantly increase the root length, the root surface area, the root tip number and the aboveground biomass of Wu Yunjing 21 rice, thus improving the concentration of the rice root (from 106.9mg/kg to 450.93mg/kg), but the mercury concentration in the upper part of the ground was strong. As the degree decreased (from 15.33 mg/kg to 8.37 mg/kg), the transfer coefficient of mercury decreased greatly (from 14.34 to 1.86). This study showed that Wu Yunjing 21 was more suitable for the growth of the rice fields polluted by mercury than the green drought 1. On the other hand, the green drought 1 rice, which has a significant response to the environmental changes, can be used as a indicator of the farmland ecosystem. In the process of planting, we should pay more attention to the regulation of different nutrient elements in the fertilizer, so as to control the risk of food safety caused by mercury pollution.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S511

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