汞胁迫下不同环境因子对水稻根系生长及其汞积累的影响

发布时间：2018-06-04 00:34

本文选题：汞 + 水稻　；参考：《华东师范大学》2017年硕士论文

【摘要】：水稻对汞具有一定的积累能力,人类活动造成越来越多稻田受到汞污染,使稻米暴露在汞环境中,影响人类健康。因此,如何管理并利用汞污染稻田,减少水稻地上部的汞积累成为了亟待解决的粮食安全问题。目前对于受到汞污染的水稻田尚未有低成本、高效率的修复方法,但已有实验发现不同品种的水稻对汞的吸收具有很大的差异性,这意味着可以通过合理的选种来降低水稻对汞的积累。但是对于其中的机理的探索还不够充分。根系是水稻主要的吸收器官,其构型不仅影响了植株对水分和养分的吸收,同时也对重金属等污染物的吸收转运具有重要影响。当环境条件发生变化时,水稻的根系会调整自身的生长,而由此造成的构型变化又会改变水稻根系的吸收特征。因此,本文以两种根系结构具有显著差异性的水稻品种(绿旱1号、武运粳21号)作为研究对象,以室内培养和统计分析为主要手段,研究了不同环境因子(养分供应、铁膜诱导、镉胁迫)对汞胁迫下水稻根系生长的影响,进而探讨其对水稻汞积累的影响,从而为农业生态系统中汞污染的防护与治理提供理论依据与实践参考。主要研究结果如下:1、正常条件下,与绿旱1号相比,武运粳21号的根系更加发达和粗壮,具有更大的根表面积与根体积。在汞胁迫(0.5mg/LHg(Ⅱ)、1mg/LHg(Ⅱ))的条件下,武运粳21号的根系表现出较强的稳定性,各根系参数(根长、根表面积、根体积、根直径、根尖数、生物量、根冠比)均无显著变化;绿旱1号的响应则比较明显,与对照组相比,水稻根系在0.5 mg/L Hg(Ⅱ)条件下根冠比显著提升,在1 mg/LHg(Ⅱ)条件下根尖数显著下降。2、与汞胁迫组(0.5mg/LHg(Ⅱ))相比,镉的加入(0.5mg/LHg(Ⅱ)+0.5mg/L Cd(Ⅱ))可以降低绿旱1号水稻的根冠比,降低了其根系与地上部的汞浓度(根系未浓度从63.35 mg/kg下降到30.74 mg/kg,地上部汞浓度从12.94 mg/kg下降到10.89mg/kg),但是汞的转移系数却有所提升(从20.41%升为35.41%)。3、在汞胁迫(0.5mg/LHg(Ⅱ))的条件下,减少氮素的施用可以使武运粳21号水稻的根直径和根体积显著降低,根系汞浓度有所下降(从160.42mg/kg降低为106.9mg/kg),但是地上部的汞浓度则从11.6mg/kg上升为15.33mg/kg,转移系数从7.23%上升为14.34%。4、对于供试的两种水稻,在正常施肥条件下,铁膜形成均能够促进其根系生长,显著地提高水稻的根长、根表面积、根尖数、根生物量及地上部生物量。但是在汞胁迫(0.5 mg/LHg(Ⅱ))的条件下,铁膜形成对两种水稻的根系各指标(根长、根直径、根表面积、根体积、根尖数、生物量、根冠比)的影响不大,但是可以有效降低汞从根系往地上部的转运(其中绿旱1号水稻汞的转运系数从20.42%下降到16.33%,武运粳21号水稻汞的转运系数从7.23%下降到3.05%)。5、本试验发现,在汞胁迫与养分缺乏的联合胁迫条件下,铁膜的形成依然可以促进水稻根系的生长。其中,在减少氮素施用并施加汞胁迫的条件下,铁膜的形成使绿旱1号水稻的根伸长,根系与地上部的生物量均有显著提升,根系汞浓度从228.61 mg/kg下降为215.54 mg/kg,地上部汞浓度从9.58 mg/kg下降为5 mg/kg,转运系数从4.19下降为2.32;相同条件下,铁膜诱导可以显著提高武运粳21号水稻的根长、根表面积、根尖数及地上部生物量,从而提高了水稻根系的汞浓度(从106.9mg/kg上升为450.93mg/kg),但地上部汞浓度则反而有所减少(从15.33 mg/kg下降到8.37 mg/kg),汞的转移系数大大下降(从14.34下降到 1.86)。本研究表明,武运粳21号比绿旱1号更适合在汞污染的稻田中生长。无论是在营养条件变化,或者是重金属的胁迫下,其根系的生长都具有较强的稳定性。另一方面,在环境变化时根系响应显著的绿旱1号水稻可以作为农田生态系统的指示生物。在种植过程中,应该重视调节肥料中不同的营养元素,从而对汞污染带来的食品安全问题进行风险调控。
[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.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S511

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