酸碱度对水稻幼苗镉离子吸收转运特性的影响

发布时间：2019-01-03 07:27

【摘要】：由于长期过量使用生理酸性肥料和化学氮肥,土壤中的酸性物质不断增加并积累,使土壤出现酸化现象。土壤酸化加速了南方酸性土壤中重金属镉(Cd)进入植物体的过程,其中稻米镉含量超过国家食品安全标准的问题最为突出。因此,剖析水稻根际环境中的酸碱度与水稻镉吸收积累的关系,对于制订Cd污染区水稻安全生产管理规程具有重要意义。本研究以湘早籼24(X24)为实验材料,通过水培实验,对培养液的酸碱度影响水稻幼苗镉离子吸收转运特性的机理进行了探讨。主要研究结果如下:1.酸碱度对水稻幼苗镉积累量和生长发育有显著影响。营养液中的pH值为5.5时,水稻幼苗中的镉含量最高。当pH值为4.0-5.5时,水稻幼苗的镉含量随pH值的升高而升高;当pH值为5.5-8.0时,水稻幼苗的镉含量却随pH值升高而降低。在pH值为4.0-4.5和6.5-8.0的营养液中处理7天后,水稻幼苗地上部分枯黄萎蔫,甚至枯死。而在pH值为6.5-7.0的环境中,水稻幼苗生长发育基本正常,镉积累量却显著下降。2.酸碱度对水稻幼苗镉离子亚细胞分布特征有显著影响。水稻幼苗根系和地上部分积累的镉主要分布在细胞壁中,细胞壁中的镉含量显著大于原生质体。酸碱度对镉在细胞壁和原生质体中的分配比例有显著的影响。当pH为5.5时,镉在细胞壁的含量是在原生质体中含量的3倍;而当pH为4.5时,细胞壁中的镉含量仅是原生质体镉含量的1.4倍。在pH5.5-7.0的含镉营养液中生长时,水稻幼苗根系细胞壁和原生质体中的镉含量随着pH的增加而显著下降;但在pH5.5的含镉营养液中生长时,根系细胞壁和原生质体中的镉含量随着pH的增加而增加。地上部的镉含量和根系原生质体中的镉含量呈显著的线性相关。3.酸碱度对水稻幼苗必需元素的吸收积累有显著影响。在pH不同的营养液中,水稻幼苗对中微量元素的吸收量也有所不同,在PH值为7时,水稻幼苗吸收中微量元素的含量最大,在pH值为5-7时,水稻幼苗吸收中微量元素的含量随pH值的升高而升高,当pH值为7-8时,随着pH值的升高,中微量元素含量明显降低。且镉对水稻幼苗吸收必需元素有着不同的差异,镉对水稻幼苗吸收镁和钙有促进作用,对吸收铁、锰和锌有抑制作用。4.酸碱度对镉离子通过非选择性阳离子通道的转运效率有显著影响。非选择性阳离子通道对水稻幼苗镉吸收转运的贡献率因pH的升高而增加,对地上部镉积累的贡献率大于根系。离子通道抑制剂对水稻幼苗根系原生质体镉积累的抑制作用最为明显,说明NSCCs是镉离子进入水稻根系的主要通道。酸碱度通过影响水稻幼苗的生长发育、必需元素的吸收转运效率、镉离子在细胞壁上的积累量和非选择性阳离子通道的活性,调控着镉离子进入根系原生质体及其向地上部转运的过程。在pH值为6.5-7.0的碱性环境中,水稻幼苗主要通过降低根系细胞质中的镉浓度和向地上部的转运率,抑制了镉在地上部细胞壁和原生质体中的积累量。
[Abstract]:Because of the long-term overuse of the physiological and acidic fertilizer and the chemical nitrogen fertilizer, the acid substances in the soil are continuously increased and accumulated, so that the soil is acidized. Soil acidification has accelerated the process of heavy metal salt (Cd) entering the plant in the acid soil of the south, in which the rice content of rice exceeds the national food safety standard. Therefore, it is of great significance to analyze the relationship between the pH value and the absorption and accumulation of rice in the rice root-to-root environment. In this study, the mechanism of the absorption and transport of rice seedlings was discussed by the experiment of water-culture with the experimental material of X24 as the experimental material. The main results are as follows: 1. The pH value has a significant effect on the accumulation and development of rice seedling. When the pH value in the nutrient solution is 5. 5, the content of the rice in the rice seedling is the highest. When the pH value is 4.0-5.5, the content of the rice seedling is increased with the increase of the pH value; when the pH value is 5.5-8.0, the content of the rice seedling is reduced with the increase of the pH value. After treatment for 7 days in the nutrient solution with the pH value of 4.0-4.5 and 6.5-8.0, the upper part of the rice seedling was withered and withered, and even died. in the environment with the pH value of 6.5-7.0, the growth and development of the rice seedlings were basically normal, but the accumulation of the rice seedlings decreased significantly. The pH value has a significant effect on the distribution of the sub-cell of the rice seedling. The root and ground part of the rice seedling is mainly distributed in the cell wall, and the yeast content in the cell wall is significantly higher than that of the protoplast. The pH value has a significant effect on the distribution ratio of the yeast in the cell wall and the protoplast. When the pH is 5. 5, the content of the yeast in the cell wall is 3 times that of the protoplast; and when the pH is 4.5, the content of the yeast in the cell wall is only 1.4 times that of the protoplast. In the growth of pH 5.5-7.0, the content of the root cell wall and the protoplast in the root system of the rice seedling decreased with the increase of the pH, but the content of the yeast in the cell wall and the protoplast of the root system increased with the increase of the pH in the growth of the pH 5.5-containing nutrient solution. There was a significant linear correlation between the content of the ground and the content of the root in the protoplast of the root system. The pH value has a significant effect on the absorption and accumulation of the essential elements of rice seedlings. in the nutrient solution with different pH, the absorption amount of the trace elements in the rice seedling is different, and when the pH value is 7, the content of the trace elements in the rice seedling absorption is the largest, and when the pH value is 5-7, the content of the trace elements in the absorption of the rice seedlings is increased with the increase of the pH value, When the pH value is 7-8, the content of trace elements is obviously reduced with the increase of the pH value. and it has the effect of promoting the absorption of magnesium and calcium in the rice seedling, and has the effect of inhibiting the absorption of iron, manganese and zinc. the pH value has a significant effect on the transport efficiency of the polar ions through the non-selective cation channel. The contribution rate of the non-selective cation channel to the absorption and transport of rice seedlings was increased by the increase of the pH, and the contribution rate of the non-selective cation channel to the accumulation of soil on the ground was greater than that of the root system. The inhibitory effect of ion channel inhibitor on the accumulation of the protoplast of the root system of rice seedling is the most obvious, and it is indicated that the NSCCs are the main channel to the root of rice. The effects of pH value on the growth and development of the rice seedling, the uptake and transport efficiency of the essential elements, the accumulation of ions on the cell wall and the activity of the non-selective cation channel, and the regulation of the transfer of the ions into the protoplast of the root system and the transport to the upper part of the root system. In the alkaline environment with the pH value of 6.5-7.0, the rice seedling mainly reduces the concentration of the yeast in the cytoplasm of the root system and the transport rate to the ground part, and the accumulation amount of the rice seedling in the cell wall and the protoplast of the ground part is inhibited.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S511

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