水稻中硅元素的分布及存在状态

Distribution and Status of Silicon in Rice Plant

利用UV-Vis分光光度计、X线分析显微镜及扫描电子显微镜(Scanning electron microscope,SEM)对水稻不同器官中硅元素的含量、分布及存在状态进行观察和分析,研究水稻中硅酸的化学性质,为水稻硅元素的综合利用提供科学依据.结果表明:水稻以可溶性原硅酸的形式吸收土壤中的硅酸,同样以可溶性原硅酸的形式输送到各器官中.不同的生长期,水稻导管液内的可溶性原硅酸的含量不同,成熟期最高可达到912 mg/L(以SiO2表示).通过比较导管汁液和土壤溶液的硅酸浓度可知,水稻选择性地吸收和浓缩硅酸,最高浓缩率可达85倍.X线分析显微镜观察发现,硅酸普遍存在于水稻各器官中,越是坚硬的部位硅酸分布得越多.SEM图像表明,沉积在水稻各器官中的硅胶体具有一定的形状且不溶于强酸.对水稻干燥组分中硅酸含量的分析结果表明,稻壳中硅酸含量最高,达到13.3%,是生产硅单质及碳化硅材料的最有效的资源之一.

The content,distribution and existing form of silicon in tissues of rice plant were analyzed by UV-Vis spectrophotometer,X-ray analytical microscope and scanning electron microscope（SEM）,and the chemical properties of silicic acid were investigated,which will provide a scientific basis for comprehensive utilization of silicon in rice plant.The results showed that silicic acid in soil was absorbed by rice plant in the form of monosilicic acid and transferred to different organs.The contents of the silicic acid varied with the growing periods,reaching 912 mg/L（expressed as SiO2） in maturity.The comparison of silicic acid concentrations in xylem sap and in soil solution showed that the silicic acid was selectively absorbed and concentrated during the transportation from soil to xylem,and the concentration ratio of silicic acid was considerably high being 85 fold at maximum.X-ray characteristic images of silicon showed that silicon existed widely in each tissue and its content was higher in the rigid parts.SEM image suggested that the silicon colloid deposited in different organs had specific shapes and was insoluble in strong acid.The content of silicic acid in each tissue was determined after decomposition of organic material with mixed acids,indicating that the highest content of silicic acid of 13.3% was observed in rice hull.As a result,the rice hull is one of the most potential nature resources to produce elemental silicon and silicon carbide materials.