不同类型土壤对水稻硅同位素分馏的影响

Effects of Different Soil Types on Silicon Isotope Fractionation of Rice

为探明不同类型土壤对水稻硅同位素组成及分馏的影响,本研究以红壤、黑土和褐土作为供试土壤,以水稻品种嘉58作为供试材料进行盆栽试验,测定土壤理化性质,水稻各器官干重、硅含量、硅同位素组成等指标。结果表明,不同类型土壤对水稻硅同位素分馏效应均影响明显,红壤、黑土、褐土栽培的水稻硅同位素分馏系数(αPre-Dsi)分别为0. 998 8、0. 997 8、0. 997 5,其中褐土栽培的水稻体内硅同位素分馏程度最大,黑土次之,红壤最小;相关性分析表明,水稻δ30Si值(整株和叶片)与土壤pH值、有机质、有效硅、游离氧化铁和游离氧化铝含量之间均存在极显著相关性(P<0. 01),其中土壤游离氧化铁、游离氧化铝含量随着土壤风化程度的增加均呈升高趋势。由此推断,水稻硅同位素组成可能主要受土壤pH值、有机质、有效硅含量及土壤风化程度的影响。本研究结果为利用硅稳定同位素示踪技术探索自然界的硅循环模式提供了理论依据。

A plot experiment was carried out to explore the effects of different soil types on Si isotope composition and fractionation of rice.Rice(Oryza sativa L.cv.Jia 58)was grown in red soil,black soil and cinnamon soil,respectively.Soil chemical properties,rice dry weight,rice Si content,rice Si isotope composition were determined.The results indicated that different types of soil had a remarkable impact on the rice Si-isotopic fractionation.The Si isotope fractionation factors(αPre-Dsi)of rice grown in red soil,black soil and cinnamon soil were 0.998 8,0.997 8 and 0.997 5,respectively,illustrating that the extent of Si isotope fractionation of rice planted in cinnamon soil was the strongest,followed by rice in black soil and rice in red soil.Correlation analysis showed that theδ30Si values of rice(bulk and leaves)were significant correlated with the contents of organic matter,available Si,free Fe oxide,free Al oxide and pH values of soils(P<0.01),indicating that rice Si-isotopic signature might be primarily affected by p H values,organic matter content,available Si content of soils and the extent of soil weathering since the contents of free Fe oxide and free Al oxide increase with weathering.The results provide a theoretical basis for using Si isotope tracing technology to explore the model of Si cycle in nature.