硒在土壤—水稻系统中的迁移转化规律

通过研究江门市都斛、牛江、宅梧3个优质稻产地土壤Se的空间分布规律及其与指示不同物质来源的特征元素组合的相互关系,得出土壤Se来源于陆相沉积,其中基性物源对土壤硒的贡献率大于花岗岩物源.Se的7种形态中,强有机态Se和腐殖酸态Se均占全量的一半以上,且此2种形态与全量间相关系数高,说明土壤中Se的富集与有机质的活动密切相关.硒在水稻植株根、茎、叶、谷壳、米粒中的分布、迁移和总量传输,是一个动态过程.从土壤和根部传输上来的硒会逐渐在各器官内积累,浓集系数大小顺序表现为C茎-谷壳,C土-根,C茎-米,C根 -茎的特点.水稻在地面以上部分的硒量不足植株总硒量的50％.高硒区土壤总硒与土壤有机态硒和残渣态硒有关,硒的含量、形态明显受土壤pH、Eh和有机质含量影响.

Migration and Transformation of Se in the Soil-Rice System

The interrelationship between the spatial distribution of soil Se and its characteristic element combinations that indicate different origin materials of three high quality rice-cultivating areas in Jiangmen city(Douhu,Niujiang and Zhaiwu) of Guangdong province was study.The results showed that soil Se in those areas resulted from continental deposits,of which the base source contributed more to soil Se than the granite source.Of the seven Se species studied,the species strongly bound in organic compounds and the humic acid-bound species accounted for more than half of total Se content,and the correlation coefficient between these two Se forms and total Se was high,indicating that the enrichment of Se in soil is closely related with organic matter activities.The distribution,migration,and the total transmission of Se in the roots,stems,leaves,chaff and grain of rice constituted a dynamic process.The Se transferred upward from the soil and the roots was gradually accumulated in various organs,the concentration factor being in the order of C stem-chaff > C soil-root> C stem-grain > C root-stem.Se content of the shoots of rice was less than 50% of total Se of the plant.Total soil Se of the high-Se areas was related to organic Se and residual Se in the soil.The content and forms of Se were significantly affected by soil pH,Eh and organic matter content.