中文摘要：

采用盆栽试验方法，研究不同生育期水稻各部位对硒的吸收累积及根表铁膜对水稻吸收积累硒的影响机制。结果表明：水稻营养器官生物量在拔节期积累最快，不同时期营养器官中硒含量不同，根中的硒在拔节期达到最大，根和茎中的硒在灌浆期和成熟期被转运至其他部位。水稻各组织中约50％的硒在拔节期和孕穗期被吸收，小穗吸收总硒的47．22％且是在孕穗期完成的，说明这两个时期对于水稻硒吸收累积非常关键。铁膜中硒占总硒的比例在幼苗期高达73．63％，是同时期茎中硒所占比例的4．87倍。随着生育期的推进，铁膜中硒所占比例显著递减，在成熟期降低至20．02％，同时期茎中硒占总硒的比例为65．42％。这表明，根表铁膜在水稻整个生长周期内通过吸附作用使其表面能够富集一定量的硒，在水稻生育后期，当土壤溶液中硒含量较少时，根表铁膜可能会作为一个硒源，吸附在根表铁膜中的硒重新被水稻所利用，铁膜在水稻硒吸收转运的过程中扮演了“缓冲器”的角色。明确不同生育期根表铁膜对水稻硒累积特性，在生产管理中可在不同生育期采取措施提高稻田硒生物有效性，从而为进一步提高农产品中硒含量提供科学依据。

英文摘要：

[Objective] Rice is a staple food for the people in China, so it is feasible to improve effectively the status of the Chinese people being generally insufficient in intake of selenium by increasing the content of selenium in rice grains. Therefore, it is of great practical significance to the country to study characteristic of Se absorption and accumulation by rice, to define critical periods of the crop absorbing and accumulating selenium, hence to effectively regulate Se intake with daily diet. Rice is a species of hydrophyte, growing for a long time in fields flooded with water, where poor in areation, the crop has a well-developed aerenchyma formed at the root, to adapt itself to the anaerobic environment. The aerenchyma releases oxygen into the rhizosphere of the rice, which acts jointly with rhizosphere microorganisms to form a thin layer of ＂iron coating＂ on the surface of the root. The coating readily adsorbs selenium, thus lowering its bio-availability. As the researches in the past focused mainly on kinetics of Se absorption by rice at the seedling stage and impact of the iron coating on Se absorption and transfer, little has been reported on Se absorption and accumulation by rice at different growth stages, and impact of the iron coating on rice root on Se absorption and accumulation in the whole growth period. [Method] A pot experiment was carried out to study Se absorption by rice at various growth stages and accumulation in various parts of the plant, and mechanism of the iron coating on rice root surface affecting Se absorption and accumulation. [Result] Results show that the jointing stage was the period of time when the nutritive organs of rice grew and accumulated the rapidest in biomass to store adequate nutrients for the growth of reproductive tissues of the rice at the next growth stage, namely, booting stage. Se content in the nutritive tissues varied with growth stage, and peaked in the root at the jointing stage. Se in the root and stem was transported to the other parts of the rice at