Abstract: Two rice genotypes differed in tolerance to iron toxicity were used to investigate the adsorption of phosphate by iron plaque on rice roots and subsequent effect on P absorption by rice. Great variation in quantities of iron plaque was observed between two genotypes, resulting in the difference in phosphate adsorption. The amount of P adsorbed increased with the increasing quantity of iron plaque on rice roots, which was indicated by a significant positive correlation between the quantity of iron plaque and its phosphate adsorbed. Phosphate adsorbed by iron plaque was likely to be a chemical process which was accomplished within 0.5-1.0 hour. The accumulation of phosphate by iron plaque remarkably enhanced the phosphorus uptake by rice, which suggested that the adsorbed phosphate was an important pool of phosphorus available to rice under the flooding conditions.

Key words: iron plaque, rice, phosphorus, adsorption, absorption

摘要： 采用溶液培养方法，使铁毒耐性不同的两个基因型水稻根表分别形成有铁膜和无铁膜的根系，研究水稻根表铁膜对磷的富集作用及其与水稻磷吸收的关系。不同基因型水稻根表形成的铁膜厚度存在显著差异，对介质中磷的富集能力也有显著差异。根表形成的铁膜越厚，对介质中磷的富集作用也越大，即根表铁膜数量与铁膜对磷的富集量呈显著正相关。铁膜对磷的富集作用是一个化学过程，吸附可在0.5~1.0 h内达到饱和。根表铁膜明显促进水稻对磷的吸收，表明在淹水降低土壤磷有效性时，水稻根表铁膜富集的磷可作为磷库，保证水稻能正常吸收利用磷。

关键词: 铁膜, 水稻, 磷素, 富集作用, 吸收