Effect of iron plaque outside roots on nutrient uptake by rice (Oryza sativa L.) : phosphorus uptake

Zhang XiKe; Zhang FuSuo; Mao DaRu

Plant and Soil 209(2): 187-192


ISSN/ISBN: 0032-079X
DOI: 10.1023/a:1004505431879
Accession: 003109222

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Under anaerobic conditions, ferric hydroxide deposits on the surface of rice roots have been shown to affect the uptake of some nutrients. In the present experiment, different amount of this iron plaque were induced on the roots of rice (Oryza sativa cv. TZ88-145) by supplying different Fe(OH)3 concentrations in nutrient solutions, and the effect of the iron plaque on phosphorus uptake was investigated. The results showed that iron plaque adsorbed phosphorus from the growth medium, and that the amount of phosphorus adsorbed by the plaque was correlated with the amount of plaque; that the phosphorus concentration in the shoot increased by up to 72% after 72 h Fe(OH)3 concentrations in the nutrient solution from 0 to 30 mg Fe/litre, corresponding with amounts of iron plaque from 0.2 to 24.5 mg/g (root dry weight); that the phosphorus concentration in the shoots of rice with iron plaque was higher than that without iron plaque though the concentration in the shoot decreased when Fe(OH)3 was added at 50 mg Fe/litre producing 28.3 mg/g (root dry weight) of plaque; and that the phosphorus concentrations in Fe-deficient and Fe-sufficient rice plants with iron plaque were the same, although phytosiderophores were released from the Fe-deficient roots. The phytosiderophores evidently did not mobilize phosphorus adsorbed on plaque. The results indicated that iron plaque on rice plant roots could be considered a phosphorus reservoir.