EFFECT OF ROOT IRON PLAQUE ON PHOSPHORUS UPTAKE BY RICE PLANT

In anaerobic condition, release of oxygen by roots to rhyzosphere caused the formation of red plaque of iron oxides or hydroxides on root surface of rice. The effect of iron plaque on P uptake was investigated with solution culture in greenhouse, arid the results are seen in the following: The amount of iron plaque was increasing with the increase of Fe2+ in medium. The plaque on rice root could adsorb P in growth medium, arid amount of P adsorbed on plaque increased with the increase of iron plaque. When there is iron plaque on rice root, P uptake by rice plant was enhanced.and the enhancement reached peak when amount of iron plaque was 24570mg/kg.Further increase in amount of iron plaque, P amount absorbed by rice plant decreased,but which was still high thari by rice root without plaque. In addition, phytosiderophore which was released by root of Fe deficient rice had no effect of P uptake by rice whose root was coated by iron plaque. So iron plaque on root was a P reservoir for rice plant.