水稻根系泌氧对水稻土磷素化学行为的影响

通过模拟试验研究了水稻根系泌氧作用对水稻土磷素化学行为以及水稻吸磷的影响。淹水极显著地增加土壤对磷的吸附，降低磷的解吸。而模拟的水稻泌氧作用则可明显降低土壤对磷的吸附，增加根际土壤的磷解吸和离子交换树脂对磷的吸收量。因此，水稻根系的泌氧作用应该是水稻在淹水明显降低土壤磷有效性情况下能正常从土壤获取磷的重要机制之一。淹水导致土壤磷有效性降低与淹水引起土壤磷组分转化有关。淹水2周，经富磷预处理而增加的Al-P组分，几乎全被转化为Fe-P。

Chemical Behavior of Phosphorus in Paddy Soil as Affected by O2 Secretion from Rice Root

A simulated experiment was carried out to study the effect of O 2 secretion of rice root on phosphorus behavior in the soil and phosphorus uptake by rice. The results showed that flooding strongly increased phosphorus (P) adsorption and decreased P desorption in the paddy soil while simulated O 2 secretion from rice root significantly reduced P adsorption and enhanced both P desorption in rhizosphere and P uptake by ion exchanger. It was suggested that the effect of O 2 secreting from rice root should be one of important mechanisms for rice take up P normally under the conditions of P availability reduction by flooding. P availability in the soil reduced by flooding should be related to the transformation of P fractions because the Al P fraction increased by P amendment in the soil was almost transformed into Fe P fraction by 2 week flooding.