Distribution and Availability of Inorganic Phosphorus Fractions in the Rhizosphere of Populus deltoides cv.'lux' Grown in Marine Soil

In the present experiment, the distribution characteristics and availability of inorganic phosphorus fractions in the rhizosphere and non-rhizosphere soil of Populus deltoides cv. 'lux' were investigated. The results showed that (1) Available P was accumulated clearly in the rhizosphere of 3,5 and 11 year-old stands and the accumulation rates were 44%, 96% and 574%, respectively; (2) The contents of Ca 2-P in the rhizosphere of 3,5 and 11 year-old poplar were higher than those in the non-rhizosphere,and the rhizospheric effects (R/S) were 2.15, 2.59 and 5.54, respectively; (3) In the rhizosphere of 5 and 11 year-old poplar, Ca 8-P was accumulated, whereas Ca 10 -P was depleted clearly and the decrease of Ca 10 -P corresponded with the changes of available P, suggesting a stronger consumption in older stands for the P-activation from Ca 10 -P to more available P;(4) There was no obvious difference in Al-P, Fe-P and O-P between rhizosphere and non-rhizosphere soil.