The phosphorus acquisition characteristics were studied in wheat varieties with different P efficiencies under Pi-sufficient and Pi-deficient conditions.It showed that the plant total P contents at maturity stage,the accumulative P amounts per plant at mid-and later-growth stages were all the highest in varieties with high-P efficiency,then in the varieties with mid-P efficiency,and the lowest in the varieties with low-P efficiency.The P utilization efficiencies at jointing stage,flag leaf expansion stage and maturity stage had little differences among the variety types with different P efficiencies.It suggested that the increases of the grain yields in the varieties with high-P efficiency under Pi-deficient condition were related to the improvement of P uptake in the plants at the mid-and later-growth stages(from flag leaf expansion to maturity).Under Pi-deficient condition,the root TTC reductive activities and soluble protein contents at flag leaf expansion stage and mid-filling stage were also the highest in the varieties with high-P efficiency,then in the varieties with mid-P efficiency,and the lowest in the varieties with low-P efficiency.These results indicated that the higher root physiological functions during the plant mid-and later-growth stages in the varieties with high-P efficiency were the important reason for their much more P accumulations and higher grain yields.It is found that there were significant differences in the root acid phosphatase(APase) activities among the varieties with different P efficiencies during the mid-and later-growth stages,implying that the root APase activities have important functions on regulating the wheat P efficiency under Pi-deficient condition.