In agricultural systems,it is vital to use limited yet optimal phosphorus(P)resources,because excessive P fertilizer application leads to the accumulation of P in soil,increasing the risk of environmental pollution and causing the waste and exhaustion of P resources.In a rice-wheat rotation system,omitting P fertilizer application in the rice-growing season is a good alternative;however,how this P fertilization reduction influences changes in P in the soil-root-aboveground system is unclear.In this study,after a seven-year rice-wheat rotation at the Yixing(YX)and Changshu(CS)sampling sites,China,compared with P fertilization in rice-and wheat-growing seasons(PR+W),reduced P fertilization(no P fertilizer application in either season,P0;P fertilization only in wheat-growing seasons,PW;and P fertilization only in rice-growing seasons,PR)did not result in substantial variation in crop biomass.The PW treatment did not reduce crop total P,root iron(Fe)-plaque P,and soil Olsen-P at three stages of rice growth(seedling,booting,and harvesting stages)at the YX and CS sites.In contrast,concentrations of soil Olsen-P,aboveground crop total P,and root Fe-plaque P decreased in the PO treatment by 45.8％-81.0％,24.6％-30.9％,and 45.6％-73.4％,respectively.In addition,a significant negative correlation was observed between the root Fe-plaque P and crop biomass at the two sites.Significant positive correlations were also observed between root Fe-plaque P and root total P,crop total P,and soil Olsen-P.In addition,the results of a redundancy analysis revealed that soil alkaline phosphatase(ALP)played a major role in the supply of P in soil,and was closely associated with root Fe-plaque P.The results of this study will enhance the understanding of the changes in P in the soil-root-aboveground system,particularly under P fertilizer reduction regimes.