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Increasing atmospheric CO2 concentration impacts the terrestrial carbon(C)cycle by affecting plant photosynthesis,the flow of photosynthetically fixed C belowground,and soil C pool turnover.For managed agroecosystems,how and to what extent the interactions between elevated CO2 and N fertilization levels influence the accumulation of photosynthesized C in crops and the incorporation of photosynthesized C into arable soil are in urgent need of exploration.We conducted an experiment simulating elevated CO2 with spring wheat(Triticum aestivum L.)planted in growth chambers.13C-enriched CO2 with an identical 13C abundance was continuously supplied at ambient and elevated CO2 concentrations(350 and 600 pmol mol-1,respectively)until wheat harvest.Three levels of N fertilizer application(equivalent to 80,120,and 180 kg N ha-1 soil)were supplied for wheat growth at both CO2 concentrations.During the continuous 62-d 13CC2 labeling period,elevated CO2 and increased N fertilizer application increased photosynthesized C accumulation in wheat by 14％-24％and 11％-20％,respectively,as indicated by increased biomass production,whereas the C/N ratio in the roots increased under elevated CO2 but declined with increasing N fertilizer application levels.Wheat root deposition induced 1％-2.5％renewal of soil C after 62 d of 13CC2 labeling.Compared to ambient CO2,elevated CO2 increased the amount of photosynthesized C incorporated into soil by 20％-44％.However,higher application rates of N fertilizer reduced the net input of root-derived C in soil by approximately 8％under elevated CO2.For the wheat-soil system,elevated CO2 and increased N fertilizer application levels synergistically increased the amount of photosynthesized C.The pivotal role of plants in photosynthesized C accumulation under elevated CO2 was thereby enhanced in the short term by the increased N application.Therefore,robust N management could mediate C cycling and sequestration by influencing the interactions between plants and soil in agroecosystems under elevated CO2.