摘要The role of wheat ears as a source of nitrogen (N) and carbon (C) in the grain filling process has barely been studied. To resolve this question, five wheat genotypes were labeled with 15N-enriched nutrient solution. N remobilization and absorption were estimated via the nitrogen isotope composition of total organic matter and Rubisco. Gas exchange analyses showed that ear photosynthesis contributed substan-tially to grain filling in spite of the great loss of C due to respiration. Of the total kernel N, 64.7%was derived from the N acquired between sowing and anthesis, while the remaining 35.3%was derived from the N acquired between anthesis and maturity. In addition, 1.87 times more N was remobilized to the developing kernel from the ear than from the flag leaf. The higher yielding genotypes showed an increased N remobiliza-tion to the kernel compared to the lower yielding genotypes. In addition, the higher yielding genotypes remobilized more N from the ears to the kernel than the lower yielding genotypes, while the lower yielding genotypes remobilized more N from the flag leaf to the kernel. Therefore, the ears contribute signi-ficantly toward fulfilling C and N demands during grain filling.