Nitrogen transportation of young sweet cherry tree in dormant period

2-year-old potted sweet cherry trees of Zhuangyuan cultivar were fertilized with 15N-labelled ammonium sulfate in autumn. The transportation of nitrogen in young sweet cherry tree in winter was studied using isotopic tracer technique. The accumulation tendency of 15N absorbed in autumn was in accordance with the accumulation tendency of total N,and 15N and total N accumulated in root were more than that in trunk and branch. Compared with October 25th,the nitrogen content in bud,one year old branch xylem,perennial branch xylem,rootstock stem xylem and big root xylem decreased,but the nitrogen content in one-year-old branch bark,perennial branch bark,rootstock stem bark,big root bark,thick root and fine root increased on December 8th. The NDFF values of all parts reduced in the period. Compared with December 8th,the nitrogen content in different parts (except rootstock stem bark) augmented and the NDFF values of all parts increased on February 12th. The nitrogen content in bud,rootstock stem bark,big root bark,fine root increased and the NDFF values of all parts reduced on April 21st. So we might get such conclusions:the nitrogen absorbed in autumn could be stored in root,trunk and branch,but the content stored in thick root and fine root was more than the content in trunk and branch. Sweet cherry tree had the ability to absorb nitrogen in dormant period,but the absorption ability was different in different dormant phase. And the nitrogen was transported to phloem from xylem at the same time.