Pedosphere 18(2): 222--226, 2008
ISSN 1002-0160/CN 32-1315/P
©2008 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Transport of nitrogen assimilation in xylem vessels of green tea plants fed with NH4-N and NO3-N
K. OH1, T. KATO2 and H. L. XU3
1 Center for Environmental Science in Saitama Saitama 347-0115 (Japan). E-mail:
2 Jinenjou-no-kai, NPO, Shizuoka 421-0302 (Japan)
3 International Nature Farming Research Center, 5632 Hata, Nagano 390-1401 (Japan)
      An experiment was carried out to study the transport process of nitrogen (N) assimilation from tea roots by monitoring the dynamic composition of N compounds in xylem sap after 15N-NO3 and 15N-NH4 were fed to the root of tea plants (Camellia sinensis L.). Results showed that the main amino acids were glutamine, thcanine, arginine, asparic acid and glutamic acid, which accounted for 49%, 17%, 8%, 7%, and 4%, respectively, of the total amino acids in the xylem sap. After the tea plants were fed with 15N-NO3 and 15N-NH4 for 48h, the amount of total amino acids in xylem sap significantly increased and those fed with 15N-NH4 had higher increment than those with 15N-NO3. Two hours after 15NNO3 and 15N-NH4 were fed, 15N abundance in glutamine, asparagine, glutamic acid, alanine, and arginine were detected and increased quickly over time. This indicated that it took less than 2h for NO3-N and NH4-N to be absorbed by tea roots, incorporated into the above amino acids and transported to the xylem sap. Rapid increase in 15N-NO3 in the xylem sap of tea plants fed with 15N-NO3 indicated that nitrate could be directly transported to the xylem sap. Glutamine, theanine, and alanine were the main amino acids transported in xylem sap of tea plants fed with both 15N-NO3 and 15N-NH4.
Key Words:  amino acid, 15N, nitrogen assimilation, tea plant, xylem sap
Citation: Oh, K., Kato, T. and Xu, H. L. 2008. Transport of nitrogen assimilation in xylem vessels of green tea plants fed with NH4-N and NO3-N. Pedosphere. 18(2): 222-226.
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