Changes of the contents of nitrate, oxalic acid and polyamines in tea plants (Camellia sinensis L.) grown with different nitrogen forms and concentrations
1999
Morita, A. (Shizuoka-ken. Tea Experiment Station, Kikugawa (Japan)) | Oota, M. | Yoneyama, T.
Four-year-old tea plants were transferred from a field to hydroponics for 16-week culturing. The nitrogen in the culture solution was varied; no N (N0), 50 mg N L(-1) ammonium nitrate (AN-50), 100 mg N L(-1) ammonium nitrate (AN-100), 500 mg N L(-1) ammonium nitrate (AN-500), 500 mg N L(-1) ammonium sulfate (A-500) and 100 mg N L(-1) nitric acid (N-100). At harvest, Samples from new shoot, mature leaves, white roots and brown roots were obtained, freeze dried and ground. The weight increase of tea plants after nitrogen treatment was largest in AN-50, AN-100 and AN-500, followed by N-100. The content of nitrate was also highest in AN-100 and AN-500. Significant nitrate in AN-50 and N-100 treatment was observed only in the white roots, while an obvious increase of nitrate was observed in the young shoots and mature leaves of plants that received AN-100 treatment, and more in those that were treated with AN-500. The content of oxalic acid was highest in mature leaves, and increased with the increase of nitrate in the culture solution. If nitrate reduction is related with oxalic acid synthesis, the major site of nitrate reduction is roots when the administration of nitrate is small while being mature leaves when nitrate addition is large. Polyamines (putrescine, cadaverine, spermine, spermidine) were present in tea organs. Putrescine content was large in roots and increased by the treatment of higher ammonium concentrations. Spermidine content was high in young shoots, and also increased with the treatment of higher ammonium nitrate concentrations
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