Changes in Nitrogen Uptake with Aging and Under Heavy Application of Nitrogen in Tea Plants

Japanese Journal of Crop Science

Toshihisa IKEDA¹  Katsuhiko IKEDA¹  Naoaki TACHIBANA¹ 

关键词: Heavy application of nitrogen;    ^<15>Nトレーサー法;    Nitrogen absorption;    多肥栽培;    ^<15>N tracer technique;    窒素吸収;    Tea plants;    チャ;   

DOI  :  10.1626/jcs.65.8

学科分类：农业科学（综合）

来源: Nihon Sakumotsu Gakkai / Crop Science Society of Japan

【 摘 要 】

Nitrogen absorption by mature tea plants was examined under different nitrogen levels. The annual increase rate of dry matter of five-year-old plants was 1.49 when no nitrogen was applied and increased with increasing nitrogen levels. The increase rate of seven-old tea plants decreased to one-half of that of five-year-old plants and differed a little among nitrogen levels. This means that seven-year-old plants have grown to the mature stage. The increase rate of dry matter of plants applied 180 kg 10 a-1 of nitrogen annually became lower than that of plants given 60 kg 10 a-1 of nitrogen. The amount of nitrogen uptake in five-year-old plants was 30 to 43 kg 10 a-1yr-1, but decreased 23 to 27 kg 10 a-1yr-1 in seven-year-old plants. Approximately 10 kg 10 a-1yr-1 of the nitrogen absorbed was estimated to derive from soil nitrogen produced by the decomposition of organic matter. When 60, 120 and 180 kg 10 a-1 of nitrogen was applied to seven-year-old plants, the uptake efficiency of nitrogen was 21.5, 13.8 and 9.9%, respectively. The amount of 15N absorbed after autumn application was so small that the ratio of the contribution to the first crop of the next year was 5 to 10%. However, the greater the amount of nitrogen supplied in both autumn and spring, the greater the amount of 15N was absorbed, and every organs showed a higher ratio of contribution. However, the nitrogen content of stems, thick roots and white roots remained at a lower level in the heavy applied plot. This was considered to be attributable to the root damage caused by a high concentration of salts in the rhyzospheres that results in restriction of nitrogen absorption.

【 授权许可】

Unknown