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棉 花 学 报 Cotton Science 2008，20(4)：318-320
Nitrogen Resorption during Cotton Cotyledon Senescence Abstract：Nitrogen (N) resorption efficiency (NRE) and changes in nitrogen metabolism indices in cotton cotyledons during leaf senescence were studied in two cotton cultivars: CCRI 58 (short season) and Handan 109 (medium season). The main results were as follows: during the process of leaf growth and senescence, total nitrogen content in unit area (NPA) decreased gradually, NRE in CCRI 58 and Handan 109 is separately 69.26% and 54.45%, N metabolism indices such as chlorophyll and soluble protein content and nitrate reductase (NR) activity, are all increased first, then declined. The first to show a decline was NR activity, 9 d and 14 d in CCRI 58 and Handan 109. The declined times in CCRI 58 are 4-8 days prior to Han 109. Glutamate dehydrogenase (GDH) activity first declined, then increased, indicting that GDH may be the key enzyme involved in N resorption.
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