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upzl铁杆木虫 (著名写手)
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【讨论】展叶过程中氮素的分配
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Allocation of nitrogen within the crown during leaf expansion in Quercus serrata saplings Miki U. Ueda1,2,*, Eri Mizumachi1 and Naoko Tokuchi3 1 Graduate School of Agriculture, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan 2 Corresponding author (m_ueda@kais.kyoto-u.ac.jp) 3 Field Science Education and Research Center, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan Abstract: Early season leaf growth requires a large amount of nitrogen, and the amount of N provided for new leaf development has been well tested. Although shoot position within the crown strongly influences leaf properties, little is known about absorbed and remobilized nitrogen allocation in the tree crown. Thus, we investigated differences in the allocation of recently absorbed nitrogen in the tree crown. To quantify nitrogen allocation, we conducted 15N tracer experiments using potted saplings of the temperate deciduous oak (Quercus serrata Thunb. ex. Murray). Allocation of 15N within the crown varied significantly: the top leaves received more remobilized nitrogen than did the lateral leaves, suggesting that remobilized nitrogen is predominantly allocated to the top shoots, which are important for height growth. On the other hand, the proportion of currently-absorbed nitrogen to total nitrogen in the lateral leaves was more than twice that in the top leaves. We also detected the input and the output of nitrogen in the top leaves after the completion of leaf expansion, indicating that significant nitrogen cycling occurs even after full leaf expansion. Keywords: flush, isotope, nitrate, oak, remobilized nitrogen, uptake 来源:http://treephys.oxfordjournals.org/cgi/content/abstract/29/7/913 非常有意思的话题, 其实个人感觉运用同位素失踪的手段已经很成熟了, 但是并没有被用来解决类似问题, 这些问题也一直困惑着我们, 包括老叶脱落后养分如何转移, 对于常绿植物而言,其转移的具体过程如何,一直未知. 对于同位素失踪的测定成本如何, 不知道有没有有经验的虫子? |
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