Reproduction affects partitioning between new organs of a pulse of 15N applied during seed ripening in Fagus crenata
Reproduction affects partitioning between new organs of a pulse of 15N applied during seed ripening in Fagus crenata
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DOI：
10.1007/s11056-019-09757-2
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发表时间：
2019-10
期刊：
影响因子：
2.2
通讯作者：
Q. Han;Daisuke Kabeya;Y. Inagaki
中科院分区：
文献类型：
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作者：
Q. Han;Daisuke Kabeya;Y. Inagaki
季节性内部氮素循环是树木将生长与氮素获取分离的重要策略。虽然氮素的吸收、分配和储存与叶片物候和营养生长密切相关，但生殖对这些关键过程的影响仍然知之甚少。因此，我们在7月18日对一株92年生的水青兰的三株结果树和三株非结果树进行了脉冲15N标记，并定期跟踪所有新梢器官从上部树冠到落叶的每器官干质量的15N含量(15N过剩)。果树新梢中15N的回收率与非果树相同，但果树果实中15N的回收率高达70%，而非果树的叶片中15N的回收率为87%。此外，坚果中15N超量的急剧增加伴随着坚果含量的大约两倍的增加。这些结果表明，土壤对新氮素的吸收极大地促进了种子的成熟，从而导致果树叶片分配的减少。另一方面，在非结果个体中，分配给叶片的15N过量并没有伴随着叶片N含量的增加，因为当施加15N时，生物量的增长已经停止。这些结果表明，生长后期的氮素吸收有助于非果树体内氮素的储存。这些与繁殖有关的季节性N周期变化对环境变化期间植物-土壤系统的N动态有一定的影响。
Seasonal internal nitrogen (N) cycling is an important strategy for trees to uncouple growth fromNacquisition. WhileNuptake, allocation and storage has been intensively studied in association with leaf phenology and vegetative growth, influence of reproduction on these key processes is still poorly understood. Therefore, we applied pulse15N labelling to three fruiting and three non-fruiting trees in a 92-year-oldFagus crenataforest on 18 July and traced15N content per organ dry mass (15Nexcess) in all new shoot organs from the upper crowns periodically until leaf fall. The amount of15Nexcessrecovered in the whole new shoots in fruiting trees did not differ from non-fruiting individuals, although up to 70% of15Nexcesswas recovered in fruits of fruiting trees but 87% in leaves of non-fruiting individuals. In addition, dramatic increase in15Nexcessamount in nuts was accompanied by about twofold increase in nutNcontent. These results indicate that newNuptake from the soil contributed greatly to seed ripening, which in turn resulted in less allocation to leaves in fruiting trees. In non-fruiting individuals, on the other hand,15Nexcessallocated to leaves was not accompanied by concomitant increase in leafNcontent because biomass growth had ceased when15N was applied. These results suggest thatNuptake in the late growing season contributed to internalNstorage in non-fruiting trees. These reproduction-related variations in seasonalNcycle have implications forNdynamics in the plant–soil system during environmental change.