A trade-off between nitrogen uptake and use increases responsiveness to elevated CO2 in infrequently cut mixed C3 grasses
A trade-off between nitrogen uptake and use increases responsiveness to elevated CO2 in infrequently cut mixed C3 grasses
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DOI：
10.1111/j.1469-8137.2005.01332.x
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发表时间：
2005-04-01
期刊：
影响因子：
9.4
通讯作者：
Dawson, L
中科院分区：
文献类型：
--
作者：
Soussana, JF;Teyssonneyre, F;Dawson, L
本研究的目的是评估是否混合C-3草种对CO2浓度升高的反应是更多地与氮吸收或氮利用效率。氮吸收和全株氮利用效率进行了研究与两个二元混合物：多年生黑麦草与高羊茅或与绒毛草混合。草地上生长的沙子或没有CO2倍增，并进行两个切割频率。一个C-20醇被用作一个标记，以确定物种比例的混合物的总根质量。根据N-15标记肥料的平均停留时间计算出N的平均停留时间，结果表明，多年生黑麦草单位根质量对N的吸收显著高于其竞争对手，但N的利用效率较低。CO2浓度升高显著降低了3种牧草对氮素的吸收，氮素利用效率与氮素吸收速率呈负相关，表现为氮素吸收与利用之间的平衡。一个高的N-利用效率，相反，低N的吸收似乎有利于响应CO2浓度升高的不经常削减草。
The aim of this study was to evaluate whether the responsiveness of mixed C-3 grass species to elevated CO2 is related more to nitrogen uptake or to N-use efficiency.Nitrogen uptake and whole-plant N-use efficiency were investigated with two binary mixtures: Lolium perenne was mixed either with Festuca arundinacea or with Holcus lanatus. The swards were grown on sand with or without CO2 doubling, and subjected to two cutting frequencies. A C-20 alcohol was used as a marker to determine species proportion in the total root mass of the mixtures. The mean residence time of N was calculated from that of N-15-labelled fertilizer.Lolium perenne took up significantly more N per unit root mass than its grass competitors, but its N-use efficiency was lower. Elevated CO2 significantly reduced the N uptake of the three grass species.A trade-off between N capture and use was found, as N-use efficiency and N-uptake rate were negatively correlated. A high N-use efficiency, and conversely low N uptake appeared to favour the responsiveness to elevated CO2 of the infrequently cut grasses.