Tradeoffs between nitrogen- and water-use efficiency in dominant species of the semiarid steppe of Inner Mongolia
Tradeoffs between nitrogen- and water-use efficiency in dominant species of the semiarid steppe of Inner Mongolia
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DOI：
10.1007/s11104-010-0525-9
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发表时间：
2011-03-01
期刊：
影响因子：
4.9
通讯作者：
Schnyder, Hans
中科院分区：
文献类型：
--
作者：
Gong, Xiao Ying;Chen, Qing;Schnyder, Hans
在水分有限的环境中，光合碳的获得和蒸腾失水是一个永久的权衡，因为两者都是由气孔导度相反调节。在半干旱草原中，水分限制可能与氮限制协变。草原物种能够优化其有限的资源，水和氮的利用，但调控仍然知之甚少。在一个为期两年的试验中，通过增加水（模拟丰水年灌溉）和氮（0、25和50 kg Urea-Nha（-1）），我们评估了四种优势C-3物种（羊草、冰草、大针茅和冷蒿）的内在水分利用效率（WUEI）、氮利用效率（NUE）和相关植物功能性状（PFT）。水和氮肥的补充显着增加植物初级生产力，和灌溉条件下的N效应更为明显。与植物生产的响应平行，检测到WUEI和NUE之间的强烈权衡：供水增加NUE，但减少WUEI，而N添加以NUE为代价略微增加WUEI。这种平衡发生在叶片水平，涉及叶片氮浓度和比叶面积的响应。WUEI的物种之间的变化处理在一个可预测的方式由每单位面积的叶片N含量的参数。优势植物通过改变PFT来提高对有限资源的利用效率，是半干旱草原植物适应可变资源限制的重要机制。
In water-limited environments, photosynthetic carbon gain and loss of water by transpiration are in a permanent tradeoff as both are contrarily regulated by stomata conductance. In semiarid steppe grasslands water limitation may covary with nitrogen limitation. Steppe grassland species are capable of optimizing their use of limiting resources, water and nitrogen, but regulation is still poorly understood. In a two-year experiment with addition of water (irrigation simulating a wet year) and nitrogen (0, 25, and 50 kg urea-Nha(-1)) we assessed intrinsic water use efficiency (WUEi), nitrogen use efficiency (NUE), and related plant functional traits (PFTs) of four dominant C-3 species (Leymus chinensis, Agropyron cristatum, Stipa grandis, and Artemisia frigida). Water and N fertilizer supplementation significantly increased plant primary production, and N effect was more pronounced under irrigated conditions. Parallel with the responses of plant production, a strong tradeoff between WUEi and NUE was detected: water supply increased NUE but decreased WUEi, whereas N addition slightly increased WUEi at the expense of NUE. This tradeoff occurred at the leaf level, and involved the responses of leaf N concentration and specific leaf area. WUEi of species changed among treatments in a predictable manner by the parameter of leaf N content per area. Dominant plant species commonly achieved a higher utilization efficiency of the more limiting resource via altering PFTs, which was an important mechanism of adaptation to variable resource limitation in semiarid grasslands.