Abstract: To study the effects of nitrogen addition on growth and photosynthetic characteristics of Elymus nutans in Alpine artificial grassland,Elymus nutans was taken as the research object in the experiment and different nitrogen levels were applied as follows[0 kg·hm^-2·a^-1 (N0),12 kg·hm^-2·a^-1 (N1),24 kg·hm^-2·a^-1 (N2),48 kg·hm^-2·a^-1 (N3),96 kg·hm^-2·a^-1 (N4),which will explore the effects of nitrogen on the growth and photosynthetic characteristics of Elymus nutans,and uncover the response law of Elymus nutans to nitrogen addition. The results showed that the plant height,leaf length,leaf width,and single leaf area of Elymus nutans increased significantly under N2 and N3 treatment;In the whole growth period,the net photosynthetic rate (Pn),transpiration rate (Tr),and water use efficiency (WUE) of Elymus nutans increased first and then decreased while the intercellular CO₂ concentration (Ci) generally showed an upward trend with the increase of nitrogen application,but the stomatal conductance (Gs) showed no significant change under any condition. In conclusion,N2 and N3 treatment can improve growth performance and promote iphotosynthetic characteristics and water use efficiency. The results provide a theoretical basis for the growth of Elymus nutans and the response of photosynthetic characteristics to nitrogen deposition.

Key words: Alpine artificial grassland, Elymus nutans, Nitrogen level, Photosynthetic characteristics

摘要： 为研究氮添加对高寒人工草地垂穗披碱草(Elymus nutans)生长及光合特性的影响，试验以高寒生态条件下垂穗披碱草为研究对象，通过施加不同水平氮素[0 kg·hm^-2·a^-1(N0)，12 kg·hm^-2·a^-1(N1)，24 kg·hm^-2·a^-1(N2)，48 kg·hm^-2·a^-1(N3)，96 kg·hm^-2·a^-1(N4)]，探讨氮素对人工建植垂穗披碱草生长以及光合特性的影响，以期揭示垂穗披碱草对氮添加的响应规律。结果表明：N2，N3处理明显提高了垂穗披碱草株高、叶长、叶宽以及单叶面积；整个生育时期，随着氮肥施用量的增加，垂穗披碱草的净光合速率、蒸腾速率、水分利用效率呈现先增后降的趋势，胞间CO₂浓度大体呈上升趋势，气孔导度变化不显著。综上，N2，N3处理可提高垂穗披碱草生长性能，促进其光合特性和水分利用效率。试验结果为垂穗披碱草的生长以及光合特性对氮沉降的响应提供理论基础。

关键词: 高寒人工草地, 垂穗披碱草, 施氮水平, 光合特性