Abstract: Based on an external nitrogen source NH₄NO₃,the impacts of different nitrogen deposition treatments (i.e.,CK (0 g·m^-2·a^-1),N5 (5 g·m^-2·a^-1),N10 (10 g·m^-2·a^-1),and N15 (15 g·m^-2·a^-1)) on the growth of the A. tauschii and its competition with wheat were investigated to forecast A. tauschii invasion risk under nitrogen deposition. The results showed that in the absence of competition,the morphological indicators (plant height,leaf area and tiller number) and biomass indicators (above ground biomass,below ground biomass and total biomass) of A. tauschii tended to increased with the increasing of nitrogen deposition,which indicated that nitrogen deposition promoted the growth of wheat. In addition,the average of plasticity index of the morphology and biomass indicators of A. tauschii was significantly higher than that of wheat. And the increase amplitude of each biomass indicator of A.tauschii was higher than that of wheat in N15 treatment under the condition of competition. All of these indicated that A. tauschii had higher nitrogen use efficiency. The result of competitive effects and competitive response based on biomass changes showed that,the effect of nitrogen deposition on the improvement of the competitive ability of A. tauschii is mainly reflected in its competitive effect on wheat. The results preliminarily suggested that N deposition may increase the potential invasion risk of A. tauschii by improving its competitive ability.

Key words: Simulated nitrogen deposition, Aegilops tauschii Coss., Competitive responses, Competitive effects, Relative interaction intensity

摘要： 设置节节麦和小麦单种及混种2种模式，以NH₄NO₃为外加氮源，研究N0、N5、N10及N15（分别为0、5、10、15 g·m^-2·a^-1）4个梯度氮沉降量对节节麦表型可塑性及竞争能力的影响，为氮沉降背景下节节麦的入侵风险预测提供参考依据。结果表明：无竞争条件下，节节麦形态指标（株高、叶面积及分蘖数）和生物量指标（地上部分、地下部分及总生物量）均随氮沉降量的增加而增加，表明氮沉降促进了节节麦生长。此外，节节麦形态及生物量指标的可塑性指数均值明显高于小麦；竞争条件下，至N15处理时节节麦生物量的各指标较CK增幅均明显高于小麦，表明节节麦较高的氮利率。基于生物量变化的竞争效应及竞争响应结果显示，氮沉降量的增加对节节麦竞争能力的提高主要体现在其对小麦的竞争效应上。综上所述，氮沉降量的增加促进了节节麦竞争能力的提升，加剧了其入侵的危害性。

关键词: 模拟氮沉降, 节节麦, 竞争响应, 竞争效应, 相对作用强度