Abstract: Aims Seed traits are of great significance for clarifying plant population reproduction and renewal strategies. Understanding the response of Artemisia ordosica seed traits to nitrogen deposition and increased precipitation can improve the understanding of desert plant community succession. Methods The study was conducted based on an 8-year field water and nitrogen control experiment (2015-2022). A full factor interaction experiment of ambient precipitation, 20% water increase, 40% water increase and 0, 20, 60 kg N ha?1 yr?1 were carried out to determine the morphological, physiological, chemical and germination traits of A. ordosica seeds. The germination traits of seeds under each treatment at two temperatures (25℃/15℃ and 20℃/10℃) were explored by using the petri dish germination experiment and calculating the germination indexes by observing the number of seedling emergence. Important Findings (1) Nitrogen and water addition, as well as their interactions, significantly influenced the morphological characteristics of A. ordosica seeds, including seed mass, length, width, curvature, volume, form coefficient and other traits. The addition of water resulted in smaller seeds while nitrogen alone led to larger seeds. However, when water was increased by 20%, it mitigated the effect of nitrogen increase on seed size. Conversely, with a 40% increase in water content, nitrogen addition caused smaller seeds. (2) The germination percentage was higher at normal temperature (25℃/15℃) than that at low temperature conditions (20℃/10℃). At low temperature, seed germination traits were more affected by parental water and nitrogen addition, and when only adding 20% and 40% water, the seeds had higher germination percentage. (3) Increase water or nitrogen alone tent to the variation of only one function (dispersal establishment or germination) of A. ordosica seeds, while simultaneous addition of water and nitrogen led to the variation of both functions of A. ordosica seeds. These findings demonstrate that populations of A. ordosica possessed a great adaptability in response to global climate change by altering their functional strategies of seed dispersal establishment and germination under different circumstances through the variation of seed traits.Methods The study was conducted based on an 8-year field water and nitrogen control experiment (2015-2022). Natural precipitation, 20% water increase, 40% water increase and 0, 20, 60 kg N ha?1 yr?1 full factor interaction were used to determine the morphological, physiological, chemical and germination traits of Artemisia ordosica seeds. Two-factor analysis of variance and principal component analysis were used to explore the effects of water and nitrogen addition on seed traits of Artemisia ordosica. Important Findinds (1) Nitrogen and water supplementation, as well as their interactions, significantly influenced the morphological characteristics of Artemisia ordosica seeds, including seed mass, length, width, curvature, volume, shape coefficient, and other traits. The addition of water resulted in smaller seeds while nitrogen alone led to larger seeds. However, when water was increased by 20%, it mitigated the effect of nitrogen increase on seed size. Conversely, with a 40% increase in water content, nitrogen addition caused smaller seeds. (2) The impact of nitrogen addition was more significant than that of water supplementation. The germination rate was higher at normal temperature (25℃/15℃) than that at low temperature conditions (20℃/10℃). However, when only adding 20% water, the seeds had higher germination rate and the highest germination rate occurred under the low temperature condition. (3) Under combined treatments of water and nitrogen supplementation, the shape coefficient, nitrogen content, and various aspects was related to germination such as 2-hour water absorption capacity and overall germination rate jointly regulated the timing function for seed germination. The increase in both water and nitrogen enhanced the ecological coordination strategy employed by Artemisia ordosica seeds. These findings demonstrates that populations of Artemisia ordosica possessed a great adaptability in response to global climate change by altering their functional traits to coordinate ecological functions under different environmental conditions.

Key words: Nitrogen deposition, increased precipitation, Artemisia ordosica, seed traits, germination, reproduction