Abstract: The genus Elymus is an important native grass species for ecological restoration. Screening low nitrogen-tolerant germination germplasm and improving nitrogen use efficiency are one of the effective approaches for near-natural restoration of degraded grasslands. In this study， twelve indicators during germination and seedling growth stages of 60 Elymus germplasms were measured under low nitrogen （0.01 mmol·L^-1） and control （1.00 mmol·L^-1）conditions using the petri dish germination method. Their responses to low nitrogen were explored， and comprehensive evaluation of low nitrogen tolerance was conducted by combining membership function and systematic clustering analysis. The results showed that under low nitrogen stress， all the indicators of the germplasms were decreased. The average germination rate， germination vigor， germination index， seedling length， root length， seedling fresh weight， root fresh weight， total fresh weight， seedling dry weight， root dry weight， total dry weight， and root-shoot ratio decreased by 5.95%， 12.07%， 8.21%， 6.40%， 14.80%， 29.04%， 36.28%， 25.54%， 30.00%， 40.74%， 28.77% and 8.08%， respectively. There were significant differences in low nitrogen tolerance among the different germplasms. Seven germplasms， including E22， E58and E47， had a comprehensive low nitrogen tolerance coefficient exceeding 0.850， while E32 and E49 were below 0.66. Based on the low nitrogen tolerance coefficient， cluster analysis divided the tested germplasms into six categories： super-strong， medium-strong， low-strong， low-weak， medium-weak， and super-weak. Among them， 10 materials， including E47 and E22， were classified as super-strong low nitrogen-tolerant germplasms， and 3 materials， including E49 and E32， were classified as super-weak low nitrogen-tolerant germplasms. This study provides excellent parental materials for the mining and functional research of candidate genes related to Elymus low nitrogen tolerance， genetic improvement， and breeding of new varieties.

Key words: Elymus, Seed germination, Low nitrogen tolerance, Comprehensive evaluation, Cluster analysis

摘要： 披碱草属（Elymus）是重要的生态修复乡土草种，筛选耐低氮萌发种质，提高氮素利用效率，是退化草地近自然恢复的有效途径之一。本研究采用培养皿发芽法对低氮（0.01 mmol·L^-1）及对照（1.00 mmol·L^-1）下60份披碱草属种质12项萌发及幼苗生长指标进行测定，探讨其对低氮的响应差异，并结合隶属函数及系统聚类分析进行了耐低氮性综合评价。结果表明：低氮胁迫下所有种质的各项指标均呈下降趋势，其平均发芽率、发芽势、发芽指数、苗长、根长、苗鲜重、根鲜重、整体鲜重、苗干重、根干重、整体干重以及根冠比依次下降5.95%，12.07%，8.21%，6.40%，14.80%，29.04%，36.28%，25.54%，30.00%，40.74%，28.77%和8.08%。不同种质间耐低氮能力差异显著，E22，E58，E47等7份种质综合耐低氮系数超过0.850，而E32和E49低于0.66，基于耐低氮系数的聚类分析将供试种质划分为超强、中强、低强、低弱、中弱、超弱6类，其中超强耐低氮种质包括E47，E22等10份材料，超弱耐低氮种质包括E49，E32等3份种质。本研究为披碱草耐低氮性候选基因挖掘与功能研究、遗传改良及新品种的选育提供了优异亲本材料。

关键词: 披碱草, 种子萌发, 耐低氮性, 综合评价, 聚类分析