Abstract: To determine the drought-tolerant capacity of bromus and to screen early drought-tolerant bromus seedlings， this study measured the adaptive response of 101 accessions of B. inermis at the seedling stage to drought stress. The morphological and physiological changes of the plants including roots were analyzed， and 17 growth indexes related to drought tolerance were determined. The drought tolerance of the seedlings was evaluated and screened by comprehensive evaluation， correlation analysis， principle component analysis， membership function and cluster analysis. The results showed that plant height， average root diameter， fresh weight above ground， total root volume， root surface area， root projected area， fresh weight below ground， total primary root length， dry-weight root aboveground ratio， maximum primary root long， fresh-weight root aboveground ratio and aboveground dry weight can be important indicators for the identification of drought tolerance in the seedlings of bromus. 101 bromus materials were divided into 4 different drought-tolerant grades by cluster analysis. There were 10 germplasm materials in class I with D value ranging from 2.00 to 2.55， which were highly drought-tolerant materials. There were 38 germplasm materials in Class II with D value ranging from 1.27 to 1.81， belonging to moderate drought tolerance. There were 42 germplasm materials in Class III with D value ranging from 0.77 to 1.25， belonging to low drought tolerance. There were 11 germplasm materials in Class IV， the D value ranged from 0.37 to 0.73， belonging to drought sensitive materials. The drought-resistant germplasm W1Z755， W1Z770 and W1Z696 were selected. The drought-sensitive materials were W1Z626， W1Z587 and W1Z763. This study can provide a theoretical basis and a material basis for the drought resistance evaluation of bromus seedlings and the selection of new varieties.

Key words: Bromus inermis, Seedling stage, Drought stress, Drought tolerance index

摘要： 为确定无芒雀麦（Bromus inermis）苗期耐旱能力，筛选苗期耐旱性较强的无芒雀麦种质材料，本研究通过测定101份无芒雀麦苗期对干旱胁迫的适应性反应，分析其植株和根系的形态及生理变化，测定了与耐旱性相关的17个生长指标，利用综合评价、相关性分析、主成分分析、隶属函数和系统聚类分析等方法对其苗期耐旱性进行评价筛选。结果表明：株高、根平均直径、地上鲜重、总根体积、根系表面积、根系投影面积、地下鲜重、总根长、干重根冠比、最大根长、鲜重根冠比和地上干重可以作为无芒雀麦苗期耐旱性鉴定的重要指标；聚类分析将101份无芒雀麦材料划分为4个不同耐旱等级：第Ⅰ类有10份种质材料，D值范围2.00~2.55，属于高度耐旱材料；第Ⅱ类有38份种质材料，D值范围1.27~1.81，属于中度耐旱材料；第Ⅲ类有42份种质材料，D值范围0.77~1.25，属于低度耐旱材料；第Ⅳ类有11份种质材料，D值范围0.37~0.73，属于旱敏感型材料。综合筛选出耐旱种质有W1Z755，W1Z770和W1Z696旱敏感型材料有W1Z626，W1Z587和W1Z763。本研究能够为无芒雀麦苗期耐旱性评价及新品种选育提供理论依据和材料基础。

关键词: 无芒雀麦, 苗期, 干旱胁迫, 耐旱指标