中文摘要：

海拔是影响植物生物进化和亲缘关系的重要因素,为了探明海拔对披碱草属植物表型特征的影响,本试验对不同海拔（3098∽4203 m）的3种披碱草属植物：六倍体垂穗披碱草（Elymus nutans）、四倍体的昆仑披碱草（Elymus burchan-buddae）和老芒麦（E.sibiricus）,27个种群810个体的13个表型性状进行测定,结果表明,垂穗披碱草的变异系数范围为8.8%∽59.1%,昆仑披碱草为8.2%∽53.7%,老芒麦为7.6%∽56.7%,外稃长是3种披碱草变异系数最小的表型性状。聚类分析可以看出形态上相似的种群海拔来源基本相同,而且聚为一类的多数种群具有相似的生境。相关分析表明：海拔和供试材料的多个表型性状之间存在着明显的相关性（P〈0.01）。本研究表明,海拔对披碱草属植物形态特征具有较强的可塑性,不同披碱草属植物的形态特征对海拔变化的反应不同,四倍体披碱草属植物对海拔的变化反应更加敏感。因此,部分形态特征可以用于披碱草属植物在海拔梯度上的演化规律的分析。

英文摘要：

Altitude is a key factor affecting biological evolution and genetic relationship in plant species.In order to study the effect of altitude on the morphological traits of Elymus species,thirteen morphological traits of 810 individuals from 27 populations of hexaploid Elymus nutans,tetraploid E.burchan-buddae and E.sibiricus were investigated.These materials were collected at the altitude ranges from 3098 m to 4203 m.The results showed that the variation coefficients of Elymus nutans,E.burchan-buddae and E.Sibiricus ranged from 8.8%to 59.1%,8.2%to 53.7%and 7.6%to 56.7%,respectively.The length of lemma had the smallest variation coefficient compared to others.The Elymus populations with similar attitude were clustered.Significant correlations were observed between altitude and morphological traits（P0.01）.The results indicated that altitude shaped the morphological traits of Elymus species.Different species and morphological traits had different responses to altitude.Tetraploid Elymus species had higher sensitivity to altitude than others.Therefore,some morphological traits can be used for analyzing the evolution of Elymus species along altitude.