Abstract: In order to study the effects of drought stress on the seedlings growth,the activities of secondary metabolism-related enzymes and the content of secondary metabolites in E. sibiricus seedlings,E. sibiricus were treated with different concentrations of polyethylene glycol (PEG) solution to simulate drought stress. The results showed that:drought stress inhibited the growth of E. sibiricus seedlings,the leaves withered in different degree and the relative water content (RWC),plant height,root length and fresh weight of leaves and roots significantly decreased compared with the control,and the decrease under moderate stress were greater than those under mild stress. The peroxidase (POD) activity under moderate drought stress changed more quickly than that under mild stress;the activity of phenylalanine ammonia lyase (PAL) changed less,and the activity of PAL was the highest in mild drought for 20 days and moderate drought for 15 days;at the 15th day of the two drought treatments,the contents of total phenol,flavonoids and tannins in the leaves of E. sibiricus significantly increased when compared with the control (P<0.05),and the increase under moderate stress was greater than that under light stress. In summary,drought stress reduced the growth of E. sibiricus seedlings,the POD of seedlings leaves responded quickly and more sensitive to drought stress,POD and PAL collaborate with each other to promote the accumulation of some secondary metabolites to adapt to drought stress.

Key words: Elymus sibiricus, PEG stress, Seedling growth, Secondary metabolites, Enzymatic activity

摘要： 本研究采用不同浓度的聚乙二醇（polyethylene glycol，PEG-6000）溶液对老芒麦（Elymus sibiricus L.）幼苗进行模拟干旱胁迫，研究干旱胁迫对老芒麦幼苗生长、次生代谢相关酶活性和相关产物含量的影响。结果表明：与对照相比，干旱胁迫抑制了老芒麦幼苗生长，叶片不同程度萎蔫，显著降低了叶片相对含水量（Relative water content，RWC）、株高、根长、叶和根鲜重，且中度干旱的降幅大于轻度干旱；干旱胁迫下，过氧化物酶（Peroxidase，POD）活性在中度干旱胁迫中响应比轻度干旱更迅速；苯丙氨酸解氨酶（L-phenylalanine ammonia-lyase，PAL）活性在轻度干旱20 d和中度干旱15 d时最强；两种干旱处理第15 d时，老芒麦叶片的总酚、类黄酮和单宁含量显著高于对照（P<0.05），且中度干旱胁迫下的增幅较大。综上所述，干旱胁迫导致老芒麦幼苗生长减缓，幼苗叶片POD快速响应，表现较为敏感，POD和PAL相互协作，促进部分次生代谢产物积累，从而使老芒麦适应干旱胁迫。

关键词: 老芒麦, PEG胁迫, 幼苗生长, 次生代谢, 酶活性