Abstract: Lespedeza davurica(Laxm.) Schindl.is a semi-shrub of perennial legume and the community dominant species of the Loess Plateau;at the same time,it is an excellent forage with resistance to drought,cold and poor soils.Dynamic changes of the leaf relative water content(RWC),membrane lipid peroxidation,and protective enzyme activities were studied in order to explore the relationship of enzymatic defensive system and drought resistance of the different L.davurica ecotypes chosen from six areas of Shanxi Province under drought stress and rewatering.The results show that leaf RWC and plant relative growth rate decreased while the contents of praline and MDA increased,and activities of SOD,POD and CAT increased firstly and then declined along with the time of drought stress.After rewatering,the activities of SOD,POD and CAT were lower than before and those in control,and the most depression was found in SOD.Strong drought-resistance L.davurica from Yangquan and Jiaokou had a little MDA accumulation,a lower cell membrane damage degree and a higher harmonious preventing ability among SOD,POD and CAT than those from Qinshui and Qinyuan under drought stress.The drought resistance of six L.davurica ecotypes from strong to weak was Yangquan>Jingle>Taigu>Jiaokou>Qinshui>Qinyuan.

Key words: Lespedeza davurica(Laxm.) Schindl., Drought stress, Rewatering, Enzymatic defensive system

摘要： 选用来自山西的6个生态型达乌里胡枝子(Lespedeza davurica)在干旱胁迫和复水后,研究植物叶片含水量、膜脂过氧化物和保护酶活性变化来探索不同生态型达乌里胡枝子在水分胁迫下和复水后酶促防御系统与抗旱性关系。结果表明:随干旱胁迫时间延长,达乌里胡枝子的叶片相对含水量和植株相对生长率逐渐下降,脯氨酸含量和丙二醛(MDA)含量上升,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性先升高后下降。复水后,各指标均有不同程度恢复,SOD、POD、CAT 3种酶活性比复水前低,而且比对照低,降低幅度最大的是SOD酶,其次是CAT和POD酶。干旱胁迫下,抗旱性强的阳泉、交口生态型MDA积累少,细胞膜受到伤害较轻,3种酶彼此协调保持酶系统的防御能力较强。抗旱性弱的沁水、沁源生态型MDA积累较多,细胞膜受到伤害较重,POD、CAT两种酶相互协调作用,而SOD同POD、CAT协调性较差。6个生态型达乌里胡枝子的抗旱性由强到弱顺序是:阳泉>静乐>太谷>交口>沁水>沁源。

关键词: 达乌里胡枝子, 水分胁迫, 复水, 酶促防御系统