干旱胁迫对大豆苗期叶片保护酶活性和膜脂过氧化作用的影响

目的]探讨干旱胁迫对大豆幼苗的伤害与膜质过氧化的关系以及保护酶系统与抗旱性的关系。方法] 以2个不同耐旱性的大豆品种为试材，研究干旱胁迫对大豆苗期叶片保护酶活性和膜脂过氧化作用的影响及其与抗旱性的关系。结果]随着干旱胁迫的加强，质膜透性和丙二醛（MDA）含量逐渐增加，超氧歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性表现为先升后降的趋势。轻度胁迫下质膜透性和MDA含量增幅较小，重度胁迫时增幅达显著或极显著水平，且MDA含量与质膜透性呈极显著正相关。SOD和CAT活性分别在胁迫的第2天和第3天达到峰值，尔后下降，第6天酶活性明显低于对照；而POD活性在第3-4天达到峰值，尔后下降，第6天仍略高于对照。耐旱性品种比不耐旱性品种具有较低的质膜透性和MDA含量，同时具有较高的SOD、CAT和POD活性。结论]为大豆抗旱机理的研究提供了理论依据。

Effects of the Drought Stress on the Protective Enzyme Activity and Membrane Lipid Peroxidation of Leaf in Soybean Seedling

Objective] The relationship between the drought stress damaging soybean seedling and membrane lipid peroxidation,the relationship between the protective enzyme system and the drought-resisting were analyzed.Method] Two soybean varieties with drought tolerance being taken as experimental material,the effect of the drought stress on the activity of the protective enzyme and membrane lipid peroxidation and its relationship with drought resistance were studied.Results] The results showed that with the drought stress being severe,the permeability of plasma membrane and the content of malondialdephyde(MDA) were gradually increased,and the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT) were firstly increased and then decreased.The drought-tolerant cultivars had lower permeability of plasma membrane and content of MDA than the drought-sensitive cultivars,and also were with higher activities of SOD,POD and CAT.