干旱胁迫对甜荞幼苗生理特性的影响

Effect of drought stress on physiological characteristics in common buckwheat seedlings

为探究甜荞(Fagopyrum esculentum Moench.)幼苗期对干旱胁迫的应答机制,以甜荞品种‘西农9976’为供试材料,采用不同质量分数(0%、5%、10%和12%)的PEG-6000溶液对荞麦幼苗进行为期5d的干旱胁迫处理,研究了甜荞幼苗期生理特性的动态变化规律。结果表明,随着PEG-6000浓度的增加以及胁迫时间的延长,甜荞幼苗的叶片相对含水量持续显著降低,叶片中的超氧阴离子自由基(O-·2)产生速率和过氧化氢(H2O2)含量总体呈上升趋势;同时,抗氧化酶SOD、POD和CAT的活性均呈现先升高后降低的趋势。此外,干旱胁迫使丙二醛(MDA)含量持续积累并于胁迫第5天达到高峰。研究结果还表明,干旱胁迫下活性氧(ROS)在甜荞幼苗叶片中均有不同程度的累积,轻度胁迫下抗氧化酶类能够对其进行有效的清除,且能维持植株的正常生长;但中度和重度胁迫下超出了抗氧化酶类的清除能力,氧化和抗氧化平衡状态受到破坏,从而导致细胞的膜脂过氧化程度加剧,植株受害严重。

In order to explore the response mechanism of buckwheat seedlings to drought stress,Xinong 9976,a common buckwheat(Fagopyrum esculentum Moench.)was used as the material,and PEG-6000 was used to simulate the drought stress.The drought stress was carried out to different mass fraction(0%、5%,10%,12%)to study the dynamic changes of physiological characteristics of common buckwheat seedlings to drought stress for 5 days.The results showed that with the increase of PEG-6000 concentration and the extension of stress time,the relative water content(RWC)of common buckwheat seedling leaves decreased continuously,and the production rate of superoxide anion radicals(O-·2)and the content of H 2O 2 in leaves showed an overall upward trend.At the same time,the activities of the antioxidant enzymes SOD,POD and CAT increased first and then decreased.In addition the content of malondialdehyde(MDA)continued to accumulate under drought stress and reached the peak on the 5th day.The results showed that reactive oxygen species(ROS)accumulated in buckwheat leaves under drought stress,ROS were accumulated in buckwheat leaves to varying degrees,antioxidant enzymes could effectively eliminate ROS and maintain the normal growth of buckwheat plants under mild stress.However,ROS exceeds the ability of antioxidant enzymes under moderate and heavy stress,and the balance of oxidation and antioxidation is destroyed,which leads to the degree of membrane lipid peroxidation of cells and the damage of plants.