大白菜幼苗对干旱胁迫和复水的响应

Response of Chinese cabbage seedlings to drought stress and rehydration

为探究大白菜幼苗对干旱胁迫及复水的响应,采用自然干旱-复水处理法,研究大白菜幼苗在干旱和复水处理的生长、气孔、生理指标和激素含量变化规律。结果表明:随着干旱处理时间的延长(0~6 d),大白菜植株鲜重、干重呈下降趋势;气孔密度呈上升趋势、气孔长度和宽度呈下降趋势,但气孔密度响应较慢,在处理4 d才显著高于对照。生理上,超氧阴离子(O2·-)和过氧化氢(H2O2)含量、超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性呈先上升后下降趋势,其中O·-响应最快,干旱胁迫1 d即显著升高;脯氨酸(Pro)含量、丙二醛(MDA)含量、相对电导率呈上升趋势,其中MDA响应较慢,在处理4 d才显著高于对照;根系活力和叶绿素含量呈下降趋势,其中根系活力在干旱胁迫1 d即显著降低。叶片中脱落酸(ABA)、赤霉素(GA)、吲哚乙酸(IAA)含量呈先上升后下降趋势,ABA和GA响应较快,在干旱胁迫1 d即显著升高。复水后,气孔密度、长度和宽度、SOD、Pro、MDA、相对电导率、根系活力、叶绿素、GA、IAA均可迅速响应。研究表明:干旱胁迫下大白菜O·-、根系活力、ABA和GA迅速响应干旱胁迫,而气孔密度和MDA响应较慢。该研究明确了大白菜幼苗对干旱胁迫和复水响应的时间,旨在初步解析大白菜的抗旱机制,为干旱胁迫下大白菜的科学生产提供理论依据。

In order to explore the response of Chinese cabbage seedlings to drought stress and rehydration,the changes of growth,stomata,physiological indexes and hormone content of Chinese cabbage seedlings were studied by natural drought-rehydration treatment.The results showed that with the extension of drought treatment(O-6 days),the fresh weight and dry weight of Chinese cabbage decreased.The stomatal length and width decreased,but the stomatal density increased slowly,which was significantly higher than that of the control after 4 days of treatment.At the physiological levels,the contents of super oxide anion(Oz)and hydrogen peroxide(H,O2),the activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)increased at first and then decreased,among which O2 response was the fastest,it increased significantly after 1 day of drought stress.Proline(Pro)content,malondialdehyde(MDA)content and relative conductivity showed an upward trend,in which MDA responded slowly and was significantly higher than that of the control after 4-day-treatment.Root activity and chlorophyll content showed the downward trend.Among them,the root activity decreased significantly after 1 day of drought stress.The contents of abscisic acid(ABA),gibberellin(GA)and indoleacetic acid(IAA)of leaves increased at first and then decreased.ABA and GA responded quickly and increased significantly after the first day of drought stress.After rehydration,stomatal density,stomatal length and width,SOD,Pro,MDA,relative conductivity,root activity,chlorophyll,GA and IAA respond quickly.The results showed that under drought stress,O2,root activity,ABA and GA responded rapidly to drought stress,while stomatal density and MDA responded slowly.This study clarified the response time of Chinese cabbage seedlings to drought stress and rehydration in order to preliminarily analyze the drought resistance mechanism of Chinese cabbage and provide a theoretical basis for the scientific production of Chinese cabbage under drought stress.