外源甜菜碱对镉胁迫下紫花苜蓿种子萌发及幼苗生理特性的影响

Effects of exogenous betaine on seed germination andphysiological characteristics of alfalfa seedlingsunder cadmium stress

摘要:

为探究外源甜菜碱对镉(Cd)胁迫下紫花苜蓿幼苗生长的影响,设置叶施和根施两种不同施加方式以及6个外源甜菜碱(glycine betaine,GB)浓度(0、10、20、30、40、50 mmol/L),在镉(25 mg/L)胁迫下测定‘甘农3号’紫花苜蓿种子萌发以及相关抗逆生理指标。结果表明,与单独胁迫对照相比,施加适宜浓度的外源GB均能提高镉胁迫下紫花苜蓿种子的发芽率、发芽势、发芽指数以及活力指数,其中30 mmol/L的GB对Cd胁迫下抑制种子萌发的缓解作用最佳;叶施和根施30 mmol/L GB,对紫花苜蓿的叶绿素、根长、株高增加值、根部含水量均有显著提高;叶施30 mmol/L和根施50 mmol/L GB显著提高紫花苜蓿幼苗叶片中游离脯氨酸(Pro)含量、抗氧化酶(SOD、POD、CAT)活性,抑制丙二醛(MDA)含量的升高;通过隶属函数分析可知,叶施和根施30 mmol/L的外源GB对缓解苜蓿幼苗Cd胁迫的效果最佳。

Abstract:

In order to explore the effect of exogenous betaine on alfalfa seedling growth under cadmiumstress,alfalfa Gannong No.3 was used as experimental material,and two application methods(spraying on theleaf and root injection)and six exogenous betaine concentrations(0,10,20,30,40 and 50 mmol/L) were used totreat the seedling of alfalfa.Seed germination and relative stress resistance indexes of alfalfa under ( cadmium Cd,25 mg/L) stress were analyzed.The results showed : compared with stress control,the germination rate,germination potential,germination index,and vigor index of alfalfa seeds under Cd stress can be improved by applyingappropriate concentration of exogenous GB,30 mmol/L GB had the best alleviating effect on inhibitingseed germination under the stress of Cd;and the content of chlorophyll,the length of root ,the added value ofplant height ,and the content of root water were increased when the leaf and root with application concentrationsof 30 mmol/L GB.Compared with Cd treatment,spraying on the leaf 30 mmol/L and root injection tendencyfor 50 mmol/L GB can effectively improve the content of free proline(Pro),the activity of SOD,POD andCAT,and inhibited the increase in the content of malondialdehyde(MDA).According to the membership functionanalysis,the exogenous GB of 30 mmol/L leaves and roots application had the best effect on alleviating theCd stress of alfalfa seedlings.