紫花苜蓿幼苗对冻融及盐碱复合胁迫的生理响应特征

发布时间：2018-03-15 21:44

  本文选题：紫花苜蓿　切入点：幼苗　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：冻融作用是东北地区常见的自然胁迫现象,春秋两季牧草常因寒流侵袭,受到冻融循环作用,容易出现生长不良、产量低等现象,降低了牧草的利用价值。目前,针对牧草的耐寒和耐盐碱能力的研究主要集中于单因素胁迫条件,有关冻融与盐碱复合胁迫下牧草的响应机制的研究甚少。紫花苜蓿(Medicago sativa)属于豆科苜蓿属多年生草本,作为人工草地的优质牧草,具有耐寒、耐盐碱、抗逆性强等优点,常被用于改良盐碱化草地。本论文以东苜1号为研究对象,通过人工模拟冻融分别与Na_2SO_4、NaCl、NaHCO_3、Na_2CO_3(四种盐分为东北地区盐碱地常见的盐碱组分)复合胁迫实验,测定了紫花苜蓿幼苗体内蛋白质、MDA、可溶性糖、脯氨酸含量和SOD、POD活性的变化趋势,系统研究了紫花苜蓿幼苗对冻融及盐碱胁迫的生理响应特征,为苜蓿耐寒性和耐盐性评价及寒冷地区盐碱地的改良提供理论基础。主要研究结果如下:实验室模拟冻融实验中,在冻融周期内,苜蓿幼苗体内渗透调节物质含量均呈现先增后降的变化趋势。在融冻阶段(10~-3℃),随着温度的降低,冻融和冻融+盐碱(Na_2SO_4、NaCl、NaHCO_3、Na_2CO_3)组中脯氨酸、丙二醛、可溶性糖含量升高,在-3℃时达到最大值,与10℃、5℃、0℃相比均有显著性差异(P0.05);蛋白质的变化趋势相同,在5℃和-3℃均达到峰值,且在-3℃时较为敏感,与融冻阶段10℃相比均有显著性差异(P0.05)。在冻融阶段(-3~10℃),随着温度升高,冻融组和冻融及中性盐(Na_2SO_4、NaCl)组中脯氨酸、MDA、可溶性糖含量略有下降,不同温度处理组间无显著性差异(P0.05),蛋白质含量则显著下降(P0.05);冻融和冻融+碱性盐(NaHCO_3、Na_2CO_3)组中蛋白质、脯氨酸、MDA、可溶性糖含量显著下降(P0.05)。紫花苜蓿幼苗体内抗氧化酶活性随温度降低而升高、随着温度升高而降低,不同处理组变化趋势不尽相同。整个冻融过程中,CK组SOD、POD活性无显著性变化(P0.05),冻融和冻融+盐碱组中SOD、POD活性变化趋势一致,冻融周期内均呈现先上升再下降后趋于稳定的趋势,且各温度处理组SOD、POD活性均大于CK组。在冻融循环过程中,随着温度降低,冻融和冻融+盐碱组中SOD、POD活性逐渐升高,在-3℃时达到最大值,与10℃、5℃、0℃相比,均有显著性差异(P0.05);随着温度升高,冻融+中性盐组中SOD、POD活性降低,而冻融+碱性盐组中SOD活性略有降低,POD活性先降低后升高。在冻融及盐碱胁迫环境中,紫花苜蓿幼苗体内细胞膜脂过氧化伤害加剧,MDA含量增加,迫使苜蓿幼苗体内产生一系列的耐盐碱性和耐寒性生理防御机制,SOD、POD活性增强,有利于快速消除活性氧,防御超氧阴离子自由基对苜蓿幼苗的伤害。同时,可溶性蛋白、脯氨酸和可溶性糖的含量增加,有利于调节细胞膜内外的渗透势、保持苜蓿幼苗细胞正常的生理活动。
[Abstract]:Freeze-thaw is a common natural stress phenomenon in Northeast China. Forage in spring and autumn is affected by freezing and thawing cycle because of cold current. It is easy to appear bad growth and low yield, which reduces the utilization value of forage. The studies on cold tolerance and saline-alkali tolerance of forage were mainly focused on the single factor stress, but the response mechanism of forage under the combination of freeze-thaw and saline-alkali stress was seldom studied. Medicago sativa belongs to the perennial herb of Medicago sativa, which belongs to leguminous alfalfa. As the high quality forage grass in artificial grassland, it has the advantages of cold tolerance, salt alkali resistance and strong resistance to stress, and is often used to improve the salinized grassland. The changes of protein MDA, soluble sugar, proline content and activity of SODPOD in alfalfa seedlings were determined by artificial simulation of compound stress experiments of freezing and thawing with NaCl-NaHCO3 + Na2CO3 (four kinds of salts are common saline-alkali components in saline and alkali land of Northeast China), and the changes of protein MDA, soluble sugar, proline content and SODPOD activity in alfalfa seedlings were determined. The contents of MDAs, soluble sugars, proline and SODPOD activities in alfalfa seedlings were determined. The physiological responses of alfalfa seedlings to freeze-thaw and saline-alkali stress were systematically studied, which provided a theoretical basis for the evaluation of alfalfa cold tolerance and salt tolerance and the improvement of saline-alkali land in cold regions. The main results were as follows: in the laboratory simulated freezing and thawing experiments, During the freeze-thaw cycle, the content of osmotic regulatory substances in alfalfa seedlings increased first and then decreased. During the thawing stage, the contents of osmotic substances increased first and then decreased. With the decrease of temperature, the contents of proline, malondialdehyde, malondialdehyde in the freezing thawing and freezing thawing and freezing thawing and freezing thawing and freezing thawing Na2SO4 / NaClCO4 / NaClCO3 / Na2COSP3) groups were observed. The content of soluble sugar increased to the maximum at -3 鈩，

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