本文選題：紫花苜蓿　切入點(diǎn)：幼苗　出處：《吉林大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：凍融作用是東北地區(qū)常見(jiàn)的自然脅迫現(xiàn)象,春秋兩季牧草常因寒流侵襲,受到凍融循環(huán)作用,容易出現(xiàn)生長(zhǎng)不良、產(chǎn)量低等現(xiàn)象,降低了牧草的利用價(jià)值。目前,針對(duì)牧草的耐寒和耐鹽堿能力的研究主要集中于單因素脅迫條件,有關(guān)凍融與鹽堿復(fù)合脅迫下牧草的響應(yīng)機(jī)制的研究甚少。紫花苜蓿(Medicago sativa)屬于豆科苜蓿屬多年生草本,作為人工草地的優(yōu)質(zhì)牧草,具有耐寒、耐鹽堿、抗逆性強(qiáng)等優(yōu)點(diǎn),常被用于改良鹽堿化草地。本論文以東苜1號(hào)為研究對(duì)象,通過(guò)人工模擬凍融分別與Na_2SO_4、NaCl、NaHCO_3、Na_2CO_3(四種鹽分為東北地區(qū)鹽堿地常見(jiàn)的鹽堿組分)復(fù)合脅迫實(shí)驗(yàn),測(cè)定了紫花苜蓿幼苗體內(nèi)蛋白質(zhì)、MDA、可溶性糖、脯氨酸含量和SOD、POD活性的變化趨勢(shì),系統(tǒng)研究了紫花苜蓿幼苗對(duì)凍融及鹽堿脅迫的生理響應(yīng)特征,為苜蓿耐寒性和耐鹽性評(píng)價(jià)及寒冷地區(qū)鹽堿地的改良提供理論基礎(chǔ)。主要研究結(jié)果如下:實(shí)驗(yàn)室模擬凍融實(shí)驗(yàn)中,在凍融周期內(nèi),苜蓿幼苗體內(nèi)滲透調(diào)節(jié)物質(zhì)含量均呈現(xiàn)先增后降的變化趨勢(shì)。在融凍階段(10~-3℃),隨著溫度的降低,凍融和凍融+鹽堿(Na_2SO_4、NaCl、NaHCO_3、Na_2CO_3)組中脯氨酸、丙二醛、可溶性糖含量升高,在-3℃時(shí)達(dá)到最大值,與10℃、5℃、0℃相比均有顯著性差異(P0.05);蛋白質(zhì)的變化趨勢(shì)相同,在5℃和-3℃均達(dá)到峰值,且在-3℃時(shí)較為敏感,與融凍階段10℃相比均有顯著性差異(P0.05)。在凍融階段(-3~10℃),隨著溫度升高,凍融組和凍融及中性鹽(Na_2SO_4、NaCl)組中脯氨酸、MDA、可溶性糖含量略有下降,不同溫度處理組間無(wú)顯著性差異(P0.05),蛋白質(zhì)含量則顯著下降(P0.05);凍融和凍融+堿性鹽(NaHCO_3、Na_2CO_3)組中蛋白質(zhì)、脯氨酸、MDA、可溶性糖含量顯著下降(P0.05)。紫花苜蓿幼苗體內(nèi)抗氧化酶活性隨溫度降低而升高、隨著溫度升高而降低,不同處理組變化趨勢(shì)不盡相同。整個(gè)凍融過(guò)程中,CK組SOD、POD活性無(wú)顯著性變化(P0.05),凍融和凍融+鹽堿組中SOD、POD活性變化趨勢(shì)一致,凍融周期內(nèi)均呈現(xiàn)先上升再下降后趨于穩(wěn)定的趨勢(shì),且各溫度處理組SOD、POD活性均大于CK組。在凍融循環(huán)過(guò)程中,隨著溫度降低,凍融和凍融+鹽堿組中SOD、POD活性逐漸升高,在-3℃時(shí)達(dá)到最大值,與10℃、5℃、0℃相比,均有顯著性差異(P0.05);隨著溫度升高,凍融+中性鹽組中SOD、POD活性降低,而凍融+堿性鹽組中SOD活性略有降低,POD活性先降低后升高。在凍融及鹽堿脅迫環(huán)境中,紫花苜蓿幼苗體內(nèi)細(xì)胞膜脂過(guò)氧化傷害加劇,MDA含量增加,迫使苜蓿幼苗體內(nèi)產(chǎn)生一系列的耐鹽堿性和耐寒性生理防御機(jī)制,SOD、POD活性增強(qiáng),有利于快速消除活性氧,防御超氧陰離子自由基對(duì)苜蓿幼苗的傷害。同時(shí),可溶性蛋白、脯氨酸和可溶性糖的含量增加,有利于調(diào)節(jié)細(xì)胞膜內(nèi)外的滲透勢(shì)、保持苜蓿幼苗細(xì)胞正常的生理活動(dòng)。
[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，

本文編號(hào)：1616930