【作者】 高战武；

【导师】 穆春生；

【作者基本信息】 东北师范大学 ， 生态学， 2011， 博士

【摘要】 土壤的盐化和碱化是人类面临的生态环境危机之一,严重制约了农牧业生产的发展,不同种类盐胁迫对植物的影响不同,前人实验证明碱性盐胁迫对植物的伤害明显大于中性盐胁迫。研究植物对盐碱胁迫的生理响应特点,提高作物和牧草的耐盐碱性和种子产量对改良和利用退化盐碱草地具有重要意义。针对东北盐碱土壤的研究现状,本论文以多年生紫花苜蓿和一年生燕麦为材料,系统地比较了六种单盐胁迫对紫花苜蓿（Medicago sativa）种子萌发的影响;复合盐碱对紫花苜蓿种子萌发以及对幼苗的影响;燕麦（Avena sative）苗对三种单盐NaCl、NaHCO₃和Na₂CO₃胁迫的适应机制的研究;同时比较了盐胁迫和碱胁迫对燕麦苗的生长、生理生化的影响。其研究主要结果和结论如下:（1）在六种单盐胁迫下,其中CaCl₂在低浓度25-75mmolL-1之间时,紫花苜蓿种子的萌发率、发芽势、发芽指数、活力指数均高于对照组,说明低浓度的CaCl₂能促进种子萌发;当浓度高于100mmolL-1时,对种子萌发有抑制作用,其他五种盐各浓度对种子的萌发均有抑制作用。其中Na₂CO₃对种子萌发的影响非常明显,低浓度时就对种子萌发有明显的抑制作用,当浓度为50mmolL-1时,种子便不能萌发。当土壤的盐分超过植物的适应阈值,植物种子的萌发受抑制最终导致不能萌发。苜蓿种子萌发对六种盐分的耐受能力不同,其顺序是:MgCl₂>CaCl₂>NaCl>Na₂SO₄>NaHCO₃>Na₂CO₃;随着浓度的增加紫花苜蓿胚芽、胚根的生长在整体上都始终起着抑制作用;随盐浓度增加,六种盐胁迫下紫花苜蓿幼苗中脯氨酸积累量上升,并且差异明显。各种盐之间的异不明显。（2）用NaCl、Na₂SO₄两种中性盐和NaHCO₃、Na₂CO₃两种碱性盐以不同的摩尔比例混合,按照碱性盐比例逐渐增大的顺序共设置六个组,每个组又设置6个总盐浓度梯度,共模拟出36种盐度和碱度（pH值）各不相同的盐碱条件,对紫花苜蓿种子胁迫处理,测定种子萌发期的生物学指标和生理学指标的变化。结果表明,随着盐浓度的增大,发芽率、发芽势、幼苗长度下降且差异显著;膜透性增大、脯氨酸含量逐渐升高,可溶性糖含量降低;Na⁺含量增加、K⁺含量减少,Cl^-、SO₄^2-含量先增后减的变化趋势。盐和碱的交互作用明显,两者存在明显协同作用。并且紫花苜蓿对pH值的反应更敏感。（3）在实验室内模拟松嫩草地土壤的盐碱条件,以紫花苜蓿的幼苗为对象,研究复合盐碱胁迫下紫花苜蓿的适应性响应。根据东北地区盐碱土组成特点及盐分组成复杂多变的特点,本研究将NaCl、Na₂SO₄两种中性盐和NaHCO₃、Na₂CO₃两种碱性盐按照不同比例混合,按两种碱性盐比例的不同使pH递增共设A-F6个组;每组内又设置5个盐浓度梯度,复合盐碱胁迫处理液共覆盖了总盐度分别为24-120mmolL^-1,pH值7.03-10.32范围的盐碱胁迫环境,共模拟出30种盐度和碱度（pH值）各不相同的盐碱条件。用相应浓度的复合盐碱分别胁迫处理苜蓿幼苗进行,之后测定胁迫后的紫花苜蓿幼苗的生态学指标和生理指标。研究表明:复合盐碱胁迫下紫花苜蓿幼苗的生态指标的响应存在一定规律性;紫花苜蓿幼苗的生理指标的响应存在规律性变化。在pH值小于8.30的情况下,幼苗能够全部存活;当pH值大于9.69时,幼苗全部死亡。盐浓度和pH值梯度以及二者间的交互作用对苜蓿幼苗地上、地下生物量和存活率均有极显著影响。（4）将三种盐NaCl、NaHCO₃和Na₂CO₃分为A、B、C三组,每个组内设置5个浓度梯度(24^-144mmolL^-1)。对燕麦幼苗进行胁迫处理,测定生长指标和生理学指标。探讨了NaCl、NaHCO₃和Na₂CO₃胁迫对其地上部分及地下部分生长和生理的影响。实验结果表明:三种盐胁迫下,生物量、分蘖数、体内含水量、叶绿素含量、K⁺、Ca²⁺均下降,下降幅度为Na₂CO₃>NaHCO₃>NaCl;Na⁺、Na⁺/K⁺、SO₄^2-、脯氨酸含量、细胞膜透性均增大,增大幅度为Na₂CO₃>NaHCO₃>NaCl。NaCl胁迫下,茎叶中和根中组织液pH、有机酸无显著影响,Cl-增加;在NaHCO₃和Na₂CO₃胁迫下,有机酸增加显著;而地下部分根干重、含水量、K⁺、Ca²⁺、Cl^-、SO₄^2-下降幅度大于地上部分,Na⁺、Na⁺/K⁺、脯氨酸含量、有机酸增加但幅度小于地上部分。同时高浓度NaHCO₃和Na₂CO₃胁迫下,而使根中pH、有机酸含量显著增加,可造成幼苗大量的死亡。从燕麦存活率看,燕麦对Na₂CO₃耐受极限为96mmolL^-1;对NaHCO₃的耐受极限144mmolL^-1;以上结果说明,NaHCO₃和Na₂CO₃胁迫对燕麦幼苗生长和生理产生了更大的影响,尤其是还破坏了根中组织液pH的稳定。燕麦幼苗为了抵御碱胁迫的危害,主要采取在体内大量积累有机酸、脯氨酸含量,改变地上地下离子的分布来适应盐碱环境。而NaCl胁迫在燕麦体内积累脯氨酸、Cl^-和SO₄^2-离子,燕麦对这三种盐生理响应机制和策略不同。（5）将两种中性盐（NaCl和Na₂SO₄）和两种碱性盐（NaHCO₃和Na₂CO₃）分别按摩尔质量比例2:1混合,以中性盐混合代表盐胁迫,以碱性盐混合代表碱胁迫,并分为A、B两组,每个组内设置6个总盐浓度梯度(48^-168mmolL^-1),共模拟出12种盐度和碱度（pH值）各不相同的混合盐碱条件,对燕麦幼苗进行胁迫处理,探讨了盐胁迫和碱胁迫对燕麦生长和生理的影响。结果表明,碱胁迫下的生物量、体内含水量和叶绿素含量下降和细胞膜透性增加更大。盐胁迫对茎叶中和根中组织液pH无显著影响,但碱胁迫使根中组织液pH显著升高,高浓度碱胁迫可造成幼苗大量的死亡。碱胁迫下的Na⁺、Na⁺/K⁺、SO₄^2-的含量增加和K⁺、NO₃^-和H₂PO₄^-含量下降更大,而Ca²⁺增加量是盐胁迫大于碱胁迫,盐胁迫下Cl-显著增加,碱胁迫下变化不大。碱胁迫下脯氨酸含量增加更大,而有机酸含量在碱胁迫下显著增加,盐胁迫下保持不变。以上结果说明,高pH的碱胁迫对燕麦幼苗生长和生理产生了更大的影响,尤其是还破坏了根中组织液pH的稳定。燕麦幼苗为了抵御碱胁迫的危害,主要采取了在体内大量积累有机酸、脯氨酸和SO₄^2-离子,而盐胁迫在体内积累的是脯氨酸、Cl^-和SO₄^2-离子,两者的生理响应机制和适应对策不同。更多还原

【Abstract】 Salinization and alkalization of soil is one of the widespread and increasing environmental crisises. It also seriously restricts the development of agriculture and stockbreeding. It is widespread recognized that alkalization of the soil may be a more severe problem than salinization. Researching on the plant response to salt and alkali stresses is very important for improving crop and pasture production under such conditions. According to the present condition of salt-alkali soil, we used oat and alfalfa as the experimental materials and explored the effects of six type of separate salts on seed germination of alfalfa, effects of mix salt-alkaline stresses on biochemistry in seed germination of alfalfa and, effects of mixed salt-alkali stresses on seedlings of alfalfa, effects of salt stress or alkali stress on biochemistry in seedlings of oat, and response mechanism of oat under three types of salt, e.g. NaCl、NaHCO₃ and Na₂CO₃. The results listed as follows:（1） Effects of six types of salt stresses on germination of alfalfa: with the increasing salinity stress, when CaCl₂ concentration was between 25-75 mmolL^-1, germination rate, germination vigor, germination index and vitality index, were all higher than that of the control, indicating that CaCl₂ can promote seed germination; but when CaCl₂ concentration was higher than 100 mmolL^-1, it had a inhibiting role in germination, which was similar to all kinds of the concentration of the other five types of salt. It was obvious that Na₂CO₃ significantly inhibited germination vigor. Low concentration of Na₂CO₃ strongly restrained germination, especially at 50mmolL^-1 salinity in which seed can not germinate. When salinity concentration in the soil was very high, and reached the impatience threshold of the seeds, they can not germinate again. The salt-tolerance of alfalfa seeds was different, i.e. MgCl₂>CaCl₂>NaCl >Na₂SO₄>NaHCO₃>Na₂CO₃. With the increasing concentration, alfalfa plumule,radicle growth were all restricted. At the same salinity stress, total biomass in alfalfa was influenced according to CaCl₂> NaCl> Na₂SO₄> Na₂CO₃. With the increasing salinity concentration, the proline contents in alfalfa seedling significantly increased in six types of salts but insignificantly under different salt type.（2） Effects of mixed salt-alkaline stresses on seed germination of alfalfa: 6 treatments were designed by two neutral salts （NaCl and Na₂SO₄） and two alkaline salts （NaHCO₃ and Na₂CO₃） in different molar ratio, and also based on the increasing alkalinity. Within each group, six concentrations were used. Total 36 mixed stress treatments （various salinity, alkalinity and pH） were set. Germination index were measured under the pH values of treatment solutions ranged from 7.03 to 10.68. The results showed that with the increasing salinity, germination rate, germination vigor and seedling length all decreased significantly. Membrane permeability and proline content increased, solute sugar content decreased; Na+ content increased, K+ content decreased, Cl-、SO₄2- content firstly increased and then decreased. The interactions of salinity and alkalinity was obvious, had a seriously synergism role. In addition, Alfalfa was more sensitive to alkalinity.（3） Effects of mixed salt-alkaline stresses on seedlings of Alfalfa: According to the complicated salt composition of local soil in Northeast China, 6 treatments were designed by two neutral salts （NaCl and Na₂SO₄） and two alkaline salts （NaHCO₃ and Na₂CO₃） in different molar ratio, and also based on the increasing alkalinity. Within each group, 5 concentrations were used. Total 30 mixed stress treatments （various salinity, alkalinity and pH） were set. The pH values of treatment solutions ranged from 7.03 to 10.32 and salinity of treatment solutions ranged from 24 to120 mmolL^-1. We used these treatment solutions to stress seedlings of alfalfa, and then measured the physiological and ecological indexes. The results showed that physiological index of alfalfa seedlings had regular changed in response to the mixed salt-alkaline stresses, all of the seedlings could survive when pH < 8.30, however, when pH>9.69, the seedlings were all died. Survival rate, belowground biomass and aboveground biomass of the seedlings were affected by salinity, pH and their interactions.（4） Responses to salt stress and alkali stresses of oat: two neutral salts （NaCl and Na₂SO₄） and two alkaline salts （NaHCO₃ and Na₂CO₃） were both mixed in a 2:1 molar ratio and used as A and B groups, respectively. Six total salt concentration gradients (48^-168 mmolL^-1) were set in each group, which simulated 12 mixed salt conditions with different salinities and alkalinities （pH value）. Stress treatments were carried out on oat seedlings and the effects of saline and alkaline stresses on the growth and physiology of oat seedlings were discussed. The results showed that biomass, moisture content and chlorophyll content decreased and cell membrane permeability significantly increased under alkaline stress. Saline stress did not have obvious effect on pH value in the tissue fluids from stem, leaves and root, but alkaline stress increased pH value in the tissue fluid of root, and high concentration alkaline stress caused mass mortality of seedlings. The contents of Na+, Na+/K+, SO₄2- increased more and the contents of K+, NO3- and H2PO4- decreased more under alkaline stress than under salt stress; the increment of Ca2+ was greater under saline stress than that under alkaline stress; the Cl- content was increased obviously under saline stress but had little change under alkaline stress. The increment of proline was largely increased under alkaline stress, and the content of organic acid was remarkably increased under alkaline stress but kept the same under saline stress. The results indicate that high pH caused by alkaline stress created more harmful effects on growth and physiological changes of oat seedlings especially broke the pH stability in root tissue fluid. Physiological response mechanisms and adaptive strategy of oat seedlings under saline stress and alkaline stress were different, which mainly took the way of accumulating organic acid, proline and SO₄2- under alkali stress but accumulating Cl-, proline and SO₄2- under saline stress.（5） Responses of oat to three types of salt stress: NaCl、NaHCO₃ and Na₂CO₃ were applied as three groups （A, B and C）, respectively. Every group included 5 salinity gradients (24^-144 mmol L^-1). Oat seedling was treated and growth and physiological indexes were measured. We explored the effects of NaCl、NaHCO₃ and Na₂CO₃ stress on growth and physiological indexes in belowground and aboveground parts of the seedlings. The results suggested that under three types of saline stress, biomass , number of tiller, water content, chlorophyl content, K+ and Ca2+ all decreased, and the extent of the decrease was that Na₂CO₃>NaHCO₃>NaCl. Na+, Na+/K, SO₄2-, proline content and membrane permeability all increased, their extent was Na₂CO₃>NaHCO₃>NaCl. Under NaCl stress, no changes were found in tissue fluid pH and organic acid in both shoot and root, Cl- content increased. Under NaHCO₃ and Na₂CO₃ stresses, organic acid increased significantly, and the extent of decrease in belowground biomass, water content, K+, Ca2+, Cl-, SO₄2- were higher than aboveground parts. Na+, Na+/K+, proline and organic acid all increased, but the increasing extent was lower than aboveground parts. Meanwhile, high concentration of NaHCO₃ and Na₂CO₃ caused root pH and organic acid content increased significantly, resulting in lots of seedlings death. The survival rate of oat indicated that tolerance limit of oat was 96mmolL^-1 under Na₂CO₃, 144mmolL^-1 under NaHCO₃. We can summarize that NaHCO₃ and Na₂CO₃ stresses had a greater effect on growth and physiology of oat seedlings, especially interrupted the pH stability of root. In order to resist the harm effects of alkaline stress, oat accumulated lots of organic acids, proline, and changed the distribution proportion between aboveground and belowground parts to adapt to salt-alkali environment. Oat accumulated proline, Cl- and SO₄2- under NaCl Response mechanism and adaptive strategy was different among the three salts for oat.更多还原