【作者】 王宁；

【导师】 曹敏建；

【作者基本信息】 沈阳农业大学 ， 作物栽培学与耕作学， 2009， 博士

【摘要】 我国土地盐碱化是玉米生产进一步稳定发展的重要制约因素之一,盐胁迫使玉米幼苗生长受阻,芽势弱,胚根少且短,苗弱,成活率低,严重影响其生长发育及产量。因此,提高玉米品种的耐盐碱性是开发和利用这部分资源的有效途径之一。本文以120份辽宁及内蒙古地区主栽品种为试验材料,通过萌发期的各项指标对其进行耐性鉴定与筛选,在砂培条件下分析了典型不同耐性品种在苗期对盐胁迫的生物学差异,并对植株形态、干物质积累、渗透调节物质、膜质过氧化及保护酶活性、光合特性及荧光特性等方面进行研究,从而探讨出不同耐性品种对盐耐性机制差异,以及在不同盐胁迫条件下的耐性机制差异。主要结论如下:1.NaCl胁迫下,180mmol/L浓度可作为不同耐性品种分级鉴定的浓度。在此浓度下进行聚类分析,可将120份玉米品种分为高耐盐、耐盐、中敏、盐敏感、盐极度敏感五个级别。Na₂CO₃+NaHCO₃（1:1）胁迫下,90mmol/L+90mmol/L浓度可作为不同耐性品种分级鉴定的浓度。在此浓度下进行聚类分析,可将120份玉米品种分为耐碱、中耐、中敏、碱性盐敏感四个级别。从分级结果看,中性盐与碱性盐的各级品种差距很大。2.NaCl、Na₂CO₃+NaHCO₃胁迫下,两玉米品种的株高、叶面积的变化趋势一致,均随生育时期增加而增加,随盐胁迫浓度增加而降低,盐敏感品种在盐胁迫下的伤害率大于耐盐品种。NaCl胁迫下,主胚根长、根系总长度、根系表面积、根系体积均随生育时期增加而增加,除了在40mmol/L浓度条件下较对照促进生长外,其余浓度条件下随盐浓度增加而降低。Na₂CO₃+NaHCO₃胁迫下,主胚根长、根系总长度、根系表面积、根系体积均随生育时期增加而增加,随盐浓度增加而降低,耐盐品种品种各项指标随盐浓度变化不如盐敏感品种的变化幅度大。根系平均直径随生育时期增加而增加,随盐胁迫浓度增加而增加。盐胁迫程度越重,平均直径越大,此规律在NaCl胁迫下不如在Na₂CO₃+NaHCO₃胁迫下明显。3.NaCl胁迫下,轻度的盐胁迫对根系生长的促进作用不如对茎叶的大,重度盐胁迫时,根系快速生长,使根冠比加大。Na₂CO₃+NaHCO₃胁迫下,生育初期地上部、地下部干重随盐浓度变化差距不明显,随生育时期增加,盐胁迫浓度越重,植物组织干重降低越大,根冠比随盐胁迫浓度加大而加大。盐敏感品种伤害率大于耐盐品种。4.两品种可溶性蛋白、可溶性糖含量、游离脯氨酸均随NaCl胁迫浓度增加而增加,盐敏感品种的增加幅度不如耐盐品种增加的幅度大。游离氨基酸在叶片中含量随盐胁迫浓度增加而增加,根系中游离氨基酸在120mmol/L浓度下含量显著高于其他处理。两品种叶片、根系中可溶性蛋白含量均随Na₂CO₃+NaHCO₃胁迫浓度增加而升高,叶片中含量显著高于根系中含量。可溶性糖含量随盐胁迫浓度增加而升高,在叶片和根系中差距不大。两品种叶片中游离氨基酸含量随盐胁迫浓度升高而增加,两品种根系游离氨基酸含量在盐胁迫下明显低于0mmol/L处理下的含量。两品种叶片、根系中游离脯氨酸含量均随盐胁迫浓度增加而明显增加,从绝对含量上看,叶片中含量高于根系中含量。两种盐胁迫下,两品种叶片、根系中K⁺、Ca²⁺、Mg²⁺含量随盐胁迫浓度增加而降低,Na⁺含量则随盐胁迫浓度增加而增加,Na⁺/Ca²⁺与Na⁺/K⁺比值均随盐胁迫浓度增加而增加。碱性盐胁迫下,总无机离子含量随盐胁迫浓度增加而明显降低。5.两品种叶片、根系中的相对电导率的含量均随盐胁迫浓度增加而增加,根系中相对电导率的值更大一些,这一点规律两种盐胁迫下表现一致。NaCl、Na₂CO₃+NaHCO₃胁迫下,两玉米品种叶片、根系中超氧阴离子自由基的含量、丙二醛含量,均随盐浓度增加而增加。从绝对含量看,碱性盐胁迫下的含量高于中性盐胁迫下的含量,说明碱性盐胁迫下的膜质过氧化程度高于中性盐。SOD、POD、CAT三种保护酶活性随NaCl胁迫浓度增加而增加,叶片、根系中变化趋势一致。Na₂CO₃+NaHCO₃胁迫下,POD、CAT变化趋势与中性盐胁迫下相一致,但是叶片中SOD在低浓度碱性盐胁迫时活性增加,在高浓度碱性盐胁迫下反而降低。6.两玉米品种叶片中叶绿素a+b、叶绿素a、叶绿素b含量均随盐胁迫浓度增加而降低,a/b比值升高,这在两种盐胁迫条件下的表现规律是一致的。玉米叶片净光合速率、气孔导度、胞间CO₂浓度、蒸腾速率随盐浓度增加而降低,光合速率、气孔导度和胞间CO₂浓度三者变化趋势一致,可以认为气孔限制是导致光合速率下降的一个主要原因,两种盐胁迫所引起的光合特性变化也是一致的。两品种的初始荧光F₀均随盐浓度升高而升高,可变荧光Fv、Fv/Fm随盐浓度增加而降低。在荧光特性变化方面,两种盐胁迫下的变化规律也是一致的。更多还原

【Abstract】 China’s soil salinization is one of the most significant constraining factors that affecting the stable development of maize production, salt stress restrains the seedlings growth, decline bud growth force, radicle few and short, enervate seedlings, low survival rate, serious affecting yield, growth and development. Therefore, improve the salt stress tolerance of maize varieties is one of the most efficient ways to development and utilize of this part of the resources. In this paper, 120 maize varieties select from Inner Mongolia and Liaoning province for the trial materials, through various indexes of the germination period identify and classify the salt stress tolerance, Screen out the typical varieties, and then cultivated these varieties in solution culture and sand culture, and then in the seedling period analyzed their salt tolerance difference under these two kinds of cultivate conditions, This research project has been studied on plant morphology, dry matter accumulation, osmotic adjustment matter, membranaceous peroxidation and protective enzyme activities, photosynthesis and fluorescence characteristics, etc., With a view to exploring the salt tolerance mechanism difference in different salt tolerance varieties as well as in different conditions of salt stress. The main conclusions are as follows:1. Under NaCl stress, the concentration of 180mmol / L can be used as identify and classify different salt tolerance varieties. In this concentration the cluster and analyze can be divided 120 maize varieties into five levels: high-tolerance, salt-tolerance, medium-sensitivity, salt-sensitivity and high-sensitivity. Under Na₂CO₃ + NaHCO₃ stress, the concentration of 90mmol / L +90 mmol / L can be used as identify and classify different salt tolerant varieties. In this concentration cluster and analyze 120 maize varieties can be divided these varieties into four levels: high-tolerance, medium-tolerance, medium-sensitivity, alkaline salt-sensitivity. From the results of the classifications, the neutral salt and the alkaline salt have significant difference between varieties at all levels.2. Under stress of NaCl, Na₂CO₃ + NaHCO₃, two maize varieties’ height and leaf area changes trend are identical, and increased with the growth stage progressing and decreased with the concentration of salt stress reducing, and under salt stress the injury rate of salt-sensitive varieties greater than the salt-tolerant varieties. Under the stress of NaCl, the main radicle length, total root system length, root surface area, root volume are all increased with the growth stage progressing, except the concentration of 40mmol / L which can be boosts the growth when compare with the checks while the rest concentrations restrains the growth of maize. Under the stress of Na₂CO₃ + NaHCO₃, the main radicle length, total roots length, root surface area and root volume are increased with the advancing of growth periods, and increased if the salt concentration reduced, and the various indexes change range of the salt-tolerant varieties less than salt-sensitive varieties. With the advance of growth periods the average diameter of the root system is increasing, and they were decreasing with the salt stress concentration increased. Average diameter becomes greater when the severe of salt stress increased. These rules are more obvious in Na₂CO₃+NaHCO₃ stress than in the stress of NaCl.3. The effects of moderate NaCl stress which boosts the growth of roots system less than stems and leaves while under severe salt stress the roots system grow rapidly thus increase the root cap ratio. Under the stress of Na₂CO₃ + NaHCO₃, in the early growth periods either above ground parts or under ground parts’ dry weight change difference isn’t obvious, yet with the progressing of growth stages and the higher salt stress concentration the dry weight of plant tissue reduced more severely, and the root-cap ratio was increased with the concentration of salt stress increasing. The varieties of salt-sensitive varieties injury rate greater than salt-tolerant varieties.4. Two varieties of soluble protein, soluble sugar content, dissociate proline were increased with increasing concentration of NaCl, salt-sensitive varieties increase range less than salt-tolerant varieties. Along with the salt stress concentration increasing the dissociate amino acid content in the leaves will be increased, if the salt stress concentrations belowl20mmol /L the dissociate amino acid content significantly higher than other treatments. Both these two varieties, the soluble protein content in roots system and leaves increased with Na₂CO₃ + NaHCO₃ stress concentration increasing, the content of soluble protein in leaves were significantly higher than in the root system. Along with the salt stress concentration raising the soluble sugar content increased in leaves while there is slightly difference between leaves and roots system. Dissociate amino acids content of these two varieties’ leaves increased with the concentration of salt stress increasing, in the root system, these two varieties the dissociate amino acids content significantly lower than the treatment which is below 0mmol / L concentration. Dissociate proline content in root system and leaves of these two varieties were significantly increased with the concentration of salt stress increasing, from absolutely content point of view, the dissociate proline content in the leaves was higher than in the root system.5. In these two varieties’ leaves and root system, the relative conductivity increased with salt stress concentration increasing, yet relative conductivity in roots system has greater value. This performance rule is identical in both these two types of salt stress. Under the stress of NaCl, Na₂CO₃+NaHCO₃, the superoxide anion and malondialdehyde content in roots and leaves of the two varieties were increased with salt concentration increasing. From an absolutely content point of view, the content of the basic salt stress more than neutral salt content, this can be illustrate that the extent of membranaceous peroxide under basic salt stress is more serious than under neutral salt stress. The activity of three types of protection enzyme SOD, POD, CAT will be increasing along with the NaCl concentration stress increased, while the changing in leaves and roots trend to be identical. Under Na₂CO₃ + NaHCO₃ stress, the changes trend of POD, CAT is same as in the natural salt stress, but in the leaves, in the low concentration of alkaline salt stress the activity of SOD will be increase, yet it will be decrease in high concentration of alkaline salt stress.6. In two maize varieties’ leaves, the content of chlorophyll a + b, chlorophyll a, chlorophyll b will be increased with the salt concentration decreasing, meanwhile, the ratio of a to b will be increase, this rule of performance is identical under the two types of salt-stress conditions. Maize leaf net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, transpiration rate decreased with the lower salt concentration, the changes trend of photosynthetic rate, stomatal conductance and intercellular CO2 concentration were identical, It can be considered that stomatal limitation is one of the main reasons that lead to photosynthetic rate decline. Photosynthetic characteristics change caused by two kinds of salt stress also are consistent. The initial fluorescence F₀ of the two varieties are increased with the salinity concentration increasing, variable fluorescence Fv, Fv / Fm decreased with higher salinity concentrations. In terms of fluorescence characteristics change, the two types of salt stress change rules also are identical.更多还原