【作者】 薛延丰；

【导师】 刘兆普；

【作者基本信息】 南京农业大学 ， 植物营养学， 2008， 博士

【摘要】 土壤盐渍化是影响农业生产以及生态环境的一个全球性问题。因此,如何改良和利用盐渍化土壤已成为各国政府和人民关注的热点问题。大量研究证明,生物学措施,特别是引种经济型耐盐植物,是解决土壤盐渍化问题最有效的措施之一。目前世界淡水资源日渐枯竭,尤其是我国已被列入全球12个严重贫水的国家之一,但是我国是一个海洋大国,海水资源丰富。因此,开发利用海水资源可以有效缓解水资源危机。本文选择了‘南芋1号’和‘南芋2号’（以下简称为‘1号’和‘2号’）两个菊芋品种,首先利用不同浓度NaCl(0、50、100、150 mmol L^-1)和Na₂CO₃(0、25、50、75 mmol L^-1)对其进行胁迫处理,研究了NaCl和Na₂CO₃胁迫对‘1号’和‘2号’的形态结构、微观结构以及生物量、根系活力、活性氧含量、抗氧化酶活性、叶绿素含量、光合作用参数、叶绿素荧光参数等生理生化指标的影响,去筛选抗盐品种,从而为充分合理的利用盐碱土壤提供理论依据。其次利用不同浓度海水（0、10%、20%、30%）对其进行浇灌,研究海水对‘1号’和‘2号’的胁迫作用。然后以‘2号’为材料,进一步研究了Ca²⁺对Nacl胁迫下菊芋生物量、离子分布、抗氧化酶活性、丙二醛（MDA）含量、净光合速率（Pn）、气孔导度（Gs）和荧光参数的影响,以探索外源Ca²⁺对缓解植物盐胁迫下光合作用下降的作用机制。最后以‘2号’为材料,利用不同浓度Ca²⁺对30%海水处理下的菊芋幼苗进行调控,研究其对海水的利用程度。主要结果如下:1.通过砂培试验比较了‘1号’和‘2号’两个菊芋品种苗期对盐碱的忍耐程度。结果表明,‘1号’在低浓度的NaCl胁迫下,对其生长无显著性影响,具体表现为,与对照相比,生物量无显著性变化,相对生长速率和根系活力增大,根冠比增加,根、茎和叶片中离子浓度不变。当NaCl浓度达100 mmol L^-1以上时,随着浓度的增加生物量显著降低,其原因主要是随着盐浓度的增加,活性氧含量增加,抗氧化酶不能及时清除活性氧,从而导致叶绿体遭到破坏,MDA含量和相对电导增加,进而影响光合作用的进行。对于‘2号’而言,在低浓度NaCl胁迫下,其生物量显著降低,活性氧含量、MDA含量和相对电导显著增加,叶绿体受到严重损伤,抗氧化酶活性和光合作用急剧下降。且随着NaCl浓度的增加,胁迫程度加剧。因此,‘1号’的耐盐性大于‘2号’。在Na₂CO₃胁迫下,无论是‘1号’,还是‘2号’,随着浓度的增加,其生物量、离子分布、活性氧含量、抗氧化酶活性以及光合机构与对照相比均受到显著的影响;但在相同浓度Na₂CO₃胁迫下,‘2号’受到的影响小于‘1号’,说明‘2号’具有一定耐碱性。在相同Na⁺条件下,进行对比,发现这两个品种的耐盐性均大于耐碱性。2.在0%-20%海水处理下,‘1号’的生物量、抗氧化酶活性、叶绿素含量、光合作用参数、叶绿素荧光参数等生理生化指标随着海水浓度的增加而增加,根系活力并没有受到明显的影响,叶绿体结构没有发生明显改变,活性氧含量虽然有所增加,但被增加的抗氧化酶及时清除,从而保护了细胞膜。随着海水浓度的继续增加,‘1号’的生物量、抗氧化酶活性等显著降低,活性氧含量、脯氨酸含量显著增加,而叶绿素含量、光合作用参数、叶绿素荧光参数等生理生化指标并没有发生显著的变化。而‘2号’仅能在低浓度10%海水处理下正常生长,随着海水浓度的继续增加,各个指标均发生显著的改变。‘1号’和‘2号’相比较,在相同浓度的海水胁迫下,‘1号’受到的伤害要小于‘2号’,由此说明‘1号’对盐的忍耐程度高于‘2号’,能够利用较高浓度的海水。3.在150 mmol L^-1 NaCl胁迫条件下,外施10 mmol L^-1的Ca²⁺可有效防护胁迫所致的氧化损伤,通过维持较高的抗氧化酶活性,抑制脂质过氧化作用,使叶片在盐胁迫条件下,维持较高的PSⅡ的电子传递强度（Fm/Fo）、PSⅡ光化学效率（Fv/Fm）、PsⅡ量子效率（φPSⅡ）、光化学淬灭系数（qP）、Pn和较低的非光化学淬灭系数（NPQ）,有利于物质积累从而使生物量增加。这主要归因于Ca²⁺可以在一定程度上弥补盐胁迫导致Ca²⁺亏缺造成的离子失衡,使植物体维持较正常的生理活动,稳定细胞膜结构,维持体内离子吸收平衡,保护光合机构。4.在30%海水处理下,‘2号’菊芋的正常生理代谢明显受到抑制;当施入钙离子后,盐对菊芋幼苗的胁迫不同程度降低,其中以10 mmol L^-1的Ca²⁺效果最好,可有效防护胁迫所致的氧化损伤,从而维持较高的抗氧化酶活性,抑制脂质过氧化作用,使叶片在盐胁迫条件下,维持较高的Fm/Fo、Fv/Fm、φPSⅡ、qP、Pn、Gs和较低的NPQ。从而证明,外源Ca²⁺能够增加不耐盐品种菊芋对海水的利用程度。更多还原

【Abstract】 Soil salinization is a global problem which influences agricultural production and ecological circumstance.Therefore,improvement and utilization of the saline soil becomes a new hotspot to many countries.A lot of studies showed that biological measure, especially economic and salt-tolerant plant introduction is one of the most effective resolvement.Now fresh water resource is becoming exhausted.Our country appeared one of the twelve countries which are in defect of fresh water seriously all over the world.There are abundant seawater resources in our country,so exploitation and utilization of seawater could effectively alleviate fresh water deficency.So two Jerusalem artichoke cultivars ’Nanyu No.1’ and ’Nanyu No.2’ were selected.Jerusalem artichoke seedlings（7-day-old） were treated with NaCl(0,50,100 and 150 mmol L^-1) and Na₂CO₃(0,25,50 and 75 mmol L^-1) in the plastic pots with sand.Then physiological indexes of different Jerusalem artichoke cultivars such as morphological structure,chloroplast ultrastructure,biomass,root activity,reactive oxygen species contents,antioxidative enzymes activity,chlorophyll content,photosynthesis and parameters of chlorophyll fluorescence were studied in order to screen salt-tolerant cultivar and offer the theory for sufficient and reasonable using the saline soil.Then Jerusalem artichoke seedlings were treated with different concentrations of seawater（0,10%,20%and 30%） to study whether they could grow in seawater.Thirdly,a regulation of Ca²⁺ on ’Nanyu No.2’ seedlings under NaCl stress was studied with different Ca²⁺ concentrations.The effects of Ca²⁺ on biomass,ion distribution,antioxidative enzymes activity,malondialdehyde（MDA） content,relative conductivity,net photosynthetic rate（Pn）,stomatal conductivity（Gs） and fluorescent parameters were studied to explore the effect of exogenous Ca²⁺ on alleviation of decreased photosynthetic ability of Jerusalem artichoke leaves under NaCl stress.Lastly,different Ca²⁺ concentrations were used to study the regulation of Ca²⁺ on ’Nanyu No.2’ seedlings under 30%seawater stress to explore whether exogenous Ca²⁺ could increase salt-tolerance and seawater utilization of ’Nanyu No.2’.The main results obtained were as follows.1.Two Jerusalem artichoke cultivars,’Nanyu No.1’ and ’Nanyu No.2’ were used to explore which was more saline-alkali tolerant in the plastic pots with sand.The results showed that low concentration of NaCl(50 mmol L^-1) had no significant impact on ’Nanyu No.1’ growth,such as biomass and ion contents of root,stem and leaves had no significant difference,relative growth rate,root activity and root/shoot ratio increased compared with the control..But high concentration of NaCl(≥100 mmol L^-1) significantly influenced the growth and physiological indexes of the Jerusalem artichoke.The reasons were that with the concentration of NaCl increased,reactive oxygen species contents increased,and antioxidative enzymes could not scavenged reactive oxygen species in time,which led to the damage of the chloroplast,MDA content and relative conductivity increased,and influenced net photosynthesis rate markedly.However,’Nanyu No.2’ growth was inhibited significantly in low NaCl concentration(50 mmol L^-1),such as reactive oxygen species contents,MDA content and relative conductivity increased markedly,chloroplast was damaged seriously,and antioxidative enzymes activity and net photosynthesis rate decreased significantly.Furthermore,the stress degree increased with the increase of NaCl concentration.All the results proved ’Nanyu No.1’ to be more salt-tolerant than ’Nanyu No.2’The changes in growth and physiology of ’Nanyu No.1’ and ’Nanyu No.2’ under Na₂CO₃ stress were different from those under NaCl stress.The growth,ion distribution, reactive oxygen species contents,antioxidative enzymes activity and photosynthesis apparatus of two cultivars were influenced significantly with the increase of Na₂CO₃ concentration compared with control.Under the same Na₂CO₃ concentration treatment, ’Nanyu No.2’ was more alkali-resisted than ’Nanyu No.1’.However,at the same concentrations of Na⁺ all the physiological indexes were markedly influenced under Na₂CO₃ stress than NaCl stress.So we concluded that the degree of saline-tolerance was higher than the alkali-tolerance of the two Jerusalem artichoke cultivars.2.The physiological indexes of ’Nanyu No.1’ such as biomass,antioxidative enzymes activity,chlorophyll content,photosynthesis indexes and parameters of chlorophyll fluorescence significantly increased with the increase of seawater concentration among 0%—20%.However,root activity was not influenced markedly,and the structure of chloroplast was not changed evidently.Although reactive oxygen species contents increased, they were scavenged by antioxidative enzymes immediately.So the cell membrane was intact and protected.When ’Nanyu No.1’ was treated by 30%seawater,the biomass and antioxidative enzymes activity decreased significantly,while reactive oxygen species contents and proline content increased markedly.But chlorophyll content,photosynthesis indexes and parameters of chlorophyll fluorescence were not influenced significantly. However,’Nanyu No.2’ could only grow normally in the 10%seawater.All the indexes were influenced significantly with the increase of seawater concentration.’Nanyu No.2’ was damaged more seriously than ’Nanyu No.1’ at the same concentration of seawater.All the results proved ’Nanyu No.1’ to be more saline-tolerant and it could utilize higher concentration seawater than ’Nanyu No.2’.3.Addition of Ca²⁺ significantly protected Jerusalem artichoke from oxidative damage caused under 150mmol L^-1 NaCl stress by maintaining high antioxidative enzymes activity, which could effectively decrease content of MDA and relative activity in Jerusalem artichoke leaves.As a result,the increases in status of electron transport by PSII（Fm/Fo）, primary photochemical efficiency of PSII（Fv/Fm）,quantum efficiency of photosystemⅡ（ΦPSII）,photochemical quenching coefficient（qP）,net photosynthetic rate（Pn） and the decrease in non-photochemical quenching coefficient（NPQ） were observed under salt stress.All these were propitious to the dry matter accumulation so that the fresh weight increased significantly.In conclusion,addition of Ca²⁺ compensated the deficient Ca²⁺ induced by salt stress,maintained the normal metabolism and intact cell membrane, balanced the ions absorbed and protected the photosynthetic system.4.Normal metabolism of ’Nanyu No.2’ was significantly inhibited by 30%seawater stress.However,addition of Ca²⁺ could alleviate the seawater stresses on Jerusalem artichoke in different degrees,especially for the 10 mmol L^-1 Ca²⁺.The addition of exogenous Ca²⁺ markedly protected Jerusalem artichoke leaves from oxidative damage by maintaining high antioxidative enzymes activity,which could effectively decrease content of MDA and relative activity in Jerusalem artichoke leaves.As a result,the increases in Fm/Fo,Fv/Fm,ΦPSII,qP,Pn and the decrease in NPQ were observed under salt stress.All the results suggested that addition of Ca²⁺ could significantly increase the seawater utilization of ’Nanyu No.2’ which was saline-intolerant Jerusalem artichoke cultivar.更多还原