【作者】 韩志平；

【导师】 郭世荣；

【作者基本信息】 南京农业大学 ， 蔬菜学， 2008， 博士

【摘要】 土壤盐渍化对农业生产的威胁是一个全球性的热点问题,是影响作物生长和产量的主要限制因素之一。国内外设施栽培中普遍存在土壤的次生盐渍化问题,严重影响着设施作物的产量和品质,是当前设施蔬菜生产中急需解决的难题。钙不仅是植物必需的矿质营养元素之一,而且作为细胞内生理生化反应的第二信使偶联胞外信号,在逆境胁迫下能通过提高胞质游离Ca²⁺浓度,并通过Ca²⁺与CaM结合启动一系列生理生化过程,在植物对逆境胁迫的响应过程中发挥着重要作用。多胺是生物体代谢过程中产生的一类具有生物活性的低分子量脂肪族含氮碱,在调节植物生长发育、控制形态建成、提高植物抗逆性、延缓衰老等方面具有重要的作用.本文通过聚类分析对国内设施栽培中常用的小型西瓜（Citrullus lanatus M.）品种进行了耐盐性鉴定和分类,并选用耐盐性较强的品种‘秀雅’和耐盐性较弱的品种‘秀丽’为材料,研究了营养液栽培中NaCl胁迫对小型西瓜的植株生长、光合作用、离子的吸收和分布及活性氧代谢的影响,分析了外源硫酸钙（CaSO₄）和腐胺（Put）对盐胁迫下小型西瓜生长抑制的缓解效应,探讨了外源Ca和Put在小型西瓜耐盐性中的生理调节功能,分析了采用外源物质提高小型西瓜耐盐性的可行性.主要研究结果如下:1.除根长外,100 mmol·L^-1NaCl胁迫使所有品种小型西瓜幼苗的形态指标和生物量显著降低;叶片质膜相对透性、MDA含量、Pro和Chl含量显著增加,根系活力的变化不同品种表现不同.以干质量相对值和与其呈显著相关性的各生长和生理指标为变量,聚类分析将供试西瓜品种分为耐盐性较强、较耐性中等和耐盐性较弱的三类.2.50 mmol·L^-1以下浓度NaCl处理对‘秀雅’幼苗的生长没有显著影响,75 mmol·L^-1以上浓度NaCl胁迫显著抑制了其幼苗的生长,‘秀丽’幼苗生长則随NaCl浓度提高而显著降低;在75 mmol·L^-1以上浓度NaCl胁迫下,随NaCl浓度提高和胁迫时间的延长,西瓜幼苗盐害指数显著增大、存活株率显著降低。与‘秀丽’品种相比,‘秀雅’幼苗在盐胁迫下生长降低幅度较小,存活株率较高,对盐胁迫的适应性较强.3.随NaCl浓度提高,小型西瓜叶片中光合色素含量先升高后降低,在75 mmol·L^-1NaCl胁迫下达到最大值;Pn、Gs和Tr均随NaCl浓度提高而显著降低;Ci在低浓度NaCl处理下降低,75 mmol·L^-1以上浓度胁迫下升高;Ls在较低浓度NaC1处理下增加,100 mmol·L^-1以上浓度下趋于稳定:WUE在较低浓度NaCl处理下增加,100mmol·L^-1以上浓度下降低.低浓度NaCl处理下小型西瓜叶片Pn下降的主要原因是气孔限制,高盐胁迫下则转变为非气孔因素限制。盐胁迫对‘秀雅’光合作用的抑制程度明显低于‘秀丽’,是其在盐胁迫下生长较好的主要原因之一.4.随NaCl胁迫增强,小型西瓜幼苗体内Na⁺和Cl^-含量显著升高,K⁺、Ca²⁺和Mg²⁺含量及K⁺/Na⁺和Ca²⁺/Na⁺比值显著降低;各种离子在器官间呈明显的区域化分布,Cl^-主要积累在茎中,Na⁺主要积累于茎和根中;茎和根中K⁺含量下降幅度较大,叶中下降幅度较小;Ca²⁺和Mg²⁺主要存在于茎和叶中,均在叶中下降幅度较小;随NaCl浓度提高,根向茎选择性运输K⁺和Ca²⁺的能力降低,而茎向叶选择性运输的能力提高,有利于减轻NaCl胁迫对叶片的伤害.与‘秀丽’品种相比,‘秀雅’叶中K⁺、Ca²⁺含量下降幅度较小,Na⁺积累量较低,K⁺/Na⁺和Ca²⁺/Na⁺比值均较高,离子在器官间区域化分布能力较强也是其耐盐性较强的重要原因之一.5.随NaCl浓度处理提高,小型西瓜叶片中O₂^·-产生速率、MDA含量和质膜相对透性显著增加,CAT和APX活性显著提高,POD活性在低浓度NaC1处理下降低而高浓度下提高,SOD活性的变化两品种有所不同;Pro、可溶性糖和AsA含量显著增加,可溶性蛋白含量在较低浓度NaCl处理下增加而高浓度下降低.高盐胁迫下,‘秀雅’叶片中抗氧化酶活性和渗调物质含量均明显高于‘秀丽’,O₂^·-产生速率、MDA含量和质膜相对透性則明显低于“秀丽”.盐胁迫下,‘秀雅’品种生长受抑制程度和脂质过氧化程度较低,与其较高的抗氧化酶活性和渗调物质含量密切相关.6.外源CaSO₄和Put对盐胁迫下小型西瓜幼苗的生长和生理代谢具有明显影响,并呈现出明显的浓度效应。其中营养液中6 mmol·L^-1Ca²⁺和1.0 mmol·L^-1Put处理对幼苗的生长有显著的促进作用,使叶片质膜相对透性、MDA含量显著降低,可溶性蛋白和AsA含量显著增加,是缓解NaCl胁迫对小型西瓜植株伤害的适宜浓度.7.外源Ca、Put或Ca+Put复配处理均可明显改善盐胁迫下小型西瓜幼苗的生长,调节各种生理代谢。使叶片光合色素含量增加,Pn、Gs、Ci和Tr提高,Ls降低,对WUE没有影响;使幼苗体内Na⁺和Cl^-积累量显著降低,K⁺和Ca²⁺含量及K⁺/Na⁺和Ca²⁺/Na⁺比值显著提高;使叶片中O₂^·-产生速率、MDA含量显著降低,SOD、POD、CAT和APX活性显著提高;使NO₃^--N和可溶性蛋白含量及NR、GS和GDH活性显著提高,NH₄⁺-N含量显著降低;使游离态Put、Spd和Spm含量显著增加,三种多胺氧化酶活性有所降低.研究表明,三种方式外源处理都可以通过改善幼苗光合作用、增强离子区域化分布能力,调节活性氧代谢、氮代谢和多胺代谢而提高小型西瓜幼苗的耐盐性,减轻盐胁迫对西瓜植株造成的伤害,三种外施方式对西瓜盐胁迫伤害的缓解效应依次为Ca+Put＞Ca＞Put,且对耐盐性较弱的‘秀丽’缓解作用较为明显。更多还原

【Abstract】 The threat of salinization in soil to agriculture production is a focus problem in the globe,and one of the major factors limiting plant growth and production.The secondary salinization in soil is ubiquitious in the protected culture,it have seriously influenced the yield and quality of crops,and become a difficult problem imparetive to solve in the protected culture.Calcium is not only one of necessary nutrient elements,but also a second messenger in connecting external signals and the physiological and biochemical process within cell.Calcium can initiate a series of physiological and biochemical process by increasing free Ca²⁺ concentration in cytoplasm and by combining Ca²⁺ and CaM under stress condition,hence play an important role in the response of plant to stress.Polyamines are low molecular mass aliphatic nitrogen-containing compounds having biological activity, produced in nitrogen metabolism of living organism.PAs have an important function in regulating growth and development,controlling morphology building,enhancing stress resistance and delaying senescence,and so on.In this paper,author identified and classified the salt tolerance of 16 mini-watermelon （Citrullus lanatus M.） cultivars by using cluster analysis.A salt-tolerant watermelon cultivar ’XiuYa’ and a salt-sensitive cultivar ’XiuLi’ were selected as materials,the experiment was carried out to study the effects of NaCI stress on plant growth, photosynthesis,ions uptake and distribution,and metabolism of reactive oxygen speices of mini-watermelon in solution culture.At the same time,we analyzed the effect of Cacium sulphate and putrescine in alleviating growth inhibition of mini-watermelon under salinity, explored the physiological function of exogenous Ca and Put in regulating salt tolerance of mini-watermelon plant,and analyzed the feasibility of improving salt tolerance of miniwatermelon by using exogenous matters.Main results were as follows:1.Apart from root length,the morphological indicators and plant biomass of all mini-watermelon cultivars were dramasticly decreased under 100 mmol·L^-1 NaCl stress; relative membrane permeability,the contents of MDA,Pro and Chl were increased significantly,while root vigor of different cultivars displayed diverse response to salinity. With RV of dry mass and RVs of other growth and physiological indicators that were significantly correlated with RV of dry mass as variables,systematic cluster analysis divided tested mini-watermelon cultivars into 3 types,including more-tolerant cultivars, middle-tolerant cultivars,less-tolerant cultivars.2.NaCl treatments below 50 mmol·L^-1 concentration did not apparently influence the growth of ’XiuYa’ seedlings,the growth was significantly inhibited above 75 mmol·L^-1; with increasing NaCl concentration,the growth of ’XiuLi’ seedlilng was significantly reduced.With inceaseing NaCl concentration and prolonging stress time,salt indury index was clearly increased,and survival percent was dramatically decreased under NaCl stress above 75 mmol·L^-1 concentration.The range of growth reduction of ’XiuYa’ seedlings was less,and survival percent was higher than ’XiuLi’ under salinity,i.e.the acclimation of ’XiuYa’ to salinity was stronger than ’XiuLi’.3.With increasing NaCl concentration,the contents of the photosynthetic pigments in leaves were increased under lower NaCl concentration,and decreased above 75 mmol·L^-1; Pn,Gs and Tr were significantly decreased,Ci was reduced under lower concentration,and increased above 75 mmol·L^-1;Ls and WUE were increased under lower concentration,and tended to stabilization for Ls,and declined for WUE above 100 mmol·L^-1 concentration. The reduction of Pn under lower concentration NaCl treatments was the result of stomatal limitation,non-stomatal limitation became the main limitation factor under higher salinity. Compared with ’XiuLi’,the inhibited extent of ’XiuYa’ photosynthesis was clearly lower, this was one of the main reasons for its better growth under salinity.4.With enhancing NaCl stress,Na⁺ and Cl^- contents dramasticly increased,K⁺,Ca²⁺ and Mg²⁺ contents and K⁺/Na⁺ and Ca²⁺/Na⁺ ratios significantly decreased in watermelon plant.All ions showed compartmentalization,Cl^-was mainly accumulated in stem,and Na⁺ was mainly in stem and root.Reduced extent of K⁺ content was maximum in stem,and minimum in leaf.Ca²⁺ and Mg²⁺ mainly existed in stem and leaf,the reduced ranges were minimum in leaf.Selective transportation of K⁺ and Ca²⁺ were declined for root to stem, and increased for stem to leaf,it contributed to alleviate salt damage to leaf.Compared with ’XiuLi’,the reduced ranges of K⁺ and Ca²⁺ contents were less,Na⁺ content were lower in leaf of ’XiuYa’,K⁺/Na⁺ and Ca²⁺/Na⁺ ratios were higher.Better ions compartmentalization among organs was one of main reasons for its more-tolerance to salinity.5.With increasing NaCl concentration,O₂（?）production rate,MDA content and relative membrane permeability significantly increased in leaf,CAT and APX activities dramasticly increased;POD activity declined under lower concentration,and increased under higher concentration;SOD activity showed different regulation for two mini-watermelon cultivars. The contents of Pro,soluble sugar and AsA clearly enhanced;soluble protein content increased under lower concentration,and decreased under higher concentration.The activities of antioxidative enzymes and the contents of osmotic regulation matters of ’XiuYa’ were higher than "XiuLi",and O₂（?） production rate,MDA content and relative membrane permeability were lower than ’XiuLi’ under higher salinity.The less extent of growth inhibition and lipid peroxidation of ’XiuLi’were closely correlated with higher activities of antioxidative enzymes and higher contents of osmotic regulation matters.6.Exogenous CaSO₄ and Put obviously influenced the plant growth and physiological metabolism of mini-watermelon under salinity,and showed apparent concentration effect.6 mmol·L^-1 Ca and 1.0 mmol·L^-1 Put in solution significantly improved the plant growth, reduced relative membrane permeability and MDA content,increased the contents of soluble protein and AsA in leaves of mini-watermelon seedlings under salinity,so 6 mmol·L^-1 and 1.0 mmol·L^-1 were the suitable concentrations to mitigate the salinity injury of mini-watermelon plant for Ca and Put,respectively.7.Exogenous Ca,Put and Ca+Put significantly improved the plant growth,regulated some physiological metabolism of mini-watermelon under salinity.Three exogenous supplement means clearly increased the contents of photosynthetic pigments in leaves, enhanced Pn,Gs,Ci,and Tr,declined Ls,not influenced WUE;siguificantly decreased the contents of Na⁺ and Cl^-,increased the contents of K⁺,Ca²⁺ and Mg²⁺,and the ratios of K⁺/Na⁺ and Ca²⁺/Na⁺ in all organs;dramatically reduced O₂（?） production rate and MDA content,increased the activities of SOD,POD,CAT and APX;obviously increased the contents of NO₃^--N and soluble protein,improved the activities of NR,GS and GDH, significantly declined NH₄⁺-N content;increased the contents of free Put,Spd and Spm, decreased the activities of three polyamine oxidases under salinity.The results revealed that exogenous Ca,Put and Ca+Put treatments clearly increased salt tolerance of miniwatermelon, alleviated the salinity damage by improving photosynthesis,enhancing ions compartmentalization,regulating the metabolism of reactive oxygen species,nitrogen and polyamines.For mitigating the salinity-induced injury of mini-watermelon,the effect of three supplement means were Ca+Put＞Ca＞Put in turn,and the effect for ’XiuLi’ seedlings was more evident than ’XiuYa’.更多还原