【作者】 魏国平；

【导师】 朱月林；

【作者基本信息】 南京农业大学 ， 蔬菜学， 2009， 博士

【摘要】 茄子(Solanum melongena L.)是一种重要的果菜类蔬菜,近年来其设施栽培面积不断扩大,在我国已成为农民增收的一条重要途径。一方面,由于长季节栽培的设施内长年得不到雨水的淋洗以及土壤水分的蒸发,使设施内土壤水分平衡受到破坏；另一方面,由于菜农粗放的肥水管理和过量化学肥料的施用,使得设施土壤次生盐渍化现象十分普遍,严重阻碍了蔬菜设施栽培的可持续发展。研究表明,设施次生盐渍化土壤的盐分组成中主要阳离子为Ca2+,主要阴离子为NO3-(占总阴离子的67-76%)。尽管在茄子嫁接栽培技术和耐盐生理方面已有少量报道,但主要集中在NaCl胁迫方面,而嫁接茄子对过量Ca(NO3)2胁迫响应的生理机制研究方面,国内外尚鲜有报道。国内外研究表明,利用耐盐砧木进行嫁接栽培是提高蔬菜耐盐性的一条有效途径。本研究以日本茄子设施栽培上专用耐盐砧木品种’Torvum Vigor’(Solanum torvum Swartz)为砧木,南京地区主栽品种‘苏崎茄’为接穗,在营养液栽培条件下,对80mmo1.L-1 Ca(N03)2胁迫下茄子嫁接苗和未嫁接苗生长和生理生化代谢进行了比较,主要试验结果如下：1.对Ca(NO3)2胁迫下茄子嫁接苗和未嫁接苗叶片光合色素含量、光合特性和渗透调节物质含量的变化进行比较。结果表明,Ca(NO3)2胁迫显著降低了茄子幼苗叶片光合色素含量,抑制了Ci和Gs,降低了Pn,幼苗通过积累渗透调节物质以减轻盐胁迫伤害。而嫁接苗株高和生物量积累显著高于未嫁接苗,叶片光合色素和渗透调节物质含量显著高于未嫁接苗,Pn、Tr、Ci和Gs显著高于未嫁接苗,Ls显著低于未嫁接苗,表明嫁接苗对Ca(N03)2胁迫的适应性更强。2.茄子嫁接苗和未嫁接苗碳同化和氮同化比较的结果表明,Ca(NO3)2胁迫下,茄子嫁接苗和未嫁接苗叶片NO3-N和NH4+-N含量呈先增加后下降趋势,而嫁接苗在胁迫后期均显著高于未嫁接苗；嫁接苗叶片硝酸还原酶(NR)活性在胁迫6 d后显著高于未嫁接苗；嫁接苗叶片可溶性蛋白含量在胁迫期间均显著高于未嫁接苗；嫁接苗和未嫁接苗叶片谷氨酰胺合成酶(GS)活性呈先上升后下降趋势,而嫁接苗GS活性在胁迫后期显著高于未嫁接苗；嫁接苗叶片可溶性糖含量呈先增加后下降趋势,而未嫁接苗叶片可溶性糖含量呈显著下降趋势,且嫁接苗在胁迫期间均显著高于未嫁接苗；嫁接苗叶片淀粉含量显著高于未嫁接苗,而a、p淀粉酶活性均显著低于未嫁接苗。综上所述,Ca(NO3)2胁迫下,嫁接苗氮同化和碳同化效率较高,且氮、碳代谢间相互抑制较小,表现出较强的胁迫适应性。3.离子吸收与分配特性方面,Ca(NO3)2胁迫下,茄子幼苗各器官中K+含量均有所下降,而嫁接苗除老叶和叶柄外其它器官中K+含量均显著高于未嫁接苗,且在根系、幼叶和功能叶中K(G2／N2)比值较高；除未嫁接苗幼叶外,嫁接苗和未嫁接苗其它器官中Ca2+含量均显著增加,而嫁接苗各器官中Ca2+含量均显著高于未嫁接苗,且幼叶中Ca(G2／N2)比值最高；嫁接苗和未嫁接苗各器官中Mg2+含量均有所下降,而嫁接苗除老叶外其它器官中Mg2+含量均显著高于未嫁接苗。因此,嫁接苗根系在Ca(N03)2胁迫后对离子的选择性吸收的能力更强,且嫁接苗将根系吸收的离子主要运输至分生组织代谢旺盛的器官(幼叶)和光合作用强烈的部位(功能叶),嫁接苗在胁迫环境中的离子吸收和分配优于未嫁接苗,从而对Ca(N03)2胁迫表现出较强的耐性。4.Ca(NO3)2胁迫下茄子嫁接苗叶片抗氧化酶活性显著高于未嫁接苗,叶片O2·-产生速率与H2O2含量显著低于未嫁接苗,叶片MDA含量与电解质渗透率显著低于未嫁接苗。因此,Ca(N03)2胁迫显著降低了幼苗叶片抗氧化酶活性,增加了O2·产生速率、H2O2与MDA含量及电解质渗透率,但嫁接苗受Ca(NO3)2胁迫的抑制程度显著小于未嫁接苗,良好的活性氧清除机制保护了植株细胞膜的完整性,使嫁接苗在Ca(N03)2胁迫下表现出较高忍耐力。5.对营养液栽培条件下,茄子嫁接苗和未嫁接苗叶片抗坏血酸-谷胱甘肽代谢进行比较。结果表明,Ca(NO3)2胁迫下嫁接苗叶片抗氧化酶(APX. DHAR和GR)活性显著高于未嫁接苗,AsA和GSH的再生率显著高于未嫁接苗,氧化还原力(AsA/DHA值和GSH/GSSG值)显著高于未嫁接苗。综上所述,Ca(N03)2胁迫下嫁接苗保持良好的AsA-GSH循环效率,清除H202效率较高,细胞受氧化损伤程度较轻,表现出较强的耐盐性。6.多胺代谢方面,Ca(NO3)2胁迫下茄子嫁接苗叶片游离态、结合态和束缚态多胺含量显著高于未嫁接苗；嫁接苗叶片Put、Spd和Spm总含量均显著高于未嫁接苗；嫁接苗叶片游离态Put/(Spd+Spm)值显著高于未嫁接苗,而结合态Put/(Spd+Spm)值显著低于未嫁接苗,束缚态Put/(Spd+Spm)值两者差异不显著；嫁接苗叶片多胺氧化酶和二胺氧化酶活性显著低于未嫁接苗。结果表明,Ca(NO3)2胁迫下嫁接苗体内三种形态多胺的积累与其耐盐性关系密切；而游离态Put的积累在嫁接苗耐盐性方面可能具有重要作用,且结合态Put向游离态Put的转化以及游离态Spd、Spm向结合态Spd、Spm的转化可能有利于提高Ca(N03)2胁迫下嫁接苗的耐盐性。更多还原

【Abstract】 With the vegetable industry developing, the area of protected cultivation of eggplant (Solanum melongena L.) is developing rapidly in China. As an important kind of fruit vegetables, protected eggplant cultivation has become an important way to increase farmers’income. However, excessive chemical fertilizer was applied usually, to achieve more economic benefit with high yield. Soil secondary salinization of the plastic film protected cultivation has become a serious problem, which were resulted both from a lack of leaching by rainfall and from strong evaporation of soil water due to long-term covering together with high fertilizer application rates, and severely limited the sustainable development of facility vegetable cultivation. In soil salinity in these systems, the most cation was Ca2+, and the most anion present was NO3- (67-76% of total anions). In recent years, a few researches on grafting techniques and salinity tolerance physiology of grafted eggplant have been carried out, which were mainly focused on NaCl stress, and few studies on physiological mechanisms of grafted eggplant in response to calcium nitrate stress have been reported. It has been well documented that grafting on salt tolerant rootstock can improve salinity tolerance of vegetable. In this study, we use Torvum Vigor’ (Solanum torvum Swartz) a salt tolerant cultivar introduced from Japan as rootstock, and’Suqi Qie’ a major cultivar in Nanjing area as scion, grafting was made to compare the differences in growth and physiological and biochemical mechanisms between hydroponically-grown grafted and non-grafted eggplant seedlings under 80 mmol·L-1 Ca(NO3)2 stress. The main results were as follows:1. The differences in photosynthetic pigments contents, photosynthetic characteristics and osmoregulation substances contents between grafted and non-grafted eggplant seedlings were observed under Ca(NO3)2 stress. The result showed that, the photosynthetic pigments contents in leaves of eggplant seedlings were significantly decreased, CO2 concentration (Ci) and stomatal conductance (Gs) were inhibited, net photosynthetic rate (Pn) was decreased under Ca(NO3)2 stress. The seedlings accumulated osmoregulation substances to reduce damage caused by Ca(NO3)2 stress. However, under Ca(NO3)2 stress, the plant height and biomass accumulation of grafted eggplant seedlings were significantly higher than those of non-grafted seedlings, photosynthetic pigments and osmoregulation substances contents in leaves of grafted seedlings were significantly higher than those of non-grafted seedlings, and grafted seedlings had significantly higher Pn, Tr, Ci and Gs than non-grafted seedlings, with significantly lower Ls in leaves of grafted seedlings. These indicated that, the adaptability of grafted seedlings to Ca(NO3)2 stress was more stronger than that of non-grafted plants.2. The differences of nitrogen metabolism and carbon metabolism between grafted and non-grafted eggplant seedlings were observed. The result showed that, under Ca(NO3)2 stress, the contents of NO3-N and NH4+-N in leaves of eggplant seedlings increased significantly at the early stage of treatment, then decreased significantly, however, the contents of NO3--N and NH4+-N in grafted seedlings were significantly higher than those of non-grafted seedlings in prolonged stress time; nitrate reductase (NR) activity in leaves of grafted seedlings was significantly higher than that of non-grafted seedlings since the 9th day of treatment; soluble protein content in leaves of grafted seedlings was significantly higher than that of non-grafted seedlings in the whole stress time; glutamine synthetase (GS) activity in leaves of eggplant seedlings increased significantly at the early stage of treatment, then decreased significantly, however, GS activity in grafted seedlings were significantly higher than those of non-grafted seedlings in prolonged stress time; soluble sugar content in leaves of grafted seedlings increased significantly at the early stage of treatment, then decreased significantly, but soluble sugar content in non-grafted seedlings decreased and was significantly lower than that of grafted seedlings in whole stress time; starch content in leaves of grafted seedlings was significantly higher than that of non-grafted seedlings, but activities of a-amylase and P-amylase were both significantly lower than those of non-grafted seedlings. The results indicated that nitrogen metabolism and carbon metabolism in grafted seedlings were more efficient than non-grafted plants, grafted seedlings were more tolerant to Ca(NO3)2 stress.3. In the aspect of characteristics of ion absorption and distribution, K+ contents decreased in all organs in eggplant seedlings, but grafted seedlings had significantly higher K+ content than that of non-grafted seedlings except in aged leaves and petiole, and K(G2/N2) ratios in root, young and functional leaves of grafted seedlings were higher; Ca2+ content increased in all organs in eggplant seedlings except in young leaves of non-grafted seedlings, but grafted seedlings had significantly higher Ca2+content than non-grafted seedlings in all organs, and Ca(G2/N2) ratio in young leaves was the highest; Mg2+content decreased in all organs in eggplant seedling, but Mg2+content in grafted seedlings was significantly higher than that of non-grafted seedlings except in aged leaves. These results indicated that, under Ca(NO3)2 stress, the ability of ionic selective absorption was stronger in root of grafted seedlings than that of non-grafted seedlings, and ions in grafted seedlings were mainly transported to vigorous meristem (young leaves) and efficient photosynthetic organ (functional leaves). Ionic selective absorption and distribution in grafted seedlings excelled than that of non-grafted seedlings under environmental stresses, and grafted seedlings showed stronger tolerance to Ca(NO3)2 stress.4. Under Ca(NO3)2 stress, in leaves of grafted eggplant seedlings, the antioxidant enzymes activities were significantly higher while the superoxide anion radicals (O2·) producing rate, hydrogen peroxide (H2O2) content, malondiadehyde (MDA) content and the electrolyte leakage rate were significantly lower than those of non-grafted seedlings. Ca(NO3)2 stress reduced the antioxidant enzymes activities, but increased O2·producing rate, H2O2 content, MDA content and the electrolyte leakage rate both in grafted and in non-grafted seedlings. However, grafted seedlings were less inhibited than non-grafted seedlings under Ca(NO3)2 stress, and the former had a stronger tolerance to Ca(NO3)2 stress owing to effectively scavenging of reactive oxygen species and preserving the integrity of membranes.5. The response of ascorbate-glutathione metabolism system of grafted and non-grafted eggplant seedlings under hydroponically-grown to Ca(NO3)2 stress was studied. The results showed that, under Ca(NO3)2 stress, activities of antioxidant enzymes [ascorbate peroxidase (APX), dehydro-ascorbate reductase (DHAR) and glutathione reductase (GR)], regenerating rates of ascorbate (AsA) and glutathione (GSH) and redox statuses (ratios of AsA/DHA and GSH/GSSG) were significantly higher in leaves of grafted seedlings than those of non-grafted seedlings. We concluded that grafted eggplant seedlings had efficient metabolism of ascorbate-glutathione cycle, which scavenged the H2O2 rapidly to alleviate the oxidative damage of Ca(NO3)2 stress; therefore, grafted seedlings had a stronger tolerance to salt stress.6. In polyamines metabolisms, under Ca(NO3)2 stress, free, soluble conjugated and insoluble bound polyamines (PAs) in leaves of grafted seedlings were significantly higher than those of non-grafted seedlings; total contents of diamine putrescine (Put), triamine spermidine (Spd) and tetraamine spermine (Spm) in leaves of grafted seedlings were significantly higher than those of non-grafted seedlings; grafted seedlings had significantly higher ratio of free Put/(Spd+Spm) and significantly lower ratio of soluble conjugated Put/(Spd+Spm), with similar level of insoluble bound Put/(Spd+Spm); activities of diamine oxidase (DAO) and polyamine oxidase (PAO) in leaves of grafted seedlings were significantly lower than those of non-grafted seedlings. We concluded that accumulations of three kinds of PAs in grafted seedlings were closely related to salinity tolerance under Ca(NO3)2 stress; however, accumulation of free Put might be important to salinity tolerance, moreover, the conversions from soluble conjugated Spd and Spm might play fundamental roles to improve the tolerance of grafted seedlings under Ca(NO3)2 stress.更多还原