【作者】 张古文；

【导师】 朱月林；

【作者基本信息】 南京农业大学 ， 蔬菜学， 2008， 博士

【摘要】 近年来,我国设施蔬菜栽培发展迅速,已成为农民增收的一条重要途径。然而,设施栽培是一种封闭的栽培方式,这不仅使设施内气温高于露地,而且由于失去了降雨对土壤的自然淋溶作用,导致了土壤水分向上运动较露地更为强烈,加之设施栽培偏施、重施化肥,土壤矿化作用明显加剧,土壤表层盐分浓度更易于升高。随着种植年限的增加,设施土壤次生盐渍化现象非常普遍,严重阻碍了设施蔬菜栽培的进一步发展。国内外的研究表明,嫁接可以提高蔬菜作物的抗逆性,是克服设施土壤盐害的一条有效途径。番茄是设施栽培的主要蔬菜之一,近年来关于番茄嫁接技术、嫁接提高番茄耐盐性方面进行了一定的研究,但均集中在NaCl胁迫方面。发生次生盐渍化的土壤中,阳离子主要以Ca²⁺为主,占土壤盐分阳离子总量的60%以上,阴离子主要以NO₃^-为主,占土壤盐分阴离子总量的67%～76%,但在嫁接番茄对Ca（NO₃）₂耐受性方面的研究,国内外尚鲜有报道。本试验以日本设施栽培上专用的耐盐砧木‘影武者’为砧木,以南京当地主栽品种‘宝大903’为接穗,在营养液栽培条件下,比较80mmol·L^-1 Ca（NO₃）₂胁迫下嫁接苗和自根苗有关生理生化特性变化。结果表明,Ca（NO₃）₂胁迫下,嫁接苗和自根苗叶片和根系SOD活性均呈显著上升的趋势,POD活性在胁迫2d时下降,之后显著上升,CAT活性呈显著下降的趋势,但嫁接苗各指标均显著高于自根苗,表现出较强的抗氧化能力。嫁接苗和自根苗叶片和根系O₂^-生成速率,H₂O₂和MDA含量显著增加,但嫁接苗各指标均显著低于自根苗,受到的氧化伤害较小。嫁接苗叶片和根系中脯氨酸、可溶性蛋白含量在胁迫期间显著上升,自根苗叶片和根系脯氨酸含量、根系可溶性蛋白含量显著上升,但其叶片可溶性蛋白含量变化不显著,嫁接苗与自根苗相比,不论叶片还是根系中,各指标均显著高于自根苗,表明嫁接苗渗透调节能力相对较强。Ca（NO₃）₂胁迫下,嫁接苗和自根苗叶片和根系APX、DHAR和GR活性均呈先上升后下降的趋势,但嫁接苗各酶活性显著高于自根苗,AsA和GSH的再生率显著高于自根苗;两者叶片和根系氧化还原力（AsA/DHA值和GSH/GSSG值）显著下降,但嫁接苗下降幅度显著小于自根苗,H₂O₂含量显著低于自根苗。表明Ca（NO₃）₂胁迫下,嫁接苗能保持良好的AsA-GSH循环效率,清除H₂O₂效率较高,细胞受氧化损伤程度较轻,表现出对Ca（NO₃）₂较强的耐受性。多胺是一类具有较强生理活性的低分子量脂肪族含氮碱,在植物的生长发育以及对环境的应激反应中发挥着重要作用。Ca（NO₃）₂胁迫下,嫁接苗叶片3种形态的腐胺、亚精胺和精胺含量均呈上升趋势;自根苗叶片3种形态的腐胺含量呈下降趋势,游离态、结合态亚精胺和精胺含量呈上升趋势,束缚态亚精胺含量呈下降趋势,束缚态精胺含量变化不显著。嫁接苗根系3种形态的腐胺、亚精胺和精胺含量均呈上升趋势;自根苗根系游离态腐胺、亚精胺和精胺含量呈上升趋势,结合态腐胺、亚精胺和精胺含量呈下降趋势,束缚态腐胺含量在胁迫前期变化不显著,胁迫后期下降,束缚态亚精胺和精胺含量变化不显著。嫁接苗与自根苗相比,整个胁迫期间,嫁接苗叶片和根系3种形态多胺总量均显著高于自根苗,精氨酸脱羧酶活性显著高于自根苗,多胺氧化酶活性则显著低于自根苗。表明Ca（NO₃）₂胁迫后,嫁接苗多胺合成能力较强且分解较少,表现出对Ca（NO₃）₂较强的耐受性。在离子吸收及分布特性方面,Ca（NO₃）₂胁迫后,嫁接苗植株各部分K⁺含量显著升高,根系增长的幅度最大;自根苗植株各部分K⁺含量显著下降,根系下降幅度最小。嫁接苗和自根苗植株各部分Ca²⁺含量均显著升高,根系增长的幅度最大,但嫁接苗增长的幅度大于自根苗。嫁接苗和自根苗植株各部分Mg²⁺含量均显著下降,功能叶下降的幅度最大,但嫁接苗下降的幅度小于自根苗。嫁接苗功能叶、老叶、叶柄和茎Fe²⁺含量下降,下降幅度最大的部位为茎,新叶和根系变化不显著;自根苗植株各部分Fe²⁺含量均显著下降,下降幅度最大的部位也是茎。嫁接苗植株各部分Mn²⁺含量显著升高,茎增长的幅度最大;自根苗功能叶、老叶和叶柄Mn²⁺含量降低,新叶、茎和根系Mn²⁺含量升高,增长幅度最大的部位为茎。Ca（NO₃）₂胁迫下,嫁接苗植株各部分的离子含量均显著高于自根苗,离子分布的区域化也优于自根苗,表明嫁接苗耐Ca（NO₃）₂胁迫的能力强于自根苗。Ca（NO₃）₂胁迫下,嫁接苗和自根苗叶片和根系NO₃^-和NH₄⁺含量均呈先上升后下降的趋势,但嫁接苗含量显著高于自根苗;两者叶片和根系的硝酸还原酶（NR）活性均呈先上升后下降的趋势,嫁接苗NR活性显著高于自根苗;嫁接苗叶片谷氨酰胺合成酶（GS）活性持续上升,嫁接苗根系、自根苗叶片和根系GS活性均呈先上升后下降的趋势。嫁接苗叶片、自根苗叶片和根系淀粉含量均呈显著下降的趋势,嫁接苗根系淀粉含量呈缓慢上升的趋势;嫁接苗叶片、根系和自根苗叶片可溶性糖含量均呈上升趋势,自根苗根系呈先上升后下降的趋势;嫁接苗和自根苗叶片淀粉酶活性均呈持续上升的趋势,嫁接苗根系淀粉酶活性变化不显著,自根苗根系呈显著上升趋势。Ca（NO₃）₂胁迫下,嫁接苗氮素同化能力较强,同时氮同化对碳同化的抑制程度较小,表现出对Ca（NO₃）₂较强的耐受性。更多还原

【Abstract】 In recent years,protected cultivation of vegetables has expanded rapidly in China. However,due to the protected cultivation is a closed system,the temperature inside the greenhouse is higher than outside,in addition,because there is less rain rinsing,the upward movement of soil water inside the greenhouse is more greatly than outside.Protected cultivation usually bring excessive nitrogen fertilization into soil and the mineralization of soil inside the greenhouse is more greatly than outside,all these will make the salt concentration of soil surface increasing easily,which inhibits vegetable growth and development,causes decline of yield and quality,brings a negative effect on further development of protected cultivation of vegetables.It has been well documented that grafting can improve vegetable tolerance to environmental stresses,become an effective approach to overcome salt stress.Tomato（Lycopersicon esculentum Mill.） is one of the most important vegetables in protected cultivation,in recent years,researches on grafting techniques and grafting improving tomato salt tolerance have been carried out all over the world,but all these researches focused on NaCl stress.In greenhouse salt soil,the most cation is Ca²⁺,taking up about 60%of all cations,the most anion is NO₃^-,taking up 67%～76%of all anions,but few reports on physiological and biochemical changes in grafted tomatoes during Ca（NO₃）₂ have been published.In this study,we use hydroponically-grown grafted and own-root tomato（cvs.’Kagemusya’ and ’Baoda 903’ as rootstock and scion respectively） seedlings as experimental materials,comparisons of physiological and biochemical changes were made between grafted and own-root tomato seedlings under 80 mM Ca（NO₃）₂ stress.The results showed that under Ca（NO₃）₂ stress,superoxide dismutase（SOD） activities of both grafted and own-root tomato seedlings increased significantly,peroxidase（POD） activities decreased during the first 2 d,then increased significantly,catalase（CAT） activities decreased significantly,but every index of grafted seedlings was significantly higher than that of own-root seedlings.Under Ca（NO₃）₂ stress,O₂^- producing rate, contents of hydrogen peroxide（H₂O₂） and malondialdehyde（MDA） of both grafted and own-root tomato seedlings increased significantly,but every index of grafted seedlings was significantly lower than those of own-root seedlings.The proline and soluble protein contents of grafted tomato seedlings increased significantly,proline contents of own-root tomato seedlings and soluble protein content in own-root tomato roots increased significantly,however,no significant difference was observed in soluble protein content in own-root tomato leaves,but each index of grafted seedlings was significantly higher than that of own-root seedlings,exhibited that grafted seedlings have a stronger osmotic adjustment ability.Under Ca（NO₃）₂ stress,the activities of antioxidant enzymes（APX,DHAR and GR） were significantly higher,the regenerating rates of AsA and GSH were significantly higher, and redox statuses（ratios of AsA/DHA and GSH/GSSG） were also significantly higher in leaves and roots of grafted seedlings than those of own-root seedlings,and H₂O₂ content was significantly lower in leaves and roots of grafted seedlings than that of own-root seedlings.These results indicated that under Ca（NO₃）₂ stress grafted tomato seedlings had an efficient metabolism of ascorbate-glutathione cycle,which scavenged the H₂O₂ rapidly to alleviate the oxidative damage,thus grafted seedlings had a stronger tolerance to Ca（NO₃）₂ stress.Polyamines are low-molecular-weight biologically active compounds,play important roles in seedlings growth and development,configuration formation and response to environmental stresses.Under Ca（NO₃）₂ stress,contents of three forms of putrescine（Put）, spermidine（Spd） and spermine（Spm） in leaves of grafted seedlings increased significantly in the whole process of stress,the contents of three forms of Put in leaves of own-root seedlings decreased significantly,the contents of free and conjugated Spd and Spm increased significantly,but the contents of bound Spd decreased significantly,however,no significant difference was observed in bound Spm after treatment.Under Ca（NO₃）₂ stress, contents of three forms of Put,Spd and Spm in roots of grafted seedlings increased significantly in the whole process of stress,the contents of free Put,Spd and Spm in roots of own-root seedlings increased significantly,the contents of conjugated Put,Spd and Spm in roots of own-root seedlings decreased significantly,no significant difference was observed in contents of bound Put at the early stage of stress,then decreased significantly, however,no significant difference was observed in bound Spd and Spm after treatment. During the whole course of stress,the contents of whole polyamines in grafted seedlings are significantly higher than those of own-roots seedlings,arginine decarboxylase（ADC） activities in grafted seedlings are significantly higher than those of own-roots seedlings,but polyamine oxidase（PAO） activities in grafted seedlings are significantly lower than those of own-roots seedlings.These results indicated that under Ca（NO₃）₂ stress,the synthesis of polyamines in grafted tomato seedlings is higher than that of own-root seedlings,but the degradation of polyamines in grafted tomato seedlings is lower than that of own-root seedlings,which showed the characteristics of stronger Ca（NO₃）₂ tolerance of grafted seedlings.In the aspect of characteristics of ion absorption and distribution,under Ca（NO₃）₂ stress,the contents of K⁺ in grafted seedlings increased significantly and the increase in roots was most obvious,however,the contents of K⁺ in own-root seedlings decreased significantly and the decrease in roots was least.The contents of Ca²⁺ in both grafted and own-root seedlings increased significantly and the increase in roots was most obvious, however,the increase in grafted seedlings was more significant than that in own-root seedlings.The contents of Mg²⁺ in both grafted and own-root seedlings decreased significantly and the decrease in functional leaves was most obvious,however,the decrease in own-root seedlings was more significant than that in grafted seedlings.The contents of Fe²⁺ in functional leaves,old leaves,petiole and stem of grafted seedlings decreased significantly and the decreased in stem was most obvious,however,no significant difference was observed in the Fe²⁺ contents in young leaves and roots,the contents of Fe²⁺ in all parts of own-root seedlings decreased significantly and the decreased in stem was most obvious.The contents of Mn²⁺ in grafted seedlings increased significantly and the increase in stem was most obvious,contents of Mn²⁺ in functional leaves,old leaves and petiole of own-root seedlings decreased significantly,but Mn²⁺ contents in young leaves, stem and root of own-root seedlings increased significantly and the increase in stem was most obvious.All these results indicated that the selective absorption,transportation of ion in grafted seedlings were stronger and the compartmentalization of ion was better than those in own-root seedlings,thus had a stronger tolerance to Ca（NO₃）₂ stress.Nitrogen metabolism and carbon metabolism are the most important two metabolic processes in crops,during the development of crops they must keep homeostasis in order to achieve maximal yield.Under Ca（NO₃）₂ stress,the contents of NO₃^- and NH₄⁺ increased significantly at the early stage of stress,then decreased significantly,each index of grafted seedlings was significantly higher than that of own-root seedlings.Nitrate reductase（NR） activities of both grafted and own-root seedlings increased significantly at the early stage of stress,then decreased and the activity of NR in grafted seedlings was significantly higher than that of own-root seedlings.Glutamine synthetase（GS） activities in leaves of grafted seedlings increased significantly during the whole stress,GS activities in own-root seedlings and roots of grafted seedlings increased significantly at the early stage of stress, then decreased significantly.The contents of starch in own-root seedlings and leaves of grafted seedlings decreased significantly,however,the starch content in roots of grafted seedlings increased slowly.The contents of soluble sugar in grafted seedlings and leaves of own-root seedlings increased significantly,the contents of soluble sugar in roots of own-root seedlings increased significantly at the early stage of stress,then decreased. Amylase activities in grafted seedlings and roots of own-root seedlings increased significantly in the whole process of stress,however,no significant difference was observed in amylase activities in roots of grafted seedlings.All these results indicated that under Ca（NO₃）₂ stress,nitrogen metabolism in grafted seedlings were stronger than that of own-root seedlings and the inhibition of nitrogen metabolism to carbon metabolism was less than that in own-root seedlings,thus grafted seedlings were more tolerant to Ca（NO₃）₂ stress.更多还原