【作者】 马海燕；

【导师】 徐迎春；

【作者基本信息】 南京农业大学 ， 园林植物与观赏园艺， 2008， 硕士

【摘要】 中山杉（Taxodium distichum×T.mucronaturm）是通过落羽杉属树木种间杂交选育出来的无性系,具有耐水湿,耐盐性强特性,在沿海盐碱地（pH8-8.5,含盐量0.1%左右）上生长良好,是开发利用滩涂广阔的土地资源,改善生态环境的优良树种。近年来以中山杉302为母本与墨西哥落羽杉回交叉选育出系列无性系,本试验以8个中山杉无性系为研究对象,评价了它们的耐盐力,并选择其中有代表性的两个耐盐性不同的无性系研究了NaCl胁迫对其生理特性及离子吸收运输的影响,初步探讨了中山杉无性系的耐盐机制。采用水培法对8个中山杉新无性系1年生扦插苗进行不同浓度NaCl(3.0,3.5,4.0,4.5,5.0 g·L^-1)处理,以苗高相对生长量、盐害指数和叶片相对电导率为主要指标,结合茎粗相对生长量、干重、根冠比、地上部相对含水量及根部相对含水量等指标,对8个中山杉无性系进行了耐盐力评价,结果表明,在水培条件下不同无性系的耐盐力从3.0 g·L^-1～4.5 g·L^-1不等。中山杉118号具有较好的耐盐性,耐盐力为4.0g·L^-1～4.5 g·L^-1;中山杉136号、1号、146号和149号耐盐力为中等,为3.5 g·L^-1～4.0g·L^-1;而中山杉102号,27号和24号的耐盐性较差,为3.0g·L^-1～3.5 g·L^-1。对以上指标进行相关性分析表明,盐害指数、苗高相对生长量和叶片相对电导率两两之间在0.01水平上均呈极显著相关,且分别与茎粗相对生长量、干重、根冠比、地上部相对含水量及根部相对含水量五个指标均有显著相关性。因此,盐害指数、苗高相对生长量和叶片相对电导率可作为中山杉耐盐能力综合评价指标。从上述无性系中选出2个耐盐力差异较大的中山杉无性系,分别为118号（耐盐性较强）和102号（耐盐性较弱）,研究了NaCl胁迫对其生理反应的影响。研究表明,盐胁迫下,叶片叶绿素含量持续下降,在低浓度(3.0 g·L^-1)NaCl处理时与对照之间差异不显著,随着盐浓度的增加,耐盐性较强无性系118号叶片叶绿素含量下降幅度低于耐盐性较弱无性系102号;耐盐性较强无性系在低浓度盐胁迫下具有较强地清除自由基的能力,叶片SOD活性在3.5 g·L^-1盐浓度时达到最大值,且显著高于对照,而随着盐浓度的增大其活性显著下降,清除能力下降;叶片可溶性蛋白含量持续增加,且在低盐浓度时耐盐性较强无性系增幅远大于耐盐性较弱无性系,随着盐浓度的增大,两者差异不显著;叶片电解质渗漏率持续增大,且耐盐性较强无性系118号增幅小于耐盐性较弱无性系102号;叶片脯氨酸含量在低浓度(3.0g·L^-1-3.5g·L^-1)盐胁迫下总体呈上升趋势,其中118号的脯氨酸含量成倍增加,102号增幅较小,当高浓度(5.0g·L^-1)盐胁迫时,118号的脯氨酸含量在增加,102号则下降;盐胁迫下,较耐盐无性系118号的叶部和根部可溶性糖含量增加,且根部可溶性糖含量增幅远远超过叶部的增幅,而102号均下降。中山杉118号无性系主要是通过增加可溶性糖的含量和增加脯氨酸的含量进行渗透调节。以2个中山杉无性系118号（耐盐性较强）和102号（耐盐性较弱）为材料,研究了NaCl胁迫对其离子吸收运输的影响。结果表明:NaCl处理下,118号根部通过选择性吸收Ca²⁺和K⁺来抑制Na⁺进入根系的能力比102号强,且叶片积累较少的Na⁺,说明118号根部吸收较多的K⁺、Ca²⁺和Mg²⁺并运输至叶片,以维持叶片的代谢活性,以及维持根茎叶较低的Na⁺/K⁺比率是其具有较强耐盐力的重要原因。更多还原

【Abstract】 Taxodium ’Zhongshansha’[（Taxodium distichum×T.mucronatum）×T.mucronatum] which have strong water-resistance and salt-tolerance characteristic,are excellent trees widly used to empoldering salina and meliorating entironment because they can grow well at littoral salina（pH8-8.5,contained salt about 0.1%）.Backcross hybrids were got by Taxodium ’Zhongshansha302’ and T.mucronatum.Their salt-tolerance and salt-tolerant mechanism are short of study.In this paper,salt tolerance of eight clones（CL） of ’Zhongshansha’ were appraised and two different salt-tolerant clones of ’Zhongshansha’ were chosen to study the salt-tolerant mechanism by comparing their physiological reaction and ion uptakes and transports in condition of salt stress.Eight clones of ’Zhongshansha’ breeding were used for studying their salt tolerance treated by different concentration(3.0,3.5,4.0,4.5,5.0 g·L^-1) of NaC1 in condition of water culture.The relative growth of breeding height（RG）,salt indexes and relative electrolytic leakage which were main indexes and the other indexes which were relative growth of stem,dry weight,root shoot ratio,RWC in overground and RWC in root were used to study their salt tolerance.Results indicated that the tested clones were classified into three groups:weak salt tolerance,moderate tolerance and strong tolerance.CL118 had strong salt-tolerance,which salt-tolerance limit was 4.0 g·L^-1～4.5 g·L^-1;CL136,CL1, CL146 and CL149 had moderate tolerance,which salt-tolerance limit was 3.5 g·L^-1～4.0 g·L^-1;CL 102,CL 27 and CL 24 had weak tolerance,which salt-tolerance limit was 3.0 g.L^-1～3.5 g·L^-1.There were exceedingly significant correlation in level of 0.01 between RG and Relative electrolytic leakage or RG and SI,or SI and Relative electrolytic leakage by twos,and three indexes（RG,SI and Relative electrolytic leakage） and five indexes （Relative growth of stem,Dry weight,Root shoot ratio,RWC in overground and RWC in root） had significant correlation.So RG,SI and Relative electrolytic leakage could be used as synthetic identification index for salt tolerance of ’Zhongshansha’. CL 118（with relatively strong salt resistance） and CL 102（with relatively weak salt resistance） were chosen and studied in NaCl stress on physiological reaction.Results indicated that chlorophyll content in leaves decreased at all times.Compared with the control,chlorophyll content was inapparent treated by lower NaC1 concentration(3.0 g·L^-1)but with NaC1 concentration increasing,chlorophyll content degressive extent of CL 118 was much lower than CL 102;CL 118 had stronger ability to clear away free radical treated by lower NaC1 concentration,which SOD activity reached maximum at 3.5 g·L^-1 concentration and was higher than the control.,but its activity observably declined with NaCl concentration increasing.The soluble protein in leave all increased and its amplitude of CL 118 was much lower than CL 102,and the difference between CL 118 and CL 102 was inapparent with NaCI concentration increasing.Relative electrolytic leakage in leave all increased and its amplitude of CL 118 was much lower than CL 102.Pro content in leave ascended as a whole at lower NaCl(3.0g·L^-1-3.5g·L^-1) concentration,that of CL 118 doubly increased,and its amplitude of CL 118 was bigger than CL 102.Pro content in leave of CL 118 ascended at higher NaC1(3.0g·L^-1-3.5g·L^-1) concentration and CL 102 failed.Soluble sugar content in leaf and root of CL 118 enhanced and its amplitude in leave was much higher than in root.Soluble sugar content in leaf and root of CL 102 were declined.CL 118 osmoregulated mainly through increasing of soluble sugar content and pro content.The effects of salt stress on ion uptakes and transports on CL 118 and CL 102 were studied.Results indicated that important reasons for stronger salt resistance of CL 118 were root selectivity absorbency toward K+ and Ca2 of CL 118 in order to restrain Na⁺ coming into root was stronger than that of CL 102,and Na⁺ in leaves of CL 118 accumulation was less than that of CL 102.It showed that root transported much more K⁺,Ca²⁺ and Mg²⁺ to leaves for keeping metabolized active and lower level of Na⁺/K⁺ value in root,stem,and leaf of CL 118.更多还原