【作者】 刘强；

【导师】 王庆成；

【作者基本信息】 东北林业大学 ， 森林培育， 2009， 博士

【摘要】 为了探讨不同树种对盐碱胁迫的反应特性及外源物质对木本植物抗盐性的作用,本文对河南白榆（Ulmus pumila）、新疆大枸杞（Lycium dasystemum）、南蛇藤（Celastrusorhiculatus）、小叶丁香（Syringa microphylla）、樟子松（Pinus sylvestris var.mongolica）等5种不同生活型树种苗木在NaHCO₃胁迫下的生理反应及海藻糖（Trehalose,TR）、精胺（Spermine,Spm）、亚精胺（Spermidine,Spd）、氯化胆碱（Choline Chloride,CC）、抗坏血酸（Ascorbic acid,ASA）等外源物质对参试树种抗盐性的影响进行了研究,一方面分析各生理指标与抗盐碱能力的相关性,探讨各生理指标能否作为评价不同生活型树种抗盐碱能力的有效标准。同时,对参试树种耐盐碱能力进行评估,确定各树种对盐碱胁迫的耐受范围;另一方面,对外源物质提高植物抗盐性的生理机制进行探讨。研究结果可以为抗盐树种的选择、植物抗盐性的提高及大庆盐碱土地区的造林绿化提供理论依据与技术支持。主要研究结论如下:（1）随盐碱胁迫强度的增加,5个树种苗木总生物量增量和根、茎、叶干重增量均呈下降趋势,但下降幅度存在差异,总生物量增量下降幅度依次为樟子松＞小叶丁香＞南蛇藤＞河南白榆＞新疆大枸杞。就各部位生物量增量下降幅度来说,白榆、丁香、樟子松依次为叶＞根＞茎;枸杞为叶＞茎＞根;南蛇藤为根＞叶＞茎。同时,随胁迫强度的增加,白榆和枸杞根冠比持续上升;南蛇藤根冠比先下降后上升;樟子松根冠比先升高后下降:丁香根冠比变化平缓。5个树种苗木抗盐碱能力依次为枸杞＞白榆＞南蛇藤＞丁香＞樟子松。（2）盐碱胁迫下不同生活型木本植物叶绿素含量一致表现下降。不同胁迫时期,随胁迫强度的增加,不同生活型树种叶绿素a、类胡萝卜素含量、叶绿素a/b值均未表现出统一的规律。长期胁迫下,不同生活型树种总叶绿素和叶绿素b含量随胁迫强度增加的变化才表现出统一的趋势。叶绿素含量不是评价不同生活型木本植物抗盐性的可靠指标。因为,通过叶绿素含量这一指标所得到的抗性排序为枸杞＞南蛇藤＞白榆＞樟子松,而这几个树种的抗性排序应为枸杞＞白榆＞南蛇藤＞樟子松。不同生活型木本植物对NaHCO₃胁迫有一致的光合响应,即净光合速率、蒸腾速率、气孔导度等光合参数均呈下降趋势。在低盐胁迫下白榆和枸杞叶片光合下降的原因是气孔限制,在高盐胁迫时,则为非气孔限制;南蛇藤和樟子松为气孔限制因素;丁香为非气孔因素。光合速率可以作为评价不同生活型木本植物抗盐性的可靠指标。因为,通过净光合速率这一指标所得到的抗盐性依次为枸杞＞白榆＞南蛇藤＞丁香＞樟子松,与这几个树种的抗性排序一致。盐碱胁迫对不同生活型树种苗木PSⅡ的功能产生了抑制,随胁迫强度的增加,Fo呈上升趋势;Fm、Fv、Fv/Fm、φPSⅡ呈下降趋势。Fo、Fv和Fv/Fm可以作为不同生活型木本植物抗盐性可靠的评价指标:Fm、NPO和φ_PSⅡ不能作为不同生活型木本植物抗盐性评价的参考指标。（3）对于有机渗透调节物质（脯氨酸、可溶性糖、可溶性蛋白）中某一个指标来说,盐碱胁迫对不同生活型树种具有一致的影响趋势,即均总体表现增加。脯氨酸含量不是评价不同生活型木本植物抗盐性的可靠指标。因为,长期胁迫下,抗性较强的枸杞和白榆脯氨酸含量上升幅度小于抗性较弱的樟子松,而抗性较强的白榆和南蛇藤上升幅度却又大于抗性较弱的丁香,脯氨酸含量变化与抗盐性既不成正相关又不成负相关。将可溶性糖积累作为不同生活型木本植物抗盐性评价标准还需慎重。因为,中期胁迫下,随胁迫强度的增加,各树种苗木可溶性糖含量均逐渐上升,上升幅度依次为枸杞＞白榆＞樟子松＞丁香＞南蛇藤,而这几个树种抗性排序为枸杞＞白榆＞南蛇藤＞丁香＞樟子松,可溶性糖含量上升幅度可以在一定程度上反映不同生活型树种的抗性差异,但抗性较弱的丁香和樟子松可溶性糖含量上升幅度却大于抗性较强的南蛇藤,表明可溶性糖积累与抗盐性之间不存在普遍必然的联系。可溶性蛋白积累也不可以作为不同生活型木本植物抗盐性的评价标准。因为,中期胁迫下,随胁迫强度的增加,各树种苗木可溶性蛋白含量总体表现升高,升高幅度依次为樟子松＞南蛇藤＞白榆＞枸杞＞丁香,而这几个树种的抗性依次为枸杞＞白榆＞南蛇藤＞丁香＞樟子松,表明可溶性蛋白积累与抗盐性之间没有必然的联系。地上部分Na⁺含量可以作为评价不同生活型木本植物的有效指标,但对于非盐生植物与盐生植物需区别对待,即非盐生植物地上部分Na⁺含量与抗盐性负相关,大多数盐生植物地上部分Na⁺含量与抗盐性正相关。地上部分Na⁺/K⁺不能作为不同生活型木本植物抗盐性评价标准。由于,中、重度胁迫下,5个树种苗木地上部分Na⁺/K⁺含量依次为樟子松＞南蛇藤＞丁香＞枸杞＞白榆,而这5个树种抗性排序为枸杞＞白榆＞南蛇藤＞丁香＞樟子松,可见,地上部分Na⁺/K⁺与抗盐性没有普遍联系。（4）SOD、CAT、GR可以作为不同生活型树种抗盐性评价标准,其中SOD、CAT更为有效。因为,各胁迫时期抗盐性较强的枸杞和白榆SOD活性随胁迫强度的增加逐渐升高,而抗盐性较弱的丁香和樟子松SOD活性却不断下降:长期胁迫下抗盐性较强的枸杞和白榆CAT活性随胁迫强度的增加逐渐升高,而抗性相对较弱的南蛇藤、丁香和樟子松CAT活性轻度胁迫下升高,较重胁迫下却降低。除南蛇藤外,其它树种叶中GR活性均随胁迫强度的增加逐渐降低,抗盐性较弱的丁香和樟子松下降幅度明显大于抗盐性较强的枸杞和白榆。POD、APX、AsA、GSH不是评价不同生活型树种抗盐性的可靠指标。POD活性增加是一种胁迫症状,而不是一种抗性表现。因为,随胁迫强度的增加,抗盐碱性较弱的丁香和樟子松POD活性增加,而抗盐碱性较强的枸杞和白榆POD活性却降低。（5）外源海藻糖处理使NaHCO₃胁迫下南蛇藤叶中活性氧O₂^-和H₂O₂产生、MDA含量以及电解质外渗率显著降低（P＜0.05）。同时,海藻糖处理明显提高了SOD、CAT、POD、APX和GR活性以及AsA和GSH含量。外源亚精胺和精胺处理使NaHCO₃胁迫下南蛇藤叶中O₂^-产生速率、H₂O₂、MDA含量和电解质外渗率显著降低（P＜0.05）。亚精胺处理明显提高盐胁迫下SOD、CAT、POD和APX等抗氧化酶的活性以及GSH、CAR和Pro等抗氧化剂的含量,但对AsA含量没有作用;精胺处理明显提高NaHCO₃胁迫下POD和APX的活性以及GSH、CAR和Pro的含量,但对SOD和AsA含量影响不显著,甚至引起CAT活性明显降低。ASA处理可以有效地抑制了丁香叶中CAT、APX、GR等抗氧化酶活性的下降,提高了SOD活性和ASA含量,延缓了H₂O₂、丙二醛含量及膜透性的增加,但抑制了GSH含量的增加。外源氯化胆碱未能有效抑制樟子松叶中H₂O₂的产生和电解质外渗率的增大,反而增加了MDA含量。外源氯化胆碱抑制了APX活性的增加,加剧了CAT活性的下降,对SOD活性的促进作用也不明显。更多还原

【Abstract】 In this paper,the responses of seedlings of Ulmus pumila,Lycium dasystemum.Celastrus orbiculatus,Syringa microphylla and Pinus sylvestris var.mongolica under NaHCO₃ stress and the effects of trehalose,spermine,spermidine,choline chloride and ascorbic acid on saline and alkaline stress tolerance of the above woody plants were studied.Through this program,the relationship of the physiological index determined in this reserch and saline and alkaline stress tolerance and the reliability of these indices as saline and alkaline tolerance selection criteria was analysed and discussed,at the same time.the tolerance scopes of woody plants refered in this research against saline and alkaline stress and the effets of exogenous substances on saline and alkaline tolerance were tested and discussed for the purpose of providing theoretical basis and technique reference for chosing salt-tolerant trees,improving salt tolerance of plants as well as afforesting and gardening successfully and effectively in Daqing saline and alkaline area.The main results were as follows:（1） With the increasing stress intensity,the dry weight increments of roots,shoots and leaves of seedlings of the five woody species expressed decresing trends as well as total biomass increments,but different species had different decresing scales.The order in decreasing scale of biomass increment of the five species followed P.sylvestris var.mongolica> S.microphylla>C. orbiculatus>U.pumila>L.dasystemum.As far as decreasing scale of biomass increment of different part of different species.U.pumila.S.microphylla and P.sylvestris var.mongolica followed leaf>root>stem;L.barbarum followed leaf>stem>root;and C.orbiculatus followed root>leaf>stem.Under different NaHCO₃ stress intensity,the root/shoot ratio of U.pumila and L. barbarum rose continuously;the ratio of C.orbiculatus under mild NaHCO₃ stress declined,and then increased;the ratio of P.sylvestris var.mongolica under mild NaHCO₃ stress increased. and then declined:the ratio of S.microphvlla changed slightly.The saline and alkaline stress tolerance of the five woody species followed L. dasystemum>U.pumila>C,orbiculatus> S.microphylla>P,sylvestris var.mongolica.（2） Under saline and alkaline stress,chlorophyll contents in the leaves of woody plants with different life forms decreased identically.At any stress stage,with the increasing stress intensity,chl.a.carotenoid contents and chl.a/b did not express identical trends.Under longtime stress stage,total chlorophyll and chl.a contents had identical trends.Chlorophyll content was not a reliable indicator for appraising salt tolerance of woody plants belonging to different living forms,because the tolerance rank judged by chlorophyll content followed L. dasystemum>C.orbiculatus>U,pumila> S.microphylla>P,sylvestris var.mongolica.But the tolerance rank of these plants should follow L.dasystemum>U.pumila>C.orbiculatus>P. sylvestris var.mongolica.These woody plants belonging to different living responsed identically to NaHCO₃ stress. that is,net photosynthetic rate,transpiration rate and stomatal conductance all declined obviously.According to the changes of photosynthesis parameters of the five seedlings,it was concluded that under lower stress intensity,the main factor leading to decreasing in photosynthesis rate of U.pumila and L.dasystemum was stomatal lilnitation,while nonstomatal limitation under higher stress intensity.The main factor leading to decreasing in photosynthesis rate of C.orbiculatus and P.sylvestris var.mongolica was stomatal limitation. Non-stomatal limitation was the main factor leading to decreasing in photosynthesis rate of S. microphylla.Photosynthesis rate could be a reliable indicator for appraising salt tolerance of woody plants with different life forms,because the tolerance rank judged by chlorophyll content followed L.dasystemum>U,pumila>C,orbiculatus> S.microphylla>P.sylvestris var. mongolica,which was identical with their salt tolerance degrees.Under saline and alkaline stress,Fm、Fv、Fv/Fm、ΦPSⅡof the five seedlings deceased gradually with the increasing stress intensity.Fo and NPQ,however,expressed increasing trends.Fo、Fv and Fv/Fm could serve as an effective index for salt tolerance assessment of woody plants with different life forms,while Fm、NPQ andΦ_PSII could not.（3） For any indicator of proline,soluble sugar and soluble protein,the five woody plants with different life forms had identical trends.Proline content was not a reliable indicator for appraising salt tolerance of woody plants with different life forms,because salt-tolerant L.dasystemum and U.pumila had a less increasing scale of proline than non-salt-tolerant U.pumila and L.dasystemum,while salttolerant U.pumila and C.orbiculatus had a larger increasing scale of proline than non-salttolerant S.microphylla.Soluble sugar and soluble protein content could not served as a reliable indicator for appraising salt tolerance of woody,plants with different life forms,too.Shoot Na⁺ content could be an effective indicator for salt tolerance assessment of woody plants with different life forms.But glycophyte and halophyte had different relationship of shoot Na⁺ content and salt tolerance.For glycophyte the relationship was negative,while it was positive for halophyte.Shoot Na⁺/K⁺ was not a good selction criterion.（4） SOD,CAT and GR could serve as a reliable indicator for appraising salt tolerance of woody plants with different life forms,and SOD and CAT were more effective.POD,APX,AsA and GSH were not reliable selction criteria.Increase in POD activity did not seem to be a tolerance component,but a stress symptom.（5） The production rate of O₂^-,H₂O₂ and MDA contents and electrolyte leakage in leaves of Celastrus ofbiculatus seedlings treated with exogenous trehalose under NaHCO₃ stress decreased significantly（P<0.05）,while the activities of SOD,CAT,POD,APX,GR.and the contents of ASC and GSH increased obviously.Significant decreases in the production of reactive oxygen species（O₂^- and H₂O₂）.MDA content as well as electrolyte leakage in leaves were observed with Spd and Spm treatments（P<0.05）.The results showed that Spd application increased the activities of SOD, CAT.POD and APX as well as the contents of GSH,CAR and Pro in leaves of stressed plants. but had no obvious effect on AsA content.Under NaHCO₃ stress,Spin spraying also increased the activities of POD and APX as well as the contents of GSH,CAR and Pro,but had no effect on SOD and AsA.Unexpectedly,it caused a obviously decrease in the activity of CAT.ASA treatment could inhibit the decrease in the activities of CAT、APX、GR,increase SOD activity and ASA content,and prohibit the increase in H₂O₂ and MDA content and electrolyte leakage.But it prohibited the increase in GSH content.Exogenous choline chloride could not effectively inhibit the increase in H₂O₂ content and electrolyte leakage.In addition,it enhanced the increase in MDA content.Choline chloride treatment prohibited the increase in APX and enhanced the decrease in CAT.It also could not effectively increase the activity of SOD.更多还原