【作者】 刘炳响；

【导师】 王志刚； 杨敏生；

【作者基本信息】 河北农业大学 ， 森林培育， 2012， 博士

【摘要】 采用盆栽试验模拟盐胁迫方法,研究不同生境2年生白榆(ulmus pumila)幼苗在盐胁迫下的生理响应,探讨盐胁迫下不同生境白榆的耐盐性差异,探索不同生境白榆对胁迫的生理生态适应机制,旨在为滨海盐碱地造林的苗木选择、培育和引种提供理论依据。结果表明:随着土壤盐浓度的增加,中强度和轻度盐土生境白榆幼苗叶片的细胞膜透性、Na+含量和Na+/K+增幅低于非盐土生境;叶片脯氨酸、可溶性糖和K+含量增幅高于非盐土生境;叶片淀粉含量、净光合速率、蒸腾速率、胞间CO2浓度和气孔导度降幅均小于非盐土生境白榆。不同生境白榆耐盐性的强弱顺序为:中强度盐土生境(0.776%)>轻度盐土生境(0.737%)>非盐土生境(0.695%)。通过各项生理指标的综合比较,与非盐土生境相比,中强度和轻度盐土生境白榆对盐土环境的适应能力更强。通过控制土壤含盐量,研究盐胁迫对种子萌发、出苗、幼苗生长及对其光合性能的影响。探讨白榆萌芽和幼苗生长状况与土壤盐分的关系,这对于进一步揭示白榆适应盐渍环境的机理和实生苗繁育具有重要的理论价值和现实意义。随着盐胁迫浓度的增加,发芽率和发芽指数下降,发芽时间延长,幼苗出苗率、成苗率和存活率均呈现下降趋势,盐胁迫抑制了幼苗苗高和根长生长。白榆幼苗阶段耐盐能力弱,出苗后一些幼苗受土壤盐分胁迫又陆续死亡。盐胁迫使叶片光合系统量子产额和能量分配比率(φPo、Ψo和φEo)、单位面积光合机构的比活性参数(ABS/CSM、TRO/CSM、ETO/CSM)、单位面积内反应中心的数量(RC/CSO和RC/CSM)、性能指数( PIABS和PICSM)和推动力( DFCSM )降低,而单位面积光合机构的比活性参数(ABS/CSO)、热耗散的量子比率(φDo)和单位面积的热耗散(DIO/CSM)增加。通过控制土壤含盐量,研究盐胁迫对1年生白榆生长、生理特性、养分平衡、电阻抗参数以及光合作用的影响,探讨白榆幼苗适应盐渍环境的机理,为耐盐苗木的选育提供理论依据。研究结果表明:1.盐胁迫条件下,白榆叶片盐害指数增加,成活率、苗高的增长量和增长速率降低,白榆生长受到抑制。随着盐胁迫浓度的增加和胁迫时间延长细胞膜的透性和体内过氧化产物丙二醛(MDA)的含量增加,而白榆叶片内SOD、POD、CAT的活性,以及游离脯氨酸、可溶性糖含量则呈现先增加后降低的趋势。2.盐胁迫下,植物叶片矿质营养平衡被破坏,随着土壤盐浓度的增加和胁迫时间的延长,叶片中Na逐渐累积,使得白榆叶片中N、K、Ca、Mg含量均下降,P和Mn含量增加,Fe和Zn含量均呈现先上升后下降的趋势,白榆叶片中各种元素与Na比值降低。Na离子的累积影响参与生理代谢的主要营养离子吸收、分配和利用,使其不能正常发挥生理功能,同时白榆自身不断地进行调整以适应盐环境。3.盐浓度低于0.3 %,白榆叶片电阻抗图谱弧度和跨度差异不大,当盐浓度高于0.4%,弧度和跨度均呈减小趋势。随着土壤盐浓度的增加,白榆叶片电阻r、电阻r1、胞外电阻、胞内电阻、弛豫时间等电阻抗参数整体出现降低的趋势,而弛豫时间分布系数呈现先升后降的趋势。盐胁迫条件下,白榆叶片中胞外电阻、胞内电阻和弛豫时间与叶片N、K、Ca、Mg、Mn含量显著正相关,与Na含量极显著负相关,而与白榆叶片P、Fe、Zn含量不显著相关。4.盐胁迫条件下,Fm、φPo和ψo降低,QA传递电子的能力下降,引起φEo下降,φDo和FO显著提高;随着盐胁迫时间的延长,φPo、ψo和φEo逐渐降低,叶片φDo逐渐升高。随着胁迫时间的延长和盐浓度的增加,叶绿素含量、净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(gs)逐渐下降,胞间CO2浓度(Ci)先下降后升高。盐胁迫使白榆叶片RC/CSO、RC/CSM、TRO/CSM、ETO/CSM、PIABS、PICSM和DFCSM都下降,DIO/CSM增加,盐胁迫使PSⅡ反应中心降解或失活,捕获的光能下降,破坏了白榆叶片电子传递链受体侧的电子传递,阻滞了叶绿素合成,降低了叶片PSII的活力,迫使叶片启动了相应的防御机制。更多还原

【Abstract】 The pot experiment in salt stress simulation method was used to research physiological responses under salt stress of 2-year Ulmus pumila seedlings and their salt tolerance differences and physiological adoption mechanism in different habitats. Finally, the theory basis was provided for tree selection, cultivation and species introduction in coast saline-alkali soil forestation. The results revealed that the membrane permeability, Na content and Na/K in leaves of U. pumila which the seeds are taken from medium-salinity and mild-salinity habitats, were lower than that of samples in non-saline habitats with increasing of salt concentration. However, leaf proline content, soluble sugar and K content had a higher growth rate than that in non-saline habitats. In addition, the decreasing rate of leaf starch content, net photosynthetic rate(Pn),transpiration rate(Tr), intercellular CO2 concentration(Ci ) and stomatic conductance (gs) were lower than that in the non-saline habitats. The order of salt-resistance (high-low) of U. pumila was: medium-saline habitat (0.776%) > mild-saline habitat (0.737%) > non-saline habitat (0.695%). U. pumila from salinity habitat may have stronger saline environment adaptability than that in non-salinity habitat. Comparing with non-salt soil habitat, various physiological indices of U. pumila in moderate and low salt soil habitat showed stronger adaptability to salt soil environment.By controlling salt content in soil, the effects of salt stress on seed germination, emergence and seedling growth and photosynthetic performance were studied. With the insights of impact mechanism salinization soil on U. pumila seed germination, emergence and seedling growth, the relationship between U. pumila germination & seedling growth status and salt concentration in soil were discussed in the paper. Consequently, it showed that adaptability mechanism had great meaning during U. pumila seed germination, emergence and seedling growth stage. The results showed that: with increasing concentration of salt stress, not only the germination rate and germination index decreased, but also the time of seedling germination delayed significantly with the increasing intensity of salt-stress. The rate of emergence, planting percent and survival rate of Seedling decreased with the increase of salt concentration and salt stress inhibits the growth of seedling height and root length of U. pumila. Because of the salt tolerance is weak in Seedling stage, a large number of seedling died under salt stress. With the increase in salt stress, Yields or flux ratios (φPo、Ψo andφEo), Phenomenological energy fluxes(ABS/CSM、TRO/CSM and ETO/CSM),Density of reaction centers (RC/CSO and RC/CSM),Performance indexes( PIABS and PICSM)and Driving force per unit area basis (DFCSM)decreased, Absorption flux per CS(ABS/CSO),quantum yield for energy dissipation (φDo) and dissipated energy flux per CS ( DIO/ CSM ) increased.By controlling salt content in soil, the growth, physiological property, nutrient balance, impedance parameter and photosynthesis of 1-year U. pumila were studied. discuss U. pumila adaptability mechanism in salting habitat was discussed and the theory basis for salt tolerant seedling breeding was provided in the paper.1. Under salt stress condition, U. pumila leaf salt damage index increased and its survival percentage and growth rate decreased. As a result, U. pumila growth will be restrained. With the growth of salt stress concentration and extension of stress time, cell membrane permeability, relative conductivity and internal per-oxidation product MDA content increased. However, U. pumila leaf SOD, POD, CAT, free proline content and soluble sugar content increased to the maximum and then decreased.2. Under salt stress, mineral nutrition balance of plant leaves is damaged. With the growth of salt concentration in soil and extension of stress time, Na accumulates in leaves continuously. As a result, N, K, Ca and Ma content decreases in the leaf. Fe and Zn content increases. However, Fe and Zn content increases to the maximum and then decreases. In addition, ratio of all elements to Na is reduced in U. pumila leaf. Accumulation of Na has influence to main nutrition ion absorption and distribution and utilization during physiological metabolism. U. pumila cannot perform its normal physiological function. Meanwhile, U. pumila adjusts itself continuously to adopt the salt habitat.3. If salt concentration is lower than 0.3 %, it has little difference in radian and span in U. pumila leaf electrical impedance map. If the salt concentration is higher than 0.4%, radian and span presents a reduction trend. In different salt concentrations, U. pumila leaf electrical impedance parameter electric resistance r, electric resistance r1, exocellular resistance, internal resistance and relaxation time shows a reduction trend generally. However, relaxation time distribution coefficient increases to the maximum and then decreases. Under salt stress conditions, U. pumila leaf exocellular resistance, internal resistance and relaxation time has positive correlation with content of N, K, Ca, Mg and Mn and negative correlation with Na content. These parameters have no significant relationship with P, Fe and Zn content in U. pumila leaf.4. With the salt stress influence, Fm,φPo andψo decreases, QA electron delivery capability is also reduced, which can results inφEo reduction and significant growth of φDo and FO With extension of salt stress time,φPo,ψo andφEo decrease andφDo in leaf increases. With addition of salt stress time and concentration, chlorophyll content, net photosynthetic rate (Pn), transpiration rate (Tr) and stomatic conductance (gs) decreases gradually. Intercellular CO2 concentration (Ci) increases to the maximum and then decreases. Salt stress pushes reduction of RC/CSO, RC/CSM, TRO/CSM, ETO/CSM, PIABS, PICSM and DFCSM in U.pumila leaf. However, it can enhance DIO/CSM. In addition, salt stress results in PSⅡreaction center degradation or inactivation and decreased light energy collection volume. It also breaks electron delivery in U. pumila leaf electron delivery chain receptor side, defers chlorophyll composition and reduces leaf PSII activity. As a result, it activates corresponding defense mechanism in leaf.更多还原