【作者】 刘正祥；

【导师】 张华新；

【作者基本信息】 中国林业科学研究院 ， 林木遗传育种， 2013， 博士

【摘要】 针对我国盐渍土面积广大、类型复杂多样的现状，本论文以北方生态脆弱区造林绿化先锋树种沙枣（Elaeagnus angustifolia L.）为对象，在温室盆栽和溶液培养控制试验条件下，采用电感耦合等离子体发射光谱仪（ICP-OES）、扫描离子选择电极技术（SIET）并结合其他常规仪器与方法，系统研究和对比分析了2种盐（NaCl和Na₂SO₄）胁迫下沙枣的（1）盐害症状、生长表现和耐盐性；（2）光合气体交换参数、光响应与CO₂响应曲线及其特征参数；（3）盐离子(Na⁺、Cl^-、SO₄^2-)的吸收、运输与分配，以及K⁺、Ca²⁺、Mg²⁺、NO₃^--N、P等矿质营养状况；以及（4）粒子流（Na⁺、K⁺、H⁺）的轴向、稳态和原初动态变化。基于上述4个方面的研究内容，本论文验证了沙枣的耐盐性并量化了其耐盐阈值，探讨了沙枣的盐适应机制，揭示了沙枣对NaCl和Na₂SO₄胁迫具有差异性响应的光合生理、离子代谢生理以及电生理学机制，旨在为沙枣的规模化推广与应用、适应不同盐碱地类型新种质的培育提供理论基础，为不同类型盐碱地生物治理中植物材料的选择提供参考和借鉴。主要研究结论归纳如下：1.盐胁迫对沙枣生长具有显著的抑制效应。经NaCl和Na₂SO₄胁迫后，沙枣幼苗呈现出不同程度的叶片脱落、枯黄等典型盐害症状，幼苗的株高、基径与侧枝生长、叶片生长参数、各组织以及全株生物量累积均低于或显著低于对照。随胁迫溶液中[Na⁺]的升高，上述盐害症状呈现出加剧的趋势，各生长参数呈不同程度的下降，根生物量分配百分比和根冠比值则呈增加的趋势。2. Na₂SO₄胁迫下沙枣的耐盐性强于NaCl胁迫。在相同[Na⁺](均为100或200mmol· L^-1)条件下，与NaCl胁迫相比，Na₂SO₄胁迫沙枣的盐害症状较轻、生长表现较好、耐受性较强，且植株的盐害率、生长抑制效应、耐盐性在NaCl和Na₂SO₄之间的差异随盐胁迫的加剧呈增大的趋势。沙枣耐盐性很强，在NaCl和Na₂SO₄胁迫下的生长临界钠离子浓度（C50）分别为180和280mmol· L^-1。3.盐胁迫显著降低了沙枣的光合能力。与对照相比，2种盐胁迫均显著降低了沙枣的Pn、Gs、Ci、Tr和LUE，增大了Ls和WUE，且Pn下降主要受气孔限制。盐胁迫对沙枣光合作用和叶片功能参数的影响最终反映到植株的生长和生物量累积上。在等[Na⁺]条件下，NaCl胁迫对沙枣光合作用的抑制效应显著强于Na₂SO₄胁迫；与NaCl胁迫相比，沙枣幼苗在Na₂SO₄胁迫下具有更高的最大光合能力、光能转化效率和Rubisco羧化效率，更为宽泛的CO₂利用域，对光的生态适应性也更强。4.沙枣的盐（NaCl）适应机制为根系拒盐和冠组织耐盐。盐胁迫改变了植株体内Na⁺和Cl^-的分配格局，200mmol· L^-1NaCl胁迫沙枣根和叶中聚积的Na⁺分别占全株Na⁺净累积量的36.2%和42.3%，而叶中聚积的Cl^-占全株Cl^-净累积量的58.9%，并显著提高了根系向叶片选择性运输K⁺、Ca²⁺的能力。200mmol· L^-1NaCl胁迫沙枣茎[Na⁺]、叶[Na⁺]、冠Na⁺净累积量以及JNa⁺shoot分别是对照植株的7.22、9.58、5.45和5.36倍，而茎[Cl^-]、叶[Cl^-]、冠Cl^-净累积量以及JCl^-shoot分别是对照的2.27、3.70、2.03和2.01倍，但植株仍正常生长，叶片并未呈现出典型的盐害症状、肉质化特征和避盐机制。5.沙枣在NaCl和Na₂SO₄胁迫下具有不同的盐适应机制和矿质营养状态。在200mmol· L^-1等[Na⁺]条件下，NaCl胁迫植株将更大比例的Na⁺滞留、聚积在根系和叶片中；而Na₂SO₄胁迫植株将更大比例的Na⁺滞留、限制在茎组织中，从而维持了较好的K⁺-Na⁺平衡。NaCl胁迫植株叶片是Cl^-净累积量最大的组织和Cl^-分配的主要组织（约占全株Cl^-净累积量的60%）；而Na₂SO₄胁迫幼苗吸收的SO₄^2-主要聚集、限制在根系中(约占全株SO₄^2-净累积量的50%)，叶片[SO₄^2-]仍维持在对照水平；NaCl胁迫植株对Cl^-的吸收或运输速率远大于Na₂SO₄胁迫幼苗对SO₄^2-的吸收或输运速率。NaCl胁迫对沙枣吸收NO₃^--N、P等矿质营养的抑制效应显著强于Na₂SO₄胁迫。6.粒子流的短期响应机制和原初响应机制具有盐类型差异性。盐胁迫改变了沙枣根系的显微组织结构，根系粒子流测定的最佳扫描位置为距离根尖约600μm(对照/50mmol· L^-1Na₂SO₄胁迫植株)和300⁴50μm范围内(100mmol· L^-1NaCl胁迫植株)。经对照、Na₂SO₄和NaCl胁迫24h，根系稳态Na⁺、K⁺均为外流，其中，K⁺流速在对照和Na₂SO₄胁迫之间无显著差异，且均显著低于NaCl胁迫，而Na⁺流速在3种处理之间的差异均达到显著水平；对于稳态H⁺，对照幼苗为内流，而Na₂SO₄和NaCl胁迫幼苗均为外流，且Na₂SO₄胁迫的流速显著低于NaCl胁迫。不同化学试剂或试剂组合（Na₂SO₄、NaCl、Choline Cl以及Na₂SO₄+Choline Cl）瞬时胁迫后初始5min以及约25min时间域内，沙枣根系平均K⁺、H⁺流速具有较大差异，且2种离子流速在Na₂SO₄与NaCl胁迫之间的差异均达到显著水平。总之，本研究证实，在NaCl和Na₂SO₄胁迫下，沙枣幼苗根系具有不同的显微组织结构以及短期（24h）和原初（10²5min）Na⁺、K⁺、H⁺粒子流动态交换特性，从而使得植株在长期（30d）盐胁迫下具有不同的离子组织区隔化水平和矿质营养状态，继而抑制幼苗叶片生长、降低叶片的光合能力并影响到光合机构的正常运转，这些最终均反映到植株的生长表现和生物量累积上，即使得沙枣在NaCl和Na₂SO₄胁迫之间具有不同的耐盐性。更多还原

【Abstract】 There are complex and diverse types of saline soil with a large total area in China. As oneof the first-choice tree species which are widely and extensively used for land afforestation innorthern China’s ecologically fragile regions, Elaeagnus angustifolia L. seedlings stressed byNaCl or/and Na₂SO₄were used as experimental materials in this research. Under the controlledconditions of potted culture and nutrient solution culture in greenhouse, the following fouraspects were investigated by Inductively Coupled Plasma Optical Emission Spectrometer（ICP-OES）, Scanning Ion-selective Electrode Technique （SIET）, and other conventionalinstruments and methods, those are,（1） salt-damaged symptoms, plant growth performanceand salt tolerance;（2） photosynthetic gas exchange parameters, net photosynthetic rate （Pn）^light intensity response curves, Pn^CO₂concentration response curves, and their characteristicparameters;（3） the absorption, transportation and allocation of salt ions (Na⁺, Cl-and SO₄^2-),and the status of mineral nutrition elements (K⁺, Ca²⁺, Mg²⁺, NO₃^--N, P, etc.); and （4） dynamicchanges in ion fluxes （Na⁺, K⁺and H⁺） in root axial direction or root meristematic zone aftervarious salt treatments for24h or different chemical shocks for25min.Based on the above-mentioned four research aspects, firstly, the salt tolerance and thecritical growth Na⁺concentration （C50） were comprehensively analyzed and compared betweenNaCl-and Na₂SO₄-treated E. angustifolia seedlings. Secondly, the adaptation mechanisms tosalt （NaCl） of E. angustifolia were elucidated clearly. Furthermore, the physiologicalmechanisms （including photosynthesis, ionic metabolism and electrophysiology） of differentialresponses of E. angustifolia seedlings to NaCl and Na₂SO₄stress were revealed and discussed.The aims of this current study were to provide theoretical basis for the large-scale extensionand utilization of E. angustifolia resources and for the selection and breeding of new E.angustifolia germplasms suitable for plantation and utilization in different types ofsaline-alkaline lands, and to provide reference for plant material selection in the process ofbiological control and development of different types of saline-alkaline lands. The main results of this study were summarized as follows:1. Plant growth was significantly inhibited by both types of salt stress. There was typicalsalt-damaged symptoms （such as abscised and turning-yellow leaves）, to a different extent, inNaCl-and Na₂SO₄-stressed E. angustifolia seedlings. The plant height, the growth of grounddiameter and branch, the various leaf growth parameters, and the biomass accumulation ofvarious plant tissues （root, stem, leaf, shoot and even whole-plant） of two types of salt-stressedseedlings were lower or significantly lower than the corresponding parameters of no saltcontrol. With the increase of stressed solution [Na⁺], the above-mentioned salt-damagedsymptoms and various growth parameters were generally exhibited an aggravated anddecreasing trend, respectively, whereas, the root biomass allocation ratio and root to shoot ratiowere both presented an increasing trend.2. The salt tolerance of Na₂SO₄-stressed E. angustifolia is higher than that ofNaCl-stressed. Under the conditions of equal [Na⁺](100or200mmol· L^-1), compared withNaCl-stressed E. angustifolia seedlings, Na₂SO₄-stressed seedlings had a lower leaf-damagedpercentage, a better growth performance and a higher tolerance, and the differences inleaf-damaged percentage, growth performance and salt tolerance between seedlings stressed byNaCl and Na₂SO₄enlarged gradually with the solution [Na⁺] increased. E. angustifolia is highsalt tolerance, its critical growth Na⁺concentration （C50） is180and280mmol· L^-1under thestress of NaCl and Na₂SO₄, respectively.3. Photosynthetic capacity was significantly decreased by both types of salt stress. Netphotosynthetic rate （Pn）, stomatal conductance （Gs）, intercellular CO₂content （Ci） andtranspiration rate （Tr）, and stomatal limitation value （Ls） and water use efficiency （WUE） of twokinds of salt-stressed seedlings was significantly lower, and higher than those of no salt control,respectively. The decreased Pnof stressed seedlings was mainly attributed to stomatalrestrictions. The effects of salt stress on photosynthesis and various leaf growth parametersultimately induced a decrease in plant growth and biomass accumulation. Under the conditionsof equal solution [Na⁺], the inhibitory effects of NaCl stress on photosynthesis were strongerthan those of Na₂SO₄stress, while the Na₂SO₄-stressed seedlings presented a higher maximum net photosynthetic rate （Pn-max）, a larger apparent quantum yield （AQY） and carboxylationefficiency （CE）, a wider CO₂utilization range, and a higher light eco-adaptability.4. The NaCl-adaptation mechanisms of E. angustifolia are root salt-rejection and shootsalt-tolerance. The Na⁺and Cl-allocation model were changed by salt stress,36.2%and42.3%of net Na⁺accumulation allocated in roots and leaves of seedlings stressed by200mmol· L^-1NaCl, respectively,58.9%of net Cl-accumulation was restricted in stems, and the abilities inK⁺and Ca²⁺selective transportation from root to leaf were enhanced substantially. Stem [Na⁺],leaf [Na⁺], net shoot Na⁺accumulation and net shoot Na⁺flux （JNa⁺shoot） of200mmol· L^-1NaCl-stressed seedlings were7.22,9.58,5.45and5.36times that of control seedlings,respectively. For Cl-, it was2.27,3.70,2.03and2.01times in the same tissue order,respectively. Even stressed by200mmol· L^-1NaCl, the seedlings still grew well, and there wasno typical salt-damaged symptoms, succulent characteristics and salt-avoidance mechanism.5. There were great differences in salt-adaptation mechanisms and mineral nutrientstatuses between NaCl-and Na₂SO₄-stressed E. angustifolia seedlings. Under the conditions of200mmol· L^-1equal [Na⁺], there was a larger proportion of root Na⁺retention and a largeramount of Na⁺transportation from stem to functional leaves in NaCl-stressed E. angustifolia,whereas for Na₂SO₄-stressed seedlings, it held a higher capacity in stem Na⁺retention, leaf K⁺selective transportation and leaf Na⁺avoidance, thus kept a better K⁺-Na⁺homeostasis. Net Cl-accumulation in leaves of NaCl-stressed seedlings was the largest among the three plant tissues,accounting for approximately60%of the total net Cl-accumulation. While for Na₂SO₄-stressedseedlings, the absorbed SO₄^2-was mainly distributed in root, approximately accounting for halfof the total net SO₄^2-accumulation, and the leaf [SO₄^2-] maintained an equivalent level withthat of control seedlings. The Cl-absorption or transportation rate in NaCl-stressed seedlingswas substantially larger than SO₄^2-rate in Na₂SO₄-stressed seedlings. The inhibitory effects ofNaCl stress on mineral nutrient （such as NO₃^--N and P） absorption were stronger than those ofNa₂SO₄stress.6. The short-term steady and initially dynamic response mechanisms of root ion fluxes aresalt-type heterogeneity. Salt stress induced a changed root functional structure, the optimal scanning position in the process of ion flux measurement are600μm (for control or50mmol· L^-1Na₂SO₄-stressed seedlings) and300⁴50μm (for100mmol· L^-1NaCl-stressedseedlings) from root tip, respectively. After stressed by no salt control,50mmol· L^-1Na₂SO₄or100mmol· L^-1NaCl for24h, the steady Na⁺and K⁺were all efflux. There was nosignificant difference in K⁺efflux between control and Na₂SO₄stress, and both weresignificantly lower than NaCl-induced K⁺efflux, while the difference in Na⁺efflux betweenany two of the three treatments reached a significant level. For steady H⁺flux, it was influx incontrol roots, and efflux in NaCl-and Na₂SO₄-stressed roots, and the NaCl-induced H⁺effluxwas significantly higher than Na₂SO₄-induced. The mean K⁺and H⁺fluxes within themeasuring periods of the initial5min and the whole25min after the transient addition ofvarious chemicals (50mmol· L^-1Na₂SO₄,100mmol· L^-1NaCl,100mmol· L^-1Choline Cl,and50mmol· L^-1Na₂SO₄+100mmol· L^-1Choline Cl) presented a great difference, of them,the difference in K⁺and H⁺fluxes between NaCl and Na₂SO₄treatment arrived a significantlevel.In conclusion, differences in microscopical root structure, short-term （24h） and initial （10²5min） ion flux dynamic exchange characteristics of Na⁺, K⁺and H⁺between E. angustifoliaseedlings stressed by NaCl and Na₂SO₄conferred the long-term （30d） stressed seedlings witha different salty ions tissue-level compartmentation and a different mineral nutrient status,which further induced a different leaf inhibitory growth, a differently reduced leafphotosynthetic capacity, and a different photosynthetic apparatus dysfunction. All thesedifferences between NaCl and Na₂SO₄stressed seedlings finally exhibited a different plantgrowth performance and biomass accumulation, and a different salt tolerance.更多还原