【作者】 李芊；

【导师】 董玉芝； 张福锁； 赵林森；

【作者基本信息】 新疆农业大学 ， 森林培育学， 2002， 硕士

【摘要】 利用盐生植物是人们大面积改造盐碱地、荒漠化土地的重要途径之一。但目前为止，人们只对少数盐生植物耐盐特性有一定的认识，对于大多数盐生植物适应生理和耐盐机理还缺乏研究。柽柳是能够在盐土生境下生长发育的一种抗逆性非常强的泌盐盐生植物。 本研究以新疆柽柳属植物的部分特有种为试验材料，在0-200mmol／L NaCl盐胁迫条件，测定柽柳对盐胁迫的生理反应。200mmol／L NaCl处理3周使细穗柽柳的与对照相比相对干重降低了17.3％，多枝柽柳相对干重下降了26.9％，盐胁迫时地上部受抑制的程度较地下部严重，相对含水量降低，而密花柽柳相对电解质渗漏率增加，紫杆柽柳脯氨酸含量增加。柽柳地上部对无机离子的累积表明，Na⁺和Cl^-是主要的渗透调节剂。总之，柽柳是兼性盐生植物。 本研究定量研究了柽柳泌盐对其叶中盐分平衡的贡献，通过连续监测刚毛柽柳扦插苗的蒸腾速率、叶的Na⁺绝对分泌量、木质部蒸腾流中的Na⁺浓度、叶中Na⁺含量，计算流入和流出柽柳幼苗的盐分，进一步分析，发现蒸腾速率与盐分分泌呈负相关，泌盐机制的效率体现在相对分泌能力上，柽柳的相对分泌能力在根际盐分低时效率最高，刚毛柽柳根际盐浓度为50mmol／L NaCl时泌盐机制效率最高，随着盐浓度继续增加，相对分泌能力反而下降。50-200mmol／L NaCl，盐分的绝对分泌量始终是增加的，Na⁺的绝对分泌量从247增加到348mmol a⁺g^-1f.w。研究表明柽柳根的排斥机制是最主要的机制，它排斥了随着蒸腾流带到根表的89-96％的盐离子，白天吸收进入植物体内的盐离子中有31-59％被盐腺分泌出去。 总之，柽柳靠三种主要机制来适应盐渍环境，1、避盐，通过根的低透性避免大量的盐离子进入植物体内；2、耐盐，植物体甚至细胞中盐离子含量高时，利用这些离子参与渗透调节，或将它们区隔化在液泡中，或产生有机小分子物质从而维持正常的代谢活动；3、泌盐，通过分泌盐分将植物体内的离子含量维持在一恒定水平，从数量上和质量上对柽柳适应盐渍环境作出贡献。更多还原

【Abstract】 Surpervised by associate Professor Dong Yuzhi&Professor Zhang FusuoThe utilization of halophyte has been proposed as a strategy to expand cultivation onto unfavorable land, however, halophyte mainly have been considered for their tolerance and performance in extremely saline environment, and only a few species have been characterized in terms of their tolerance and physiological responses to salinity .The functional biology underlying salt tolerance in plants is still poorly understood. Tamarix-spp is a perennial recretohalophyte capable of growing under extreme condition, from very dry environments to highly saline soils. To quantify its response to salinity , Tamarix .leptostachys seedlings were exposed to ON 50s 100s 150> 200mM NaCl for 4weeks, in a sand culture and growth, root activity ,and solute accumulation were measured, the presence of NaCl induced a 26.9 % relative decrease in dry weight of Tamarix ramosissima.,and a 173% decrease in dry weight of Tamarix .leptostachys relative to non-salinized controls, these changes were associated with a decrease in relative water content, The solute leakage and proline content were increased in Tamarix arceuthoides. Analysis of ion accumulation revealed that Tamarix .spp accumulated Na* and Cl’ as a primary osmoticum in contrast to proline. Generally, Tamarix is a facultative halophyte.The contribution of each of the salt-transporting processes to the NaCl balance of the leaves of the salt-recreting Tamarix was quantitatively investigated. Transpiration rates, xylem sap concentration , shoot salt content ,recretion rates were continuously monitored during three day periods and the salt fluxes in and out of the shoot were calculated . The diurnal excretion pattern ,which gradually decreased toward midday, showed a negative correlation with the daily transpiration pattern, The relative excretion, which is the ratio between the absolute excretion of Na* and the change in its internal content ,was maximal at 50mM NaCl ,and decreased when the concentration of NaCl in the root environment increased ,by contrast ,the absolute excretion increased from 247 to 348 mmol Na+g-1 f.w with increase in the total media salinity from 50 to 200 mM NaCl .respectively .Selectivity of the salt-excretion mechanism is in favor of sodium and against potassium, on the other hand ,potassium has a high affinity for the accumulation systems within the shoots. The results indicated that salt filtration by the roots is by far the most important salt-rejecting mechanism, preventing some 89- 96% of the salt which is carried towards the root surface by the transpiration stream, from entering the shoot .out of the remaining quantity of salts which enter the root xylem and reach the leaves ,only 31-59% is removed by the salt-recreting glands.In conclusion, it is suggested that salt resistance of Tamarix.spp is based upon three different mechanisms: 1) Salt avoidance -where the roots have low permeability to salts, this is by far the most important mechanism .2)Salt tolerance-the capability to preserve normal metabolic activity even in the presence of high intraceliular salt levels.3)Salt evasion -recretion of the penetrating ions, but retention of others .the magnitude of salt recreation in Tamaruuspp does not yield a quantitative solution to the problem of excess accumulation of salt ,Still, recreation may contribute to the mineral balance of T. in a qualitative way ,by changing the ratio between the nutritive ions and the interfering ones. The rejection mechanism at the plant roots and the secrection mechanism at shoots allow the plant to maintain its internal salt content at an approximately constant level despite the great variation in rhizosphere salinity .更多还原