【作者】 向芬；

【导师】 陈功锡； 周强；

【作者基本信息】 吉首大学 ， 生态学， 2014， 硕士

【摘要】 河谷是山地区域河流深切形成的一个自然生态系统，河谷特殊生境下植物的生态适应机制是植物生理生态学研究的热点问题之一。本论文以河谷特殊生境专性种的代表植物——吉首蒲儿根为研究材料，研究了吉首蒲儿根及其伴生植物矿质元素含量特性，不同生境吉首蒲儿根叶片形态、荧光特性，干旱胁迫对吉首蒲儿根的光合作用和叶绿素荧光参数的影响。研究结果如下（1）吉首蒲儿根根部K、Mn的含量均高于其伴生植物，茎部K、Cu、Fe的含量均高于其伴生植物，叶部K、Mn、Zn、Cu的含量均高于其伴生植物，Fe、Mg也处于较高水平。吉首蒲儿根体内，Mg、Mn、P、Zn、B含量以叶中为高, Fe、Ba含量以根中为高，K、Cu含量以茎中为最高。除Zn和Cu是茎部的富集系数最大外, K、P、Mg、Fe、Ba、Mn、B在叶部的富集系数最大，各部位富集情况基本表现为叶>根>茎>。吉首蒲儿根对矿质元素表现较强吸收富集能力，特别是新陈代谢旺盛的叶部对矿质元素吸收富集能力最强。（2）本文选择野外自然分布的3种河谷生境和人工引种的2种河谷外生境中吉首蒲儿根为研究对象，比较其叶片形态特征，研究发现：3种河谷生境吉首蒲儿根的叶面积、比叶面积要高于2种河谷外生境，而气孔密度、SPAD值则低于2种河谷外生境。吉首蒲儿根可通过减小叶面积、比叶面积、增加气孔密度来适应一定高光照、低湿度的环境。其对光照强度、空气相对湿度有较广的适应性。（3）五种生境（河谷瀑布生境、河谷山坡生境、河谷林下生境、谷外阴生生境、谷外阳生生境）吉首蒲儿根的Fv/Fm、Fv/Fo、Y(NPQ)没有显著差异，但谷外阳生生境下的吉首蒲儿根ETR max、Ik、qP和Y(Ⅱ)均高于其它各生境，而河谷林下生境吉首蒲儿根的ETR max、Ik、qP和Y(Ⅱ)均显著低于其它各生境，河谷瀑布生境、河谷山坡生境、谷外阴生生境吉首蒲儿根的以上4参数则无显著差异。（4）测量阴生环境中吉首蒲儿根的叶片相对含水量（RWC）和净光合速率（Pn）、气孔导度(gs)、蒸腾速率(Tr)、胞间CO2浓度(Ci)等光合作用参数及初始荧光(Fo)、最大荧光(Fm)、PSⅡ的最大光化学效率(Fv/Fm)、最大表观电子传递速率（ETR max）、初始斜率（α）、PSⅡ实际光量子效率Y(Ⅱ)、PSⅡ调节性能量耗散Y(NPQ)、PSⅡ非调节性能量耗散Y(NO)等8项叶绿素荧光参数在土壤自然干旱过程中的变化。在高温的夏秋季节，吉首蒲儿根的光合生理对干旱胁迫较为敏感。停止浇水6d，吉首蒲儿根光的PSⅡ即受到显著伤害，光化学途径利用的光能减少，电子传递受到较大抑制，净光合速率趋近于0。处理12d，吉首蒲儿根植株已死亡。更多还原

【Abstract】 A typical and important physical feature of mountainous region is the naturalhabitats associated with the deeply cut river valleys. Having a certain amount of streamor river runoff is one of significant ecological characteristics of river valley. Canyons,rivers and mountain valleys are three typical river valleys. So far, the ecologicaladaptation mechanism of plant growing in special habitat is one of the hot issues inresearch of plant physiological ecology. This thesis selects the canyon microhabitatspecies--Sinosenecio jishouensis as the research material, and studies the S.jishouensisand associated plant mineral element content characteristics, the leaf morphology andchlorophyll fluorescence parameters in leaves of S. jishouensis within different habitat,influence of photosynthesis and chlorophyll fluorescence parameters of S.jishouensisdrought stress. The results are as follows:(1) The content of K, Mn in S. jishouensis root were higher than that of itsaccompanying species. The content of K, Cu, Fe in stem were higher than that of itsaccompanying species. The content of K, Mn, Zn, Cu in leaf were higher than itsaccompanying species, and the content of Fe, Mg in leaf were at a higher level. In S.jishouensis body, the content of Mg, Mn, P, Zn, B is high in the leaves, while thecontent of Fe, Ba is high in the root. And the highest content of K, Cu is in the stem.The maximum concentration factor of Zn and Cu is in the stem, besides, theconcentration coefficient of K, P, Mg, Fe, Ba, Mn, B in leaf is the largest one in all parts.The basic performance of concentration is for leaf> root> stem>. S.jishouensis hasstrong accumulation ability on mineral elements, especially the strongest ability ofenrichment mineral elements in the leaf which has exuberant ability of metabolism.(2) Generally, its natural habitats consist of valley falls habitat, valley sidehillhabitat and valley understory habitat. In order to reveal the adaptive ability to differentenvironments and the underlying mechanisms, S. jishouensis were transplanted fromvalley to sun habitat and shade habitat. Since the light intensity and the relativehumidity are different among5habitats, especially, there are higher light intensity andlower relative humidity in2artificial distribution habitats than in3natural distributionhabitats, the leaf morphology in leaves of S. jishouensis within above5habitats wereinvestigated The results showed that.as compared with3natural distribution habitats,the leaf area, specific leaf area of S. jishouensis were smaller and their stomata density,SPAD value were higher in2artificial distribution habitats, especially in sun habitat. Itthus indicated that S. jishouensis had tolerance to greater light intensity and moderate airhumidity realized by reduced leaf area, specific leaf area, and increased stmata density,SPAD value, while low light intensity and high relative humidity was not an importantecological factor in limiting development of S. jishouensis, providing a theoretical foundation for ex situ conservation of S. jishouensis.(3) The maximal PSⅡquantum yield (Fv/Fm), latent PSⅡ quantum yield (Fv/Fo),the quantum yield of regulated energy dissipation (Y(NPQ)) had no significantdifference between5habitats. However, the maximal electron transport rate (ETR max),minimum saturating irradiance(Ik), the coefficient of photochemical quenching (qP) andthe effective PSⅡ quantum yield (Y(Ⅱ)) of S. jishouensis in sun habitat were higherthan other4habitats, and above4parameters in valley understory habitat weresignificantly lower than other4habitats. At the same time, those values showed nosignificant difference among valley falls habitat, valley side-hill habitat and shadehabitat.(4) we investigated the effects of drought stress on photosynthetic physiology ofS. jishouensis, the leaf relative water content (RWC), photosynthesis parametersincluding net photosynthetic rate (Pn), stomatal conductance (gs), Transpiration rate(Tr), intercellular CO2concentration (Ci), and chlorophyll fluorescence parametersincluding the minimal fluorescence of dark-adapted state (Fo), the maximalfluorescence of dark-adapted state (Fm), the maximum efficiency of PS II (Fv/Fm), themaximum electron transport rate（ETR max）, initial slope（α）, effective quantum yieldof PS II photochemistry (Y(Ⅱ)), quantum yield of regulated energy dissipation in PS II(Y(NPQ)) and quantum yield of nonregulated energy dissipation in PS II (Y(NO)) of S.jishouensis living shade environment were investigated in July. The result showed：Inthe heat of the summer-autumn season, the S. jishouensis photosynthetic physiology issensitive to the drought stress of short time. Without watering for6days, PS Ⅱof S.jishouensis were significant harm. With photochemical reduction of energy use and agreater inhibition of electron transfer, net photosynthetic rate approached0. Especiallyafter no watering for12days, the S. jishouensis plants were dead.更多还原