【作者】 李强；

【导师】 王晓春；

【作者基本信息】 东北林业大学 ， 生态学， 2013， 博士

【摘要】 水分是影响植物生长的主要环境因子之一。近年来,随着全球气候变暖,我国水资源的匮乏日益严重,尤其是东北的广大地区,这一问题尤为突出。干旱胁迫已经成为制约东北地区植物生长发育和城市绿化的重要生态问题。荻和芒是理想的第二代能源植物,具有广泛的应用价值,但东北地区水资源匮乏的状况制约了荻和芒在该地区的推广和应用。因此研究干旱胁迫下荻和芒的生长、光合特性和生理特性的变化规律,对提高它的水分管理水平,促进荻和芒在东北地区的可持续发展具有重要意义。本研究选用芒属植物荻(Miscanthus sacchariflorus)和芒(Misconstrues sinensis)为实验材料,采用聚乙二醇(PEG)模拟干旱法对其种子进行4个PEG浓度水平的胁迫处理(5%、10%、15%、20%),研究荻和芒种子在PEG干旱胁迫下的萌发特性；采用盆栽控水的方法分别对荻和芒的实生苗进行4种土壤水分处理即：正常供水(土壤含水量为最大田间持水量80%,下同)、轻度土壤干旱胁迫(65%)、中度土壤干旱胁迫(50%)和重度土壤干旱胁迫(35%),分别测定了不同土壤干旱胁迫下荻和芒光合、生理和生长指标,研究荻和芒对土壤干旱胁迫的适应性；同时调查了东北地区荻和芒的分布和生境特征,主要研究结果如下：(1)东北野生荻芒分布和生境特征荻和芒在东北地区属点状分布,喜低海拔、土壤湿润,光照充足的生境；不同生境下荻和芒的生长性状存在差异,随着生境内土壤含水量的上升和光照条件的改善,荻和芒的生长性状和生物量提高,各生境间部分性状差异显著；荻和芒的叶形指数(叶长／叶宽),株高、地下茎粗、分布深度等表型性状受环境因素影响小,相对稳定；荻和芒的株高、茎粗等茎部性状与生物量显著相关。(2)PEG胁迫对荻和芒种子萌发特性的影响低浓度的PEG(5-20%)对芒和荻种子的发芽率没有明显的影响,但对芒种子的发芽指数、活力指数、胚根长度、胚根鲜重以及荻种子胚芽的长度有一定的促进作用；高浓度的PEG(15～20%),对芒和荻种子的发芽率、发芽指数、活力指数、胚根胚芽长度以及鲜重都有明显的抑制作用；荻种子的半致死浓度为15%,致死浓度为20%,而芒种子的半致死浓度为20%；随着PEG浓度的升高,芒和荻的萌发抗旱指数逐渐下降,芒在20%PEG处理时表现为中间型,而荻在15%PEG处理时就表现为不抗旱。(3)土壤干旱胁迫对荻和芒光合特性的影响土壤干旱胁迫下,荻和芒叶片的相对含水量(RWC)、叶绿素含量(Chl)、净光合速率(Pn)、最大净光合速率(Pmax)、表观量子效率(AQE)、暗呼吸速率(Rd)、光饱和点(LSP)、蒸腾速率(Tr)、最大羧化速率(Vcmax)和电子传递速(Jmax)均随着土壤干旱胁迫程度的加剧而下降；光补偿点(LCP)和水分利用效率(WUE)随土壤干旱胁迫程度的加剧而上升。荻和芒的气孔导度(Gs)随着土壤干旱胁迫程度的加剧而下降;胞间C02浓度(Ci)随着土壤干旱胁迫程度的加剧呈先下降后上升的趋势；气孔阻力值(Ls)随着土壤干旱胁迫程度的加剧呈先上升后下降的趋势。荻在轻度土壤干旱胁迫下、芒在轻度和中度土壤干旱胁迫下,对光合作用的抑制由气孔限制所引起；而荻在中度、重度土壤干旱胁迫下,芒在重度土壤干旱胁迫下对光合作用的抑制由非气孔限制所引起。(4)土壤干旱胁迫对荻和芒的生理特性的影响在土壤干旱胁迫下荻和芒的细胞膜相对透性,丙二醛(MDA)和过氧化氢(H202)含量随着土壤干旱胁迫程度的加剧而显著增加。在轻度干旱胁迫下,荻的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性随着干旱胁迫时间的延长而逐渐上升；而在中度和重度干旱胁迫下SOD、CAT和POD活性随着干旱胁迫时间的延长呈先上升后下降趋势。在不同程度土壤干旱胁迫下,芒的SOD和CAT活性随着干旱胁迫时间的延长而逐渐上升；而POD活性则在不同干旱胁迫处理下无明显变化。在不同程度干旱胁迫下芒叶片的抗坏血酸过氧化物酶(APX)、甘肽还原酶(GR)活性和还原型抗坏血酸(AsA)、还原型谷胱甘肽(GSH)含量始终保持上升趋势；而荻在轻度干旱胁迫下也可以保持较高的抗坏血酸合成和代谢活性,但在中度和重度干旱胁迫下,随着干旱胁迫的加剧和胁迫时间的延长荻的APX、GR活性和AsA、GSH含量开始下降。(5)土壤干旱胁迫对荻和芒的生长和生物量的影响荻和芒的株高、地径、茎节间长度、叶面积和比叶重随着土壤干旱胁迫程度的加剧而下降。轻度干旱胁迫下,芒的地下茎粗和长度均高于正常供水处理,表明适宜的土壤干旱胁迫对芒地下茎的生长有一定的促进作用；而在荻和芒在中、重度干旱胁迫下,地下茎粗、长度和分蘖数量均随着土壤干旱胁迫程度的加剧而显著下降。土壤干旱胁迫下,除芒在轻度干旱胁迫下地下部分生物量增加外,其余胁迫处理中荻和芒的单株总生物量、地上部分生物量、地下部分生物量和冠根比均随土壤干旱胁迫程度的加剧而下降,胁迫越重,生长速度越慢,生长量越小,生物量越低。更多还原

【Abstract】 Water is one of the main environmental factors affecting plant growth. In recent years, with the global climate warming, the shortage of water resources is increasingly serious in our country, especially in Northeastern China. Water stress has become an important ecological problem of reducing plant growth and development in Northeastern China. Miscanthus sacchariflorus and Miscanthus sinensis are the ideal second generation of energy plants, and have wide application value, but a lack of water resources restricts the promotion and application of Miscanthus in the Northeast of China. Therefore it is great significance to study on growth, photosynthetic characteristics and physiological characteristics of M. sinensis and M. sacchariflorus under water stress for improving its moisture management level, promoting Miscanthus sinensis and Miscanthus sacchariflorus in the Northeastern region’s sustainable development.The characteristics of seed germination under different PEG stress (5%,10%,15%,20%) were studied taking the selected M. sinensis and M. sacchariflorus as experimental materials. For the purpose of studying the adaptability to natural soil water stress, the photosynthetic characteristics, physiological and biological index were measured under4treatments, normal water (soil moisture content for the maximum80%field capacity, the same below), mild soil drought stress (65%), moderate soil drought stress (50%) and severe soil drought stress (35%).Meanwhile the distribution and habitat characteristics of M. sacchariflorus and M. sinensis in northeastern China were investigated. The main research results are as follows.(1) Miscanthus in the northeast China is dotted and prefer the habitat of low altitude, soil moisture and high light intensity. There were differences of Miscanthus growth traits under different habitats, and the growth potential and biomass increased with the soil water content increasing and light conditions improving. There was a significant difference of some growth traits among different habitats (P<0.05). The coefficient of Variance in Miscanthus the growth traits, leaf shape index, plant height、stem diameter and depth of underground distribution of phenotypic traits were relatively stable, and were less influenced by environmental factors. The plant height and stem diameter were significantly related to plant biomass by using principal component analysis.(2)There is no significant effect of lower concentration PEG (5-10%) on the seeds’ germination rate of M.sinensis and M. sacchariflorus. But it increased the germination index, vigor index, radicle length, radicle fresh weight of M. sinensis and plumules growth of M. sacchariflorus. The higher PEG concentration(15-20%) inhibited significantly the growth of seed, and the germination rate termination index, vigor index and radicles/plumule were reduced. The half of lethal concentration of M. sacchariflorus was15%, and the lethal concentration of M. sacchariflorus was20%. However, the half of lethal concentration of M. sinensis was15%, the lethal concentration of M. sinensis was higher than20%.(3)Under soil drought stress, leaf relative water content (RWC), chlorophyll (Chl)contentnet, photosynthetic rate (Pn), maximum net photosynthetic rate(Pmax), apparent quantum efficiency (AQE), dark respiration rate (Rd), light saturation point (LSP),transpiration rate (Tr), maximum carboxylation rate (Vcmax) and the maximum electron transport rate (Jmax) reduced, while light compensation point (LCP) and water use efficiency (WUE)increased along with the soil drought stress degree enhancing.The stomatal conductance (Gs) of M. sinensis and M. sacchariflorus decreased with soil drought stress degree enhancing. The intercellular CO2concentration (Ci) decreased firstly and then increased, while stomatal resistance value (Ls) increased firstly and then decreased.The photosynthesis inhibition of M. sacchariflorus under mild soil drought stress and M. sinensis under mild and moderate soil drought stress were caused by the stomatal limitation; while the photosynthesis inhibition of M. sacchariflorus under moderate and severe soil drought stress and M. sinensis under serious soil drought stress were caused by non-stomatal limitation.(4)Under soil drought stress, cell membrane relative permeability, the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) increased significantly with soil drought stress degree enhancing.Under mild drought stress, the superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activity of M. sacchariflorus increased gradually along with soil drought stress proceeding; under moderate and severe drought stress, the SOD, CAT and POD activity increased firstly and then decreased; SOD and CAT activity of M. sinensis increased gradually along with soil drought stress proceeding; While there is no obvious change of the POD activity under different treatments.Under soil drought stress, there are rising trend of the value of ascorbic acid peroxidase (APX) activity, leaf glutathione reductase (GR) activity, ascorbic acid (AsA) content and reduced glutathione (GSH) content of M. sinensis. Under mild drought stress M. saccharifloru also could maintain high ascorbic acid synthesis and metabolic activity, but under the moderate and severe drought stress, with the intensification of soil drought stress, APX, GR activity and GSH, AsA content began to decrease.(5) Under soil drought stress, the plant height, ground diameter, stem internode length, leaf area, specific leaf weight decreased along with the soil drought stress degree enhancing. Under mild drought stress, rhizome stem diameter and length of M. sinensis were higher than normal, which showed that suitable soil drought stress on M. sinensis could promote rhizome growth. However under the moderate and severe drought stress, rhizome stem diameter, length and number of tillers decreased significantly as the soil drought stress degree intensified.Under soil drought stress, the per plant total biomass, the biomass on the ground, underground biomass and crown root ratio decreased with soil drought stress degree intensifying except of the increase of the underground biomass under mild drought stress.The heavier stress, the slower the growth rate, the smaller the increment and lower biomass.更多还原