裂叶沙参气孔行为与光合蒸腾特性通径分析

通过相关系数和通径系数分析方法,对不同海拔高度裂叶沙参(Adenophora lobophylla)气孔行为与光合、蒸腾特性的关系进行了相关性分析。气孔行为对光合、蒸腾均缺乏显著的相关性,说明裂叶沙参光合、蒸腾作用的气孔控制不显著;裂叶沙参叶片气孔开度直接影响光合速率和胞间CO₂浓度,气孔导度对裂叶沙参蒸腾速率影响较大。     

裂叶沙参气孔行为与光合蒸腾特性通径分析

通过相关系数和通径系数分析方法,对不同海拔高度裂叶沙参（Ａｄｅｎｏｐｈｏｒａ ｌｏｂｏｐｈｙｌｌａ）气孔行为与光合、蒸腾特性的关系进行了相关性分析。气孔行为对光合、蒸腾均缺乏显的相关性,说明裂叶沙参光合、蒸腾作用的气孔控制不显;裂叶沙参叶片气孔开度直接影响光合速率和胞间ＣＯ２浓度,气孔导度对裂叶沙参蒸腾速率影响较大。     

遮光条件下裂叶沙参和泡沙参气孔行为的对比研究

通过遮光实验研究了裂叶沙参(Adenophora lobophylla)和泡沙参(A. potaninii)叶片的气孔行为,比较了不同遮光处理对裂叶沙参和泡沙参气孔的生理特性以及生态适应的影响。结果表明:裂叶沙参对不同遮光处理的适应性较差,相反,泡沙参具有较强的适应性和抗逆性;在自然光照和轻度遮光条件下,中午时泡沙参叶片的气孔开度逐渐减小和部分气孔关闭;裂叶沙参光合作用的非气孔限制占主要地位,泡沙参光合作用的气孔限制较明显。     

遮光条件下裂叶沙参和泡沙参气孔行为的对比研究

通过遮光实验研究了裂叶沙参（Ａｄｅｎｏｐｈｏｒａ ｌｏｂｏｐｈｙｌｌａ）和泡沙参（Ａ．ｐｏｔａｎｉｎｉｉ）叶片的气孔行为,比较了不同遮光处理对裂叶沙参和泡沙参气孔的生理特性以及生态适应的影响。结果表明：裂叶沙参对不同遮光处理的适应性较差,相反,泡沙参具有较强的适应性和抗逆性;在自然光照和轻度遮光条件下,中午时泡沙参叶片的孔开度逐渐减小和部分气关闭;裂叶沙参光合作用的非气孔限制占主要地位,泡沙参光合     

裂叶沙参与泡沙参种群分布格局分形特征的分析

 裂叶沙参与泡沙参种群在不同海拔区域分布格局的计盒维数与其在群落中占据空间的能力成正比,并且与环境因素密切相关。在裂叶沙参与泡沙参种群较为适生的区域,海拔2700～3100m,两者在群落中占据空间的能力最强,他们的计盒维数达到最高。在低于海拔2700m或高于海拔3100m,环境条件严酷的区域,裂叶沙参种群与泡沙参种群占据空间的能力不同程度的下降。在不同的海拔区域,广布种泡沙参种群占据空间的能力均比裂叶沙参种群高,而其受环境因素影响较弱。在海拔2700m以下地区,泡沙参种群水平分布格局的计盒维数比裂叶沙参种群高4.5倍;在两种群较为适生的区域,海拔2700～3100m,泡沙参计盒维数比裂叶沙参种群高1.5倍,差异最小;在泡沙参与裂叶沙参种群分布的上限,海拔3100m以上地区,两者计盒维数差异又增加,泡沙参计盒维数比裂叶沙参种群高1.8倍。这说明裂叶沙参种群的内在适应力、竞争力比泡沙参种群相对较弱。     

不同海拔高度泡沙参叶片形态研究

对不同海拔高度的泡沙参叶表形态、气孔特征进行了观察,比较了不同海拔高度对泡沙参叶片生态适应的影响。结果表明：泡沙参叶表皮角质层较厚,被有大量表皮毛和蜡质颗粒,海拔越高越明显;泡沙参气孔复体类型均为不规则型,气孔保卫细胞角质层较厚,气孔口较小,气孔密度与气孔大小成反比,并且气孔大小随海拔升高而减小,气孔密度随海拔升高而增大,是一种抗旱适应的表现。     

濒危物种裂叶沙参及其近缘广布种泡沙参的遗传多样性研究

根据对１２个形态性状的统计分析和１０个基因位点的等位酶检测,探讨了濒危植物裂叶沙参及其近缘广布种泡沙参的遗传多样性水平,对３个裂叶沙参和６个泡沙参天然群体的遗传分析表明,两种沙参属植物均具有很高的遗传变异水平,这种变异性既体现在形态学水平上,也体现在酶位点水平上,在２个茎叶形状以及１０个花果和种子形状上,濒危种裂叶沙参的变异性均与广布种相当,同样,根据７个酶系统１０个等位酶位点的度量,裂叶沙参群体     

裂叶沙参与泡沙参解剖生态学的比较研究

借助于光镜和扫描电镜,系统观察了濒危植物裂叶沙参(Adenophora lobo-phylla Hong.)的根、芦头、茎和叶的解剖特征及茎、叶、种子的表面形态特征,并将有关性状与广布种泡沙参(A.potaninii Korsh.)作了对比研究。结果表明,两种沙参在叶表皮细胞形状,垂周壁式样,角质层初级雕纹及次级雕纹;叶片气孔形状及外拱盖外缘纹饰及内缘形状,保卫细胞上角质层薄厚及蜡质纹饰;叶表毛状体形状及纹饰,茎中皮层占茎横切面的比例;茎中有无髓纤维等方面存在着明显差异。相对于泡沙参,裂叶沙参单株叶面积大,生物量高,表皮角质层薄,单位面积内被毛数量少,栅栏组织薄,气孔周围蜡质沉积颗粒少;茎的直径大,皮层较薄等。这些特征表明裂叶沙参对旱生生境适应能力弱,而泡沙参对旱生生境适应能力强。     

裂叶沙参和泡沙参种群有性生殖和无性繁殖的比较

通过对裂叶沙参(Adenophora lobophylla Hong)和泡沙参(A.potaninii Korsh.)种群有性生殖和无性繁殖特性的对比,揭示濒危植物裂叶沙参的种群内部致濒机制。结果表明:裂叶沙参种群幼苗抢占草本层上层空间能力弱于泡沙参种群;裂叶沙参种群是以相对长的生殖期和高产籽量来适应环境;裂叶沙参种群开花结实量虽高于泡沙参种群,但其中成熟种子少,种子质量差,致使其种群由种子到一年生幼苗的转化率极低,并且幼苗生活力弱,是导致其种群濒危的重要内部原因。裂叶沙参种群除有性生殖外还兼有较弱的无性繁殖,是对其有性生殖的一个重要补充。     

濒危种裂叶沙参种群生命表和存活曲线的研究及其与广布种泡沙参的对照

以近缘广布种泡沙参为对照,本文编制了濒危种裂叶沙参种群的标准生命表、存活曲线以及海拔２３００～２４００ｍ、２７００～２９００ｍ、２９００～３１００ｍ和３１００～３４００ｍ区域４个种群的生命表,存活曲线。根据其生活史,讨论了裂叶沙参各种群特定年龄的存活量、死亡量和死亡率等重要参数。裂叶沙参种群存活曲线属ＤｅｖｅｙＣ型,１～５年生死亡率最高,个体最长寿命２５年。而泡沙参种群的死亡高峰期是１～３年,个体最长寿命２１年。导致裂叶沙参种群幼龄个体死亡的内在原因是其较弱的抗逆性和适应能力;外在原因是严重的干旱、外界干扰和群落内的光照不足。裂叶沙参种群适应不良环境的能力较泡沙参弱：在海拔２７００ｍ以下地区,由于外界干扰和环境干旱,除水份条件较好的特殊生境,大多种群呈严重衰退趋势,不能满足编表条件,只有海拔２７００ｍ以上区域的种群呈稳定或扩展趋势;而泡沙参各种群在不同海拔区域均呈稳定或扩展趋势,满足编表条件。从海拔２３００ｍ到３４００ｍ,不同裂叶沙参种群个体寿命呈：短长短的格式,与外界严酷较好严酷的环境相对应。这表明裂叶沙参种群在严酷环境条件下改变了其生存对策,缩短了个体寿命。     

Biosystematic studies on Adenophora potaninii Korsh.complex (Campanulaceae) V.A taxonomic treatment

Adenophora is an extremely variable genus,and its taxonomy is very controversial.Of the genus,Adenophora potaninii complex,including A.potaninii,A.bockiana,A.wawreana,A.lobophylla,A.biformifolia,A,polydentata,and A.wawreana var.lanceifolia,is a typical group with different taxonomical treatments due to high level of morphological diversity.We carried out extensive biosystematic studies based on population sampling,transplantation experiments and offspring tests,cluster analysis,and a crossing experiment.The results reveal four main findings.(i) Leaf forms of the A.potaninii complex were extremely polymorphic; the leaf form of A.potaninii and A.bockiana,and that ofA.wawreana and A.biformifolia could be found,respectively,on a single population or among the offsprings of a single plant.(ii) Cluster analysis and a crossing experiment indicated that A.bockiana and A.polydentata could not be separated from A.potaninii,nor d.biformifolia from A.wawreana.(iii) Adenophora potaninii and A.wawreana were gradational in morphology and their compatibility value was slightly reduced compared to that within each entity.(iv) Adenophora lobophylla was distinct from the other members of the complex in shape and size of corolla,relative length of style,and shape of capsule.This species was incompatible reproductively with the other members of the complex,but partly compatible with A.stenanthina,a species in another section.Therefore,we recognized only one species with two subspecies in the complex,A.potaninii subsp.potaninii and subsp,wawreana,moved A.lobophylla out of the complex,and reduced all the other names as new synonyms.     

Acclimation to humidity modifies the link between leaf size and the density of veins and stomata

The coordination of veins and stomata during leaf acclimation to sun and shade can be facilitated by differential epidermal cell expansion so large leaves with low vein and stomatal densities grow in shade, effectively balancing liquid‐ and vapour‐phase conductances. As the difference in vapour pressure between leaf and atmosphere (VPD) determines transpiration at any given stomatal density, we predict that plants grown under high VPD will modify the balance between veins and stomata to accommodate greater maximum transpiration. Thus, we examined the developmental responses of these traits to contrasting VPD in a woody angiosperm (Toona ciliata M. Roem.) and tested whether the relationship between them was altered. High VPD leaves were one‐third the size of low VPD leaves with only marginally greater vein and stomatal density. Transpirational homeostasis was thus maintained by reducing stomatal conductance. VPD acclimation changed leaf size by modifying cell number. Hence, plasticity in vein and stomatal density appears to be generated by plasticity in cell size rather than cell number. Thus, VPD affects cell number and leaf size without changing the relationship between liquid‐ and vapour‐phase conductances. This results in inefficient acclimation to VPD as stomata remain partially closed under high VPD.     

北京山区油松和元宝槭冠层气孔导度特征及其环境响应

叶片气孔是植物进行水汽交换的通道, 影响着植物的蒸腾和光合作用。然而叶片气孔行为受环境条件和树种类型的影响, 不同树种冠层气孔导度对环境因子响应的差异性, 以及在生长季不同时期叶片气孔对冠层蒸腾的调节作用是否会发生改变, 仍不清楚。该研究目的是通过探究各环境因子对不同树种冠层气孔导度的相对贡献率以及叶片气孔对冠层蒸腾的调节作用, 为深入了解植物水分利用状况和山区森林经营提供参考依据。于2018年生长季以北京八达岭国家森林公园内的58年生油松(Pinus tabuliformis)和39年生元宝槭(Acer truncatum)为研究对象, 利用热扩散技术对其树干液流进行连续监测, 并同步监测环境因子。利用彭曼公式计算冠层气孔导度(G_s)。主要结果: (1)油松和元宝槭日间G_s在日、月时间尺度上存在明显差异。5-7月油松和元宝槭日动态G_s均随饱和水汽压差(VPD)和太阳辐射(GR)的增加呈上升趋势, 上升持续时间比8月和9月长; 在月尺度上, 随着VPD、GR的降低和土壤湿度(VWC)的升高, G_s从5月到9月整体上升。(2)利用增强回归树法分析得到VWC和VPD对G_s的贡献率最大, 其次是GR、气温和风速。VWC和VPD对油松G_s的贡献率分别为66.4%和17.4%, 对元宝槭G_s的贡献率分别为54.8%和21.0%。(3)油松和元宝槭的dG_s/dlnVPD值与参考冠层气孔导度之间的斜率均显著高于0.6, 气孔调节作用相对较强。综上所述, 气孔对环境因子的响应在树种以及生长季不同时期之间存在差异, 为防止水分过度散失, 两树种在不同土壤水分条件下均通过严格的气孔调节控制蒸腾量。     

Comparative Studies of Sexual Reproduction and Asexual Propagation Between Populations of Adenophora lobophylla and A. potaninii

To reveal the internal mechanism which lead to the endangerment of the AdenophoUa lobophylla Hong population, comparative studies of sexual reproduction and asexual propagation between the populations of A. lobophylla and A. potaninii Korsh were carried out. Young seedlings of A. lobophylla had less ability to occupy the uper space of the herbaceous layer than those of A. potaninii. The A. lobophylla population produced much more seeds and lived a long reproductive life to adapt the ambient environment. Though the number of flowers and fruits of A. lobophylla population was more than those of A.potaninii population, the number of its ripe seeds as well as the quality was less. Thus, the development rate from its seeds to one-year old seedlings was very low, and viability of its young seedlings was very poor. This could be the important factor causing the imminent population endangerment of A. lobophylla. Besides the sexual reproduction, the A. lobophylla population also had a comparatively tiny ability of asexual propagation, which was advantageously complementary to its sexual reproduction.     

Gas Exchange and Water Use Efficiency of Adenophora lobophylla (Campanulaceae) at Different Altitudes on the East Boundary of the Qing- Zang Plateau

Field measurements were made of leaf net photosynthetic rate (Pn), apparent quantum yield (AQY), dark respiration (Rd), transpiration (Tr), water use efficiency (WUE), stomatal conductance (Gs), intercellular CO2 concentration (Ci), leaf temperature (TI), stomatal density, air temperature (Ta) and relative soil water content (SWC) for Adenophora lobophylla Hong in August, 1996. The species grows in the region from an altitude of 2 300 m to 3 400 m on the eastern boundary of the Qing-Zang Plateau in Sichuan Province, China. Leaf gas exchange, water use efficiency and plasticity of populations in field were compared among different altitudes to evaluate the possible interactions between adaptation of A. lobophylla and environmental factors in these habitats. Pn and AQY at low altitudes were lower than those at high altitudes. They strongly responded to SWC and Ta. On the other hand, Rd at low altitudes was higher than that at high altitudes because of the higher air temperature there. The growth rates at low altitudes were associated with the increases in Rd and a relevant less Pn. Stomata showed strong responses to leaf-to-air vapor pressure deficit at the leaf surface (Vpdl) and Tl in these habitats. Increasing stomatal limitations to photosynthesis appeared to be responsible for the reduction in Pn at high Tl, Vpdl and low available soil water for A. lobophylla at low ahitudes. Nonstomatal limitation to photosynthesis also happened at extreme soil water deficits and high Tl and Vpdl at an altitude of 2 300 m. Tr had a close relationship with stomatal conductance and was also affected by leaf temperature and leaf-to-air vapor pressure deficit at the leaf surface among habitats grown in different ahitudes. WUE increased with altitude. Increasing stomatal densities showed different plasticity of A. lobophylla as altitude increased. SWC and Ta appeared to be important factors to limit carbon assimilation in A. lobophylla at low altitudes, primarily through the process of stomatal closure. The overall results are in consistence with the hypothesis that strong pressure from tmfavorable environmental factors to gas exchange and wateruse of A. lobophylla may prevent their population expansion at low altitudes, which indicate that the above-mentioned restrictions might lead to the endangerment of A. lobophylla.