烟草气孔特性、抗氧化酶活性与臭氧伤害的关系

 2001～2002连续两年在大田生产条件下研究了10个烤烟基因型气孔密度和气孔导度的变异情况及其与抗臭氧伤害的关系;2002年在控制条件下采用低温加臭氧的方法处理烟草植株,研究分析了烟草叶片遭受臭氧伤害后抗氧化酶活性的变化及其与抗臭氧伤害的关系。结果表明：烤烟不同基因型对臭氧伤害的抗性存在显著的差异。烟草叶片下表皮气孔密度和气孔导度与臭氧伤害引起的气候斑点病具有相关关系,在烟株下部叶中,其相关性分别达到显著（R2001＝0.68,R2002＝0.65）和极显著水平（R2001＝0.87,R2002＝0.80）。因此,下部叶气孔密度和气孔导度可以作为抗病育种的选择指标。在控制条件下的试验结果表明：只有低温加臭氧复合因子才能诱发烟草叶片产生臭氧伤害症状。烟草叶片低温下遭遇臭氧伤害后,超氧化物歧化酶（SOD）活性升高,升幅与气候斑点病病情指数负相关,过氧化氢酶（CAT）活性略有升高,过氧化物酶（POD）活性急剧下降。抗性较差的烟草基因型抗氧化酶反应不敏感,臭氧伤害症状严重,抗性较强的烟草基因型抗氧化酶反应敏感,臭氧伤害症状较轻。低温和臭氧同时作用明显影响了活性氧清除系统,致使系统中酶活性比例失调,POD活性急剧下降,可能是烟草叶片产生臭氧伤害的原因之一,SOD和CAT活性升高对消除臭氧伤害具有一定的防御作用。     

陆地生态系统臭氧通量观测和气孔吸收估算研究进展

近地面大气中臭氧(O3)对植物生长发育和产量会产生不良影响。工业和交通排放的增加使得全球地面O3浓度逐年增加,不断升高的O3浓度已开始影响到我国的粮食产量。O3对植物的影响是由于其进入植物体内发生生化反应所引起的,所以需要建立一种考虑到植物生理生态状况的评估指标来评估O3对植物的影响。其中基于O3通量(特别是植物气孔吸收)的评价指标和方法,被认为比传统的基于O3浓度的评价指标和方法更符合O3对植物的影响机理。介绍了O3对生态系统影响评估方法和评价指标,重点评述了生态系统尺度O3通量观测和气孔吸收估算的主要方法以及在不同生态系统上的研究进展分析了我国关于O3对植物和生态系统影响的研究现状,并对未来的研究工作进行了展望。     

白刺叶片气孔特征对人工模拟降雨的响应

以荒漠生态系统典型植物白刺(Nitraria tangutorum Bobr)叶片为研究对象,利用数码图像显微镜处理系统,研究了不同人工模拟增雨处理下的白刺叶片气孔密度及形态特征的变化情况。结果表明,荒漠植物固有特征决定了白刺叶片下表皮气孔密度大于上表皮,上表皮、下表皮气孔密度对增雨响应差异不显著(P0.05)。增雨处理上表皮、下表皮气孔密度与对照差异显著(P0.05)。相同增雨季节,50%处理下叶片气孔密度高于100%处理;不同增雨季节,气孔密度对生长季后期增雨响应更明显。白刺叶表皮气孔分布遵循"一细胞间隔(one cell spacing rule)"法则。增雨后叶片上表皮和下表皮气孔长度、宽度均有不同程度的增加,气孔形态特征对100%处理的响应较50%处理更为明显,且生长季后期增雨对叶片气孔形态特征的影响更大。     

黄龙山林区不同演替时期典型树种光诱导的气孔动力学研究

光诱导的气孔动力学响应快慢是影响植物叶水分利用效率的重要因素,为探索黄土高原不同演替阶段树种水分利用效率差异的生理机制,该研究以黄龙山林区典型树种(演替早期种山杨和白桦、演替后期种辽东栎)的幼龄实生苗为材料,采用盆栽试验,研究了叶片光诱导的气孔导度动力学参数差异及其与气孔特征、叶长期水分利用效率的关系。结果表明：(1)山杨和白桦气孔开放过程中气孔导度(g_s)增加的时间常数(K_i)小于辽东栎,但气孔关闭过程中气孔导度降低的时间常数(K_d)则大于辽东栎,表明山杨和白桦气孔开放更快,而辽东栎的气孔关闭更快。同时,气孔开放过程中山杨和白桦的g_s响应幅度均大于辽东栎,气孔关闭过程中山杨的g_s响应幅度亦大于辽东栎。(2)3种树种中,辽东栎的气孔密度最大,气孔最小,气孔指数最大,辽东栎气孔特征无法解释其慢速的气孔开放过程。 (3)山杨和白桦具有高的光合速率、最大羧化效率和最大电子传递速率,3种树种碳同位素比率(δ¹³C)表征的长期水分利用效率表现为山杨>白桦>辽东栎。研究认为,演替早期种山杨和白桦的高水分利用效率与其快速的气孔开放有关,而演替后期种辽东栎快速的气孔关闭并未增加其水分利用效率,且长期水分利用效率低于山杨和白桦,可能与辽东栎慢速的气孔开放限制了其光合速率有关。     

青藏高原和内蒙古高原典型草地植物叶片肾型和哑铃型气孔器气孔特征及其与环境的关系

该研究利用植物制片技术,以中国青藏高原和内蒙古高原典型草地常见种或优势种植物的叶片为研究对象,通过比较分析叶片哑铃型气孔器和肾型气孔器的特征及其与环境因子的关系,揭示植物叶片两类气孔器对环境因子的响应策略。结果表明:(1)叶片哑铃型气孔器气孔指标的变异系数小于肾型气孔器。(2)叶片哑铃型气孔器气孔指标与环境气候指标的关系弱于肾型气孔器。(3)叶片哑铃型气孔器气孔特征与环境关系在叶片上下表面之间存在显著差异,而肾型气孔器气孔特征与环境因子的关系在叶片上下表面之间无显著差异。(4)叶片哑铃型气孔器的气孔特征与降水关系密切,而肾型气孔器气孔特征与温度关系密切。(5)同一种气孔器的气孔特征在两个地区(青藏高原和内蒙古高原)间存在显著差异。研究认为,肾型气孔器和哑铃型气孔器的气孔特征及其与环境之间的关系存在差异,在分析气孔特征时有必要将肾形与哑铃形保卫细胞形成的气孔器加以区分,该研究结果有助于进一步理解中国草地植物叶气孔特征对气候变化的响应与适应策略。     

乙酰胆碱与蚕豆气孔运动的关系

在蚕豆（ViciafabaL）幼苗中,很尖的切除可以引起植株蒸腾速率的逐渐下降;而在这一过程中植株地上部水势保持不变;外施乙酰胆碱可以使蒸腾速率基本恢复到断根前的水平。利用气质联动技术对乙酰胆碱的内源性进行了鉴定,结果表明蚕豆的类乙酰胆碱提取物具有与人工合成的乙酰胆碱和高等动物脑组织中类乙酰胆碱提取物相同的质谱谱线,说明乙酰胆碱是蚕豆中的一种内源物质。为了对乙酰胆碱进行快速而准确的测定,建立了测定乙酰胆碱的热裂解的气相色谱法。利用这种方法测定的结果表明,在从根的切除到不定根重新长成的整个过程中,叶片下表皮中乙酰胆碱的含量与叶片的蒸腾速率及根的存在和生长状态密切相关,表明内源的乙酰胆碱可能参与调控植物的气孔行为;这一推论又为乙酰胆碱对表皮条中气孔开度的刺激效应和乙酰胆碱酯酶抑制剂neostig－mine可以增加气孔对乙酰胆碱的敏感性的实验进一步证实。     

乙酰胆碱与蚕豆气孔运动的关系

在蚕豆(Vicia faba L.)幼苗中,根尖的切除可以引起植株蒸腾速率的逐渐下降;而在这一过程中植株地上部水势保持不变;外施乙酰胆碱可以使蒸腾速率基本恢复到断根前的水平。利用气质联动技术对乙酰胆碱的内源性进行了鉴定,结果表明蚕豆的类乙酰胆碱提取物具有与人工合成的乙酰胆碱和高等动物脑组织中类乙酰胆碱提取物相同的质谱谱线,说明乙酰胆碱是蚕豆中的一种内源物质。为了对乙酰胆碱进行快速而准确的测定,建立了测定乙酰胆碱的热裂解的气相色谱法。利用这种方法测定的结果表明,在从根的切除到不定根重新长成的整个过程中,叶片下表皮中乙酰胆碱的含量与叶片的蒸腾速率及根的存在和生长状态密切相关,表明内源的乙酰胆碱可能参与调控植物的气孔行为;这一推论又为乙酰胆碱对表皮条中气孔开度的刺激效应和乙酰胆碱酯酶抑制剂neostigmine可以增加气孔对乙酰胆碱的敏感性的实验进一步证实。     

不同生境下入侵种假臭草叶片的气孔特征

【背景】探讨入侵种假臭草不同生境下气孔的变化规律,揭示假臭草种群在不同生境下所采取的生长对策及适应机制,可为入侵生物的防治提供参考。【方法】采取光学显微镜系统观察桉树林、木薯地、弃耕地、公路边4种生境下假臭草叶片的气孔特征。【结果】光照和土壤肥、水条件对假臭草叶片的气孔孔径（横轴方向和纵轴方向）、单个气孔器面积、气孔器总面积、气孔密度及气孔指数的影响显著。低光照及肥沃、湿润土壤生境与高光照及贫瘠、干旱土壤相比,假臭草的气孔孔径（横轴方向和纵轴方向）、单个气孔器面积、气孔器总面积较大,气孔密度及气孔指数较小。【结论与意义】假臭草叶片气孔特征表现可塑性,说明其对异质环境具有一定的生态适应能力。     

3种地被竹对大气臭氧胁迫的光合生理响应

以美丽箬竹(Indocalamus decorus)、黄条金刚竹(Pleioblastus kongosanensis f.aureostriatus)、白缟椎谷笹竹(Sasa glabra f.albostriata)3种优良地被观赏竹为试材,用开顶式同化箱(OTCs)模拟大气O3浓度,研究了不同O3浓度胁迫(环境背景大气、100nL L-1和150 nL L-1)对竹子光合生理指标的影响。结果表明,随着大气O3浓度的升高,美丽箬竹叶片叶绿素含量先升高后降低,黄条金刚竹呈相反变化规律,白缟椎谷笹竹呈下降趋势;它们的叶片类胡萝卜素含量变化不明显。美丽箬竹的Pn日均值先缓慢升高后降低,黄条金刚竹先略有升高后急剧降低,白缟椎谷笹竹逐渐降低;大气O3浓度升高明显影响3种竹的光合参数日变化进程;大气O3浓度为100 nL L-1时,美丽箬竹的光合作用未受到抑制,黄条金刚竹和白缟椎谷笹竹则出现明显的抑制效应;大气O3浓度达150 nL L-1时,3竹种的光合生理都受到严重的伤害。耐受O3胁迫能力存在种间差异,美丽箬竹明显高于黄条金刚竹、白缟椎谷笹竹。     

干热河谷9种造林树种在旱季的水分关系和气孔导度

 对元谋干热河谷人工混交林中9个树种叶片的水势、饱和渗透势、气孔导度、渗透调节和季节变化进行了测定,同时对树高和胸径也进行了比较。水分生理特征表明: 1)随着旱季的深入,除刺槐（Robinia pseudoacacia）、黄荆（Vitex negundo）、滇榄仁（Terminalia franchetii）落叶外,其余常绿树种叶片的气孔导度、水势和饱和渗透势都呈下降的趋势,在最旱的三、四月份,它们适应干旱的方式有4种：①低水势、气孔导度近似关闭的厚荚相思（Acacia leptocarpa）、大叶相思（A. auriculiformis）和肯氏相思（A. cunninghamii）;②低水势、低气孔导度的赤桉（Eucalyptus dulebsis）、娟毛相思（A. holosericea）和车桑子（Dodonaea wiscosa）loserice气孔导度的柠檬桉（Eucalyptus citriodora）和新银合欢（Leucaena leucocephala）;④较高水势、气孔导度近似关闭的马占相思（Acacia mangium）。2)在干旱胁迫过程中,主要渗透调节物质出现的先后顺序是K+、游离脯氨酸、游离氨基酸和可溶性糖, K+和可溶性糖贡献最大,分别在干旱的前后期起渗透调节作用,游离脯氨酸和游离氨基酸在干旱的中期起渗透调节作用。大多数树种适应干热河谷生境的主要抗旱途径是有效的吸水能力和完善的保水机制。     

A unifying explanation for variation in ozone sensitivity among woody plants

Tropospheric ozone is considered the most detrimental air pollutant for vegetation at the global scale, with negative consequences for both provisioning and climate regulating ecosystem services. In spite of recent developments in ozone exposure metrics, from a concentration‐based to a more physiologically relevant stomatal flux‐based index, large‐scale ozone risk assessment is still complicated by a large and unexplained variation in ozone sensitivity among tree species. Here, we explored whether the variation in ozone sensitivity among woody species can be linked to interspecific variation in leaf morphology. We found that ozone tolerance at the leaf level was closely linked to leaf dry mass per unit leaf area (LMA) and that whole‐tree biomass reductions were more strongly related to stomatal flux per unit leaf mass (r² = 0.56) than to stomatal flux per unit leaf area (r² = 0.42). Furthermore, the interspecific variation in slopes of ozone flux–response relationships was considerably lower when expressed on a leaf mass basis (coefficient of variation, CV = 36%) than when expressed on a leaf area basis (CV = 66%), and relationships for broadleaf and needle‐leaf species converged when using the mass‐based index. These results show that much of the variation in ozone sensitivity among woody plants can be explained by interspecific variation in LMA and that large‐scale ozone impact assessment could be greatly improved by considering this well‐known and easily measured leaf trait.     

春季辽宁西北部主要绿化树种根叶抗旱生理性状评价

对辽宁西北部主要绿化树种杨树、榆树、丁香和山杏的抗旱生理性状进行研究,分析春季干旱胁迫下4个树种叶片与根系生理性状间的关系,采用隶属函数法和灰色关联度法对其抗旱性进行评价.结果表明: 渗透调节物质可溶性糖、可溶性蛋白和脯氨酸含量、抗氧化酶——超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,以及丙二醛含量在4个树种及不同器官(叶片与根系)中均存在显著差异.4个树种平均隶属函数值在叶片中的顺序为榆树(0.673)>丁香(0.412)>杨树(0.346)>山杏(0.245),在根系中的顺序为杨树(0.558)>丁香(0.552)>山杏(0.383)>榆树(0.315);杨树、丁香和山杏叶片平均隶属函数值小于根系,而在榆树叶片中大于根系.各项生理指标与抗旱性的关联顺序在叶片中表现为丙二醛>SOD>CAT>可溶性蛋白>脯氨酸>可溶性糖>POD,在根系中为丙二醛>可溶性蛋白>可溶性糖>CAT>POD>脯氨酸>SOD.4个树种的叶片和根系中抗旱能力不同,各抗旱指标在叶片与根系中的作用不同,对不同树种的不同器官应该采取不同的管护措施.     

Chronic exposure to increasing background ozone impairs stomatal functioning in grassland species

Two species found in temperate calcareous and mesotrophic grasslands (Dactylis glomerata and Leontodon hispidus) were exposed to eight ozone treatments spanning preindustrial to post‐2100 regimes, and late‐season effects on stomatal functioning were investigated. The plants were grown as a mixed community in 14 L containers and were exposed to ozone in ventilated solardomes (dome‐shaped greenhouses) for 20 weeks from early May to late September 2007. Ozone exposures were based on O₃ concentrations from a nearby upland area, and provided the following seasonal 24 h means: 21.4, 39.9 (simulated ambient), 50.2, 59.4, 74.9, 83.3, 101.3 and 102.5 ppb. In both species, stomatal conductance of undamaged inner canopy leaves developing since a midseason cutback increased linearly with increasing background ozone concentration. Imposition of severe water stress by leaf excision indicated that increasing background ozone concentration decreased the ability of leaves to limit water loss, implying impaired stomatal control. The threshold ozone concentrations for these effects were 15–40 ppb above current ambient in upland UK, and were within the range of ozone concentrations anticipated for much of Europe by the latter part of this century. The potential mechanism behind the impaired stomatal functioning was investigated using a transpiration assay. Unlike for lower ozone treatments, apparently healthy green leaves of L. hispidus that had developed in the 101.3 ppb treatment did not close their stomata in response to 1.5 μm abscisic acid (ABA); indeed stomatal opening initially occurred in this treatment. Thus, ozone appears to be disrupting the ABA‐induced signal transduction pathway for stomatal control thereby reducing the ability of plants to respond to drought. These results have potentially wide‐reaching implications for the functioning of communities under global warming where periods of soil drying and episodes of high vapour pressure deficit are likely to be more severe.     

上海城市绿化利用树种资源的现状与发展对策

在对上海城市园林植物群落进行树种调查的基础上,统计了常用城市绿化树种资源数量、各树种的应用频繁以及各类园林植物群落的加权平均树种数量的指标,对上海城市绿化树种资源利用现状和影响因子进行初步分析,提出了若干发展对策。     

Effect of ozone treatment on reactive oxygen species and adenosine production during hepatic ischemia-reperfusion

This study investigates whether ozone could confer protection from hepatic ischemia reperfusion by modifying the accumulation of adenosine and xanthine during ischemia. A significant increase in both adenosine and xanthine accumulation was observed as a consequence of ATP degradation during hepatic ischemia. Adenosine exerts a protective effect on hepatic ischemia reperfusion injury since the elimination of endogenous adenosine accumulation with adenosine deaminase increased the hepatic injury associated with this process. On the other hand, the high xanthine levels observed after ischemia could exert deleterious effects during reperfusion due to reactive oxygen species generation from xanthine oxidase. The administration of allopurinol, an inhibitor of xanthine oxidase, attenuated the increase in reactive oxygen species and transaminase levels observed after hepatic reperfusion. Ozone treatment in liver maintained adenosine levels similar to those found after ischemia but led to a marked reduction in xanthine accumulation. In order to evaluate the role of both adenosine and xanthine, we tried to modify the protection confered by ozone, by modifying the concentrations of adenosine and xanthine. The metabolization of endogenous adenosine after ischemia abolished the protective effect conferred by ozone. When xanthine was administered previous to ozone treatment, the protection conferred by adenosine disappeared, showing both postischemic reactive oxygen species and transaminase levels similar to those found after hepatic ischemia reperfusion. Ozone would confer protection against the hepatic ischemia reperfusion injury by the accumulation of adenosine that in turns benefits the liver and by blocking the xanthine/xanthine oxidase pathway for reactive oxygen species generation.     

11种温带树种粗木质残体呼吸的时间动态

粗木质残体(CWD)呼吸释放出的CO2(RCWD)与温度的关系是森林生态系统RCWD年通量估测的基础,是随树种和时间而变化的,但这种关系的时间动态目前尚不清楚。采用红外气体分析法测定自然条件下东北东部山区典型天然次生林中11个主要树种RCWD的时间动态,尤其注重于其日变化格局及其对温度的响应。测定树种包括:白桦、山杨、紫椴、胡桃楸、蒙古栎、色木槭、春榆、红松、黄檗、兴安落叶松和水曲柳。结果表明:在测定的生长季期间,11个树种RCWD的日动态多表现为受10cm深的CWD温度(TCWD)驱动的单峰曲线日变化格局,RCWD最高值出现在13:0015:00时,明显滞后于气温(TA)的日变化。然而,在7月和8月份RCWD对温度的响应不明显,呈现出无峰或多峰的日变化格局。各树种均表现为白昼RCWD平均值高于黑夜。RCWD与TCWD、TA有显著的相关关系(P0.05),但与测定前两个小时的TA相关更紧密,说明RCWD对TA响应的滞后性。RCWD温度系数(Q10)平均为2.61,但随树种和季节而变化。Q10值波动在1.74(白桦)和4.20(蒙古栎)之间,并有随温度升高而减小的趋势。本研究结果表明粗木质残体分解碳释放的估算应该考虑RCWD温度敏感性随树种和时间的变化特性。     

Stomatal and nonstomatal limitations of photosynthesis in 19 temperate tree species on contrasting sites during wet and dry years

A unique approach was used to evaluate stomatal and nonstomatal constraints to photosynthesis in 19 naturally occurring, deciduous tree species on xeric, mesic and wetmesic sites in central Pennsylvania, USA, during relatively wet (1990) and dry (1991) growing seasons. All species exhibited significantly decreased stomatal conductance to CO₂ (g_c) in 1991 compared to 1990. The mesic species had drought related decreases in photosynthesis (A) attributed primarily to increased absolute stomatal limitation to A (L_g), whereas in the wet-mesic species, the absolute mesophyll limitation (Lm) was at least as important as L_g in limiting A during drought. The xeric species maintained relatively high A during drought despite decreased g_c. In the xeric and mesic species, L_m decreased and L_g increased during drought due to stomatal closure. From xeric to mesic to wet-mesic, the relative stomatal limitation (I_g) generally decreased faster, and relative mesophyll limitations to A increased faster, with increasing g_c suggesting greater photosynthetic capacity (i.e. greater potential maximum A) with increasing drought tolerance rank of species. Few species exhibited a significant drought-related decrease in photosynthetic capacity. The results of this landscape-based study indicate that the interaction of stomatal and nonstomatal limitations of A vary in a manner consistent with species' drought tolerance and site conditions, and that nonstomatal constraints to A in field plants during a moderate, season-long drought were generally not as severe as reported in controlled studies.     

Leaf development and photosynthetic properties of three tropical tree species with delayed greening

Leaf developmental patterns were characterized for three tropical tree species with delayed greening. Changes in the pigment contents, photosynthetic capacity, stomata development, photosystem 2 efficiency, rate of energy dissipation, and the activity of partial protective enzymes were followed in developing leaves in an attempt to elucidate the relative importance of various photoprotective mechanisms during leaf ontogeny. Big leaves of Anthocephalus chinensis, a fast-growing light demanding species, expanded following an exponential pattern, while relatively small leaves of two shade-tolerant species Litsea pierrei and Litsea dilleniifolia followed a sigmoidal pattern. The juvenile leaves of A. chinensis and L. pierrei contained anthocyanin located below the upper epidermis, while L. dilleniifolia did not contain anthocyanin. Leaves of A. chinensis required about 12 d for full leaf expansion (FLE) and photosynthetic development was delayed 4 d, while L. pierrei and L. dilleniifolia required 18 or 25 d for FLE and photosynthetic development was delayed 10 or 15 d, respectively. During the leaf development the increase in maximum net photosynthetic rate was significantly related to changes in stomatal conductance and the leaf maturation period was positively related to the steady-state leaf dry mass per area for the three studied species. Dark respiration rate of leaves at developing stages was greater, and pre-dawn initial photochemical efficiency was lower than that of mature leaves. Young leaves displayed greater energy dissipation than mature leaves, but nevertheless, the diurnal photoinhibition of young L. dilleniifolia leaves was higher than that of mature leaves. The young red leaves of A. chinensis and L. pierrei with high anthocyanin contents and similar diurnal photoinhibition contained more protective enzymes (superoxide dismutase, ascorbate peroxidase) than mature leaves. Consequently, red leaves may have higher antioxidant ability.