浙江天童常绿植物当年生与往年生叶片性状的变异与关联

植物叶片性状随叶龄的变化是植物生活史策略的体现, 反映了植物叶片的物质投资和分配方式。该研究通过在个体和物种2个水平, 比较浙江天童1 hm ²样地内常绿阔叶树种的平均叶面积(MLA)、比叶面积(SLA)和叶片干物质含量(LDMC)在当年生和往年生叶片间的差异和关联, 探究叶片物质分配策略在异龄叶间的变化, 并分析叶龄对植物叶片性状, 特别是叶片面积建成消耗的影响。结果显示: 1)在个体和物种水平上, MLA变异系数最大(个体: 79.5%; 物种: 66.5%), SLA次之(个体: 28.1%; 物种: 24.7%), LDMC较低(个体: 17.0%, 物种: 14.1%); 当年生叶片MLA、LDMC和SLA的变异系数均高于往年生叶片; 2)往年生叶MLA显著大于当年生叶(t = -38.53, p < 0.001), 往年生叶SLA显著小于当年生叶(t = 45.30, p < 0.001), 往年生叶LDMC显著大于当年生叶(t = -9.71, p < 0.001); 3)在个体水平, 当年生叶片MLA、SLA和LDMC值分别解释了往年生叶片MLA、SLA和LDMC变异的86%、48%和41%; 在物种水平, 当年生叶片MLA、SLA和LDMC值分别解释了往年生叶片MLA、SLA和LDMC变异的97%、83%和85%; 4) SLA在异龄叶间的变化表明, 与往年生叶片相比, 投资相同干物质, 当年生叶片可形成较大的叶面积, 其叶片面积建成消耗较小。研究认为, 植物叶性状在异龄叶间具有较大的变异性和关联性, 叶面积形成过程中生物量建成与消耗的协调可能影响植物叶片的发育。     

Isolation and functional analysis of two Cistus creticus cDNAs encoding geranylgeranyl diphosphate synthase

Cistus creticus ssp. creticus is an indigenous shrub of the Mediterranean area. The glandular trichomes covering its leaf surfaces secrete a resin called “ladanum”, which among others contains a number of specific labdane-type diterpenes that exhibit antibacterial and antifungal action as well as in vitro and in vivo cytotoxic and cytostatic activity against human cancer cell lines. In view of the properties and possible future exploitation of these metabolites, it was deemed necessary to study the geranylgeranyl diphosphate synthase enzyme (GGDPS, EC 2.5.1.30), a short chain prenyltransferase responsible for the synthesis of the precursor molecule of all diterpenes. In this work, we present the cloning, functional characterisation and expression profile at the gene and protein levels of two differentially expressed C. creticus full-length cDNAs, CcGGDPS1 and CcGGDPS2. Heterologous yeast cell expression system showed that these cDNAs exhibited GGDPS enzyme activity. Gene and protein expression analyses suggest that this enzyme is developmentally and tissue-regulated showing maximum expression in trichomes and smallest leaves (0.5–1.0 cm). This work is the first attempt to study the terpenoid biosynthesis at the molecular level in C. creticus ssp. creticus.     

Trichoderma spp. as elicitors of wheat plant defense responses against Septoria tritici

Leaf blotch of wheat is a widespread and highly active disease that affects wheat production. In addition to the use of chemicals and proper cultivation methods, microbial antagonists are used to control plant pathogens. Trichoderma spp. stimulate a systemic induced response in plants. Therefore, the efficacy of Trichoderma spp. against wheat leaf blotch was evaluated under greenhouse conditions. The susceptible plants were sprayed with Septoria tritici conidiospores. In order to select an efficient method of pretreatment with Trichoderma spp., leaf spraying and seed coating with 14 isolates were tested in 2003 and 2004. The extent of leaf necrosis area and pycnidial coverage was estimated. Antagonism was assessed by the capacity of each Trichoderma spp. isolate to restrict the progress of leaf blotch, 21 days after inoculation. Of the two methods, seed coating was more efficacious against leaf blotch than leaf spraying. Amongst the 14 isolates tested, the isolate prepared from T. harzianum (Th5) produced the highest level of protection. None of the treatments caused changes in plant stem diameter or dry weight. Trichoderma spp. did not get into leaves while S. tritici was present, even in asymptomatic leaf extracts. In addition, the leaf apoplast antifungal proteolytic activity was measured in plants 7, 15, and 22 days after sowing. This antifungal action decreased in plants only inoculated with S. tritici, but increased in those grown from seeds coated with the T. harzianum (Th5) isolate. This increase conferred resistance to the susceptible wheat cultivar. The endogenous germin-like protease inhibitor coordinated the proteolytic action. These results suggest that T. harzianum stimulates a biochemical systemic induced response against leaf blotch.     

长白山阔叶红松林5种主要树种水分利用效率与叶片养分特征

以长白山阔叶红松林中5种优势树种(红松、水曲柳、色木槭、蒙古栎、紫椴)为研究对象,利用稳定碳同位素技术分析了植物的水分利用效率(WUE),测定了叶片碳(C)、氮(N)、磷(P)3种营养元素的含量用以分析植物对养分的利用特征,并综合分析了植物WUE与叶片养分含量之间的关系.结果 表明:冠层不同位置微气象因子的差异导致WU...     

不同来源可溶性有机物对亚热带森林土壤CO2排放的影响

采用室内培养法, 比较分析了亚热带地区杉木(Cunninghamia lanceolata)和米槠(Castanopsis carlesii)鲜叶及凋落叶浸提得到的可溶性有机物(dissolved organic matter, DOM)组成和化学性质差异对土壤CO₂排放的影响。结果表明: 添加不同来源的DOM后, 土壤CO₂瞬时排放速率在培养第1天内均显著高于对照(添加去离子水) (p < 0.05), 分别比对照增加了91.5% (添加杉木鲜叶DOM)、12.8% (添加米槠鲜叶DOM)、61.0% (添加杉木凋落叶DOM)和113.3% (添加米槠凋落叶DOM), 但培养5天后, 分别下降到对照的24.1%、8.3%、14.6%和13.2%, 随后逐渐趋于平稳。单次添加外源DOM到土壤中, 引起土壤CO₂排放速率增加的强度较大, 但持续时间短暂。培养31天时, 添加不同来源的DOM均对土壤CO₂累积排放量具有显著影响(p < 0.05), 而在培养59天时, 添加杉木鲜叶和凋落叶DOM的土壤CO₂累积排放量均显著高于添加米槠鲜叶和凋落叶DOM的土壤CO₂累积排放量, 但添加相同树种鲜叶与凋落叶DOM的土壤CO₂累积排放量之间差异不显著。培养结束后, 添加杉木鲜叶DOM和杉木凋落叶DOM后增加的土壤碳排放量, 分别是外源添加可溶性有机碳量的1.76倍和2.56倍, 而添加米槠鲜叶DOM和米槠凋落叶DOM后增加的土壤碳排放量只占外源添加可溶性有机碳量的22.5%和50.0%, 表明单次添加不同来源的DOM对土壤总有机碳库的影响是不一致的。     

红豆杉幼树异龄叶的功能性状

植物叶片功能性状随叶龄的变化体现了植物的生活史策略,反映着植物对有限资源的权衡与配置特征.本研究以红豆杉幼树异龄叶为对象,测定了3个年龄段叶片的14个功能性状,分析红豆杉叶片老化过程中生态策略的调整方式.结果 表明:1年生叶的比叶面积显著大于2、3年生叶,3年生叶的叶厚、叶面积、叶体积、叶鲜重和叶干重显著大于1、2年生...     

Light adaptation and the role of autotrophic epiphytes in primary production of the temperate seagrass, Zostera marina L.

Photosynthetic features of Zostera marina L. and its autotrophic epiphyte community were investigated in a population inhabiting a shallow (1.3 m depth) water meadow in Great Harbor, Woods Hole, MA (U.S.A.). Photosynthesis versus irradiance (P-I) relationships were measured with respect to leaf age determined by the leaf position in the shoot bundle and by location of the tissue along the leaf axis. Therefore both age and light intensity gradients along the leaf axis were considered. The maximum photosynthesis (P_max) per dm² typically increased nearly two-fold along the leaf axis from leaf bases to apices. Photosynthetic rate on a chlorophyll (Chl) basis did not increase as dramatically along the leaf axis, and rates were usually lowest in tissues with the highest Chl content. The P-I relationships of leaves of different ages did not reveal photoinhibition even at light intensities > 1400 μE • m⁻² • s ⁻¹. Furthermore, no photoinhibition was observed in tissues from leaf blade bases, which never experienced high light levels (> 500 μE • m ⁻² • s⁻¹) in situ in Great Harbor. The initial slopes of the P-I curves and light compensation and saturation values varied along the leaf axis in relation to in situ light intensity gradients and in relation to leaf or tissue age. It appeared that leaf and/or tissue age was more important than light environment in determining P-I responses. The contribution of the autotrophic epiphyte community on Z. marina leaves to total photosynthesis per dm² was between 27 and 50%, and between 10 and 44% per mg chlorophyll. These levels of epiphyte photosynthesis can double the primary production of Z. marina leaves. No detrimental effects of epiphyte cover were realized in leaf maximal photosynthesis or P-I relationships. Non-epiphytized leaves and leaves from which epiphytes were removed showed essentially identical photosynthetic features. Light intensity and age gradients along the leaf axis control both the photosynthetic performance of the leaves and epiphyte biomass and photosynthesis.     

A comparison of spectral reflectance indices in response to water: A case study of Quercus aliena var. acuteserrata

Aims Using leaf spectral reflectance to detect plant status in real time and non-destructively is a new method of forest drought assessment, but each spectral index possesses considerable moisture sensitivity. Therefore, determining moisture index applicable to tree leaf and its sensitive spectral index are both very important. Methods This study selected Quercus aliena var. acuteserrata leaves in different growth stages and canopy positions as the research object, and measured leaf moisture index and its synchronous reflectance spectral response curve during the dehydration process, explored the relationship between changes of leaf spectral reflectance and water status, compared and evaluated the advantages and disadvantages of correlation between the moisture indices of leaves in different growth stages and space positions and different spectral reflectance indices. Important findings Results indicated: (1) The variability of relative water content (RWC) and equivalent water thickness (EWT) in different growth stages and canopy positions was smaller than specific leaf water content (SWC) and leaf moisture percentage on fresh quality (LMP) as measured by the four different moisture indices. RWC and EWT could steadily characterize the holistic water status of trees, and they had greater spectral sensitivity. Therefore, they were suitable for application in remote sensing detection. (2) Spectral reflectance difference analysis and spectral reflectance sensitivity analysis showed that the leaf spectral sensitivity is strongly influenced by growth stage. In short wave infrared region, spectral reflectance of mature leaves changed slightly in the initial stage of dehydration stress, but new expended leaves showed obvious spectral differences during the dehydration process. (3) Through the correlation analysis between 15 different spectral indices and moisture indices, we found that water index (WI)-RWC and double difference index (DD_{n (1530,525)})-EWT has higher correlation. The fitted relations of WI-RWC are greatly influenced by leaf growth stage and canopy position, while those of DD_n(1530,525)- EWT are more stable.     

中亚热带同质园不同树种氮磷重吸收及化学计量特征

于2019年8月研究中亚热带同质园11个树种叶片的比叶面积、氮(N)和磷(P)养分重吸收和化学计量特征,分析其养分利用策略。结果表明: 常绿阔叶树种(香叶、香樟、木荷、米槠、醉香含笑和杜英)和常绿针叶树种(杉木和马尾松)成熟叶和衰老叶的比叶面积、N和P含量普遍低于落叶阔叶树种(枫香、无患子和鹅掌楸),而成熟叶片C∶N和C∶P则表现为常绿阔叶树种和常绿针叶树种高于落叶阔叶树种。除米槠外,同质园其他树种N∶P均小于14。相对于其他树种,基于单位质量与单位面积计算的无患子N和P重吸收率均高于50%,马尾松、杉木和香樟P重吸收率也高于50%,而醉香含笑N和P重吸收率最低,仅为15%～30%。成熟叶比叶面积与N和P含量呈显著正相关,而与C∶N和C∶P呈显著负相关。在同质园中,米槠和香叶等常绿阔叶树种与马尾松等常绿针叶树种属于缓慢投资-收益型树种,其通过降低叶片比叶面积以及N、P含量,减少养分损失,从而实现较高的N、P重吸收程度与利用效率。然而,无患子等落叶阔叶树种属于快速投资-收益型树种,N和P利用效率相对较低。此外,同质园树种多受N限制,却不具有较高的N重吸收率,而唯一受P限制的米槠也不具有高P重吸收率。这些结果深入认识了中亚热带不同类型树种的N和P养分利用特点,可为区域造林实践提供科学依据。     

黄土丘陵区两种丛藓科植物展叶时长及关键影响因子

藓类植物是变水植物,展叶时长是影响其生长发育的关键。目前,干旱半干旱区藓类植物野外生长发育动态及其影响因子的研究鲜见报道。本研究以黄土丘陵区常见的土生对齿藓和扭口藓为对象,研究了9月5日—11月25日野外自然条件下两种藓类的展叶情况。结果表明: 9—10月,两种藓类叶片表现出有规律的“展开-闭合-展开”的日动态变化,并且土生对齿藓叶片在上午闭合时间较扭口藓平均提前0.68 h,下午叶片展开时间则推后了1.79 h。两种藓类在雨季时展叶时间较长,土生对齿藓展叶时长为251 min,较扭口藓(361 min)低30.4%。近地表大气相对湿度是影响藓株展叶时长的关键因子,藓种的形态结构也会影响展叶时长;相比于土生对齿藓,扭口藓植株较为低矮,中肋占叶片比例大,茎皮部细胞镶嵌结构更为突出,其展叶时的湿度阈值(54.3%)低于土生对齿藓(60.1%)。展叶时长主要受湿度的影响,扭口藓对环境的适应性更强。     

高粱、紫苏叶脉密度与光合特性的关系

叶脉是植物叶片光合作用水分输送的重要结构。为阐述叶脉与光合特性之间的关系,以C4植物高粱(Sorghum bicolor)、C3植物紫苏(Perilla frutescens)为实验材料研究了叶脉密度和光合特性之间的关系。结果表明,与紫苏相比,高粱叶片叶脉密度大,导水能力强,蒸腾速率高,但气孔密度小。进一步分析表明,高粱叶片近轴侧气孔密度占总气孔的比例明显高于紫苏。叶脉密度大的高粱具有较高的净光合速率;而紫苏叶脉密度小,净光合速率也较低。由此表明,较高的叶脉密度有利于支持较高的光合速率,但研究表明叶脉密度和气孔密度可能不存在严格的协同变异关系。研究结果对理解植物光合作用适应有重要意义。     

典型阔叶红松林主要树种叶性状的垂直变异及经济策略

分析不同树种叶片性状的变化有助于了解植物群落结构。该文通过对典型阔叶红松(Pinus koraiensis)林15种阔叶树种的比叶质量、叶片厚度、叶干物质含量、叶绿素含量指数、叶片碳、氮、磷含量的测定, 分析了冠层高度对叶性状及叶性状间相关关系的影响。结果表明, 水曲柳(Fraxinus mandshurica)和大青杨(Populus ussuriensis)上层的比叶质量显著大于下层, 而其他树种冠层间的比叶质量无显著变化; 叶绿素含量指数在白桦(Betula platyphylla)和春榆(Ulmus japonica)冠层间的分布分别为上层显著大于下层和上层显著大于中层; 单位质量氮含量在水曲柳的中层显著大于上层。叶片性状间存在着广泛的相关性, 比叶质量与叶片厚度、干物质含量在三层间均呈显著正相关关系, 而有些性状, 只在一或二个冠层中存在一定的相关性。山杨(Populus davidiana)和大青杨的叶片倾向于选择光合能力较低、营养浓度较低、呼吸速率较慢的一端, 而黄檗(Phellodendron amurense)和山槐(Maackia amurensis)叶片更倾向于光合能力强、营养物质浓度高的一端。不同树种对光照响应的差异可能会改变不同冠层中叶片的形态和化学性状, 从而有助于群落构建和物种共存。     

Vertical variation and economic strategy of leaf trait of major tree species in a typical mixed broadleaved-Korean pine forest

分析不同树种叶片性状的变化有助于了解植物群落结构。该文通过对典型阔叶红松(Pinus koraiensis)林15种阔叶树种的比叶质量、叶片厚度、叶干物质含量、叶绿素含量指数、叶片碳、氮、磷含量的测定, 分析了冠层高度对叶性状及叶性状间相关关系的影响。结果表明, 水曲柳(Fraxinus mandshurica)和大青杨(Populus ussuriensis)上层的比叶质量显著大于下层, 而其他树种冠层间的比叶质量无显著变化; 叶绿素含量指数在白桦(Betula platyphylla)和春榆(Ulmus japonica)冠层间的分布分别为上层显著大于下层和上层显著大于中层; 单位质量氮含量在水曲柳的中层显著大于上层。叶片性状间存在着广泛的相关性, 比叶质量与叶片厚度、干物质含量在三层间均呈显著正相关关系, 而有些性状, 只在一或二个冠层中存在一定的相关性。山杨(Populus davidiana)和大青杨的叶片倾向于选择光合能力较低、营养浓度较低、呼吸速率较慢的一端, 而黄檗(Phellodendron amurense)和山槐(Maackia amurensis)叶片更倾向于光合能力强、营养物质浓度高的一端。不同树种对光照响应的差异可能会改变不同冠层中叶片的形态和化学性状, 从而有助于群落构建和物种共存。     

北京西山绿化树种秋季滞纳PM2.5能力及其与叶表面AFM特征的关系

以北京西山6种绿化树种白皮松、油松、柳树、五角枫、银杏、山杨为对象,应用气溶胶再发生器对植物叶片秋季PM_2.5吸附量进行定量研究,同时应用原子力显微镜(AFM)观察叶表面微形态特征,分析了叶表面粗糙度等参数,阐释了各树种叶片吸附PM_2.5的机制.结果表明: 不同树种单位叶面积PM_2.5吸附量排序为白皮松(2.44±0.22 μg·cm^-2)＞油松(2.40±0.23 μg·cm^-2)＞柳树(1.62±0.09 μg·cm^-2)＞五角枫(1.23±0.01 μg·cm^-2)＞银杏(1.00±0.07 μg·cm^-2)＞山杨(0.97±0.03 μg·cm^-2);从秋季不同月份来看,不同树种单位叶面积PM_2.5吸附量表现为11月(2.33±0.43 μg·cm^-2)＞10月(1.62±0.64 μg·cm^-2)＞9月(1.51±0.50 μg·cm^-2).白皮松和油松有大量凹陷和突起,相对高差较大,粗糙度较大,吸滞PM_2.5能力强;柳树和五角枫叶片有褶皱,粗糙度相对较高,分布有大量的突起和凹陷,吸滞PM_2.5能力居中;银杏和山杨因其叶表面平滑、气孔多为长圆形,粗糙度较小,吸滞PM_2.5能力较弱.不同树种正背面粗糙度平均值为白皮松(149.91±16.38 nm)＞油松(124.47±10.52 nm)＞柳树(98.85±5.36 nm)＞五角枫(93.74±21.75 nm)＞银杏(80.84±0.88 nm)＞山杨(67.72±8.66 nm),这与不同树种单位叶面积PM_2.5吸附量排序完全一致,叶片粗糙度与单位叶面积PM_2.5吸附量呈显著正相关(R²=0.9498).为提高城市植被的环境效应,可选择叶表面形态有利于吸滞PM_2.5等颗粒物的树种.     

北京西山绿化树种秋季滞纳PM2.5能力及其与叶表面AFM特征的关系

以北京西山6种绿化树种白皮松、油松、柳树、五角枫、银杏、山杨为对象,应用气溶胶再发生器对植物叶片秋季PM_2.5吸附量进行定量研究,同时应用原子力显微镜(AFM)观察叶表面微形态特征,分析了叶表面粗糙度等参数,阐释了各树种叶片吸附PM_2.5的机制.结果表明: 不同树种单位叶面积PM_2.5吸附量排序为白皮松(2.44±0.22 μg·cm^-2)＞油松(2.40±0.23 μg·cm^-2)＞柳树(1.62±0.09 μg·cm^-2)＞五角枫(1.23±0.01 μg·cm^-2)＞银杏(1.00±0.07 μg·cm^-2)＞山杨(0.97±0.03 μg·cm^-2);从秋季不同月份来看,不同树种单位叶面积PM_2.5吸附量表现为11月(2.33±0.43 μg·cm^-2)＞10月(1.62±0.64 μg·cm^-2)＞9月(1.51±0.50 μg·cm^-2).白皮松和油松有大量凹陷和突起,相对高差较大,粗糙度较大,吸滞PM_2.5能力强;柳树和五角枫叶片有褶皱,粗糙度相对较高,分布有大量的突起和凹陷,吸滞PM_2.5能力居中;银杏和山杨因其叶表面平滑、气孔多为长圆形,粗糙度较小,吸滞PM_2.5能力较弱.不同树种正背面粗糙度平均值为白皮松(149.91±16.38 nm)＞油松(124.47±10.52 nm)＞柳树(98.85±5.36 nm)＞五角枫(93.74±21.75 nm)＞银杏(80.84±0.88 nm)＞山杨(67.72±8.66 nm),这与不同树种单位叶面积PM_2.5吸附量排序完全一致,叶片粗糙度与单位叶面积PM_2.5吸附量呈显著正相关(R²=0.9498).为提高城市植被的环境效应,可选择叶表面形态有利于吸滞PM_2.5等颗粒物的树种.     

基于几何形态分析的栎属白栎组叶片形态特征

以壳斗科栎属白栎组的5个种作为研究对象进行叶片几何形态学分析(GMMs)。选取了20个天然种群,共采集182个个体,887张叶片,对每张叶片采用几何形态学的标点法,数字化叶形态特征,使5个种的叶形态差异可视化。结果表明: 广义普氏分析可以有效地排除叶片位置和大小对叶片形状的影响。基于个体水平的主成分分析表明,槲树分别与槲栎和枹栎2个种的叶片形态差异明显,基于个体水平的典型变量分析表明,叶片的对称组分可以将槲栎与其他4个种准确区分。叶片非对称组分的多变量分析表明,5个种彼此间区别不明显。基于叶片水平的分析表明: 区分度较高的两组是槲栎vs.槲树(99.5% vs. 100%)和槲树vs.枹栎(99.0% vs. 100%),可以通过叶形准确区分;区分度略低的两组是白栎vs.枹栎(90.5% vs. 86.8%)和槲树vs.蒙古栎(85.1% vs. 82.9%)。本研究为存在频繁杂交渐渗的物种间叶型鉴定提供了新思路。     

Effects of ozone and aerosol pollution on photosynthesis of poplar leaves

由于经济的快速发展, 中国大部分地区正面临着严峻的复合型大气污染, 其中臭氧和气溶胶是两种主要污染物。已有的研究表明臭氧对叶片的氧化性伤害能够抑制光合作用, 而气溶胶可通过增加散射辐射比例或缓解高温抑制促进光合作用。但复合污染下, 臭氧和气溶胶如何共同调控叶片光合作用, 仍缺乏研究。该研究利用北京及周边地区之间的污染梯度, 选择加杨(Populus × canadensis)作为实验对象, 于2012-2013年生长季期间对叶片光合速率进行连续观测, 并同时监测臭氧浓度(AOT40)、气溶胶光学厚度(AOD)、空气温度和冠层内外光合有效辐射(PAR)等环境因子, 以期探讨大气复合污染下臭氧和气溶胶变化对植物叶片光合作用的影响及相关机制。结果表明: (1)臭氧浓度与空气温度、气溶胶浓度之间均呈显著正相关关系, 但气溶胶浓度与空气温度没有显著相关关系; (2)臭氧浓度增加显著抑制了阳生叶片的光合作用, 但气溶胶浓度上升促进了阳生叶片的光合作用; 臭氧浓度升高对阴生叶片光合作用的影响较小, 但气溶胶浓度上升促进了阴生叶片的光合作用; (3)标准化后的结果显示, 臭氧对阳生叶片光合作用的影响最大, 此时气溶胶的促进作用一定程度上补偿了臭氧浓度上升所带来的抑制效应。对于阴生叶片光合作用而言, 气溶胶则是最重要的影响因素。该研究发现复合污染下阴生叶和阳生叶光合响应不同, 这表明冠层结构可能通过影响阴生叶和阳生叶的比例, 从而对植物生长产生不同影响。该研究对理解大气复合污染如何影响光合作用提供了的机理支持, 同时也表明, 为了维持生态系统生产力及功能, 需要同时控制气溶胶和臭氧污染。     

臭氧和气溶胶复合污染对杨树叶片光合作用的影响

由于经济的快速发展, 中国大部分地区正面临着严峻的复合型大气污染, 其中臭氧和气溶胶是两种主要污染物。已有的研究表明臭氧对叶片的氧化性伤害能够抑制光合作用, 而气溶胶可通过增加散射辐射比例或缓解高温抑制促进光合作用。但复合污染下, 臭氧和气溶胶如何共同调控叶片光合作用, 仍缺乏研究。该研究利用北京及周边地区之间的污染梯度, 选择加杨(Populus × canadensis)作为实验对象, 于2012-2013年生长季期间对叶片光合速率进行连续观测, 并同时监测臭氧浓度(AOT40)、气溶胶光学厚度(AOD)、空气温度和冠层内外光合有效辐射(PAR)等环境因子, 以期探讨大气复合污染下臭氧和气溶胶变化对植物叶片光合作用的影响及相关机制。结果表明: (1)臭氧浓度与空气温度、气溶胶浓度之间均呈显著正相关关系, 但气溶胶浓度与空气温度没有显著相关关系; (2)臭氧浓度增加显著抑制了阳生叶片的光合作用, 但气溶胶浓度上升促进了阳生叶片的光合作用; 臭氧浓度升高对阴生叶片光合作用的影响较小, 但气溶胶浓度上升促进了阴生叶片的光合作用; (3)标准化后的结果显示, 臭氧对阳生叶片光合作用的影响最大, 此时气溶胶的促进作用一定程度上补偿了臭氧浓度上升所带来的抑制效应。对于阴生叶片光合作用而言, 气溶胶则是最重要的影响因素。该研究发现复合污染下阴生叶和阳生叶光合响应不同, 这表明冠层结构可能通过影响阴生叶和阳生叶的比例, 从而对植物生长产生不同影响。该研究对理解大气复合污染如何影响光合作用提供了的机理支持, 同时也表明, 为了维持生态系统生产力及功能, 需要同时控制气溶胶和臭氧污染。