刺槐叶绿素荧光特性的研究

用L I-6400光合仪对黄土高原常用造林树木刺槐的叶绿素荧光动力学曲线、淬灭分析、荧光光曲线以及荧光AC I曲线等生理特性进行测定和对比分析.结果表明:随着光照时间的加大,刺槐的荧光参数ETR、qP和N PQ逐渐上升并在21 m in左右达到稳定,与光合同步.最大荧光产量F m在叶片转入黑暗后逐渐上升,在44 m in左右趋于稳定;N PQ则开始下降,在35 m in左右达到稳定.当光强度>200μm o l.m-2.s-1时,Ph iPS2和Ph iCO2呈线性正相关,而当光强度<200μm o l.m-2.-s 1时,Ph iPS2和Ph iCO2呈线性负相关.CO2浓度和刺槐的荧光光合速率、Ph iPS2、Ph iCO2值存在着一定的正相关关系.     

一种新型植物动力学荧光仪

当植物从暗中转到光下时 ,其体内叶绿素 (Ｃｈｌ)荧光强度会随照光时间产生有规律的变化 ,这就是植物荧光诱导现象。由于它能够灵敏、快速、简便和无损伤地探测植物体内光合生理状况及环境因子对植物的影响 ,近年来在植物生理、植物生态、农业、林业、环境污染和遥感等领域得到重视和应用［１,２,３］。植物动力学荧光仪有调制式和非调制式两类 ,非调制式荧光仪特别适合于荧光诱导上升曲线及曲线中偏转荧光 (ＦＩ)和荧光上升互补面积 (ＣＡ)的研究 ,其中ＦＩ 是快速简便地探测体内ＰＳＩＩ无活性中心相对含量的重要途径 ,后者与光合激发能…     

遮荫对月季光合特性及生长发育的影响

采用人工遮荫法研究不同程度遮荫(75%、50%和25%全光照,以全光照为对照)处理对月季的生长发育、光合特性及叶绿素荧光参数的影响。结果表明:(1)随着遮荫程度的增加,月季的叶片厚度、花径、成花率均呈降低趋势,叶绿素含量呈增加趋势;净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)降低,气孔限制值(Ls)升高,Pn下降的主要原因可能为气孔限制。(2)月季在遮荫条件下的光饱和点和光补偿点、暗呼吸速率下降,表现出其对光照降低的生理适应机制;其光饱和点在600~1 200μmol·m-2·s-1,光补偿点在29.89~62.95μmol·m-2·s-1,CO2补偿点在78.16~89.41μmol·mol-1,CO2饱和点在1 100μmol·mol-1左右,潜在光合能力13.06~25.63μmol·m-2·s-1,其对光的适应范围较宽,光照和CO2浓度对其光合能力的影响较大。(3)各处理条件下叶绿素荧光参数显示,月季在自然光和低光下(50%和25%全光照)叶片PSⅡ受到了明显伤害,光合作用原初反应过程受到抑制,光合电子传递受到影响。研究发现,月季虽是阳生植物,但光照生态幅较宽,轻度遮荫(75%全光照)能促进其光合作用效率,减少光抑制,植株长势好,成花率高。     

利用调制荧光仪在线监测叶绿素荧光

介绍了利用便携式调制荧光仪PAM-2100在线监测叶绿素荧光的技术。该技术不影响植物的自然光合状态,司以在线监测Ft、F′m、Y、rETR、qP、qN或NPQ、PAR和叶温等指标。以凤眼莲为例进行了在线监测,每隔5min监测一次,共进行了225min的监测。结果表明叶绿索荧光参数的变化依赖于PAR的变化。Ft、rETR、qN和NPQ的变化与PAR的变化趋势一致,F′m、Y和qP的变化与PAR的变化相反。通过对风眼莲的在线监测,说明该技术是可靠的,具有简单、快速、灵敏等特点。随着新型调制荧光仪的出现,该技术可能在植物生态学领域得到广泛应用。     

崖柏与侧柏光合特性和叶绿素荧光参数的比较研究

以盆栽的中国特有濒危植物崖柏及其近缘广布种侧柏幼苗为材料,测定了二者的光照和二氧化碳响应特征参数、光合作用气体交换参数和叶绿素荧光参数,比较分析两者间差异并探讨崖柏异地保存的可行性。结果显示:(1)在光响应参数方面,崖柏和侧柏的表观量子效率分别为0.039和0.027 mol.mol-1,但二者差异不显著;崖柏的光补偿点(81.04μmol.m-2.s-1)显著高于侧柏(59.72μmol.m-2.s-1),但二者的最大净光合速率(Pmax)、光饱和点(LSP)和暗呼吸速率(Rd)均无显著差异;崖柏的CO2补偿点(129.17μmol.mol-1)显著高于侧柏(95.86μmol.mol-1),而光呼吸速率则崖柏略高于侧柏,但二者的羧化效率相当。(2)气体交换参数方面,崖柏的叶片气孔导度和蒸腾速率均低于侧柏,而瞬时水分利用效率和气孔限制值则略高于侧柏;随着光照强度增加,崖柏和侧柏的净光合速率和胞间CO2浓度增加,而气孔限制值则降低。(3)2个树种的叶绿素荧光参数,如初始荧光、最大荧光、可变荧光、光系统Ⅱ原初光能转换效率、光系统Ⅱ实际光化学量子效率、非光化学猝灭等均无显著差异,但崖柏光化学猝灭系数(0.218)显著低于侧柏(0.322)。研究表明,崖柏与侧柏在光合特性和叶绿素荧光参数方面具有较大的相似性,也表明崖柏在生长季对北迁环境具有较强的适应性。     

利用叶绿素荧光监测微藻的生长及生理状态

衣藻与扁藻是生产生物柴油的优势藻种,监测其生长和生理状况是利用它们生产生物柴油的关键环节。本研究通过叶绿素荧光对这两种微藻的细胞密度进行监测并利用多激发波长调制叶绿素荧光仪(MultiColor-PAM)检测其在不同生长条件下的生理状况,获得本研究中两种藻的适宜的培养温度/光照强度:衣藻为28℃/80μmol/m~2·s~(-1),扁藻为28℃/100μmol/m2·s~(-1),利用叶绿素荧光可以便捷准确的监测微藻的生长及生理状态,为微藻培养及其代谢产物积累的研究提供切实可行的无损伤的检测方法。     

两种不同生态型麻疯树夏季光合特性的比较

以来源于海南及贵州的两种不同生态型麻风树(Jatropha curcas L.)为试材,利用LI-6400便携式光合作用测量系统及PAM-2100调制叶绿素荧光仪,在夏季对其气体交换特性及叶绿素荧光参数等进行测定.光强-光合速率响应曲线显示两种不同生态型叶片最大净光合速率(Pmax)和光饱和点(LSP)分别为18.9μmol · m-2 · s-1、1600μmol · m-2 · s-1(贵州型)和20.4μmol · m-2 · s-1、1700μmol · m-2 · s-1(海南型),而CO2光合速率响应曲线则显示两者的差异不大.两者的净光合速率(Pn)的日变化曲线都呈双峰型,主峰出现在10:00,在14:00左右出现低谷,次峰出现在16:00左右,有明显的光合"午休"现象.海南麻风树的Pmax、LSP、光补偿点(LCP)、表观量子效率(AQY)和暗呼吸速率(Rd)均高于贵州麻风树.两种生态型麻风树PSⅡ最大原初光化学效率(Fv/Fm)日变化无显著差异, 而实际光化学效率(ΦPSⅡ)变化趋势与Pn相同.这表明麻风树是一种具有较高的光合速率和强光适应性的木本能源植物,不同生态型麻风树的气体交换特性及叶绿素荧光参数有一定的差异,海南麻风树对强光的适应能力强于贵州麻风树.     

三种大型绿藻光合能力的差异及其在珊瑚养殖中的应用

利用水下饱和脉冲调制叶绿素荧光仪(Diving-PAM)测定了珊瑚养殖水处理中3种常见大型海藻石莼(Ulva lactuca)、条浒苔(Enteromorpha clathrata)和羽状蕨藻(Caulerpa mexicana)光能转化效率(Fv/Fm),快速光曲线(RLC)相关参数和非光化学淬灭(NPQ)。结果表明:石莼和条浒苔的Fv/Fm分别为0.808±0.004和0.816±0.009,显著高于羽状蕨藻。最大相对电子传递速率rETRmax(17.52±2.92和19.59±4.43μmol e·m-2·s-1)、半饱和光强Ik(53.41±8.18和59.71±13.52μmol photons·m-2·s-1)也明显高于羽状蕨藻(rETRmax和Ik分别为13.72±5.41μmol e·m-2·s-1和32.67±14.06μmol photons·m-2·s-1),表明石莼和条浒苔有着比羽状蕨藻更高的光合能力和对强光的耐受能力,光保护能力更强;羽状蕨藻较高的RLC初始斜率α表明其在弱光下拥有更强的光捕获能力,弱光下光合效率更高;随光照的增强(0~373μmol photons·m-2·s-1),羽状蕨藻NPQ的增幅有限(0~0.2),最大值仅为条浒苔和石莼的38.1%和62.5%,表明这种藻类更容易受到强光的抑制。因此,在珊瑚养殖的水处理中,可以根据不同的光照选择适宜的藻种或藻种组合并根据光梯度进行布局,反之也可以根据藻种来选择合适的光源,以达到最佳的处理效率。     

光呼吸条件下栾树和辣椒光合电子流的分配研究

用Li-6400光合仪同时测定了栾树和辣椒在温度为30℃、CO2浓度为380μmol·mol-1下的气体交换和叶绿素荧光数据。结果表明,栾树在饱和光合有效辐射时光合电子用于碳同化、光呼吸和其他途径的量分别为72.68、45.68和29.40μmol·m-2.s-1;辣椒在光合有效辐射为2000μmol·m-2.s-1时光合电子用于碳同化、光呼吸和其他途径的量分别为142.24、40.24和131.52μmol·m-2.s-1。揭示了在光呼吸条件下用Valentini和Epron等方法高估了辣椒和栾树的光合电子用于光呼吸的量,同时也高估了光呼吸在辣椒和栾树中的保护作用。     

3种石斛光合作用和叶绿素荧光特性的比较研究

以美花石斛、春石斛和铁皮石斛为材料,对它们的叶片进行光合作用、叶绿素含量和叶绿素荧光等参数的测定.结果表明:3种石斛的光饱和点都低于300 μmol·m-2·s-1,且美花石斛具有较高的净光合速率和较低的光饱和点,容易引起光抑制;美花石斛的羧化效率高于春石斛和铁皮石斛,其净光合速率随着CO2浓度的升高而迅速升高,并在CO2浓度达到500 μmol·m-2·s-1时达到最大值;美花石斛的非循环电子传递速率(ETR)、实际光化学反应量子效率(Yield)和光化学猝灭系数(qP)都明显高于铁皮石斛和春石斛,而春石斛具有较高的非光化学猝灭系数(qN),其光合机构的自我保护能力较强;美花石斛的叶绿素a、叶绿素b以及总叶绿素含量都较低.研究发现,3种石斛的光饱和点均比较低,具有石斛喜阴的生活习性,都表现出对密林和悬崖等独特生长环境的适应,并以美花石斛的这种特性更为突出.     

Fluorometric equipment for monitoring P680+• reduction in PS II preparations and green leaves

Newly developed equipment is described that permits the monitoring of laser flash induced transients of the normalised chlorophyll-a fluorescence quantum yield in isolated PS II preparations and whole leaves with a high time resolution. The essential operational unit of the set-up is a rapidly gated photomultiplier. In this way, the fluorescence artefact, due to the high intensity excitation laser flash, is sufficiently suppressed and the dead time of the signal response is reduced to about 500 ns. It is shown that the fluorescence rise kinetics in the s time-domain, after flash excitation is strongly dependent on the redox state of the primary electron donor of PS II (P680). At high excitation energies, the decay of carotenoid triplets, which are very efficient quenchers of chlorophyll singlet states, dominates the rise kinetics of the flash induced fluorescence yield in the s time domain.     

Continuous recording of photochemical and non-photochemical chlorophyll fluorescence quenching with a new type of modulation fluorometer

A newly developed fluorescence measuring system is employed for the recording of chlorophyll fluorescence induction kinetics (Kautsky-effect) and for the continuous determination of the photochemical and non-photochemical components of fluorescence quenching. The measuring system, which is based on a pulse modulation principle, selectively monitors the fluorescence yield of a weak measuring beam and is not affected even by extremely high intensities of actinic light. By repetitive application of short light pulses of saturating intensity, the fluorescence yield at complete suppression of photochemical quenching is repetitively recorded, allowing the determination of continuous plots of photochemical quenching and non-photochemical quenching. Such plots are compared with the time courses of variable fluorescence at different intensities of actinic illumination. The differences between the observed kinetics are discussed. It is shown that the modulation fluorometer, in combination with the application of saturating light pulses, provides essential information beyond that obtained with conventional chlorophyll fluorometers.     

Chlorophyll fluorometry as a method of determining the effectiveness of a biological control agent in post-release evaluations

ABSTRACT

The impact of the planthopper Megamelus scutellaris, a biocontrol agent of water hyacinth in South Africa, was assessed using chlorophyll fluorometry in a greenhouse study under two different eutrophic nutrient treatments and agent densities (high and low). The results indicated that plants grown in low nutrients with high densities of M. scutellaris showed the greatest reduction in the fluorescence parameters Fv/Fm and PI_abs. The successful use of chlorophyll fluorometry for the detection of subtle insect damage to water hyacinth leaves could have future application in post-release studies to measure the impact of M. scutellaris in the field.     

Sensitivity of the relative Fpl level of chlorophyll fluorescence induction in leaves to the heat stress

The (F_pl-F_o)/F_v value of the fluorescence induction curve is shown to be a more suitable parameter to detect a wider range of heat stress damage to thylakoid membranes as compared to quantities t _1/2 (time of fluorescence rise from F_o to (F_o+F_m)/2 level) and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaacq% aHepaDaaaaaa!39D5!\[\overline \tau \] (the fluorescence induction time defined as the area above the induction curve normalized to F_v=1). A method for exact and automatic F_pl determination is presented.A break point in the quality and behaviour of the fluorescence induction curve of barley leaves incubated at 49°C was reached at the moment (about 240 s) when the transformation of PS II active (Q_B-reducing) to PS II inactive (Q_B-non-reducing) centres was completed. The meaning of the standard F_v and F_v/F_m parameter was then changed.The method of F_pl determination described here may help to increase the analytical value of the standard chlorophyll fluorometers.Abbreviations F_o initial fluorescence - F_m maximal fluorescence - F_pl fluorescence at first inflection point (plateau) - F_v variable fluorescence (F_v=F_m–F_o) - PSM plant stress meter - SD standard deviation     

Phytoplankton patchiness in Winam Gulf,Lake Victoria: a study using principal component analysis of in situ fluorescent excitation spectra

1. In order to characterise phytoplankton patchiness at fine scales, a profiling multiwavelength fluorometer was cast at numerous locations throughout Winam Gulf in Lake Victoria to measure fluorescent excitation spectra, which are indicators of both phytoplankton diversity and coloured dissolved organic matter (CDOM). 2. Processing the spectral data with principal component analysis (PCA) revealed that linear combinations of four fundamental ‘base’ spectra could explain almost all of the variation in spectral measurements. Three of the base spectra were associated with spatially distinct patches of phytoplankton containing different species assemblages, while the fourth base spectrum was due to CDOM fluorescence. 3. The locations of the phytoplankton patches were traced to the south‐east of Winam Gulf, the western end of the Rusinga Channel and the open waters of Lake Victoria adjacent to Winam Gulf, respectively. The high CDOM fluorescence was traced mainly to relatively deep water in the Rusinga Channel. 4. The phytoplankton and CDOM patchiness were interpreted in the context of physical and chemical gradients that were measured at the site at the same scale as the spectral data. Strong relationships were found between the gradients in spectral data and other environmental variables, which suggested several underlying explanations for the phytoplankton and CDOM patchiness.     

Photoadaptation of an ice algal community in thin sea ice,Saroma-Ko Lagoon,Hokkaido, Japan

We investigated the shade adaptation of a seasonally well-developed ice algal community in thin sea ice at Saroma-Ko Lagoon, Hokkaido, Japan on 3–4 March 2006 and 4–5 March 2007, by examining photosynthetic pigment concentrations, the chlorophyll a-specific light-absorption coefficient (a _ph *), and the light-saturation index (E _k ). The high proportions of photosynthetic pigments, including chlorophyll a, fucoxanthin, and chlorophyll c, and the low values of a _ph *₍₄₄₀₎ and a _ph *₍₆₇₅₎ suggested that the lagoon’s ice algal community was shade-adapted. The high ratio of E _k to total photosynthetically active radiation (PAR) in the ice algal habitat suggested that the degree of shade adaptation is weak. Scaling of E _k to total PAR could be extended to studies of the degree of photoadaptive succession of ice algal communities in the Northern Hemisphere. The degree of shade adaptation of ice algal communities in the Northern Hemisphere might be related to ice thickness, regardless of latitude.     

The chlorophyll fluorescence ratio F690/F730 in leaves of different chlorophyll content

The red laser-induced chlorophyll-fluorescence induction kinetics of predarkened leaf samples were registered simultaneously in the 690 and 730 nm regions i.e., in the region of the two chlorophyll fluorescence emission maxima. From the induction kinetics the chlorophyll fluorescence ratio F690/F730 was calculated. The ratio F690/F730 shows to be dependent on the chlorophyll content of leaves. It is significantly higher in needles of damaged spruces (values of 0.45–0.9) than in normal green needles of healthy trees (values of 0.35–0.5). During development and greening of maple leaves the ratio F690/F730 decreases with increasing chlorophyll content. Determination of the ratio F690/F730 can be a suitable method of monitoring changes in chlorophyll content in a non-destructive way in the same leaves during development or the yellowish-green discolouration of needles of damaged spruces in the Black Forest with the typical tree decline symptoms.Abbreviations F690/F730 ratio of the fluorescence yield at the two fluorescence-emission maxima in the 690 and 730 nm regions - F_m maximum fluorescence - F_s steady-state fluorescence     

Detection of rapid induction kinetics with a new type of high-frequency modulated chlorophyll fluorometer

A newly developed modulation fluorometer is described which operates with 1 sec light pulses from a light-emitting diode (LED) at 100 KHz. Special amplification circuits assure a highly selective recording of pulse fluorescence signals against a vast background of non-modulated light. The system tolerates ratios of up to 1:10⁷ between measuring light and actinic light. Thus it is possible to measure the dark fluorescence yield and record the kinetics of light-induced changes. A high time resolution allows the recording of the rapid relaxation kinetic following a saturating single turnover flash. Examples of system performance are given. It is shown that following a flash the reoxidation kinetics of photosystem II acceptors are slowed down not only by the inhibitor DCMU, but by a number of other treatments as well. From a light intensity dependency of the induction kinetics the existence of two saturated intermediate levels (I₁ and I₂) is apparent, which indicates the removal of three distinct types of fluorescence quenching in the overall fluorescence rise from F₀ to F_max.Abbreviations Q_A and Q_B consecutive electron acceptors of photosystem II - PS II photosystem II - P 680 reaction center chlorophyll of photosystem II - F₀ minimum fluorescence yield following dark adaptation - F_max maximum fluorescence yield - DCMU 3-(3, 4-dichlorophenyl)-1, 1-dimethyl-urea - DCCD N,N-dicyclohexylcarbodiimide - PQ plastoquinone - DAD diaminodurene Dedicated to Prof. L.N.M. Duysens on the occasion of his retirement.     

PAM fluorometer based on medium-frequency pulsed Xe-flash measuring light: A highly sensitive new tool in basic and applied photosynthesis research

A newly developed modulation fluorometer is described which employs repetitive 1 s Xe-flashes for excitation light. Similar to the standard PAM Chlorophyll Fluorometer, which uses 1 s LED pulses for measuring light, the integrated measuring light intensity is sufficiently low to monitor the dark-fluorescence level, F_o. The maximal fluorescence yield, F_m, can be determined with high selectivity upon application of a saturating light pulse. The Xe-PAM displays exceptionally high sensitivity, enabling quenching analysis at chlorophyll concentrations as low as 1 g/l, thus allowing to assess photosynthesis of phytoplankton in natural waters like lakes, rivers and oceans. Due to high flexibility in the choice of excitation and emission wavelengths, this system also provides the experimental basis for a thorough study of fluorescence and photosynthesis properties of various algae classes with differing antenna organisation. By appropriate modifications, the instrument may as well be used to measure with great sensitivity and selectivity other types of fluorescence (e.g. NADPH-fluorescence), as well as light-scattering and absorbance changes.