嫁接对低温弱光下甜椒幼苗光合作用的影响

以‘卫士’和‘部野丁’为砧木,以‘赤峰特选’为接穂进行嫁接,在光照培养箱内对甜椒自根苗和嫁接苗进行低温(8 ℃/ 5℃)弱光(100 μmol·m^-2·s^-1)处理,处理7 d后在正常条件（25 ℃/18 ℃,PFD 550～600 μmol·m^-2·s^-1）下恢复3 d,研究低温弱光下甜椒嫁接苗和自根苗气体交换参数、羧化效率和荧光参数等的变化.结果表明：低温弱光胁迫3 d时,甜椒幼苗叶片的光合速率（P_n）、气孔导度（G_s）和羧化效率（CE）均下降50%以上,之后P_n、G_s趋于平稳,CE持续下降;胞间CO₂浓度（C_i）呈先下降后上升趋势.低温弱光下,甜椒幼苗的暗下最大光化学效率(F_v/F_m)、光下实际光化学效率（Ф_PSⅡ）及电子传递速率（ETR）显著降低,初始荧光(F_o)有所升高,表明其光合机构受到一定伤害,但处理结束3 d后基本恢复.与自根苗相比,嫁接苗在各处理阶段的P_n、G_s、CE、Ф_PSⅡ、F_v/F_m和ETR都有不同程度的提高,F_o明显降低.可见,嫁接可显著提高甜椒幼苗的光合功能,减轻低温弱光对其光合作用的影响.     

温度对黄瓜幼苗光合生理弱光耐受性的影响

以不耐弱光的津研2号和较耐弱光的戴多星黄瓜(Cucumis sativus L.)为试材,在人工气候室内研究适温25 ℃/18 ℃（昼/夜）、亚适温15 ℃/9 ℃和低温9 ℃/7 ℃对弱光(75～85 μmol·m^-2·s^-1)耐受性的影响.结果表明：弱光下黄瓜叶片的SPAD、净光合速率（P_n）、气孔导度（G_s）、蒸腾速率（T_r）、水分利用效率（WUE）、实际光化学效率（Φ_PSⅡ）、光化学猝灭（q_P）等指标下降,下降程度随温度的降低而加剧,而超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性上升.逆境解除后的恢复过程中,光合和荧光参数逐渐恢复,荧光参数恢复速度快于气体交换参数.弱光下温度越低对黄瓜幼苗叶片光合机构造成的伤害越重,低温降低了叶片对弱光的耐受性.在低温、弱光处理过程中,津研2号P_n、Φ_PSⅡ、q_P等下降程度较戴多星明显,而在随后的恢复过程中其回升速度较戴多星迟缓,表明弱光下戴多星对低温的耐受性强于津研2号.     

光波动频率影响黄瓜幼苗光合作用的机制

自然条件下环境光强往往是波动的,但波动光变化频率影响植物光合作用的机制尚不清楚.为了探讨植物光合作用对波动光频率的响应及机制,本文以黄瓜为材料,对植物生长、叶绿素含量、气体交换、叶绿素荧光以及抗氧化酶进行了研究.结果显示,相对于弱光(T4),强光下(T1, T2和T3)黄瓜株高、生物量、叶面积和比叶重均明显较高,但波动频率增加(T2, T3)能够导致这些参数值降低.强光与弱光处理相比其叶绿素总量较低,且随着波动光频率的提高叶绿素含量轻微下降.强光下的光合速率和气孔导度均高于弱光,不过随着强光波动频率增加,两者呈下降趋势.荧光诱导动力学的结果显示,尽管各处理间光系统Ⅱ(PSⅡ)最大光化学效率没有明显差异,但波动频率较大时黄瓜的PSⅡ的电子传递活性略有降低;而且增加强光波动频率还导致光系统Ⅱ天线转化效率(Fv′/Fm′)明显降低和非光化学猝灭(NPQ)大幅增加.此外,强光下黄瓜的酶促抗氧化系统的主要酶活性高于弱光,但波动光频率提高能够降低其活性.因此,提高波动光的频率不仅导致黄瓜光合能力下降,还导致其主要抗氧化酶的活性降低,所以增强的热耗散可能是其应对波动光下过剩激发能的重要机制.此外,本文还对黄瓜适应波动强光和稳态强光的差异进行了讨论.     

低温弱光胁迫及恢复对切花菊光合作用和叶绿素荧光参数的影响

以切花菊品种‘神马’为试材,在偏低温弱光(16℃/12℃,PFD100μmol.m-2.s-1)和临界低温弱光(12℃/8℃,PFD60μmol.m-2.s-1)下分别胁迫11d,然后转入正常条件(22℃/18℃,PFD450μmol.m-2.s-1)恢复11d,研究不同低温弱光强度及恢复对菊花光合作用和叶绿素荧光参数的影响.结果表明:低温弱光导致菊花叶片的净光合速率(Pn)和气孔限制值(Ls)下降,而胞间CO2浓度(Ci)上升.偏低温弱光胁迫下菊花叶片暗适应下最大光化学效率(Fv/Fm)和初始荧光(Fo)无明显变化,但光适应下最大光化学效率(Fv′/Fm′)在处理前期略有下降,后期则有所回升;而临界低温弱光处理的Fo明显升高,Fv/Fm和Fv′/Fm′显著降低.PSⅡ光合电子传递量子效率(ΦPSⅡ)、光化学猝灭系数(qP)和表观光合电子传递速率(ETR)均随着低温弱光胁迫程度的增加和时间的延长而降低;偏低温弱光处理植株在解除胁迫后能迅速恢复到对照水平,而临界低温弱光处理植株回升速度较慢;同时,低温弱光胁迫下吸收光强用于分配光化学反应部分(Prate)的比例减少,而天线热耗散(Drate)和反应中心的能量耗散(Ex)比例上升,但天线热耗散为过剩光能的主要分配途径.     

氯化胆碱对低温弱光下黄瓜幼苗叶片细胞膜和光合机构的保护作用

1.07mmol／L氯化胆碱处理降低了低温弱光（6℃．PFD100μmol m^-2s^-1）下黄瓜幼苗叶片膜脂组分中主要是磷脂酰甘油（PG）的饱和脂肪酸含量,增加了膜脂不饱和度：减缓了膜透性的下降、MDA的产生速率、叶绿素的降解及PSII最大量子效率（Fv/Fm）、捕光效率（Fv＇／Fm＇）、光化学猝灭系数（qp）、实际光化学效率（ФPSII）和抗氧化酶POD、APX及CAT活性的下降;提高了非光化学猝灭系数（NPQ）和脯氨酸的含量。以上结果表明氯化胆碱处理保护了低温弱光对黄瓜叶片细胞膜和光合机构的伤害。     

外源6-BA对低温胁迫下茄子幼苗光合作用、叶绿素荧光参数及光能分配的影响

本文研究了外源6-BA对低温胁迫下茄子幼苗光合作用、叶绿素荧光参数和能量分配的影响。结果表明,外源6．BA显著增加了低温胁迫下茄子叶绿素含量、净光合速率（Pn）、蒸腾速率（t）、气孔导度（Gs）和胞间CO2浓度（c1）;同时外源6-BA明显提高了低温胁迫下茄子幼苗叶片的PSⅡ最大光化学效率（Fv/Fm）、PSⅡ潜在活性（R／Fo）、PSII天线转化效率（FvFm）、实际光化学效率（φpsⅡ）、光化学猝灭系数（g,）和光化学反应能量（P）,降低了非光化学猝灭系数（NPQ）、天线热耗散能量（D）,对非光化学反应耗散能量（E）无明显影响。表明外源6-BA处理通过促进低温胁迫下茄子幼苗光合作用,提高光合电子传递效率,从而保护光合系统,降低低温胁迫对植物的损伤。     

温州蜜柑叶片光合作用光抑制的保护机理

晴天条件下,使用便携式调制荧光仪和分光光度计观察了温州蜜柑叶片光合作用光抑制发生过程中几个主要荧光参数（初始荧光F0、最大荧光Fm、PSⅡ的光化学效率Fv/Fm、非光化学猝灭qN及其快相qNf和慢相qNs）、电子传递速率（ETR）和玉米黄素相对含量的日变化,结果表明,随着光强的增强,ETR、qN及其qNr与qNs以及玉米黄素相对含量升高,Fv/Fm、Fm和F0下降。用DTT处理后,qNs较对照明显下降,F0较对照明显上升,可以认为,柑橘在光合作用日变化中存在依赖于叶黄素循环和类囊体膜质子梯度两种非辐射能量耗散方式,而且它们在防御光破坏方面起着重要作用。     

花后不同时期弱光和高温胁迫对小麦旗叶荧光特性及籽粒灌浆进程的影响

在田间试验条件下研究了花后不同时期弱光和高温胁迫对小麦旗叶荧光特性及籽粒灌浆进程的影响.结果表明,弱光处理3 d后,旗叶PSⅡ最大光化学效率（Fv/Fm）和光合速率（Pn）显著降低,但PSⅡ实际光化学效率（ΦPSⅡ）、荧光光化学猝灭系数（qP）和非光化学猝灭（NPQ）与对照相比差异较小;高温处理3 d后,Fv/Fm、Pn、ΦPSⅡ和qP均极显著降低, NPQ升高幅度较小.胁迫解除后,灌浆前期（花后8～10 d）弱光和高温处理后的旗叶荧光参数和光合速率略有恢复,但灌浆中期（花后15～17 d）处理后的各参数始终呈下降趋势, 说明前期处理效应是可逆的,而中期处理加速其衰老进程.用Logistic方程对各处理的籽粒灌浆过程模拟明,弱光和高温处理后籽粒粒重的降低主要是平均灌浆速率、最大灌浆速率和渐增期灌浆速率显著降低所致.灌浆持续期、最大灌浆速率出现时间、缓增持续期和缓增期灌浆速率受弱光和高温影响较小.     

田间小麦叶片光合作用的光抑制不伴随D1蛋白的净降解

通过测定田间小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ ）叶片Ｄ１蛋白的含量、光合放氧和叶绿素ａ 荧光,探讨了叶片光合作用的光抑制与Ｄ１蛋白净降解的关系。田间的小麦叶片受到晴天中午光照约３ ｈ 以后,表观光合量子效率（Φ）、光系统Ⅱ的光化学效率（Ｆｖ／Ｆｍ ）和初始荧光（Ｆ０）明显下降;若将叶片转入弱光下,这３个指标可在１ ｈ 内基本恢复;强光照射过程中Ｄ１蛋白的含量没有显著变化;Ｄ１蛋白合成抑制剂ＳＭ 使强光下叶片的慢驰豫的非光化学荧光猝灭（ｑＥ－ｓｌｏｗ ）明显增加;在弱光下恢复时引入链霉素（ＳＭ）不影响叶片光合功能的恢复;用二硫苏糖醇（ＤＴＴ）抑制叶黄素循环使中午强光照射后的叶片中Ｄ１蛋白的含量降低３０％ 左右。这些结果都表明,田间小麦叶片光合作用的光抑制不是由于Ｄ１蛋白的净降解,而是由于非辐射能量耗散的增加引起的。     

γ-氨基丁酸（GABA）对低氧胁迫下甜瓜幼苗光合作用和叶绿素荧光参数的影响

采用营养液水培方法,研究了低氧胁迫下外源γ-氨基丁酸（GABA）对甜瓜幼苗光合色素含量、光合作用及叶绿素荧光参数的影响.结果表明：低氧胁迫导致甜瓜幼苗光合色素含量显著下降,光合作用降低;外源GABA能显著提高正常通气和低氧胁迫下甜瓜幼苗的光合色素含量、净光合速率、气孔导度、胞间CO₂浓度、CO₂羧化效率、最大光化学效率、光化学猝灭系数、表观光合电子传递速率和PSⅡ光合电子传递量子效率,而气孔限制值、初始荧光和非光化学猝灭系数显著降低,GABA在低氧胁迫下的提高效果更明显;同时添加GABA和GABA转氨酶抑制剂γ-乙烯基-γ-氨基丁酸（VGB）处理显著降低了低氧胁迫下GABA对甜瓜幼苗光合特性的缓解效果.     

基于叶绿素荧光成像及荧光参数分布特征的叶片光合异质性定量分析

植物叶片光合作用具有高度的空间异质性,叶绿素荧光成像技术为叶片光合异质性的研究提供了便利,但叶片光合异质性的定量分析并没有得到广泛应用。本文利用ImagingPAM叶绿素荧光成像系统,获得 中亚热带地区越冬期小叶榕（Ficus microcarpa）阳生叶和阴生叶的叶绿素荧光参数图像,并利用仪器的分析软件对其进行分析,定量比较了阳生叶和阴生叶的光合异质性特征。研究发现：越冬期小叶榕阳生叶的光合异质性和光抑制程度明显高于阴生叶,变异系数可作为光合异质性的定量指标。低温强光导致阳生叶坏死率（P_LN）达4.30%,并有53.30%的区域处于严重光抑制（0<F_v/F_m<0.627）,但仍有42.27%的区域仅为轻度光抑制（0.627≤ F_v/F_m<0.800）。而低温弱光并未造成阴生叶坏死和严重光抑制。通过对光系统Ⅱ（PSⅡ）的实际光合效率 （Y（Ⅱ））、调节性能量耗散的量子产额（Y（NPQ））和非调节性能量耗散的量子产额（Y（NO））荧光参数异质性的定量分析表明,阳生叶具有相对较高的光化学能力,阴生叶则具有相对较高的热耗散能力;冬季强光虽然会导致小叶榕阳生叶PSⅡ严重激发压积累,存在严重光抑制的潜在风险,但其致死面积并不大,叶片中仍存在一定面积低激发压的低风险区,而低温弱光下的阴生叶则主要以低风险区域为主。     

叶片发育影响紫罗勒花青素的强光诱导和激发能分配

通过气体交换、叶绿素荧光、反射光谱和显微技术等研究了叶片发育与花青素强光诱导的关系及其对激发能分配的影响。结果表明,遮荫导致紫罗勒叶片变薄,花青素含量显著降低。当弱光下生长的植株转入强光后,转光前发育成熟的叶片花青素含量很低,而此后强光下发育成熟的叶片花青素含量高。转强光后,弱光下发育成熟的叶片光合速率低、光抑制严重,且天线耗散增强;强光下发育成熟的叶片净光合速率高,光抑制程度轻,天线耗散低。因此,我们认为叶片发育影响紫罗勒花青素合成的强光诱导,而转强光后花青素的诱导差异进一步改变了光合作用过程中的激发能分配。     

The long-wavelength limit of plant photosynthesis

It is a common knowledge that the photosynthesis efficiency drops rapidly under the long-wavelength light excitation above 680 nm. We discovered that in sunflower leaves attached to the plant the initial fall is replaced by an unexpected increase at much longer wavelengths, so that a detectable O(2) evolution is remained till 780 nm. The quantum yield of O(2) evolution at the local maximum at 745 nm reaches almost 20% of the yield at 650 nm. We conclude that extreme long-wavelength chlorophylls may be present in the intact photosystem II antenna system, similarly to photosystem I.     

6-BA预处理对低温弱光胁迫下辣椒幼苗叶绿素a荧光参数和膜脂过氧化的

研究6-BA预处理对低温（15℃/5℃）弱光（100μmol·m^-2·s^-1）下辣椒品种‘湘研16号’幼苗叶片中叶绿素a荧光参数和膜脂过氧化影响。结果表明,0．08mmol·L^-16-BA减缓低温弱光下辣椒幼苗光系统II（PSII）最大光化学效率（Fv/Fm）、PSH实际光化学效率（ΦPSII）和PSII反应中心光能捕获效率（Fv’/Fm’）的下降以及叶片膜透性和丙二醛（malondialdehyde,MDA）含量的增加,但是提高了超氧化物歧化酶（superoxidedismutase,SCD）、过氧化物酶（peroxidase,POD）、过氧化氢酶（catalase,CAT）以及抗坏血酸过氧化物酶（ascorbate peroxidase,APX）的活性。     

超级高产小麦旗叶荧光动力学研究

探明超级小麦品种的旗叶光合作用与荧光动力学特性,为超级小麦品种选育利用提供理论依据。以超级小麦临麦4号为试验材料,应用CI-301PS型便携式光合作用测定系统和FMS-2便携式荧光测定仪(英国Hansatech公司)在田间试验中测定旗叶光合作用与荧光动力学参数。结果表明,与普通高产对照品种皖麦52和烟农19相比,超级小麦临麦4号的光合作用参数光合速率、光饱和点和CO2饱和点、羧化效率高,光补偿点和CO2补偿点低;光合机构系统工作参数PSII实际的光化学效率(ΦPSII)、光化学猝灭系数(qP)、PSII反应中心的激发能捕获效率(Fv/Fm)、PSⅡ潜在活性Fv/Fo和电子传递速率(ETR)值高,非光化学猝灭系数(NPQ)值低。这表明超级小麦临麦4号的光合机构系统工作能力强和工作效率高,保证旗叶光合作用的高效运行,为子粒灌浆提供充足的能量和碳水化合物。     

Mechanisms of photoinhibition induced by high light in Hosta grown outdoors

Aims It has long been recognized that photoinhibition of photosynthesis is induced by high light. However, our recent studies are not consistent with this traditional view. Therefore, the objective of this study is to explore the induction of photoinhibition and its mechanisms under full sunlight outdoors.
Methods Changes of leaf morphology, gas exchange, and chlorophyll a fluorescence were measured to investigate the induction and mechanisms of photoinhibition under high light in Hosta, which is a typical shade-tolerant plant.
Important findings Hosta plants grown under full sunlight (HT) and low light (LT) developed sun- and shade-type leaf morphological characteristics, respectively. Under a full sunlight, Hosta plants had lower photosynthetic rate and chlorophyll content than under the LT; whereas, there were only slight difference in the maximum quantum yield of photosystem II (F_v/F_m) between the two treatments, suggesting that Hosta plants could grow normally under full sunlight without severe photoinhibition. After transition from the low to a high light (LHT), the photosynthetic rate and maximum quantum yield of photosystem II decreased sharply, reflecting that the LHT treatment led to irreversibly inactivation of photosystem II. Additionally, the shape of chlorophyll a fluorescence transients also changed significantly; the relative fluorescence yield of the K and J steps were reduced by 24.3% and 34.2%, respectively, indicating that the acceptor side of photosystem II was damaged more severely than the donor side. Consequently, we postulate that photoinhibition in Hosta leaves is mainly induced by the sudden enhancement of light intensity outdoors. Hosta can acclimate to high irradiance through leaf development outdoors. Our finding is of great significance in understanding the acclimation of plants to high light and cultivation of shade-tolerant plants in field.     

Analysis of the photosynthetic response induced by variation potential in geranium

Electrical signals (action and variation potentials) caused by environmental stimuli induce a number of physiological responses in plants including changes in photosynthesis; however, mechanisms of these changes remain unclear. We investigated the influence of the variation potential on photosynthesis in geranium (Pelargonium zonale) under different conditions (control, low external CO₂ concentration, and actinic light absence). The variation potential caused by lamina burning induced a reduction in photosynthesis (decreases in effective quantum yields of photosystem I and II, CO₂ assimilation rate, and stomatal conductance) in unstimulated leaves under control conditions. Changes in the majority of light-stage parameters (photosystem I and II quantum yields, coefficients of photochemical and non-photochemical quenching, quantum yield of non-photochemical energy dissipation in photosystem I due to donor-side limitation) were correlated with a decrease in CO₂ assimilation rate. The changes were similar to those caused by lowering [CO₂]; their magnitudes decreased both under low external CO₂ concentration and without actinic light. These results support the hypothesis that Calvin cycle inactivation plays a key role in photosynthetic response induced by electrical signals. However, a decrease in electron transport through the PSI acceptor side also induced by variation potential was not correlated with a decrease in the CO₂ assimilation rate and did not depend on the external CO₂ concentration or actinic light intensity. Thus, we suggest that there are two different mechanisms of light-stage inactivation induced by the variation potential in geranium: one strongly dependent on dark-stage inactivation and one weakly dependent on dark-stage inactivation.     

Evaluation of instant light‐response curves of chlorophyll fluorescence parameters obtained with a portable chlorophyll fluorometer on site in the field

Miniaturized pulse‐amplitude modulated photosynthesis yield analysers are primarily designed for measuring effective quantum yield (ΔF/F_m′) of photosystem II under momentary ambient light conditions in the field. Although this provides important ecophysiological information, it is often necessary to learn more about the potential intrinsic capacities of leaves by measuring light‐response curves. Thus, instruments provide light‐curve programmes, where light intensities are increased in short intervals and instant light‐response curves are recorded within a few minutes. This method can be criticized because photosynthesis will most likely not be in steady state. This technical report shows that with the appropriate precautions instant light curves can nevertheless provide reliable information about cardinal points of photosynthesis. First, the geometry of the light source of the instrument in relation to the quantum sensor must be considered and quantum sensor readings must be corrected. Second, the measurements of the light‐response curves must be compared with readings of effective quantum yield of photosystem II under ambient light conditions where photosynthesis is in steady state. This may show that in the critical range of the light curves either both measurements perfectly coincide or are offset against each other by a constant value (examples are given here). In the first case results of light curves can be taken at face values, and in the second case a simple correction can be applied. With these precautions and careful interpretations instant light‐response curves can be an enormous advantage in ecophysiological field work.     

几种树木的树皮中绿色组织的光合特性初探

测定10个树种树木上的三年生枝条树皮内绿色组织的叶绿素含量、光合速率和枝干的呼吸速率的结果表明：10个树种树皮内叶绿素含量为0.0649～0.3460mg·g^-1（FW）,叶绿素a/b为1.05～1.91,均低于叶片或针叶;树皮内绿色组织的光合速率为0.21（红松）～2.06（水曲柳）μmol（O2）·m^-2·s^-1,枝干呼吸速率1.76（红松）～3.21（落叶松）μmol（O2）·min^-1·g^-1（FW）。树皮内绿色组织的光补偿点（LCP）、光饱和点（LSP）低于叶片,而表观量子效率（AQY）高于叶片或针叶。据此认为,树皮内绿色组织适应于阴生环境,所以有较强的耐阴能力。