外源水杨酸对镉胁迫甜瓜幼苗生长与光合气体交换和叶绿素荧光特性的影响

以甜瓜品种‘哈密绿’为试验材料,采用基质栽培方式,研究了10~200μmol·L-1外源水杨酸(SA)对镉胁迫(100mg·L-1 Cd2+)下甜瓜幼苗生长、叶绿素含量、光合气体交换参数和叶绿素荧光参数的影响,以探讨外源SA调控Cd2+胁迫伤害的可行性。结果显示:Cd2+胁迫能显著影响甜瓜幼苗的生长和相关光合指标。适宜浓度外源SA能不同程度缓解甜瓜幼苗所受Cd2+胁迫伤害,并以100μmol·L-1 SA处理效果最好,其显著促进了幼苗生长,提高了叶片叶绿素含量、净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs),以及PSⅡ最大光化学效率(Fv/Fm)、PSⅡ天线转化效率(Fv′/Fm′)、实际光化学效率(ФPSⅡ)、光化学荧光猝灭系数(qP)和光化学反应能量(P);显著降低了初始荧光(F0)、非光化学荧光猝灭系数(NPQ)、天线热耗散能量(D)和非光化学反应耗散能量(E)。研究表明,外源SA缓解甜瓜幼苗Cd2+胁迫伤害具有剂量效应,以100μmol·L-1 SA的效果最好,有利于甜瓜幼苗在Cd2+胁迫下光合作用的维持,提高光合电子传递效率和对光能的捕获与转换,降低Cd2+胁迫对植物的损伤,从而促进生长。     

水分胁迫对长期UV—B辐射下柚树苗生理特性的影响

水分胁迫下,柚[Citrus maxima(Burm.)Merr.]树苗叶片相对含水量（RWC）、水势（ΨW)、净光合速率（Pn)、可溶性蛋白质和叶绿素（Chl)含量下降,丙二醛（MDA）、脯氨酸（Pro)含量和超氧化物歧化酶（SOD）活性升高,过氧化氢酶（CAT）活性先上升后下降,抗坏血酸过氧化物酶（APX）活性、抗坏血酸（AsA)和还原型谷胱甘肽（GSH）含量明显降低。叶绿素荧光参数中光系统Ⅱ光化学原初效率（Fv/Fm)、光系统Ⅱ电子传递量子效率（ΦPSⅡ）和光化学猝灭（qp)下降,非光化学猝灭（qN)和热能耗散系数（KD）升高。显示膜系统和PSⅡ是水分胁迫的主要抑制位点。抗旱性强的品种具有较高的活性氧清除能力。长期紫外线－B（UV－B）增强辐射能缓解水分胁迫下柚树苗叶片RWC、ΨW、APX活性和GSH、AsA含量下降,但对水分胁迫下的Pro含量、Pn和叶绿素荧光特性作用不明显。初步推测：UV－B和水分胁迫对植物有部分相同的作用机制,都导致植株膜脂过氧化程度加剧和PSⅡ的失活,同时存在各自作用方式的特异性。     

夜间低温胁迫后外源SA对恢复中黄瓜幼苗光合特性的影响

为明确低温胁迫后恢复过程中水杨酸(SA)对植物光合特性的影响,以黄瓜品种‘津研四号’幼苗为材料,通过沙培试验,研究了外源SA对夜间5℃低温胁迫后常温(25℃)恢复中黄瓜幼苗叶绿素含量、光合速率、叶绿素荧光参数、气体交换参数等的影响。结果显示:(1)与喷施清水处理相比,外源SA处理显著促进了夜间低温胁迫后的常温(25℃)恢复效果,显著提高了恢复速度和水平,表现在黄瓜幼苗叶绿素含量、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci)显著升高,黄瓜幼苗净光合速率在恢复6h时达到对照水平的82.18%。(2)外源SA还明显加快了恢复过程中黄瓜幼苗叶片最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)及非循环电子传递速率(ETR)的恢复,提高了非光化学猝灭系数(NPQ)值,增强了幼苗自身光保护能力。(3)外源SA也促进了黄瓜幼苗叶片表观量子效率(AQY)和羧化效率(CE)的恢复,它们在恢复2d时分别达到对照水平的92.59%和90.62%。研究表明,在夜间低温胁迫后的常温恢复过程中,外源SA可有效地促进黄瓜幼苗光合作用的恢复,增强其对低温环境的适应能力。     

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。     

高温胁迫下外源NO对高灌蓝莓PSⅡ光化学活性和抗氧化系统的影响

以高灌蓝莓品种‘都克’试管苗移栽到田间6个月的植株为试材,研究了高温胁迫条件下,外源一氧化氮(NO)对高灌蓝莓幼苗生长、PSⅡ光化学活性和抗氧化系统的影响.结果表明:0.2、0.5和1.0 mmol·L^-1外源NO供体硝普钠(SNP)处理显著减缓了高温胁迫对高灌蓝莓光合系统Ⅱ(PSⅡ)的抑制,高灌蓝莓PSⅡ最大光化学效率(F_v/F_m)、实际光化学效率(Φ_PSⅡ)、光化学猝灭系数(q_P)和非光化学猝灭系数(NPQ)下降缓慢,使光合机构免受高温胁迫的伤害;叶片质膜透性和丙二醛含量降低,而超氧化物歧化酶和过氧化氢酶活性升高,从而促进了脯氨酸的积累.适当浓度的SNP能显著缓解高温胁迫对高灌蓝莓植株的伤害,其中0.5 mmol·L^-1 SNP的缓解效果最好.     

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.     

外源水杨酸对黄瓜幼苗叶片PSⅡ活性和光能分配的影响

以黄瓜品种‘中农203号’幼苗为试材,采用水培法研究了根际施用0.05、0.10和0.50 mmol/L水杨酸对黄瓜幼苗叶片PSⅡ活性和光能分配的影响,以探讨水杨酸对光合作用的调节机制。结果显示:黄瓜幼苗叶片净光合速率(Pn)、荧光参数和光能分配对水杨酸的响应存在明显的浓度依赖性。0.05和0.10 mmol/L水杨酸处理提高了叶片PSⅡ最大光化学量子产量(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)、PSⅡ潜在活性(Fv/F0)、电子传递速率(ETR)、光化学猝灭系数(qP),降低了非光化学猝灭系数(NPQ),使PSⅡ吸收光能中分配于光化学反应的能量增加,进而提高了Pn,并以0.10 mmol/L水杨酸施用效果最明显,差异达极显著水平(P<0.01);而0.50 mmol/L水杨酸处理降低了ΦPSⅡ、Fv/Fm等,使光能分配于热耗散和荧光耗散的比例升高,导致Pn下降。研究表明,水杨酸对黄瓜叶片光合的正负调节作用与浓度依存下的PSⅡ活性和光能分配改变有关。     

外源脱落酸对干旱胁迫下滇润楠幼苗生长及生理特性的影响

以滇润楠一年生实生苗为试验材料,研究在良好水分条件(土壤含水量为70%～75%田间持水量)、轻度干旱胁迫及重度干旱胁迫处理下(50%～55%和30%～35%田间持水量)进行外源脱落酸(ABA)喷施对其生长及生理特性的影响。结果表明: 干旱胁迫使得滇润楠幼苗叶片的相对含水量、株高和生物量显著下降,净光合速率及叶绿素荧光参数(PSⅡ最大光化学效率,F_v/F_m)有不同程度的下降,而根冠比、膜脂过氧化产物丙二醛(MDA)含量显著增加。外源ABA的喷施可提高干旱胁迫下滇润楠幼苗的适应性,尤其是重度干旱下,外源ABA显著提高了叶片相对含水量21.0%,同时增加了植株株高和生物量的累积,提高了根冠比,为良好水分条件的2.1倍;减少了干旱下膜脂过氧化产物MDA的累积,提高了抗氧化酶过氧化氢酶、超氧化物岐化酶的活性,显著增加了脯氨酸的含量,为良好水分条件的7.7倍。外源ABA的喷施显著缓解了干旱胁迫对植株光合器官的不利影响,减少干旱引起的叶片净光合速率及气孔导度的下降,并且减轻了PSⅡ受到干旱的伤害程度,重度干旱下喷施ABA的植株的F_v/F_m显著高于未喷施ABA的植株。外源ABA的喷施可以减轻干旱对滇润楠植株的伤害,提高其抗旱性。     

干旱胁迫对丹参叶片气体交换和叶绿素荧光参数的影响

研究了干旱处理15d后,大叶型丹参和小叶型丹参2个品种幼苗气体交换和叶绿素荧光参数的变化.结果表明:在干旱胁迫15d后,大叶型丹参叶片净光合速率(Pn)和PSⅡ最大光化学效率(Fv/Fm)分别下降了66.42%和10.98%,而小叶型丹参的Pn和Fv/Fm分别下降了29.32%和5.47%,干旱胁迫对大叶型丹参Pn和Fv/Fm的影响明显大于小叶型丹参.小叶型丹参Pn下降主要由气孔因素造成,而大叶型则主要由非气孔因素所致.干旱胁迫使丹参叶片的气孔导度(Gs)下降,但明显诱导了水分利用效率(WUE)、非光化学猝灭系数(qN)和光呼吸速率与净光合速率比率(Pr/Pn)的增加,以提高干旱胁迫抗性.其中小叶型丹参的增幅明显大于大叶型丹参.表明小叶型丹参的抗干旱胁迫能力更强.     

低氧胁迫下黄瓜植株热耗散途径

采用营养液栽培,研究了低氧(营养液溶氧浓度为0.9～1.1 mg·L-1)胁迫下黄瓜幼苗光合作用热耗散与叶黄素循环的关系.结果表明:低氧胁迫下,黄瓜叶片PSⅡ的实际光化学效率(φPSⅡ)、饱和光强下的净光合速率(Pn)、表观量子效率(AQY)和PSⅡ的最大光化学效率(Fv/Fm)均显著降低,表明黄瓜植株的光合作用受到了光抑制;同时,光化学猝灭系数(qp)降低,而热耗散(NPQ)和天线耗散能量(D)的比值显著升高,说明黄瓜叶片热耗散增强;NPQ与叶黄素脱环氧化状态(DEPS)呈显著正相关,且两者均被抗坏血酸(AsA)所促进,被二硫苏糖醇(DTT)所抑制,说明低氧胁迫下,叶黄素循环是黄瓜植株光合作用热耗散的主要途径.     

24-epibrassionlide improves photosynthetic response of Rhododendron delavayi to drought

Rhododendron delavayi is an alpine evergreen ornamental plant with strong tolerance to drought stress. Brassinosteroids are promising agents for alleviating the negative effects of drought on plants, but the mechanism by which BRs induce plant resistance to drought is not well understood. The present study investigated the effects of exogenous spray of 24-epibrassionlide (EBR) at different concentrations (0~1 mg l⁻¹) on the physiological response of R. delavayi to drought caused by no watering for 10 days. With the increase in EBR concentration, net photosynthetic rate, stomatal conductance, transportation rate, light saturated photosynthetic rate, light compensation point, light saturation point, excitation energy capture efficiency of reaction center, actual photochemical efficiency of photosystem II (PSII), photochemical quenching and electron transport rate significantly increased, but there were no significant effects on photosynthetic pigment content. These results suggested that the EBR-induced improvement in CO₂ assimilation under drought was mainly related to stomatal and non-stomatal factors, and partially attributed to the increased photochemical efficiency of PSII. In addition, the leaf water potential increased with the increase in EBR concentration, while the malondialdehyde, superoxide dismutase, catalase, proline and soluble protein decreased. The results suggested EBR application partially alleviated the negative effect of drought on R. delavayi by improving water relations and decreasing lipid peroxidation and reactive oxygen species production. We concluded that exogenous application of EBR improved photosynthesis and alleviated the negative effects of drought-induced membrane peroxidation and severe oxidative stress.     

麻疯树幼苗对干旱胁迫的响应

以不同浓度(5%～25%)的聚乙二醇(PEG-6000)模拟干旱胁迫处理麻疯树三叶期幼苗,研究了不同程度干旱胁迫下麻疯树叶片光合特性及其对干旱的耐受能力.结果表明:在较低浓度PEG(≤15%)处理下,随PEG浓度的增加,麻疯树叶片净光合速率(P_n)、气孔导度(G_s)、胞间CO₂浓度(C_i)、PSⅡ实际光化学量子产量(Φ_PSⅡ)、光化学猝灭(q_P)和表观光合电子传递速率(ETR)下降,PSⅡ原初光能转化效率(F_v/F_m)轻微下降,水分利用效率(WUE)则逐渐升高,非光化学猝灭(NPQ)明显上升,初始荧光(F_o)无显著变化(P＞0.05);在高浓度PEG(＞15%)处理下,C_i随PEG浓度的增加而显著上升,P_n、G_s和WUE持续下降,F_v/F_m、Φ_PSⅡ、q_P和ETR下降幅度明显增大,F_o显著上升,而NPQ下降.低浓度PEG处理导致麻疯树叶片P_n下降主要是由气孔因素造成的;在高浓度PEG处理下,P_n的下降则是由非气孔和气孔因素的共同限制作用造成的.当PEG浓度<20%时,虽然出现P_n下降,但光合机构未受损伤.经15 d高浓度PEG处理的植株叶片,在胁迫解除后光合活性能够迅速恢复,且植株可以存活.说明麻疯树对干旱胁迫有较强的耐受能力.     

CPPU提高柚树苗抗旱性的研究

水分胁迫下,柚树苗叶片RWC、ψW、Pn及可溶性蛋白质、叶绿素含量下降,游离脯氨酸、MDA含量及SOD活性升高,CAT活性先上升后下降,APX活性、AsA和GSH含量明显下降,抗旱性强的品种具有较高的活性氧清除能力。CPPU处理提高柚树苗叶片RWC、Pn、叶绿素、游离脯氨酸、AsA、GSH含量,并增强SOD、APX活性,降低MDA水平,从而提高柚树苗抗旱性。实验结果表明,CPPU处理提高叶片对膜脂过氧化作用的保护能力可能是其提高柚树苗抗旱性的原因。     

Effect of 24-epibrassinolide on drought stress-induced changes in Chorispora bungeana

Brassinosteroids (BRs) have been proposed to increase the resistance of plants to drought stress. The effect of foliar application of 0.1 μM 24-epibrassinolide (EBR) on chlorophyll (Chl) content, photosystem 2 (PS 2) photochemistry, membrane permeability, lipid peroxidation, relative water content (RWC), proline content, and the antioxidant system in drought-stressed Chorispora bungeana plants was investigated. The results showed that polyethylene glycol (PEG) induced water stress decreased RWC, Chl content and variable to maximum Chl fluorescence ratio (F_v/F_m) less in plants pretreated with EBR than in non-pretreated plants. In addition, lipid peroxidation, measured in terms of malondialdehyde content, membrane permeability and proline content in drought-stressed plants were less increased in EBR pretreated plants, while antioxidative enzyme activities and reduced ascorbate and glutathione contents were more increased in EBR pretreated than in non-pretreated plants. These results suggested that EBR could improve plant growth under drought stress     

干旱胁迫对杨树幼苗生长、光合特性及活性氧代谢的影响

2011年4-10月在山东省林业科学研究院试验苗圃,选取欧美I-107杨扦插苗为试材,采用盆栽控水试验,研究了不同水分处理(正常水分、轻度干旱、中度干旱和重度干旱)对杨树幼苗生长和气体交换、叶绿素荧光特性、活性氧代谢的影响.结果表明: 与正常水分处理相比,轻度、中度和重度干旱胁迫下的地径生长量分别下降12.8%、44.5%和65.6%,苗高生长量分别下降12.2%、43.1%和57.2%;随着胁迫强度的增加和胁迫时间的延长,杨树幼苗叶片的PSⅡ光能转化效率、实际量子产量、光化学猝灭系数、净光合速率和气孔导度在轻度胁迫下缓慢下降,而在中度和重度胁迫下迅速下降;非光化学猝灭系数在轻度胁迫下显著升高,而在中度和重度胁迫下先升高后降低;叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均先升高后降低,但对干旱胁迫和活性氧的响应存在一定差异;叶片相对电导率、丙二醛含量显著增加,质膜受损,大量离子外渗,且重度胁迫下质膜的损害最严重.轻度干旱胁迫下,I-107杨树幼苗具有较高的光合效率和较强的抗氧化保护酶系统;而中度和重度干旱下,其光合效率显著下降,抗氧化保护酶系统明显遭到破坏.     

Response of Barley Seedlings to UV-B Radiation as Affected by Proline and NaCl

Barley (Hordeum vulgare L. cv. Alfa) seedlings were treated for 4 d before UV-B irradiation with 0.05 mM proline or 150 mM NaCl. UV-B exposure induced synthesis of yellow coloured compounds with maximum absorbance at 438 nm. The content of these compounds was increased in proline-treated and decreased in NaCl-treated plants. UV-B radiation reduced chlorophyll/carotenoids ratio, oxygen evolution rate and photochemical efficiency of PS 2 as estimated by chlorophyll fluorescence and increased proline accumulation, H₂O₂ generation and lipid peroxidation. Exogenous proline had no effect on the parameters studied and did not change the response of plants to UV-B radiation. NaCl inhibited photochemical efficiency of PS 2, reduced oxygen evolution and increased H₂O₂ concentration and lipid peroxidation. The combination of NaCl and proline treatment led to lowering the inhibitory effect of NaCl in non UV-B irradiated seedlings. There was not relationship between the level of UV-B-induced compounds and UV-B tolerance of barley seedlings.     

Hexanoic acid 2-(diethylamino)ethyl ester enhances chilling tolerance in strawberry seedlings by impact on photosynthesis and antioxidants

Strawberry (Fragaria ananassa Duch.) seedlings were pretreated with hexanoic acid 2-(diethylamino)ethyl ester (DA-6) in concentrations of 0, 10, 20 and 40 mg dm⁻³ and then subjected to chilling and rewarming. The effects of applied DA-6 on the generation of reactive oxygen species (O₂ ⁻, H₂O₂), lipid peroxidation, proline accumulation and photosynthesis were evaluated. Pretreatment with DA-6 alleviated the inhibition of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities caused by chilling stress thus reducing O₂ ⁻ and H₂O₂ production and lipid peroxidation in pretreated plants. DA-6 pretreatment also accelerated accumulation of proline and reduce the decrease in proline content after rewarming. DA-6 pretreatment increases maximum quantum yield of photosystem 2 (F_v/F_m), actual photochemical efficiency of photosystem 2 (Φ_PS2), photochemical quenching coefficient (qP) and net photosynthetic rate (P_N) and decreases non-photochemical quenching coefficient (qNP) of the seedlings under chilling stress. DA-6 pretreatment also increased the recovery rate of photosynthesis after rewarming.     

水杨酸对高温强光胁迫下小麦叶绿体D1蛋白磷酸化及光系统Ⅱ功能的影响

为了研究水杨酸（SA）对高温强光胁迫下小麦叶片类囊体膜D₁蛋白磷酸化和PSⅡ功能的影响,用0.5 mmol·L^-1 SA溶液预处理灌浆期小麦叶片,以水预处理为对照,然后将预处理植株进行高温强光（35 ℃,1 600 μmol·m^-2·s^-1）处理,测定胁迫处理过程中小麦旗叶光合电子传递速率、净光合速率、叶绿素荧光参数及D₁蛋白的变化.结果表明：SA预处理有效抑制了高温强光下D₁蛋白的净降解,保持了较高的D₁蛋白磷酸化水平、全链电子传递速率和PSⅡ电子传递速率,维持了较高的PSⅡ原初光化学效率（F_v/F_m）、实际光化学效率(Ф_PSⅡ)、光化学淬灭系数（q_P）和净光合速率（P_n）.表明外源SA通过调节小麦叶绿体D₁蛋白的周转,减轻了高温强光胁迫对叶片光合机构的损伤,有利于PSⅡ的正常运转.