油蒿(Artemisia ordosica)光化学量子效率和非光化学淬灭的动态及其影响因子

叶绿素荧光的测定是探究干旱半干旱区沙生植物对环境变化响应的重要手段,叶绿素荧光的动力学研究对认识植物适应环境胁迫的生理生态过程与机制具有重要意义。本文于2012年6—10月研究了宁夏盐池油蒿(Artemisia ordosica)的光化学量子效率(Φ)和非光化学淬灭(NPQ)的季节变化和日变化,及其与光合有效辐射(PAR)、相对湿度(RH)和空气温度(Ta)的关系。结果表明:在观测期内,油蒿的Φ随PAR和Ta升高而降低,随RH的升高而升高,NPQ的变化与Φ相反;在日变化尺度,油蒿的Φ(R20.92)和NPQ(R20.90)与PAR紧密相关,而与空气温度(Ta)和相对湿度(RH)的日变化存在3~4 h的滞后;此外,在相同PAR下,生长季前期的Φ大于后期,生长季旺期的NPQ大于末期;因此,PAR、Ta和RH对Φ和NPQ均有影响。     

植物叶片和冠层光化学反射指数与叶黄素循环的关系

以一串红(Salvia splendens Ker-Gawl.)和白车轴草(Trifolium repens Linn.)为材料,使用光谱反射技术测定了这两种植物叶片水平和冠层水平的光化学反射指数(PRI)的日变化,同时使用高效液相色谱分析法测定了这两种植物叶黄素循环的日变化,分析了单叶、群体冠层的PRI与叶黄素循环和叶片实际光化学效率(ΦPSⅡ)和非光化学淬灭(NPQ)之间的关系.结果表明,不论是叶片水平还是冠层水平,两种植物PRI的变化均与叶黄素的脱环氧化程度和NPQ之间呈显著的负相关、与ΦPSⅡ呈显著的正相关.研究结果表明无论叶片水平还是冠层水平上的光谱反射指数均能非常好地反映植物光合机构对光能的利用效率.     

植物光合机构对光环境的适应机制: 状态转换

在自然条件下,植物接受的照光量经常变化,而植物在进化过程中已形成了相应的适应机制,用以维持光环境变化过程中2个光反应之间光能转换的能量平衡.植物的调控系统不但能通过调控叶片和叶绿体的运动以及光合色素的积累调节光的吸收,还可以通过光系统的状态转换灵活地调节捕光色素蛋白复合体吸收的能量分配.特别是在低光强下,植物通过可对电子传递链的氧化还原状态做出响应的激酶和磷酸酶调控光系统Ⅱ捕光色素蛋白复合体(LHCⅡ)的可逆磷酸化,从而调节激发能在PSⅠ与PSⅡ之间的分配.植物的状态转换机制是植物适应光质等光环境变化的重要机制.本文综述了植物状态转换机制的研究进展,阐述了LHCⅡ的磷酸化及其在PSⅠ与PSⅡ两个光系统间的移动及其状态转换在植物适应光环境变化中的生理意义,并展望了今后的主要研究方向.     

应用非光化学淬灭初始变化率作为浮游植物光保护能力指标的可行性

在非光化学淬灭(Non-Photochemical Quenching,NPQ)荧光诱导的早期(1 min),NPQ随时间的变化率(NPQ/t)可作为衡量浮游植物光保护能力的指标,与常用的传统指标NPQm(最大NPQ)相比,这一新指标具有更易标准化、测量效率更高且包含的信息更丰富的优点。通过实验测量和理论推导证明了NPQ/t的常数性质,并通过可控光照条件下的室内培养实验证明了应用NPQ/t反映浮游植物光保护能力的合理性和有效性:NPQ/t和NPQm、光保护色素浓度呈线性相关,高光强下培养的藻类其NPQ/t高于低光强下培养的藻类,不同藻种之间的NPQ/t:扁藻(Tetraselmis chui)牟氏角毛藻(Chaetoceros mulleri)叉鞭金藻(Dicrateria inornata)。这一方法解决了野外实测研究中传统指标难以满足结果标准化和快速测量等要求的问题,对于推动浮游植物光保护生态学研究具有重要意义。     

不同叶龄杂交酸模叶片光合速率及PSⅡ光化学效率诱导对NaCl胁迫的响应

通过气体交换和叶绿素荧光分析方法研究了杂交酸模(Rumex K-1)幼叶、功能叶和衰老叶的光合速率及PSⅡ光化学效率诱导对NaCl胁迫的响应特征。结果表明,老叶的光合作用对盐胁迫最为敏感,幼叶次之,功能叶对盐胁迫的抗性最强。对照植株幼叶、功能叶和老叶的光合诱导速率相差不大,幼叶和功能叶光合诱导后期受气孔限制的影响。盐胁迫后幼叶和功能叶的光合诱导推迟,出现了一个新的光合适应阶段;老叶仍有部分电子传递功能,但已丧失碳同化能力。盐胁迫后气孔导度不再是叶片光合碳同化诱导过程的限制因素,不同叶龄叶片PSⅡ光化学效率启动所需时间远远小于光合速率启动所需时间,盐胁迫对叶片的PSⅡ光化学效率诱导过程几乎没有影响。     

增温和升高CO2浓度对桑树幼苗的生长和叶片品质的影响

研究了增温(+2 ℃)、升高CO₂浓度(+300 ppm)及同时增温和升高CO₂浓度(+2 ℃和+300 ppm CO₂)处理60 d后1年生桑树幼苗的形态、生物量积累及叶片品质的变化.结果表明: 与对照相比,增温显著增加桑树的基径、叶片数、总叶面积、叶干质量、叶干质量分数和可溶性蛋白含量,分别增加了9.9%、17.4%、23.0%、9.2%、10.1%和23.1%;升高CO₂浓度显著增加了桑树幼苗的茎干质量、根干质量和总干质量,比对照分别增加10.7%、15.9%和9.2%,但对幼苗的形态和叶片品质无显著影响;同时增温和升高CO₂浓度条件下,叶片数、株高、基径、总叶面积、叶干质量、根干质量、总干质量、叶片可溶性糖和粗蛋白含量均显著升高,与对照相比分别增加28.8%、9.1%、19.4%、32.6%、12.4%、17.2%、10.1%、45.8%和11.9%,但粗纤维含量显著降低16.8%.短期增温和升高CO₂浓度对桑树幼苗的生长发育和叶片品质有促进作用.     

高CO_2和UVR对叉节藻和刚毛藻生长及光化学效率的影响

为研究高CO2及UVR对大型海藻耦合效应的影响,实验选择红藻门可进行钙化的叉节藻(Amphiroa sp.)与绿藻门不具钙化能力的刚毛藻(Cladophora sp.)进行对比,探讨了高CO2与UVR对这两种藻生长及光化学效率的影响,并分析高CO2和UVR的耦合效应。结果表明,CO2浓度由360μmol/mol当前空气中CO2浓度)提高到1000μmol/mol培养73d后,叉节藻的生长下降了40.01%,而刚毛藻却增加了40.08%,UVR对叉节藻的光华学效率造成的抑制率增加了77.76%,对刚毛藻的抑制率增加了17.02%,这说明高CO2引起的海水酸化加剧了UVR对藻体的负面效应,且对具有钙化能力的叉节藻影响更显著。而叉节藻和刚毛藻之间的差异体现了藻体对海水酸化和UVR响应的种间特异性。     

季节性干旱对白皮乌口树(Tarenna depauperata Hutchins)水分状况、叶片光谱特征和荧光参数的影响

干热河谷稀树灌丛常绿植物能够忍受长达半年以上的季节性干旱胁迫,但对这些常绿植物响应干旱胁迫的生理生态机制研究很少。本研究以干热河谷稀树灌丛优势常绿植物白皮乌口树(Tarenna depauperata Hutchins)为研究对象,分别在雨季和干季测定其叶片的水势、压力-体积曲线、气体交换参数、叶片光谱特征以及叶绿素荧光和P700的光能分配。结果显示:受严重季节性干旱胁迫的影响,与雨季相比,干季的凌晨叶片水势(Ψpd)下降至-4.5 MPa,水分传导的叶比导率(KL)下降了49.5%,叶绿素反射指数(NDVI)下降了40.6%,花青素反射指数(ARI)上升至0.074(约为雨季的12.3倍),并且雨季和干季的叶片水势、水分传导效率、叶绿素含量和花青素含量均差异显著(P0.05)。与雨季相比,干旱导致光系统Ⅱ(PSⅡ)最大光化学量子效率(Fv/Fm)显著下降至0.72(P0.05),即PSⅡ发生光抑制,而光系统Ⅰ(PSⅠ)的活性(Pm)未发生明显变化;干季叶片的最大非光化学淬灭(NPQ)增加了31%,而激发的最大环式电子传递速率(CEF)下降了66%。表明长期干旱胁迫使CEF的激发受到强烈抑制,即光能捕获效率的降低和NPQ的增强促进了白皮乌口树在长期干旱胁迫下的光保护。     

静止和充气培养条件下短期紫外辐射对钝顶螺旋藻光化学效率的影响

为了研究短期太阳紫外辐射对钝顶螺旋藻的影响,作者将静止和充气培养的藻体,暴露在全波长太阳辐射PAB(PAR UVA UVB),去除UVB辐射PA(PAR UVA)及切断所有紫外辐射的光合有效辐射P(PAR)三种光处理条件下,测定了其光化学效率的变化。结果表明,紫外辐射(UVP)及光合有效辐射(PAR)均能导致钝顶螺旋藻的光化学效率降低,表现出了明显的光抑制,但是,UVR可导致更大程度的光抑制。充气培养条件下,与早晨(07:00)初始值相比,PAR导致了11%~20%的光抑制,而UVR(PAB-P)所产生的额外光抑制占9%~31%;静止培养条件下,UVR的存在使得螺旋藻的光化学效率趋近于零(无法检出)。在两种培养条件下,藻细胞所受最大光抑制均发生在中午,下午(17:00)表现出不同程度的恢复。紫外辐射使得类胡萝卜素及藻蓝蛋白与叶绿素a含量的比例增大。与PAB和P相比,PA处理使得螺旋藻类胡萝卜素和藻蓝蛋白与叶绿素含量之比明显升高,UVA可能会诱导类胡萝卜素及藻蓝蛋白的合成。     

Cd2+对紫球藻生长及光化学活性的影响

以紫球藻(Porphyridium purpureum)为供试材料, 研究了5个不同浓度的Cd2+对紫球藻的细胞密度、叶绿素a含量、藻红蛋白含量及ATP含量的影响, 以及对紫球藻的最大光量子产额(F_v/F_m)、实际光量子产额(YII)、相对电子传递效率(ETR)及非光化学淬灭(NPQ)的影响, 探讨了各荧光参数在不同浓度的Cd2+胁迫下的变化规律。研究结果表明, 在Cd2+胁迫的6d内, 紫球藻的生长速度显著下降, 且Cd2+的浓度越高, 生长速度下降越快; Cd2+胁迫显著的减少叶绿素a、藻红蛋白及ATP含量, 且浓度越高, 减少的幅度越大; 在Cd2+浓度低于200 μmol/L时, 紫球藻的叶绿素荧光参数F_v/F_m、YII及ETR呈现先下降后上升的趋势,而且随着胁迫时间的延长, 下降幅度逐步增大; NPQ在低浓度下(<200 μmol/L)呈现显著上升趋势, 高浓度下(>500 μmol/L)呈现显著下降趋势。因此, 水体中浓度超过50 μmol/L的Cd2+就会显著影响紫球藻的生长及光化学活性, 水生环境中不断累积的Cd2+将会对紫球藻的生态平衡产生影响。     

Plants regenerated from mesophyll protoplasts of white mulberry

INTRODUCTIONProtoplastcultureis0neofthen1ostrapidlydevel0pingareasinp1anttissueculture,becauseofitsimportancei11plantgeneticmanipulation.However,sofar,thereareonlyafewforesttreespeciesinwhichplantregenerationfr0mprotoplastshaJsbeensuccessful,namelyLiriode…     

模拟干旱胁迫下构树和桑树的生理特征比较

在不同浓度聚乙二醇(PEG 6000)的处理下,测定构树和桑树的碳酸酐酶活性、光响应曲线、二氧化碳响应曲线和叶绿素荧光等指标,比较它们的抗干旱能力.结果表明:(1)构树的碳酸酐酶活力变化不显著,而桑树的碳酸酐酶活力不同的PEG 6000浓度间差异较大.(2)构树的净光合速率受PEG 6000的影响较小,而桑树受到抑制较...     

Quantitative Determination of Xylooligosaccharides by Gas-liquid Chromatography of the Alditol Trifluoroacetates

A gas chromatographic method for the quantitative determination of xylooligosaccharides up to the tetraose is described. For analysis, saccharides are reduced to the corresponding alditols with sodium borohydride and subsequently converted into their trifluoroacetyl (TFA) derivatives with sodium trifluoroacetate and trifluoroacetic anhydride (TFAA) at 70°C for 15 min. Excess TFAA is evaporated to dryness, then the TFA derivatives are dissolved in methylene chloride for injection into the chromatograph. Quantitative data are obtained in an overall working time of 2~3 hr per sample. The average recoveries inherent in this method are comparable to those obtained by paper chromatography.     

Photoinhibitory responses of the epiphytic bromeliad Guzmania monostachia during the dry season in Trinidad maintain photochemical integrity under adverse conditions

The C₃–CAM epiphytic bromeliad Guzmania monostachia var. monostachia may be exposed to high incident photosynthetically active radiation (PAR) during the dry season in Trinidad, and resultant variations in photochemical efficiency have been investigated for ‘exposed’ (receiving ～100% incident PAR), ‘semi-exposed’ (～60% PAR) and shaded populations under natural conditions. The more succulent leaves of the plants growing fully exposed within the canopy had higher overall CAM activity (measured as ΔH⁺, the dawn-dusk titratable acidity), a smaller proportion of chlorenchyma and lower total chlorophyll content. There was a gradation of morphological and physiological characteristics between these and shaded leaves. Diurnal time-courses of photosynthetic light responses (as O₂ evolution) showed marked variations in apparent quantum yield (AQY) and light-saturated rates for both exposed and semi-exposed populations, dependent on incident PAR during the day. Similar measurements of photosystem II fluorescence characteristics showed that F_v/F_m declined from 0·70 to 0·42 at midday for exposed plants (on a day when total incident PAR was 44 mol photon m^?2), indicating non-photochemical quenching (qNP) of photosynthesis. However, in contrast to AQY determinations, F_v/F_m recovered during the afternoon. The decrease in F_v/F_m was reduced from 0·72 to 0·64 under 24 mol photon m^?2 d^?1. The long–term recovery of photo-synthetic efficiency was assessed for exposed plants placed under three shading regimes (60, 30 and 3% of incident PAR) over a 17-d period. During this time, total chlorophyll content increased from 228 to 515 and 585 μg g^?1 fresh weight (for 3 and 30%, respectively) and chlorophyll a:b declined. While AQY recovery was much longer under the lowest PAR (17d), under 30% PAR both AQY and F_v/F_m had recovered after 2d shading. The differences between timing of recovery for F_v/F_m during diurnal time courses and in the long term suggest that, while quenching associated with PSII recovers rapidly, enzyme activation and/or protein synthesis of other photosynthetic components may be limiting under low PAR. However, it is suggested that the occurrence of qNP on a daily basis may preclude long-term photoinhibitory damage under natural conditions during the dry season.     

温度升高对高光强环境下蛋白核小球藻(Chlolorella pyrenoidosa)光能利用和生长的阻抑效应

以蛋白核小球藻（Cholorella pyrenoidosa）为实验材料,研究了温度变化对不同光照水平下蛋白核小球藻的光能利用和生长的影响,以明确光照强度对微藻的光能利用和生长的影响是否因温度不同而发生变化。实验中共设置了3个光照强度水平（50,150,300μmol·m^-2s^-1）和2个温度水平（15℃,25℃）。实验结果表明,不同光照水平下小球藻叶绿素荧光的非光化学淬灭（NPQ）大小与温度有关,光照强度为150,300μmol·m^-2s^-1时,温度升高使小球藻叶绿素荧光NPQ提高,并且光照强度越高小球藻叶绿素荧光NPQ增大越多,50μmol·m^-2s^-1光照强度下温度升高对叶绿素荧光NPQ没有影响。实验发现,25℃培养温度下小球藻的光合电子传递速率（ETR）随光照强度增高而上升的速率要低于15℃时小球藻ETR上升的速率;随着光照强度增高,温度升高使小球藻ETR降低程度增大。实验结果还表明,15℃时小球藻培养液叶绿素a浓度随光照强度升高而增高,300μmol·m^-2s^-1培养光强下具有最高的叶绿素a浓度。但在25℃时,光照强度升高叶绿素a浓度并不一定增高,300μmol·m^-2s^-1光照强度下的叶绿素a浓度比150μmol·m^-2s^-1光照强度下要低。本研究表明,温度升高增大了高光照水平下蛋白核小球藻对光能的热耗散,使光照增强对小球藻生长的促进作用减弱。由于温度升高对小球藻光能利用和生长的阻抑作用,小球藻生长的适宜光照水平因温度升高而降低。     

干旱胁迫对条墩桑生物量分配和光合特性的影响

以1年生红皮花桑为材料,采用盆栽的方法,研究了不同水分条件下条墩桑幼苗的生物量、荧光参数、净光合速率、气孔导度、蒸腾速率及水分利用效率的变化.结果表明： 随着干旱胁迫程度的增加,植株地上部分的生物量和总生物量逐渐降低,但光合产物向根部的分配比例逐渐增大,根冠比逐渐增加;叶片的荧光参数F_o、F_v和F_v/F_m逐渐降低;气孔导度、蒸腾速率、净光合速率和水分利用效率逐渐下降.     

Induction of haploid callus and embryogenesis in in vitro cultured anthers of mulberry (Morus indica)

Anthers of Morus indica L., with microspores at the uninucleate stage were cultured; and the influence of temperature and kinetin pretreatment on induction of androgenic calluses was examined. The effects of various pretreatments revealed that 24 h cold pretreatment increased the percentage of cultures inducing callus. First microspore division was observed after 16 to 20 days of culture. Th anthers split and developed embryogenic calluses on MB medium supplemented with NAA (0.5 mg l^–1 and BA (1.0 mg l^–1)) using 8% sucrose. Rhizogenesis was induced on medium supplemented with NAA and BA (each 0.5 mg l^–1) with reduced myo-inositol (75 mg l^–1). Cytological study of induced roots confirmed the haploid nature of calluses. Different type of embryos were initiated upon transfer of calluses to medium supplemented with NAA, BA (each 0.5 mg l^–1), 2,4-d (1.0 mg l^–1) and PVP (600 mg l^–1). These embryoids further developed roots on removal of 2,4-d from the medium and developed precociously without developing cotyledons and formed elongated shoots.Abbreviations BA 6 benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - FAA formalin: Acetic acid: Alcohol - GA₃ gibberellic acid - IBA indole-3-butyric acid - MB modifed Bourgin (Qian et al., 1982) - NAA 1-naphthalene acetic acid - PVP polyvinylpyrrolidone - RFS-135 rainfed selection 135 - SE standard error     

Induction characteristics and response of photosynthetic quantum conversion to changes in irradiance in mulberry plants

A study was conducted, using rapid time course of chlorophyll (Chl) fluorescence parameters, and light-response curves of Chl fluorescence parameters, to determine the induction requirements and response of photosystem II (PSII) photochemistry and non-photochemical reactions after changes in irradiance in greenhouse mulberry plants. The induction of PSII photochemistry rapidly approached to steady state after leaves were treated from darkness to low irradiance (LI). When irradiance of leaves changed from darkness to high irradiance (HI), a biphasic induction was observed. A slight photoinhibition occurred in the leaves exposed to sunlight coming to the greenhouse, whereas a chronic photoinhibition occurred in the leaves fully exposed to sunlight outside the greenhouse. The chronic photoinhibition was demonstrated by sustained reduction of maximal quantum yield of PSII photochemistry (Fv/Fm). Moreover, the leaves of mulberry plants in greenhouse were sensitive to abrupt changes in irradiance and the sensitivity of leaves suffered in a short-term (1h) high light treatment was reduced, based on the changes in photosynthetic quantum conversion. These results demonstrated an inducible response of photosynthetic quantum conversion to changes in irradiance in mulberry.     

Effect of soil strength on root growth under different water conditions

The objective of this study was to determine the effects of soil water and soil strength on root growth in situations where the individual effects of both of these factors were important. Three grain legumes were grown from pre-germinated seeds for five days on 50-mm compacted columns of two major soils of Sri Lanka. Four or five levels of bulk density (1.1 to 1.8 Mg.m^–3) and five or six levels of matric potential (–0.02 to–2.0 MPa) were used.Soil strength and matric potential effects on root growth were independently significant for most crop and soil combinations. Under high (wet) matric potential (>–0.77 MPa) soil conditions, the effect of soil water on root growth was evident only in its effect on soil strength. Bulk density had a significant effect on root growth independent of soil strength and matric potential in three cases.For all crops and soils, root penetration was 80% of the maximum or greater when the average soil strength (soil water not limiting) was 0.75 MPa or less, and when the average matric potential (soil strength not limiting) was –0.77 MPa or greater (wetter). Root penetration was 20% of the maximum or less when the soil strength was greater than 3.30 MPa (soil water not limiting), and when matric potential (soil strength not limiting) was less than –3.57 MPa. The use of pre-germinated seeds, which contained imbibed water, combined with a lack of water loss from the closed chambers containing the plants is the probable cause for the very low (–3.57 MPa) matric potential that allowed root growth at 20% of the maximum.