不同温度下CO2浓度增高对坛紫菜生长和叶绿素荧光特性的影响

大气CO2浓度升高对海藻的影响已有许多的研究报道,但鲜见有关温度与CO2相互作用的研究.在4种条件下对坛紫菜进行连续通气培养:(1)15℃+ 390tmol/mol CO2,(2) 15℃+700 μmol/mol CO2,(3) 25℃+390 μmol/mol CO2,(4) 25℃+ 700 μmol/mol CO2.从而探讨这种南方海域重要栽培海藻种类的生长和叶绿素荧光特性对温度和CO2相互作用的响应.结果表明:CO2对坛紫菜的生长的影响具有温度依赖性,在低温生长条件下提高CO2浓度更有利于坛紫菜的生长.CO2对坛紫菜叶绿素a(Chlorophyll a,Chl a)和类胡萝卜素(Carotenoid,Car)的促进作用远大于温度对其产生的影响.相对于25℃的生长温度而言,15℃生长温度下的坛紫菜表现出较高的最大相对电子传递速率(rETRmax),表明坛紫菜在低温环境下有较高的光合潜力;而CO2对坛紫菜的rETRmax没有明显影响.对于在不同测定温度下的光合荧光特性而言,在10-30℃测定温度范围内,在各生长条件下的海藻的rETRmax、光能利用效率(α)和最大光化学量子产量(Fv/Fm)随温度的升高变化不明显;但在较高测定温度下(≥30℃),上述荧光参数显著下降,说明高温易引发海藻光能利用效率和光合能力的下降,这可能与光系统(PS)Ⅱ反应中心活性下调有关.同时,当测定温度大于30℃时,15℃生长条件下的坛紫菜的rETRmax、α和F/Fm值下降趋势远大于25℃生长条件下的坛紫菜的值,表明在低温生长条件下的坛紫菜对短期高温胁迫的适应能力较弱;而在高CO2浓度生长条件下的坛紫菜的rETRmax总是低于正常CO2浓度生长下的值,说明CO2浓度升高会抑制坛紫菜在短期高温条件下的光合电子传递能力.     

银杏种子生长特性及其生理变化的研究

从纵径、横径、体积、重量等方面分析了银杏种子的生长特性及其生长过程中水分、糖类物质、脂肪酸、氨基酸的生理变化.结果表明,银杏种子的生长过程曲线为典型的单“S”型,种子纵径、横径、体积、重量、绝对含水量随生长过程呈“S”形变化.各种生理物质含量随种子生长过程呈规律性变化,且各有其特点.其中在种子生长后期糖类物质总量表现出上升的趋势,表明它们是种子中主要的营养储存物质.成熟种子含淀粉8.4%、葡萄糖6.7%、果糖4.2%、多糖0.02%、二糖0.01%;含肉豆蔻酸10.6%、棕榈烯酸4.1%、亚麻酸2.4%、硬脂酸1.9%、油酸1.1%、亚油酸0.4%.银杏种子富含15种氨基酸,成熟种子中总含量为1.56g·100g^-1FW,其中以赖氨酸、天门冬氨酸、丙氨酸、精氨酸、组氨酸、谷氨酸、异亮氨酸的含量较高,它们的含量依次为0.287%、0.163%、0.136%、0.133%、0.123%、0.115%、0.095%.     

不同温度与CO2浓度对坛紫菜生长和光合作用温度反应特性的影响

论文研究了不同CO₂浓度(390 μL/L和700 μL/L)和温度(15℃和25℃)对坛紫菜(Porphyra haitanensis)生长与光合作用-温度反应特性的影响。结果表明,相对于25℃生长的海藻,15℃生长的海藻具较高的相对生长速率和色素含量(叶绿素和类胡萝卜素),并且在高CO₂下增加趋势更显著。在两种CO₂浓度下,15℃生长的坛紫菜可溶性蛋白质和可溶性碳水化合物含量高于25℃生长的坛紫菜。低温10℃胁迫下,15℃生长的坛紫菜最大光量子产量(Fv/Fm)、光能利用效率(α)及非光化学淬灭(NPQ)相对于25℃生长的坛紫菜更稳定;高温35℃使得坛紫菜rETRmax、Fv/Fm、α值均下降,这种下降的程度在15℃生长藻中比25℃生长的藻更大;此外,15℃生长条件下,高CO₂生长的坛紫菜受35℃高温胁迫时的Fv/Fm和α下降程度小于正常空气生长下的坛紫菜。高温40℃使坛紫菜 rETRmax、Fv/Fm、α、NPQ及qP均急剧下降。结果表明高CO₂使得坛紫菜耐高温性能提高。     

旺长期遮光及光照转换对不同肥料条件下烟草叶片光合特性的影响

采用盆栽方法研究了旺长期遮光及光照转换对不同肥料条件下烟草叶片光合速率(Pn)与荧光特性的影响。结果表明,遮光促进两种肥料条件下烟草叶片叶绿素(Chl)和类胡萝卜素(Car)含量的积累,却降低它们的Pn。其中施无机肥的烟草叶片Chl含量增加较多,而50%无机肥+50%饼肥配施烟草叶片的Car增幅显著,从而,施无机肥烟草叶片Chl/Car上升,而无机肥+饼肥配施烟草叶片Chl/Car却下降。无论从自然光转至遮荫条件下还是从遮荫条件转至自然光下,两种肥料条件下生长的烟草叶片的Pn、实际光化学效率(ΦPSⅡ)、最大光化学效率(Fv/Fm)及光化学猝灭系数(qP)均急剧下降,但与施无机肥相比,无机肥+饼肥配施烟草叶片保持较高的Pn、ΦPSⅡ、Fv/Fm、及qP,可能是饼肥促进了栽培条件下烟草植株的光生态适应性。     

水体无机碳条件对常见沉水植物生长和生理的影响

为了解水华引起的水体无机碳变化对沉水植物生长的影响,对8种沉水植物:金鱼藻、穗花狐尾藻、篦齿眼子菜、光叶眼子菜、微齿眼子菜、伊乐藻、菹草和黑藻在不同无机碳浓度下的生物量、株高、叶绿素以及光合和呼吸速率进行了比较研究.结果表明8种沉水植物均能利用HCO3-作为光合无机碳源,在1.5 mmoL/L外源HCO3-浓度下能促进金鱼藻、菹草和伊乐藻的生长,提高其光合速率;在2.5 mmol/L外源HCO3-浓度下能促进狐尾藻、光叶眼子菜、黑藻、微齿眼子菜和蓖齿眼子菜的生长,提高其光合速率.在CO32-为优势碳源时,8种沉水植物表现出不同的适应性,发现微齿眼子菜、篦齿眼子菜和黑藻在整个实验范围内生长未受抑制,且在不同浓度下表现生长和光合速率的促进,说明这三种沉水植物对[HCO3-]/[CO32-]比值和pH具有较广适应范围.而当CO32-成为优势碳源时,金鱼藻和伊乐藻的生长受到抑制,狐尾藻、菹草和光叶眼子菜均死亡,表明[HCO3-]/[CO32-]比值和pH是这5种沉水植物生长的重要限制因子.     

低浓度CO2对水车前和黑藻光合特性的影响

本实验通过对沉水植物水车前(Ottelia alismoides)和黑藻(Hydrilla verticillata)进行低浓度CO2诱导,研究其光合特性的变化.研究显示,诱导后,水车前的PEPC/Rubisco活性比值由0.45上升到4.17,黑藻由0.47上升到4.17,两种植物的C4途径光合酶PEPC和NAD-M...     

低浓度CO2对水车前和黑藻光合特性的影响

本实验通过对沉水植物水车前（offelia alismoides）和黑藻（Hydrilla verticillata）进行低浓度C02诱导,研究其光合特性的变化。研究显示,诱导后,水车前的PEPC／Rubisco活性比值由0．45上升到4．17,黑藻由0．47上升到4．17,两种植物的C4途径光合酶PEPC和NAD—ME的活性升高了10倍左右,其他C4光合酶如NAD—MDH和PPDK的活性也大幅升高;诱导后,水车前和黑藻的其他光合特性也发生了显著变化：净光合速率比对照分别提高了50．8％和74．1％,O2对处理组光合速率的抑制分别为对照组的35％和60％,叶绿素荧光基本参数也有显著性变化。研究结果表明,经低浓度C02诱导,水车前和黑藻光合碳同化途径可能由C3转变成为C4。     

烟草花叶病毒对烟草叶片光合特征和POD表达的影响

以烤烟(Nicotiana tabacum L.)品种'中烟5号'为实验材料,对烟草健康株与感染烟草花叶病毒(TMV)株的叶绿素、光合速率、光合速率对光强的响应曲线、光暗反应荧光特征、POD活性及其表达等进行研究,以探讨TMV感染对烟草植株生理生态特征的影响.结果显示:病株的叶绿素a(Chl a)和叶绿素b(Chl b)含量显著低于健康株,但Chl a/Chl b值基本相同;病株暗中初始荧光(F0)、暗中最大荧光(Fm)、暗中可变荧光(Fv)、光下初始荧光(F0′)、光下最大荧光(Fm′)、光下可变荧光(Fv′)、非光化学猝灭系数(NPQ)、PSⅡ捕光效率(Fv′/Fm′)、PSⅡ实际光化学效率(ФPSⅡ)及光饱和点显著低于健康株;净光合速率在光强较大(＞1 500 μmol·m-2·s-1)时病株比健康株低,光强适中(1 500 μmol·m-2·s-1左右)时两者相差不大,光强较弱(＜1 500 μmol·m-2·s-1左右)时病株比健康株高;病株叶片的过氧化物酶(POD)活性显著升高,POD同工酶中一些大分子量蛋白分子表达量加大.研究表明,感染TMV使烟草植株对光抑制更为敏感,叶片的荧光激发能力和热耗散能力下降,PSⅡ反应中心捕光效率和光化学反应效率降低,光合电子传递能力和碳同化能力受到抑制;POD活性提高和表达量增加可能是诱导烟草抗病性的一个关键生理过程.     

光照和氮营养对水曲柳苗木光合特性的影响

采用室内沙培方式,设计不同光强(2水平)和N浓度(4水平)处理,探讨1年生水曲柳幼苗叶片光合速率和荧光参数对环境变化的生理响应.结果表明:与全光照相比,遮光处理使苗木叶片最大光合速率(Amax)、光补偿点(LCP)以及光化学猝灭系数(qP)明显下降,但使表观量子效率(AQY)、最大荧光(Fm)和最大光化学效率(Fv/Fm)明显增加.同时,苗木叶片单位面积的叶绿素a、类胡萝卜素、总叶绿素含量以及叶绿素a/b在遮光条件下较低.2种光强下的Fm、Fv/Fm、ψpsⅡ和qP均随着供N浓度的增加而显著增加(P＜0.05),其中ψpsⅡ在低N时增加较快而高N时较慢,甚至略有下降.光强和N浓度在水曲柳苗木叶片Fm、ψpsⅡ、Fv/Fm、qN以及qP上均具有显著的交互作用(P＜0.05).     

光照、温度和pH对雨生红球藻光合特性的影响

采用测定光合放氧速率和荧光动力学的方法,研究分析了光照强度、温度和pH对雨生红球藻Haematococcus pluvialis CG-11绿色游动细胞阶段光合作用特性的影响。结果表明,H. pluvialis CG-11光合作用的饱和光强为109.1 μmol/m2·s,最大光合放氧速率为75.9 μmol O2/mg Chla·h;适宜的生长温度范围在25－30℃之间,温度在25℃时光合速率最大;pH在7.5－8.0范围内,光合效率较高,在pH为7.5时放氧速率最大,为75.5 μmol O2/mg Chla·h。在实验pH条件下,H. pluvialis CG-11叶绿素荧光动力学参数呈现出相似的趋势,在6.0－7.5范围内,Fv/ Fm、Fv/ F0、ΦPSⅡ和ETR值随pH升高而增大,pH为7.5时达到最大值,pH超过7.5时,Fv/ Fm和Fv/ F0值明显下降,而ΦPSⅡ和ETR的下降趋势不明显。     

北京市湿地削减大气细颗粒物PM_(2.5)功能

基于野外观测与遥感反演相结合的方法,在点位和区域尺度上研究北京城区湿地在削减大气细颗粒物PM2.5中的作用。结果表明,北京城区湿地能够显著削减周边大气环境中的细颗粒物浓度,其中翠湖湿地附近的PM2.5浓度显著低于周边裸地(P0.05),可削减空气中17%的PM2.5,降低幅度最高可达50%。而且,湖库湿地在削减PM2.5浓度方面作用更加显著,优于河流湿地(P0.05)。北京市PM2.5浓度的空间分布格局表现出西北东南、郊区城区的空间分布规律。因此,在未来的湿地建设中应合理选择湿地类型,更多地考虑紧凑型湿地如湖库湿地的建设,科学配置湿地和植物资源,使湿地更加有效地发挥其增湿、促使局地流场发生变化的作用,最终改善局地微气象条件,削减大气细颗粒物,缓解城市雾霾天气。研究结果为北京市湿地保护管理、规划和布局以及及时制定控制PM2.5的政策和措施提供了科学依据。     

Effect of external pH on inorganic carbon assimilation in unicellular marine green algae

Carbonic anhydrase (CA) induction has been studied in three marine green algae under acidic (pH 4.5) or alkaline (pH 8.0) conditions. An inhibition of the induction of the external CA in acidic conditions, similar to that observed in some freshwater green algae, could be observed in only Chlorella saccharophila. In the two other species, Chlorococcum littorale and Stichococcus bacillaris, no significant difference in CA induction was found under two pH conditions. The exact function of the external CA of C. saccharophila remains unclear, since cells grown under acidic conditions (under which this enzyme is repressed) possess the same abilities to use inorganic carbon (Ci) as alkaline‐grown cells. Internal pH values were not modified by the pH of the medium used to cultivate C. saccharophila. Regardless of the growth conditions, activities related to carbon fixation, that is, photosynthetic oxygen evolution, Ci uptake and assimilation were enhanced when the measurements were performed at acidic pH. This indicates that this marine alga is able to use CO₂ more efficiently than HCO₃^?. No evidence could be found for a specific Ci uptake and assimilation system in the acid‐grown cells.     

Influence of carbon supply on the circadian rhythmicity of photosynthesis and its stimulation by blue light in Ectocarpus siliculosus: clues to the mechanism of inorganic carbon acquisition in lower brown algae

Stimulation or light-saturated rates of photosynthesis in Ectocarpus siliculosus (Dillwyn) Lyngb. by blue light was eliminated by increasing dissolved inorganic carbon (DIC) or by lowering pH in natural seawater. The amplitude of the circadian rhythm of photosynthesis was also diminished under these conditions, and the pH compensation points in a closed system were higher in the presence of blue light and during the circadian day. These observations suggest that blue light and the circadian clock regulate the activity of a carbon acquisition system in these plants. The inhibitor of external carbonic anhydrase, acetazolamide, reduced overall rates of photosynthesis by only about 30%, but ethoxyzolamide suppressed the circadian rhythm of photosynthesis almost completely and markedly reduced the duration of responses to blue light pulses. Similar patterns were obtained when photosynthesis was measured in strongly limiting DIC concentrations (0–0.5 mol m^?3). Since blue light stimulated photosynthesis under these conditions of strong carbon limitation, we suggest that blue light activates the release of CO₂ from an internal CO₂ store. We propose a metabolic pathway with similarities to that of CAM plants. Non-photosynthetic fixation leads to the accumulation of a storage metabolite. The circadian clock and blue light control the mobilization of CO₂ at the site of decarboxylation of this metabolite. In the presence of continuous blue light the pathway is proposed to cycle and act as a pump for CO₂ into the chloroplasts. This hypothesis helps to explain a number of previously reported peculiarities of brown algal photosynthesis.     

Effect of red and blue light on acclimation of <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> to CO<Subscript>2</Subscript>-limiting conditions

Effects of red (RL) and blue (BL) light on acclimation of the unicellular green alga Chlamydomonas reinhardtii to the low level of ambient CO₂ were studied. C. reinhardtii cells grown at 5% CO₂ and under white light (170 μmol/(m²s)) had a relatively low activity of extracellular carbonic anhydrase (CA), a low affinity for dissolved inorganic carbon, and a low rate of photosynthesis under CO₂-limiting conditions. These cells readily started acclimation to the low CO₂ concentration when they were exposed to atmospheric air (～ 0.03% CO₂) under RL or BL (150 μmol/(m² s) each). The acclimation was manifested in a significant increase in the CO₂-limited rate of photosynthesis, the affinity for dissolved inorganic carbon, and the extracellular CA activity with no difference between RL-and BL-cells. Independently of light quality, the acclimation was completed for 5–7 h after cell exposure to air. As is evident from RL-and BL-dependent changes in the sum of chlorophylls and chlorophyll a/b ratio, transfer of C. reinhardtii cells to air and RL or BL triggered also the process of algal photosynthetic adaptation to light quality. However, this process did not interfere with acclimation to low CO₂ because started 4 h later. On the basis of similarity in the low CO₂-induced changes under RL and BL, it is concluded that acclimation of C. reinhardtii to CO₂-limiting conditions does not depend on light quality.     

Influence of carbon supply on the stimulation of light-saturated photosynthesis by blue light in Laminaria saccharina: implications for the mechanism of carbon acquisition in higher brown algae

In saturating irradiances of red light, photosynthesis of Laminaria saccharina (L.) Lamouroux was stimulated by low irradiances of continuous blue light only when the supply of dissolved inorganic carbon (DIC) was limiting. The degree of this stimulation was inversely proportional to the logarithm of the concentration of free CO₂, whether this was adjusted by varying the total DIC or the pH at a given DIC concentration. The final pH reached in a closed system was higher in blue light than in red light. Both acetazolamide and ethoxyzolamide suppressed the responses to blue light almost completely, but reduced photosynthesis in red light by only 30%. Buffering the pH of the seawater also suppressed the stimulation of photosynthesis by blue light without affecting the photosynthetic rate in red light. The transient stimulation of O₂ evolution by a blue light pulse was not accompanied by a corresponding increase in CO₂ consumption. These observations could be explained if, in analogy to the mechanism proposed for Ectocarpus (Schmid, Mills & Dring 1996, Plant Cell and Environment 19,373–382, this issue, accompanying paper), photosynthesis was supported by a blue-light-activated release of CO₂ from an internal store. We suggest that the store is located in the vacuoles of the cortical tissue of the blades. The main photosynthetic tissue, however, is in the overlying meristoderm, and blue-light-activated mobilization of the store could stimulate O₂ evolution only if periplasmic carbonic anhydrase was available to facilitate CO₂ uptake from the cortex.     

贵州玉舍国家森林公园三种造林植物光合生理特征研究

该研究以贵州省玉舍国家森林公园三种造林植物水榆花楸(Sorbus alnifolia)、近轮叶木姜子(Litsea elongata var.subverticillata)、山杨(Populus davidiana)为对象,测定其光合作用日变化和叶绿素荧光、叶片碳酸酐酶活力以及叶绿素含量和稳定碳同位素组成,并测定了植物生长地土壤理化性质,综合分析了三种植物的喀斯特生态适生能力。结果表明:水榆花楸和山杨的净光合速率明显高于近轮叶木姜子,这与其较高的气孔导度和光化学效率有关;而山杨因具有较高碳酸酐酶活力和叶绿素含量,表现出较高的水分利用效率。水榆花楸和山杨的光合生产能力较高,且受光强和温度限制,可在光照较好的地区大范围种植,作为速生植物来加快经济收入并改造当地脆弱生境的优选植物;近轮叶木姜子作为中药型植物,且在低光强下能够保持最大生长能力,可在光照条件不好的地区优先种植,既增加植被覆盖率又增加经济收入。该研究结果为山地森林资源的保护和开发利用提供了科学依据。     

Photosynthesis of Ulva fasciata. IV. pH, carbonic anhydrase and inorganic carbon conversions in the unstirred layer

Abstract. The common marine macroalga Ulva was found to have a surface pH of about 10 during photosynthesis. Under such a condition, the equilibrium CO₂ concentration within the unstirred layer would be below reported CO₂ compensation points, and dehydration of HCO₃ could not occur. Even at a compensation point approaching zero, uncatalysed rates of HCO₃ to CO₂ conversion within the unstirred layer volume could not support photosynthetic rates as measured under stirred conditions in the presence of a carbonic anhydrase inhibitor. Based on this, it is concluded that Ulva takes up HCO₃. It is likely that HCO₃ uptake leads to high internal CO₂ levels which, in turn, suppress photorespiration and thus cause this plant's efficient gas exchange features. Carbonic anhydrase activity was measurable only in plant extracts. However, inhibitor studies suggest the presence of a surface enzyme. The possible functions of extracellular carbonic anhydrase in Ulva are assessed in terms of CO₂ hydration during emergence and a possible HCO₃, transport system.     

水淹导致皇冠草光合机构发生变化并加剧其出水后光抑制

通过气体交换和叶绿素荧光等方法研究了水淹及胁迫解除后皇冠草不同功能叶的光合特性及光抑制的变化.结果表明:与对照相比,气生叶(全淹组淹水前形成的功能叶)在水淹条件下叶片大小和气孔没有明显变化,但沉水叶(全淹组淹水后新生的功能叶)的叶面积增加,气孔变小,上表皮气孔密度增加.水淹导致气生叶碳同化能力、光化学效率和叶绿素含量下降.沉水叶在发育过程中碳同化能力、光化学效率和叶绿素逐渐升高.气生叶和沉水叶出水后其活体叶片在强光下的相对含水量急剧下降,发生明显的光抑制;而弱光下无明显光抑制发生.出水后离体叶片强光照射下6h后两种功能叶均发生严重光抑制,且弱光下不能恢复.因此,可以认为淹水条件下,沉水叶上表皮气孔密度的增加使其蒸腾速率提高;沉水叶较强的碳同化能力和增加的叶面积是确保其植株水下生存的重要因素;强光使气生叶和沉水叶出水后均发生严重光抑制,导度和蒸腾速率提高导致的叶片失水则加剧了这一过程,两者共同作用导致自然条件下两种功能叶的出水死亡.