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^-2•s^-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^-2•s^-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^-2•s^-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^-2•s^-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^-2•s^-1光照强度下的叶绿素a浓度比150μmol•m^-2•s^-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。      

不同光照强度和湿度以钗石斛生长的影响

为了系统地研究不同光照强度下湿度以金钗石斛（Dendrobium nobile)生长的影响,在金钗石斛分蘖期,于80μmol.m^-2.s^-1、160μmol.m^-2.s^-1、320μmol.m^-2.s^-1、640μmol.m^-2.s^-1的不同光强下,各设置5个温度（15℃、20℃、30℃、35℃）梯度对石斛进行处理。结果表明：石斛的生长与代谢随温度由低到高,表现出弱－强－弱的变化规律℃;80μmol.m^-2.s^-1与640μmol.m^-2.s^-1的中、强光照下,25℃处理石斛的生长优势尤为明显;不同光强下,石斛鲜重的大多以25℃处理更快,繁殖力则以20℃和25℃处理较高;各光强下的MDA含量随温度升高而先降后升,且均以25℃最低;可溶性蛋白质、可溶性总糖及叶绿互含量则表现出随温度由低到高而先增后减的趋势,其含量最高点均出现在25℃左右;净光合速率和叶绿素含量随光强和温度的变化趋势基本一致;各种光强下的暗呼吸速率均随温度升高而增大。因此,在不同的光照条件下,石斛生长的适宜温度均在25℃左右。光温处理引起石斛生理生化过程明显的相应变化表现出：高温和弱光照条件有利于石斛的株高增长,但不利于产量和质量提高;石斛的生长与MDA含量呈显著负相关（r80=-0.9082、r160=0.8892、r320=-0.8075、r640=-0.8586),与可溶性糖含量一定正相关（r80=-0.7673、r160=0.8892、r320=0.8179、r640=0.9278）,并且石斛的生长与可溶性蛋白含量、叶绿素含量、光合速率之间的变化趋势基本一致。     

林床清理对落叶松(Larix gmelinii)人工林土壤呼吸和物理性质的影响

林下可再生生物质资源的利用是当今森林资源利用的热点,通过林床清理可以获得廉价可再生生物质资源,但其对林分土壤碳收支的影响尚不清楚。运用红外气体分析法（IRGA法）连续两年观测了林床清理对落叶松（Larix gmelinii）人工林土壤呼吸及物理性质的影响,并估算了林床清理生物质资源利用对落叶松人工林碳收支的影响。结果表明：林床清理能够降低落叶松人工林的土壤呼吸,2a的平均值由2．20μmol·m^-2s^-1降低到1．18μmol·m^-2s^-1,平均降低幅度1．02μmol·m^-2s^-1,年呼吸总量由41．2μmol·m^-2a^-1降至22．4μmol·m^-2a^-1,而且,使土壤呼吸Q10值从2．33降低到2．22,R0值从0．61μmol·m^-2s^-1降至0．36μmol·m^-2s^-1;林床清理能够使林床土壤温度冬季低于对照,而夏季则有相反趋势,清理使得林床土壤湿度变化幅度加大,而且秋季和春季较对照低,而夏季偏高;林床清理使得表层土壤容重要比对照未清理样地高53％（P〈0．05）,土壤非毛管孔隙度比未处理样地低49．5％（P〈0．001）,毛管孔隙度较对照未清理降低约15％（P〈0．001）。林床清理导致林下生物质资源所储藏的碳非呼吸性释放约175．0mol·m^-2,当考虑到林床清理导致的土壤呼吸的降低作用时,所测定的2a内土壤净碳支出由175．0mol·m^-2降低至137．4mol·m^-2。林床清理措施增加生物质资源利用和其所导致的土壤呼吸释放减少,能够减少非冉生资源利用导致的碳释放压力。但仍然需要注意到林床清理使得土壤物理结构发生改变,可能不利于落叶松的生长和落叶松林生态系统的稳定。     

低磷和高照度光下两种不同磷效率玉米幼苗的几种光合参数变化

以完全培养液（HP,1000μmol·L^-1KH2PO4）培养15d的玉米自交系KH5（磷高效）和SD502（磷低效）幼苗转入低磷（LP,5μmol·L^-1KH2PO4）条件下培养20d后,检测叶中几种与光合作用有关参数的结果表明,低磷下两自交系玉米叶中无机磷含量、植株生物量和叶片的净光合速率（Pn）均下降,KH5的降幅小于SD502。两自交系玉米叶片以高照度光（1600μmol·m^-2·s^-1）照射1h后,叶片的PSII实际光化学效率（ФPSII）、PSII最大光化学效率（Fv/Fm）和表观光合电子传递速率（ETR）均下降,而初始荧光（F0）、非光化学猝灭（NPQ）和天线热耗散（HDR）均升高。在强光胁迫过程中,玉米幼苗叶片发生光抑制,自交系SD502在低磷下的光抑制比KH5严重。     

蚊子花的组织培养与快速繁殖

1植物名称蚊子花（Lopezia cordata Hornem．）。 2材料类别茎段和顶芽。 3培养条件基本培养基为MS。（1）芽诱导培养基：1／2MS（MS大量元素用量减半）;（2）增殖培养基：MS＋6-BA0．2mg·L^-1（单位下同）＋NAA0．2;（3）生根培养基：I／2MS＋NAA0．5。以上培养基中均加入6g·L^-1琼脂和30g·L^-1蔗糖,pH5．9—6．0。培养室中温度为（24＋1）℃,光照时间为16h·d^-1,光照强度约为60μmol·m^-2·s^-1。     

影响小黑杨花药培养中花粉愈伤组织诱导与不定芽分化的几个生理因素

建立了小黑杨花粉愈伤组织与不定芽诱导体系,观察到：（1）25℃和暗培养条件下花粉愈伤组织的诱导率最高（达到89．2％）;（2）25℃、16h·d^-1。光照（光照强度为35μmol·m^-2·s^-1左右）下培养的不定芽诱导率最高（为72.3％）;（3）花芽于0℃下低温储藏时间延长不利于花粉愈伤组织的诱导,而培养早期诱导出的愈伤组织,其不定芽分化能力高于后期诱导的愈伤组织,分化培养基中添加0.1mg·L^-1苯基噻二唑基脲（TDZ）对不定芽分化有促进作用。     

矾根杂种‘银王子＇的组织培养和快速繁殖

1 植物名称 矾根杂种‘银王子＇（Heuchera hybrid Hort.‘Prince of Silver＇）. 　　2 材料类别 带顶芽和腋芽的幼嫩茎段或叶鞘. 　　3 培养条件 （1）芽诱导培养基：MS＋6-BA 0.5mg·L^-1（单位下同）＋IBA 0.1;（2）生根培养基：1/2MS＋NAA 0.2.芽诱导培养基加入3%蔗糖,生根培养基加入2%蔗糖;以上培养基均加入0.6%琼脂,pH 6.0.培养温度（23±2）℃.光照时间12 h·d^-1,光照强度30 μmol·m^-2·s^-1左右. 　　……[第一段]     

欧洲小叶椴的胚培养与快速繁殖

1植物名称欧洲小叶椴（Tilia cordata Mill．）。 2材料类别成熟胚。 3培养条件（1）／3动培养基：MS＋6-BA2．0mg·L^-1（单位下同）＋NAA0．1;（2）增殖培养基：MS＋6．BA1．0＋NAA0．1;（3）壮苗生根培养基：1／2MS＋IBA1．0＋NAA0．3。以上培养基均加入0．55％琼脂和20g·L^-1。蔗精,pH5．8-6．0。培养温度为（25±2）℃;光照培养时间12h·d^-1,光照强度40．50μmol·m^-2·s^-1。     

不同光强下交替氧化酶基因修饰的两种拟南芥叶片叶绿素荧光特性的变化

采用叶绿素荧光测定系统,研究在不同光强下交替氧化酶(alternative oxidase; AOX)基因超表达突变体(XX-2)和野生型(WT)拟南芥(Arabidopsis thaliana)叶片的叶绿素荧光参数的变化。结果表明:两种拟南芥叶片的最大光化学效率(Fv/Fm)没有显著差别; 而不同光强下两种拟南芥叶片的实际光量子效率(Y(II))、光化学猝灭系数(qp)均随光照强度的增加呈下降趋势; 同光强下XX-2叶片的上述参数均高于WT。非光化学猝灭系数(NPQ)与调节型能量耗散的量子产额(Y(NPQ))均随着光照强度的增加呈上升趋势; 同光强下XX-2叶片的NPQ与Y(NPQ)均低于WT。非调节型能量耗散的量子产额(Y(NO))均随光照强度的增加呈下降趋势; 当光强超过165 μmol·m^-2·s^-1后,同光强下XX-2叶片的Y(NO)高于WT; 表观电子传递速率(ETR)随着光照强度的增加均表现出先上升后下降的趋势; 同光强下,XX-2叶片的ETR高于WT。以上结果表明,交替氧化酶超表达体在不同光照条件下具有更加优化的叶绿素荧光性能。     

不同含水量下尖叶拟船叶藓光合速率对光温的响应及其模型

对不同大气温度、藓体含水量及光照条件下尖叶拟船叶藓光合速率测定研究结果表明,光合速率(Pn)与光照强度(PAR)、大气温度(Ta)及藓体含水量(PWC)之间密切相关,光合速率的光响应曲线为直角双曲线,温度、藓体含水量影响图形的曲度参数,在低含水量、高气温组合和高含水量、低气温组合的藓体高光强下都使光合速率降低．弱光下(PAR<200μmol·s^-1·m^-2),光合速率最大值Pmax出现在PWC：为50％～80％,但随着Ta的升高而增大,当Ta>25℃,Pmax随Ta升高而降低;随着光照强度的增大,Pmax出现的PWC水平随之提高,当PAR<200μmol·s^-1·m^-2时,光合速率最大值Pmax出现在Ta比较高的范围(20～25℃),并随PWC的升高而增大,当PWC>80％时,Pmax随PWC升高而降低;随着光照强度的增大,Pmax出现的Ta水平降低、在230     

Inversion of gravitropism by symmetric blue light on the clinostat

Gravitropic stimulation of maize (Zea mays L.) seedlings resulted in a continuous curvature of the coleoptiles in a direction opposing the vector of gravity when the seedlings were rotated on a horizontal clinostat. The orientation of this response, however, was reversed when the gravitropic stimulation was preceeded by symmetric preirradiation with blue light (12.7 mol photons·m^–2). The fluence-response curve of this blue light exhibited a lower threshold at 0.5 mol·m^–2, and could be separated into two parts: fluences exceeding 5 mol·m^–2 reversed the direction of the gravitropic response, whereas for a range between the threshold and 4 mol·m^–2 a split population was obtained. In all cases a very strong curvature resulted either in the direction of gravity or in the opposite orientation. A minor fraction of seedlings, however, curved towards the caryopsis. Furthermore, the capacity of blue light to reverse the direction of the gravitropic response disappeared with the duration of gravitropic stimulation and it depended on the delay time between both stimulations. Thistonic blue-light influence appears to be transient, which is in contrast to the stability observed fortropistic blue-light effects.This work was supported by the Deutsche Forschungsgemeinschaft.     

Phototropism of maize coleoptiles Influences of light gradients

The lateral fluence-rate gradients in unilaterally irradiated maize (Zea mays L.) coleoptiles were calculated on the basis of the proportions of P _fr (far-red-absorbing form of phytochrome) measured spectroscopically in transverse slices of the coleoptiles (top 1 cm). The results showed the occurrence of significant gradients that are wavelength-dependent. The gradient at 449 nm was steeper than those measured at 516, 534 and 551 nm, which were steeper than that measured at 665 nm. The ratios between the sides proximal and distal to the light source were, for example, 1:0.12 (449 nm), 1:0.23 (534 nm), and 1:0.28 (665 nm). Fluence-response curves for coleoptile phototropism (first positive curvature produced by less than 100 s unilateral irradiation) were measured at 449, 516, 534 and 551 nm. Comparison of the threshold fluences indicated that the responsiveness to 551 nm is about 10^4.8 less than that to 449 nm. Increasing wavelengths led to a decrease in maximal curvature, which correlated with the decrease of the fluence-rate ratios between the proximal and distal sides. Phototropic fluence-response curves were also measured using bilateral irradiation (449 nm). In one set of experiments, the fluence ratio was kept constant (either 1:1/2, 1:1/4 or 1:1/16) and the total fluence was varied, and in the other set the fluence applied to one side was kept constant and the fluence ratio was varied. A simple model based on the assumption that only one photoreaction occurs, and that the response is a function of the difference between the proximal and distal sides in the local photoreceptor action was tested. A fluence-response curve for this local photoreceptor action was calculated based on the fluence-rate ratio and the phototropic fluence-response curve measured for 449 nm. This curve was used, in conjunction with the measured fluence-rate ratios, as a basis for calculating phototropic fluence-response curves for other wavelengths and those for 449 nm obtained with bilateral irradiation. The calculated fluence-response curves showed excellent agreement with the experimental data. It is concluded that the threshold for maize coleoptile phototropism reflects the apparent photoconversion cross-section of the blue-light receptor whereas the maximal curvature depends on the steepness of the light gradient across the coleoptile.Abbreviations and symbols I(x) fluence rate at the depth x - P _fr phytochrome (far-red absorbing) - P _r phytochrome (red absorbing) - P _tot total phytochrome (P _r+P _fr) - photoconversion cross-section     

Long-term chilling of young tomato plants under low light and subsequent recovery

The influence of unfavourable climatic conditions at the onset of the growth period on chilling-sensitive tomato (Lycopersicon esculentum Mill., cv. Abunda) was studied by exposing young plants to combinations of low temperature and low light (60–100 mol quanta · m^–2 · s^–1) for several weeks. When the temperature did not decrease below a critical point (8 ° C) no loss of developmental capacity of the plants was detected. However, while new leaves were readily formed upon return to normal growth conditions (22/18 °C, day/night, in a greenhouse), net accumulation of biomass showed a lag phase of approximately one week. This delay was accompanied by a strong, irreversible inhibition of photosynthesis in the fully expanded leaves which had been exposed to the chilling treatment. When plants were subjected to temperatures below 8 ° C, survival rates decreased after three weeks at 6 ° C and irreversible damage of apical meristematic tissue occurred. Drought-hardening prior to chilling ensured survival at 6 ° C and protected the plants against meristem loss.Abreviation Chl chlorophyll Thanks are due to G.P. Telkamp for technical assistance. This research is financially supported by the Netherlands Technology Foundation (STW, Utrecht, The Netherlands), and is coordinated by the Foundation for Biological Research (BION, 's-Gravenhage, The Netherlands).     

Resonance light scattering spectrometric study of poly diallyldimethylammonium chloride–antibody–antigen system

The interaction of antigen (Ag) and antibody (Ab) with poly diallyldimethylammonium chloride (PDDA) in aqueous solutions has been studied by optical absorption and resonance light‐scattering (RLS) spectroscopies. The formation of the three‐component‐complex is due to aggregates of Ab or Ag with PDDA by electrostatic interaction and aggregates of Ab with Ag by immunoreaction. The influences of some experimental factors, including incubation time, pH value, concentration of PDDA and concentration of Ab, on the aggregation process have also been studied. A linear relationship between the concentration of Ag and the RLS intensity was found. Under the optimal conditions, for a given concentration of Ab (4.6 µg/mL), the enhancement of RLS intensity is in proportion to the concentration of Ag in the range 0.03–0.83 µg/mL. The RLS could, in combination with immunoassay, be a rapid and sensitive detection method for Ag. Copyright © 2009 John Wiley & Sons, Ltd.     

Modelling photosynthesis in fluctuating light with inclusion of stomatal conductance, biochemical activation and pools of key photosynthetic intermediates

Photosynthetic carbon gain in rapidly fluctuating light is controlled by stomatal conductance, activation of ribulose-1,5-bisphosphate carboxylase-oxygenase, a fast induction step in the regeneration of ribulose-1,5-bisphosphate, and the build-up of pools of photosynthetic intermediates that allow post-illumination CO₂ fixation. Experimental work over recent years has identified and characterised these factors. A physiologically-based dynamic model is described here that incorporates these factors and allows the simulation of carbon gain in response to any arbitrary sequence of light levels. The model output is found to conform well to previously reported plant responses of Alocasia macrorrhiza (L.) G. Don. observed under widely differing conditions. The model shows (i) responses of net assimilation rate and stomatal conductance to constant light levels and different CO₂ concentrations that are consistent with experimental observations and predictions of a steady-state model; (ii) carbon gain to continue after the end of lightflecks, especially in uninduced leaves; (iii) carbon gain to be only marginally reduced during low-light periods of up to 2 s; (iv) a fast-inducing component in the regeneration of ribulose-1,5-bisphosphate to be limiting for up to 60 s after an increase in light in uninduced leaves: the duration of this limitation lengthens with increasing CO₂ concentration and is absent at low CO₂ concentration; (v) oxygen evolution to exceed CO₂ fixation during the first few seconds of a lightfleck, but CO₂ fixation to continue after the end of the lightfleck whereas oxygen evolution decreases to low-light rates immediately. The model is thus able to reproduce published responses of leaves to a variety of perturbations. This provides good evidence that the present formulation of the model includes the essential rate-determining factors of photosynthesis under fluctuating light conditions. Received: 27 January 1997 / Accepted: 15 April 1997     

Chloroplast proliferation based on their distribution and arrangement inAdiantum protonemata growing under red light

Chloroplast proliferation was investigated inAdiantum protonemata growing under continuous red light. Cell division is absent when cells are grown under red light. The chloroplast number increases as the cell length increases, therefore the chloroplasts divide in the absence of cell division. Chloroplasts in the basal part of the filamentous protonemal cell migrate gradually toward the cell apex, but there is no large net migration from the tip to the base or vice versa, indicating that chloroplast division takes place in the apical part of the protonemata. Chloroplast number in the apical 100 μm was maintained at about 200 during cell growth at least over eight days. The chloroplasts were either dumbbell- or ellipsoid-shaped. Dumbbell-shaped chloroplasts are abundant everywhere in a protonema, ranging from 30 to 50% of the total chloroplasts. The dumbbell-shaped chloroplasts attached to or very close to the plasma membrane seem to be the ones that are dividing but the dumbbell-shaped ones in the other regions do not divide. These data support the hypothesis that a signal from the plasma membrane induces the dumbbell-shaped chloroplasts to divide.     

光能竞争对农林复合生态系统生产力的影响

农林复合生态系统是改善渭北黄土区脆弱生态环境、促进该区域经济发展的重要举措.以该区具有代表性的核桃(Juglans regia L.)、李子(Prunus salicina),绿豆(秦豆6号)、辣椒(陕椒981)农林复合模式为对象, 研究不同农林复合系统对光能分布、农作物生长、生产的影响.研究结果表明,不同复合模式下,玉米、辣椒的光合有效辐射、光合速率、生物量及产量均有不同程度的下降,且距树行愈近,影响愈大.叶片水势与玉米、辣椒的光合速率、地上部分生物量以及产量不相关或负相关.而10～20cm土壤含水量与绿豆的生物量和产量以及辣椒的地上部分生物量正相关.但绿豆、辣椒的生产量与其光合有效辐射呈显著正相关性,这说明,农林复合系统中光能竞争是导致间作绿豆、辣椒产量下降的主要原因.     

The impact of light intensity on shade-induced leaf senescence

Plants often have to cope with altered light conditions, which in leaves induce various physiological responses ranging from photosynthetic acclimation to leaf senescence. However, our knowledge of the regulatory pathways by which shade and darkness induce leaf senescence remains incomplete. To determine to what extent reduced light intensities regulate the induction of leaf senescence, we performed a functional comparison between Arabidopsis leaves subjected to a range of shading treatments. Individually covered leaves, which remained attached to the plant, were compared with respect to chlorophyll, protein, histology, expression of senescence-associated genes, capacity for photosynthesis and respiration, and light compensation point (LCP). Mild shading induced photosynthetic acclimation and resource partitioning, which, together with a decreased respiration, lowered the LCP. Leaf senescence was induced only under strong shade, coinciding with a negative carbon balance and independent of the red/far-red ratio. Interestingly, while senescence was significantly delayed at very low light compared with darkness, phytochrome A mutant plants showed enhanced chlorophyll degradation under all shading treatments except complete darkness. Taken together, our results suggest that the induction of leaf senescence during shading depends on the efficiency of carbon fixation, which in turn appears to be modulated via light receptors such as phytochrome A.     

The Casparian strip in pea epicotyls: Effects of light on its development

The Casparian strip, which is specific to roots, was studied in the epicotyls of dark-grown seedlings of pea (Pisum sativum L.) where it was found to have the same morphology and properties as the strip in roots. In dark-grown seedlings, the distance between the upper-most position of the Casparian strip and the bending point of the hook (about 37 mm) did not change during growth of the seedlings. In the uppermost 0.5-mm region of the region in which the Casparian strip could be detected by fluorescence microscopy, the plasma membrane was not firmly attached to the cell wall. The development of the Casparian strip continued for about 42 h after dark-grown seedlings were transferred to the light, indicating that (i) the cells that have been determined to form the Casparian strip in darkness form the strip in the light, and that (ii) it takes about 42 h for the cells to complete formation of the strip. Cells in the hook of dark-grown seedlings did not form a Casparian strip when such seedlings were transferred to the light. The Casparian strip was formed in rapidly elongating internodes of light-grown seedlings when the seedlings were transferred to darkness. Light did not control the formation of the Casparian strip in roots.Abbreviation PBS phosphate-buffered saline