遮阴对4种紫堇属植物光合特性和叶绿素荧光参数的影响

采用盆栽试验,设置0、20%、40%、60%和80%遮阴度5种遮阴处理,研究遮阴对刻叶紫堇、伏生紫堇、紫堇和黄堇4种紫堇属植物叶绿素含量、光合特性和叶绿素荧光参数的影响,以加快其在园林方面的应用。结果表明: 随着遮阴度的提高,4种植物叶绿素a、叶绿素b和叶绿素(a+b)总量不断增加,刻叶紫堇在80%遮阴处理均达到最大,而伏生紫堇、紫堇和黄堇在60%遮阴处理达到最大;叶绿素a/b、光饱和点、光补偿点和暗呼吸速率的变化趋势呈相反的趋势。4种植物中,刻叶紫堇在80%遮阴处理下,伏生紫堇、紫堇和黄堇在60%遮阴度下各叶绿素荧光参数达到最大。4种植物耐阴性大小为刻叶紫堇＞伏生紫堇＞紫堇＞黄堇。刻叶紫堇在80%遮阴处理,以及伏生紫堇、紫堇和黄堇在60%遮阴处理下光能利用率最大,光合能力最强,最有利于植物的生长。     

Effects of Light on Chlorophyll Formation in Cultured Tobacco Cells I. Chlorophyll Accumulation and Phototransformation of Protochlorophyll(ide) in Callus Cells under Blue and Red light

A marked accumulation of chlorophyll was observed in calluscells of Nicotiana glutinosa when they were grown under bluelight, while under strong red light no chlorophyll accumulated.This blue light effect saturated at an intensity of about 500mW.m^–2. The effects of white, blue and red light on the transformationof protochlorophyll (ide) (Pchl) accumulated in dark-grown calluscells were studied by following the changes in the intensityof fluorescence emitted by Pchl and different forms of chlorophyll(ide) (Chi). Pchl with a fluorescence maximum at 633 nm (absorptionmaximum: 630 nm) decreased slowly, concomitant with an increasein Chl having a fluorescence maximum at 677 nm (absorption maximum:675 nm), which was subsequently transformed, independently oflight, to Chi with a fluorescence maximum at 683 nm (absorptionmaximum: 680 nm). Both blue and red light of low intensitieswere effective for the phototransformation, while red light,but not blue light, of high intensities caused significant destructionof Pchl. An action spectrum for this photodestruction showedthat the maximum destruction took place at 630 nm. White lightof high intensities was effective for the photoreduction withonly slight destruction of Pchl, suggesting that blue lightcounteracts the destructive effect of red light. At low temperatures,however, blue light as well as red light of low intensitiescaused photodestruction of Pchl. It was inferred that blue lightenhances a certain step or steps involved in the productionof a reductant required for the photoreduction of Pchl to Chl. (Received July 3, 1981; Accepted November 11, 1981)     

Effect of Various Light Treatments on Chlorophyll Formation in Excised Potato Roots

Potato root tips were grown in cultures and the effect of blue, red, and white light on chlorophyll formation was studied. The roots grown in white light turned green in 4–6 weeks, whereas in blue or red light, green colour occasionally appeared at places. The chlorophyll contents, as determined by the spectrophotometeric method, were found to be maximum in unfiltered light followed by blue and red light. In white and blue light treatments chlorophyll a contents were higher than chlorophyll b, however in red light this was reversed. The results are compared with earlier experiments on chlorophyll formation in excised roots.     

Partial characterization of a minor chlorophyll-protein found in primary thylakoids of intermittently illuminated maize

A mild solubilization with sodium dodecyl sulphate of intermittently illuminated maize (Zea mays L. Mvsc 429) thylakoids allows the separation of a minor chlorophyll-protein in the position of the light harvesting chlorophyll-protein monomer of green plants by polyacrylamide gel electrophoresis. It contains mainly chlorophyll a, its chlorophyll b content may come from the slightly contaminating light harvesting chlorophyll a/b-protein. It represents about 15% of the chlorophyll in protochloroplasts. The new chlorophyll-protein has an absorption maximum at 672 nm, and only one fluorescence emission peak at 680 nm. A 34 kD polypeptide is the most abundant one in the polypeptide pattern of the complex. The function of the new chlorophyll-protein is unknown at present. Its relationship to other chlorophyll-proteins is discussed.     

生长光强对六个橡胶树品种幼苗光合特性的影响

研究了6个橡胶树品种幼苗(适应1年后)在不同生长光强(100%、50%、25%和5%自然光)下的叶片光合系统对光强和CO2浓度的响应特性。结果表明,6个橡胶树品种对不同的光环境均表现出较强的适应性。在不同生长光强下,橡胶树幼苗叶片的最大光合速率(Pmax)、光补偿点(LCP)、暗呼吸速率(Rd)、磷酸丙糖利用速率(TPU)、最大羧化速率(Vcmax)和最大电子传递速率(Jmax)以及叶绿素含量(Chl)均有显著差异(P<0.05),而光饱和点(LSP)和AQY(表观量子效率)则无显著差异。相同生长光强下,6个橡胶树品种间叶片的最大光合速率(Pmax)、暗呼吸速率(Rd)、磷酸丙糖利用速率(TPU)、最大电子传递速率(Jmax)和叶绿素含量(Chl)有显著差异(P<0.05),其光补偿点(LCP)、最大羧化速率(Vcmax)和表观量子效率(AQY)则无显著差异。综合比较各参数,RRIM600、云研77-4和PR107适宜于相对光强为100%~50%的植胶环境,而云研77-2、GT1和热研523适宜于相对光强为50%~25%的植胶环境。     

Symbiotic association of the ciliate Ophrydium naumanni with Chlorella causing a deep chlorophyll a maximum in an oligotrophic South Andes lake

Vertical profiles of temperature, light and chlorophyll a concentration were examined in Lake Moreno Oeste, an oligotrophic South Andean lake (Argentina), during the warmest period of the year (November-April), when thermal stratification is characteristic. Concurrent samples for the enumeration of phytoplankton and green ciliates were taken, and the different contribution of these fractions to total chlorophyll a concentration was analysed. The development of a distinctive deep chlorophyll maximum was observed during summer months. The deep chlorophyll maximum was situated near the limit of the euphotic zone and just below the upper limit of the metalimnion. The results showed that the green ciliate Ophrydium naumanni with endosymbiotic Chlorella dominated the metalimnion causing the deep chlorophyll maximum. Additional laboratory experiments revealed a strong dependence of O.naumanni on light. Therefore, the symbiotic association appears to be an effective exploitation of the water column in poor-nutrient-high-light ecosystems like large Andean lakes.      

Distribution of excitation energy among photosystem I and photosystem II in red algae. I. Action spectra of light reactions I and II

Action spectra of light reaction I and light reaction II from red algae (marine members of Florideae and Bangiales) were measured with 550 nm (light 2) or 699 nm (light 1) background light, using a Teflon-covered platinum electrode for O₂ measurement. Care was taken to ensure that maximum enhancement was reached by the background light.The action spectra of light reaction I, we found under these conditions, are very similar to the thallus absorption, whilst the action spectra of light reaction II show, besides strong bands of the phycobilins, only minor bands of chlorophyll a, which account for only 10–20% of the total chlorophyll.The spectra are discussed on the basis of two main types of models of energy distribution over both photosynthetic systems. If this distribution is considered to be invariable (models 1a and b), one has to assume that almost exactly half of the total chlorophyll is not involved in the supply of the non-cyclic electron transport with excitation energy. This part, however, has to be thought of as incorporated in the thylakoid membrane in a similar manner to the chlorophyll in photosystem I. However, if one supposes an almost complete equilibration in the energy distribution over both systems as long as the primary absorption in photosystem II prevails (models 2a and b), there is no need for the assumption of such photosynthetically ‘inactive’ or less active chlorophyll. Some evidence is shown that strongly supports model 2.     

Pigment Composition of a Novel Oxygenic Photosynthetic Prokaryote Containing Chlorophyll d as the Major Chlorophyll

The principal pigment found in the majority of oxygenic photosyntheticorganisms is known to be chlorophyll a. However, we isolateda new oxygenic photosynthetic prokaryote that contained chlorophylld as a predominant pigment with chlorophyll a being a minorpigment. Chlorophyll d had previously been noted but its naturaloccurrence and function remained unclear. Cells of the new prokaryotehad an absorption maximum at red region of 714–718 nmdue to chlorophyll d absorption, but no characteristic absorptionpeak of chlorophyll a around 680 nm was observed. Chlorophylld of the new organism was identified spectrophotometricallyin several solvents and its chemical structure was confirmedby NMR and FABMS analysis. The cell also contained a chlorophyllc-like pigment, zeaxanthin and a-carotene but not chlorophyllb and ß-carotene. The content of chlorophyll d accountedfor more than 2% of the cell dry weight, while the content ofchlorophyll a was less than 0.1%. The chlorophyll a/d ratioremained between 0.03 and 0.09 under different culture conditions.The light absorption characteristics and the high content ofchlorophyll d along with the small content of chlorophyll aindicated the existence of a new light utilization mechanisminvolving chlorophyll d. (Received October 7, 1996; Accepted December 16, 1996)     

遮荫对异株荨麻光合特性和荧光参数的影响

系统研究了全光照和不同程度的遮荫(43%,58%,73%,87%,97%)对异株荨麻光合特性和荧光参数的影响。结果表明,异株荨麻的光补偿点和光饱和点均较低,且随着遮荫程度的提高,其值以及暗呼吸速率均依次降低。净光合速率日变化曲线呈单峰型,光合速率高峰值和日平均光合速率均随着遮荫程度的提高而明显下降。蒸腾速率和气孔导度的日变化与光合速率的日变化趋势一致,遮荫对蒸腾作用和气孔导度均有显著的影响,随着遮荫程度的提高,蒸腾速率和气孔导度均显著下降。在各光照条件下,蒸腾速率与气孔导度呈显著正相关。蒸腾速率和气孔导度与光合速率的相关性随遮荫条件的不同而异,全光照条件下蒸腾速率与光合速率呈显著正相关,而所有遮荫条件下相关性不显著。气孔导度与光合速率在所有光照下相关性均不显著。各遮荫条件下叶片总叶绿素、叶绿素a、叶绿素b含量均显著高于全光照的,且随遮荫程度的提高叶绿素含量呈上升趋势,而叶绿素a/b的值则随着遮荫程度的提高而下降。叶绿素荧光参数PSⅡ内禀光能转化效率(Fv/Fm)和潜在活性(Fv/Fo)日变化呈单谷曲线。各遮荫条件下Fv/Fm和Fv/Fo值均高于全光照的,且随着遮荫程度的提高其值均依次增加。这说明,异株荨麻是一种耐荫性很强的植物,遮荫可使其降低光补偿点、光饱和点、净光合速率、暗呼吸速率以及叶绿素a/b,但增加总叶绿素、叶绿素a、叶绿素b含量、光能利用率以及PSⅡ原初光能转化效率和潜在活性,以增强在弱光条件下的生长发育能力。     

遮光条件下不同种源土沉香幼苗的光合特性与生长速率分析

以3个来源于广东茂名的土沉香[ Aquilaria sinensis (Lour.) Spreng.]种源(大白、小白和大黄)和1个来源于云南的土沉香种源的1年生幼苗为研究对象,对不同遮光条件下[相对光强100％(对照,自然光强)、50％、25％和5％]4个种源幼苗叶片的净光合速率(Pn)的光响应和CO2响应曲线、光合和气体交换参数、叶绿素含量和叶绿素a/b( Chla/b)值进行了分析,并比较了4个种源幼苗的相对生长速率(RGR).结果表明:4个种源的Pn均随光合光量子通量密度的增加而上升,且对照组各种源的Pn值均明显高于各处理组;4个种源的Pn值均随胞间CO2浓度的升高或相对光强的增大逐渐提高.随相对光强的降低,4个种源的最大光合速率、光补偿点、光饱和点、暗呼吸速率、最大电子传递速率、最大羧化速率和磷酸丙糖利用速率均下降或显著下降(P＜0.05),而表观量子效率则略有升高.在相对光强100％ ～ 25％条件下,随相对光强降低,4个种源的叶绿素含量显著提高、Chla/b值显著减小;大白和小白种源的RGR逐渐增大,大黄种源的RGR差异不显著,而云南种源的RGR显著减小.而在相对光强5％条件下,大黄和云南种源的叶绿素含量显著降低,Chla/b值显著增大,RGR显著减小;大白和小白种源幼苗全部死亡.由种源间的比较可见:4个种源的各项光合参数以及叶绿素含量、相对生长速率均有一定的差异,其中云南种源的各项指标总体上均最低.综合来看,土沉香为半阳生植物,对不同的光环境表现出相对较强的适应性.     

A system for imaging transverse distribution of scattered light and chlorophyll fluorescence in intact rice leaves

In order to examine the transverse distribution of scattered light and chlorophyll fluorescence in intact rice leaves, a micro-fluorescence imaging system was devised using a microscope, a CCD camera with an image intensifier, an Ar and a He-Ne laser light source, an image processor, and a microcomputer. A laser light was projected vertically on to the surface of a rice leaf segment at a cut-edge, and scattered light and induced fluorescence were observed at the cut-section from a 90° angle to the axis of the laser beam. The intensity of scattered light showed a maximum at several micrometres depth from the leaf surface and a steep gradient afterwards. Fluorescence reached a maximum crossing with the decline curve of the scattered light. The maximum of fluorescence measured at 741 nm was observed at a greater depth from the leaf surface than that at 687 nm, suggesting that part of the fluorescence of the longer wavelength was emitted due to absorption of fluorescence of the shorter wavelength. Profiles of the scattered light and the chlorophyll fluorescence depended on leaf anatomy.     

The role of phytoplankton in determining the underwater light climate in Lake Constance

At all seasons, the underwater light field of meso-eutrophic large (480 km²) deep (mean: 100 m) Lake Constance was studied in conjunction with the assessments of vertical distributions of phytoplankton chlorophyll concentrations. Vertical profiles of scalar, downwelling and upwelling fluxes of photosynthetically available radiation, as well as fluxes of spectral irradiance between 400 and 700 nm wavelength were measured.The overall transparency of the water for PAR is highly dependent on chlorophyll concentration. However, the spectral composition of underwater light is narrowing with water depth regardless of phytoplankton biomass.Green light is transmitted best, even at extremely low chlorophyll concentrations. This is explained by the selective absorption of blue light by dissolved organic substances and red light by the water molecules. Nevertheless, significant correlations were found between vertical attenuation coefficients of downwelling spectral irradiance and chlorophyll concentrations at all wavelengths. The slopes of the regression lines were used as estimates of chlorophyll-specific spectral vertical light attenuation coefficients (K _c()).The proportions of total upwelling relative to total downwelling irradiance (reflectance) increased with water depth, even when phytoplankton were homogeneously distributed over the water column. Under such conditions, reflectance of monochromatic light remained constant. Lower reflectance of PAR in shallow water is explained by smaller bandwidths of upwelling relative to downwelling light near the water surface. In deeper water, by contrast, the spectra of both upwelling and downwelling irradiance are narrowed to the most penetrating components in the green spectral range. Reflectance of PAR was significantly correlated with chlorophyll concentration and varied from 1% and 1-% at low and high phytoplankton biomass, respectively. Over the spectrum, reflectance exhibited a maximum in the green range. Moreover, in deeper layers, a red maximum was observed which is attributed to natural fluorescence by phytoplankton chlorophyll.     

Functional Analysis of the Intrathalline and Intracellular Chlorophyll Concentrations in the Lichen Family Umbilicariaceae

Intrathalline and intracellular chlorophyll concentrations togetherwith thallus structure were studied in 12 species of the lichenfamily Umbilicariaceae in order to explore pigment limitationsfor light absorption and for maximum rates of net photosynthesis(A_max). Species from high light environments tended to haverelatively low chlorophyll concentrations and vice versa. Chlorophyllconcentration on a surface area basis of all species studiedwas sufficient to absorb 80–99% of the incident light,which led us to believe that chlorophyll concentration was nota limiting factor for A_max. A_maxof Umbilicariaceae was smallerthan A_maxof leaves of vascular plants, both on a dry weightand on a surface area basis. These differences slightly decreasedbut did not disappear when referred to the chlorophyll concentrationof the photosynthetic tissues, but reference units had a confoundingeffect in the comparisons. Differences in A_maxon a dry weightbasis between Umbilicariaceae and vascular plants disappearedwhen comparisons were made with the whole plant and not simplywith the leaf. We found a significant, inverse relationshipbetween amount of alga and chlorophyll concentration withinthe algal cells in the lichens studied. This was interpretedas a mechanism to avoid pigment self-shading within the algallayer, distributing more efficiently the photosynthetic pigmentsover a given surface area, and is the first indication of sucha mechanism in lichens. It is suggested that thallus structureand physiology have a larger influence on the observed low A_maxofthe lichens studied than chlorophyll content. Algal cells; chlorophyll concentration; lichens; light harvesting; net photosynthesis; stereology; thallus structure; Umbilicariaceae     

Effects of Anaerobiosis on Chlorophyll Fluorescence Yield in Spinach (Spinacia oleracea) Leaf Discs

When spinach (Spinacia oleracea) leaf discs were incubated in a dark anaerobic environment, the chlorophyll fluorescence yield was much increased relative to the aerobic control. Occasionally, the fluorescence yield of the darkened anaerobic samples approached 80% of the maximum fluorescence. The anaerobic incubation period also induced in a leaf disc the capacity to exhibit a low light-mediated chlorophyll fluorescence induction phenomenon. This involved a rapid and slow increase in fluorescence yield, followed by a slow quenching. This could be induced by light levels as low as 400 [mu]W m-2. The anaerobic-dependent increase in chlorophyll fluorescence yield could be relaxed by either far-red light, O2, or a saturating pulse of white light. It was concluded that the anaerobic-dependent increase in chlorophyll fluorescence yield was due to a dark reduction of the plastoquinone pool and its relaxation by reoxidation. Darkened isolated chloroplasts did not exhibit a fluorescence yield increase under anaerobic conditions. Fluorescence slowly increased only when dithiothreitol or dithionite was added.     

Photoinduced formation of pheophytin/chlorophyll-containing complexes during the greening of plant leaves

Illumination of etiolated maize leaves with low-intensity light produces a chlorophyll/pheophytin-containing complex. The complex contains two native chlorophyll forms Chl 671/668 and Chl 675/668 as well as pheophytin Pheo 679/675 (with chlorophyll/pheophytin ratio of 2/1). The complex is formed in the course of two successive reactions: reaction of protochlorophyllide Pchlde 655/650 photoreduction resulted in chlorophyllide Chlde 684/676 formation, and the subsequent dark reaction of Chlde 684/676 involving Mg substitution by H₂ in pigment chromophore and pigment esterification by phytol. Out data show that the reaction leading to chlorophyll/pheophytin-containing complex formation is not destructive. The reaction is in fact biosynthetic, and is competitive with the known reactions of biosynthesis of the bulk of chlorophyll molecules. The relationship between chlorophyll and pheophytin biosynthesis reactions is controlled by temperature, light intensity and exposure duration.The native complex containing pheophytin a and chlorophyll a is supposed to be a direct precursor of the PS II reaction centre in plant leaves.Abbreviations Chl chlorophyll - Chlde chlorophyllide - Pchl protochlorophyll - Pchlde protochloropyllide - Pheo pheophytin - PS II RC Photosystem II reaction centres. Abbreviations for native pigment forms: the first number after pigment symbol corresponds to the maximum position of low-temperature fluorescence band (nm); the second number corresponds to the maximum position of long wave absorption band     

Development of the photosynthetic apparatus during light-dependent greening of a mutant of Chlorella fusca

The formation of chlorophyll, cytochrome f, P-700, ribulose bisphosphate carboxylase as well as photosynthesis and Hill reaction activities were tested during the light-dependent greening process of the Chlorella fusca mutant G 10. Neither chlorophyll nor protochlorophyllide was detected in the darkgrown cells. When transferred to light the mutant cells developed chlorophyll and established its photosynthetic capacity after a short lag phase. In the in vivo absorption spectra a spectral shift of the red absorption peak position from 674 to 680 nm was indicated during the first 3 h of greening. Cytochrome f was already present in the dark-grown cells, but during the greening phase a threefold increase in the cytochrome f content could be seen. At the early stages of greening a characteristic primary oscillation in the content of cytochrome f was observed. P-700 was lacking in the dark and during the first 30 min of illumination. From the first to the second h of light a forced synthesis of P-700 took place and the time-course curve for the ratios of P-700/chlorophyll rose to a sharp maximum. The synthesis of P-700 started together with photosystem I activity and showed similar kinetics. We found the simultaneous appearance of photosystem II, photosystem I, and photosynthetic activities 30 min after the beginning of the illumination. Based on chlorophyll content they attained maximum activity after 2 h of light, but at this time photosystem I capacity proved to be remarkably higher than photosynthetic and photosystem II activities. Highest carboxylase activity existed in darkgrown cells. During the greening process the activity of the enzyme decreased continuously. After 2 h of illumination chlorophyll synthesis partially served to increase the size of the photosynthetic unit, which consequently led to a decrease in the light energy needed to saturate photosynthesis and also to a decrease of photosynthetic rate based on chlorophyll content.Abbreviations Chl chlorophyll - Cyt f cytochrome f - DPIP 2,6-dichlorophenolindophenol - EDTA ethylenediaminetetraacetic acid - GSH glutathione - LH light-harvesting - PS photosystem - RuBP ribulose bisphosphate     

The pelagic system in the photic zone of the tropical Atlantic

Summary A multidisciplinary study of the carbon budget in the upper 300 meter of permanently stratified waters was started by two NECTAR-expeditions (North Equatorial Current Trans Atlantic Research) with HMS TYDEMAN in 1977 and 1978 (BAARS, ZIJLSTRA and TIJSSEN, 1979). In 1979 additional measurements were performed during the Gulf of Guinea-expedition with MS TYRO.Primary production in the nutrient depleted mixed layer of the North Equatorial Current estimated from the diurnal cycle in the O₂ concentration (TIJSSEN, 1979) and in POC (POSTMA and ROMMETS, 1979) revealed values 4–10 times higher than the data from the¹⁴C method in the literature: 800–2000 against ca. 200 mg C/m²/day. Moreover,¹⁴C incubations performed in bottle volumes of 4 liter and over 2 hour periods, instead of the recommended 12 hours for oligotrophic waters, gave 5–15 times higher values as incubations in the commonly used 300 ml (or smaller) bottles (GIESKES, KRAAY and BAARS, 1979). In the latter bottles a dramatic decrease of chlorophyll concentrations was observed, suggesting either heavy damage to fragile microflagellates by glasswall contacts and/or insufficient nutrient recycling by the lack of zooplankton in small samples. This then could account for the phenomena of low production and decreasing algal stock in long incubations with small bottles. These results suggest that today's picture of the primary production in the world's oceans (DE VOOIJS, 1979) needs probably a thorough reexamination. On the other hand, experiments in the North Sea and in the Gulf of Guinea did not indicate an effect of bottle size on¹⁴C incorporation and the¹⁴C method gave comparable estimates of primary production as the high precision oxygen method (photometric endpoint detection in the Winkler titration,cf. TIJSSEN, 1979). However, in these waters nutrient concentrations are always clearly above detection levels so that all previous data from somewhat richer areas may have been correct. In relation to the large oligotrophic parts of the oceans a question remains about the fate of the probably high primary production. Is it consumed by the algae themselves by night (POSTMA, 1980), are bacteria and microzooplankton more important consumers than formerly thought, or is the daily ration of zooplankters much higher as expected from extrapolation of filtration experiments in more eutrophic waters? We hope to clarify this topic during the coming NECTAR'82 expedition.Another main objective of the programme concerns the character of the deep chlorophyll maximum in permanently stratified waters. This layer is in the North Equatorial Current located at the depth of the nitratocline and at ca. 1% of the incident light at the surface (SPITZER and WERNAND, 1981). Primary production in the layer seems to be negligible while detailed vertical profiles of zooplankton, obtained with a Longhurst-Hardy Plankton Recorder, revealed no obvious concentrations in the layer. Chlorophyll analysis by thin-layer-chromatography (GIESKES, KRAAY and TIJSSEN, 1978) demonstrated that more than half of the chlorophyll a in the layer consists of an isomer which bleaches rapidly when transferred to higher light levels. The hypothesis was formulated that the chlorophyll maximum layer, at least in this region of the Atlantic, is an accumulation of chlorophyll breakdown products with a quite long turnover time at low light levels. In contrast to these findings, chlorophyll maxima near West-Africa and in the Gulf of Guinea were located at 5–10% light and contained more living algal cells (most of them as small as 1–3 m) than the nutrientpoor mixed layer above it. Primary production profiles had therefore a bimodal shape, with peaks at 30–50% light and at the chlorophyll maximum. Chlorophyll isomers, now analysed with High Pressure Liquid Chromatography, were also in these waters present at nearly all stations and comprised 30–70% of total chlorophyll comparable to the situation in the North Equatorial Current (GIESKES and KRAAY, 1981). It could be shown that these isomers are not involved in primary production, so that well established relationships between chlorophyll, light and primary production, found in oceanographic literature, have to be reconsidered.     

盐雾胁迫对极小种群植物日本荚蒾光合生理的影响

为评价日本荚蒾(Viburnum japonicum)的耐盐雾能力,对4 a生实生苗用不同盐雾浓度处理(盐雾NaCl质量浓度分别为0%、1%、2%、3%),测定叶片净光合速率、最大光化学效率(F_v/F_m)和叶绿素含量(Chl)等指标的变化。结果表明,1%盐雾处理的日本荚蒾植株能够存活,但生长不良,大于2%的盐雾处理的植株全部死亡。随着浓度的升高,日本荚蒾叶片的最大光合速率、F_v/F_m及Chl含量下降,而光饱和点及光补偿点总体呈上升趋势。这说明盐雾胁迫通过伤害光系统Ⅱ反应中心、改变植物可利用光能范围及降低叶绿素含量影响植物的光合作用。     

Function of terahertz spectra in monitoring the decomposing process of biological macromolecules and in investigating the causes of photoinhibition

Chlorophyll α and β-carotene play an important role in harvesting light energy, which is used to drive photosynthesis in plants. In this study, terahertz(THz) and visible range spectra of chlorophyll α and β-carotene and their changes under light treatment were investigated. The results show that the all THz transmission and absorption spectra of chlorophyll α and β-carotene changed upon light treatment, with the maximum changes at 15 min of illumination indicating the greatest changes of the collective vibrational mode of chlorophyll α and β-carotene. The absorption spectra of chlorophyll α in the visible light region decreased upon light treatment, signifying the degradation of chlorophyll a molecules. It can be inferred from these results that the THz spectra are very sensitive in monitoring the changes of the collective vibrational mode, despite the absence of changes in molecular configuration. The THz spectra can therefore be used to monitor the decomposing process of biological macromolecules; however, visible absorption spectra can only be used to monitor the breakdown extent of biological macromolecules.     

Low-Temperature Fluorescence Excitation Spectra for Long-Wavelength Emission as a Function of Greening in Euglena gracilis and Chlorophyll A Concentration In Vitro: A Mathematical Model to Describe Both Systems

A systematic study was made of the spectrum for exciting long-wave-length fluorescence (at 77°K) during the first 100 hr of greening in Euglena gracilis. A band at 705-710 nm is observable after cells have been greening in light for 30 hr. The ratio of the 705-nm to the 675-nm peak increases during greening, reaching a maximum value at 85 hr, then declining. With concentrated solutions of chlorophyll a, fluorescence excitation spectra are similar to those observed in vivo. The ratio of aggregate to monomer bands increases with concentration of chlorophyll, reaching a maximum value in ethanol and in pyridine at about 3 × 10^-2 M and 6 × 10^-2 M respectively, then declining. Several model systems were analyzed. It is shown that the band observed in solution with maximum at 705-710 nm is not an artifact of the fluorescence apparatus; it does not arise from undissolved chlorophyll; it does not arise from a fluorescent or nonfluorescent impurity; it does not arise solely from light absorption by a dimer or larger aggregate of chlorophyll. Agreement is obtained between the experimental observations and the results of a mathematical model by including terms for the efficiency of energy transfer from monomeric to dimeric chlorophyll, as well as for the formation of dimers by an equilibrium reaction.