Action Spectrum Of Photosynthesis Research Articles

Highly matched spectrum needed for photosynthesis in Ce3+/Er3+/Yb3+ tri-doped oxyfluoride glass ceramics

A series of oxyfluoride glass ceramics containing CaF2 nano-crystals tri-doped with Ce3+/Er3+/Yb3+ ions were prepared by high temperature melting method and subsequent heat treatment. The structural properties were examined by X-ray diffraction measurements. The absorption, excitation, and emission spectra of the glass ceramics were investigated. Difference in erbium emission spectra between glass and glass ceramics had been studied. The emission bands originating from the 4F9/2 state of Er3+ were enhanced when the CaF2 nano-crystal created. By down-converting the ultraviolet wavelength region (280∼400 nm) light and up-converting the near-infrared wavelength region (900∼1100 nm) light, the glass ceramics can also emit strong reddish orange emission. The emission spectra consisting of bluish violet (400∼500 nm) and reddish orange (640∼680 nm) bands match well with the action spectrum of photosynthesis and absorption spectra of chlorophylls. Our materials will be favored to promote the development of glass greenhouses for green plant.

A 5-Year Study of a New Kind of Photosynthetically Active Radiation Sensor¶*

Light-emitting diodes (LED), which are designed as quasi-monochromatic light sources, can also function as spectrally selective photodiodes. This provides a new kind of photosynthetically active radiation (PAR) sensor that is inexpensive and has much better stability over time than interference filters used in some PAR sensors. The action spectrum of photosynthesis in green plants has principle peaks in the blue and red regions. LED with response peaks in the UV-A (380 nm) and red (620 nm) regions have been used to measure PAR at or near solar noon in an ongoing study begun on 30 April 1996. The sum of the signals from the two LED is highly correlated with measurements by a calibrated filterless PAR sensor (Apogee QSO; Logan, Utah) from 13 September 1997 to 16 January 2002 (r2= 0.97). The sum of the LED signals is also highly correlated with measurements by a calibrated filter PAR sensor (LI-COR LI-190SA; Lincoln, Nebraska) from 20 April 1998 to 16 January 2002 (r2= 0.97). Thus, pairs of spectrally selective LED can function as PAR detectors in economical PAR radiometers. The separate 380 and 620 nm responses also permit an assessment of the differential impact of aerosol events on blue and red PAR and phototropic radiation.

Studying photosynthesis by measuring fluorescence

This paper describes an easy experiment to study the absorption and action spectrum of photosynthesis, as well as the inhibition by heat, high light intensity and the presence of the herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on the photosynthetic process. The method involves measuring the chlorophyll fluorescence emitted by intact leaves of oat (Avena sativa, var. Prevision) plants. Measuring the variable fluorescence emission in leaves illuminated by monochromatic light (blue, green, red and far red), an action spectrum of photosynthesis was obtained, showing that blue and red lights are the most effective to produce photosynthesis. The quantum yield of the photosystem (PS) II and the variable fluorescence values in the leaves decreased by treatments with white light of high intensity and with heat (up to 35°C), indicating inhibition of the PS II. A synergistic effect of both stress factors on photosynthesis inhibition was also observed. Incubation with DCMU of the leaves also decreased the quantum yield of PS II and the variable fluorescence emission, as a consequence of the inhibition of PS II by DCMU. This practical is intended for students of plant biochemistry and plant physiology.

The impact of spectral composition and light periodicity on the activity of two antioxidant enzymes (SOD and CAT) in the coral Favia favus

In oligotrophic waters the light spectrum is mostly blue, and therefore the physiological and biochemical responses to blue light occurring in the coral tissue and in the symbiotic algae are important. Examination of the wavelength dependence of two free radical scavenger enzyme activity revealed an increase in activity in the blue light range (440–480 nm) compared to the red (640–680 nm) in the full visible light (400–700 nm) range. These data show for the first time the relationship between the action spectra of photosynthesis and the activity of two main antioxidant enzymes in the symbiotic coral Favia favus. It was found that in the animal (host) the enzyme response to the spectral distribution of light was higher than that of the zooxanthellae, probably due to accumulation of free radicals within the host tissue. Furthermore, we found that the activity of these enzymes is affected in nature by the length of the day and night, and in the laboratory, by the duration of the illumination. Changes in the pigment concentrations were also observed in response to growth under the blue region and the whole PAR spectrum, while fluorescence measurements with the fast repetition rate fluorometer (FRRF) showed a decrease in the sigma cross section and a decrease in the quantum yield also in the blue part of the spectrum. These changes of scavenger enzymes activity, pigment concentration and fluorescence yield at different light spectra are vital in acclimatization and survival of corals in shallow water environments with high light radiation.

A 5-year study of a new kind of photosynthetically active radiation sensor.

Light-emitting diodes (LED), which are designed as quasi-monochromatic light sources, can also function as spectrally selective photodiodes. This provides a new kind of photosynthetically active radiation (PAR) sensor that is inexpensive and has much better stability over time than interference filters used in some PAR sensors. The action spectrum of photosynthesis in green plants has principle peaks in the blue and red regions. LED with response peaks in the UV-A (380 nm) and red (620 nm) regions have been used to measure PAR at or near solar noon in an ongoing study begun on 30 April 1996. The sum of the signals from the two LED is highly correlated with measurements by a calibrated filterless PAR sensor (Apogee QSO; Logan, Utah) from 13 September 1997 to 16 January 2002 (r2 = 0.97). The sum of the LED signals is also highly correlated with measurements by a calibrated filter PAR sensor (LI-COR LI-190SA; Lincoln, Nebraska) from 20 April 1998 to 16 January 2002 (r2 = 0.97). Thus, pairs of spectrally selective LED can function as PAR detectors in economical PAR radiometers. The separate 380 and 620 nm responses also permit an assessment of the differential impact of aerosol events on blue and red PAR and phototropic radiation.

Evaluation of maize productivity considering solar energy use limitation by environmental factors.

Evaluation of maize productivity under different climatic conditions was made by determination of the amount of the incident solar radiation energy in the PAR range, which can be potentially used by plants for photosynthesis. An irradiance, which can be stored in primary photosynthesis, designated as photosynthetic energy, W (ph), was estimated taking into account the action spectra of photosynthesis. Limitation of the W (ph) usage, owing to unfavorable environmental factors was considered. Quantitative evaluation of limitations by two such factors, air temperature and soil water potential, was made by means of the coefficients F(i), which were defined as the ratio between the photosynthetic rate at a given value of a particular environmental factor and that at the optimal value for this factor. The coefficients F(i), were determined from the dependencies of the photosynthesis rate on air temperature and soil water potential as obtained in chamber and field experiments. In general terms, the fraction of W (ph), which can be utilized under a given climatic condition, was named bioclimatic potential, W (pc). In our model, the effect of monodominancy, when strong action of one factor suppresses the influence of any other factor, was considered. In this case, the bioclimatic potential, designated W'(pc), was calculated by multiplying W (ph) times the coefficient F, for the factor which was most limiting during the period of measurement. There was close correlation between values of bioclimatic potential for the period of vegetation, W'(pc,v), and total dry matter. W'(pc,v) use efficiency in the maize crop was also evaluated for five variants of mineral nutrition.

MICROENVIRONMENTAL CONTROL OF PHOTOSYNTHESIS AND PHOTOSYNTHESIS‐COUPLED RESPIRATION IN AN EPILITHIC CYANOBACTERIAL BIOFILM1

ABSTRACTThe photosynthetic performance of an epilithic cyano‐bacterial biofilm was studied in relation to the in situ light field by the use of combined microsensor measurements of O2, photosynthesis, and spectral scalar irradiance. The high density of the dominant filamentous cyanobacteria (Oscillatoria sp.) embedded in a matrix of exopolymers and bacteria resulted in a photic zone of < 0.7 mm. At the biofilm surface, the prevailing irradiance and spectral composition were significantly different from the incident light. Multiple scattering led to an intensity maximum for photic light (400–700 nm) of ca. 120% of incident quantum irradiance at the biofilm surface. At the bottom of the euphotic zone in the biofilm, light was attenuated strongly to < 5–10% of the incident surface irradiance. Strong spectral signals from chlorophyll a (440 and 675 nm) and phycobilins (phycoerythrin 540–570 nm, phycocyanin 615–625 nm) were observed as distinct maxima in the scalar irradiance attenuation spectra in the upper 0.0–0.5 mm of the biofilm. The action spectrum for photosynthesis in the cyanobacterial layer revealed peak photosynthetic activity at absorption wavelengths of phycobilins, whereas only low photosynthesis rates were induced by light absorption of carotenoids (450–550 nm).Respiration rates in light‐ and dark‐incubated biofilms were determined using simple flux calculations on measured O2 concentration profiles and photosynthetic rates. A significantly higher areal O2 consumption was found in illuminated biofilms than in dark‐incubated biofilms. Although photorespiration accounted for part of the increase, the enhanced areal O2 consumption of illuminated biofilms could also be ascribed to a deeper oxygen penetration in light as well as an enhanced volumetric O2 respiration in and below the photic zone. Gross photosynthesis was largely unaffected by increasing flow velocities, whereas the O2 flux out of the photic zone, that is, net photosynthesis, increased with flow velocity. Consequently, the amount of produced O2 consumed within the biofilm decreased with increasing flow velocity. Our data indicated a close coupling of photosynthesis and respiration in biofilms, where the dissolved inorganic carbon requirement of the photo‐synthetic population may largely be covered by the respiration of closely associated populations of heterotrophic bacteria consuming a significant part of the photosynthetically produced oxygen and organic carbon.

Pigment composition and photosynthetic action spectra of sporophytes ofLaminaria(Phaeophyta) grown in different light qualities and irradiances

Young plants of Laminaria hyperborea collected from the field were grown for 2·5–4 weeks in blue, green, red and white (simulated underwater) light fields at 5, 20 and 100 μmol m-2s-1. The absolute concentrations of all pigments showed little variation with irradiance in green and white light, but decreased in high irradiances of red and blue light. The ratio of fucoxanthin to chlorophyll a also increased in the latter treatments, as did the chlorophyll c:a ratio in bright red light. There was little difference in the action spectrum for photosynthesis between the different light qualities at any one irradiance, but the action spectra for plants grown at 100 μmol m-2s-1 showed deeper troughs and higher peaks than those for plants grown at lower irradiances. Gross photosynthesis per unit of thallus area at 10 μmol m-2s-1 decreased in plants with low total pigment concentrations, but the photosynthesis per unit of pigment concentration increased. This suggestion of self-shading of pigment molecules within the algal thalli was supported by a flattening of the action spectrum in plants with higher chlorophyll a contents. The variations observed between the action spectra for different plants could thus be attributed to the decrease in pigment content at high irradiances, and not to the light quality in which the plants were grown.

Light and Branch Formation in the Alga Vaucheria dichotoma (Xanthophyceae)

AbstractBranches of Vaucheria dichotoma (L.) Ag. were induced in two ways: by cutting, which led to a branch in the wound area and by exposure to light.Blue and red light were most active in branch formation. The light intensity dependence and the action spectrum of branch formation showed patterns similar to those of photosynthesis. Photosynthetic involvement was also indicated by the DCMU inhibition of branch formation. Elongation‐branching studies at different photoperiods showed that branching was increased by the presence of more photosynthetic light than was necessary for elongation.It may be concluded that photosynthesis exerted the main control of the branch formation of V. dichotoma. However, the action spectrum of branch formation showed a higher efficiency in blue light than would be expected from the action spectrum of photosynthesis. It is therefore possible that apart from the main induction via the photosynthetic pigments, other blue light sensitive pigments may have a regulatory effect.Far‐red light treatment of filaments pre‐exposed to 8‐h and 16‐h light periods did not affect branch formation. Spectrophotometrical detection of phytochrome was not successful. This may indicate that there is no participation of phytochrome in branch formation.I am indebted to Dr. Lisbeth Fries for her interest. I also wish to thank Prof. Lars Olof Björn and his friendly staff at the Institute of Plant Physiology at the University of Lund, where some of the experiments were carried out. I am grateful to AB Tomaso Minori for revising the English test and to Miss Inga‐Britt Jansson for typing it.The investigation was supported financially by a grant to Dr. Lisbeth Fries from the Swedish National Science Research Council.

Pigmentzusammensetzung und photosynthetische CO2-Fixierung von Cyanidium caldarium und Porphyridium aerugineum

Summary The influence of a change in growth conditions on pigment composition and action spectrum of photosynthesis were studied with Porphyridium aerugineum (strain 1380-2) and Cyanidium caldarium . Under low white light (0.5 • 10 3 erg/cm 2 • sec) the relation between chlorophyll a to phycocyanin was 1: 5,3 in the red alga Porphyridium and 1: 9.2 in Cyanidium. Growing the algae under high light intensity (50.8 • 10 3 erg/cm 2 • sec) reduced the phycocyanin content and changed the relations to 1: 1.6 in Porphyridium and to 1: 6.5 in Cyanidium. In red light of high intensity (20.0 • 10 3 erg/cm 2 sec) practically no changes in the pigment relations were observed. Photosynthetic CO 2 uptake measured with an infrared gas analyzer was relatively low in high white light grown algae. The action spectrum of apparent photosynthesis showed a minimum at 483 nm in all differently grown algae cultures. The highest rate of photosynthesis could be found between 621 and 651 nm. Patterns of 14 C-labelled photosynthetic products were very similar to those of the Calvin cycle which is the main carboxylation pathway in these algae. In Porphyridium cells grown in low white light the effect of blue (432 nm) and red (621 nm) on 14 C-labelled photosynthetic products were investigated. 14 CO 2 incorporation into sugar monophosphates increased under red light. In blue light the percentage distribution of 14 C-labelling into amino acids (aspartate, glutamate, alanine) was higher than under red light. In both algae the behaviour of variations in pigment composition was very similar. Therefore we believe Cyanidium could be a red alga.

Induction of Two-dimensional Growth and Hair Formation by Blue Light in the Brown Alga Scytosiphon lomentaria

Summary Plants of Scytosiphon lomentaria grown in blue light form two-dimensional crusts and bear long, multicellular hairs, whereas the prostrate system of plants in red light consists entirely of sparingly-branched and mostly uniseriate filaments, which are completely hairless. The early stages in the morphogenesis of this species have been studied in sporelings growing at similar rates in white, blue, green and red light. After 6 days, plants grown in blue and white light were shorter and broader than plants of identical size in red and green, and almost all plants in blue had formed hairs, whereas red-grown plants were all without hairs. Both of these responses could be induced to occur in red-grown plants by 24–48 h of blue light at an irradiance of 2.3 nE × cm-2 × s-1, and the action spectra for both responses peaked in the region 4207#x2013;450 nm, with additional peaks at shorter and longer blue wavelengths, and in the near-UV. Red and far-red light was completely ineffective. The action spectrum for photosynthesis in young sporelings, however, peaked in red (670–680 nm) and blue (420–450 nm) wavelengths. Substantial photosynthesis also occurred at 540 and 630 nm, although the photosynthesis of red-grown plants was higher at these subsidiary wavelengths than in blue-grown plants. The results indicate that the induction of two-dimensional growth and of hair formation in Scytosiphon are specific morphogenesic effects of blue light, which occur independently of photosynthesis and growth.

Reproduction, growth and photosynthesis of gametophytes of Laminaria saccharina grown in blue and red light

The induction of reproductive activity by blue light in female gametophytes of the brown alga Lamnaria saccharina has been investigated and related to other effects of red and blue light on these plants. Although germination of zoo-spores is slightly delayed in red light, female gametophytes grow at similar rates in blue and red light of the same quantum irradiance up to an age of 8 to 10 days, when plants in blue light begin to form eggs. The percentage of plants forming eggs is proportional to the total quanta of blue wavelengths received up to a saturating value of about 400 μE·cm-2; a 50% response is induced by 200 μE·cm-2. The action spectrum for the induction of fertility has a main peak at 430 to 450 nm, with two subsidiary peaks in the blue and one in the near-ultraviolet light, but the action spectrum for photosynthesis is quite different, with peaks in the red, green and blue regions. These results indicate that egg formation in female gametophytes occurs as a specific morphogenetic response to blue light, which is independent of photosynthesis and growth, and trial experiments with male gametophytes of L. saccharina and gametophytes of other species of Laminariales indicate that these plants react similarly.

Significance of Enhancement for Calculations Based on the Action Spectrum for Photosynthesis

Calculations of the errors involved in measuring "photo-synthetically active radiation" in different ways are based on the assumption that the photosynthetic rate of a leaf in "white" light is equal to the sum of the products of (a) the photo-synthetic rate per unit of incident energy flux (action spectrum) by (b) the spectral energy flux distribution of the white light, the products being summed over all wavelengths at which the action spectrum is greater than zero. The calculations are valid only if the effects of different wavelengths are independent and additive. Although interactions are well documented in photo-synthesis ("enhancement"), tests showed that the photosynthetic rates of leaves of six species, in four different types of white light, were within +/-7% of the rates calculated in this way.

Test of current definitions of photosynthetically active radiation against leaf photosynthesis data

The photosynthetic rates ( P) of an “average leaf”, in light from 2 natural and 7 artificial sources, were calculated from the action spectrum for photosynthesis (McCree, 1971) and the spectral energy distributions of the light. The flux densities of photosynthetically active radiation ( E), variously defined as: (1) the energy flux in the waveband 400–700 nm; (2) the energy flux in the waveband 380–710 nm; (3) the incident quantum flux in the waveband 400–700 nm; and (4) the absorbed quantum flux in the waveband 400–700 nm, were also calculated, from the spectral energy distributions. The ratio P/E was then calculated, for all combinations of light source and flux definition, and normalized to 1.00 for sun+sky radiation. For any one flux definition, the deviation of this number from unity is the systematic error involved in an extrapolation to natural sun+sky light, from data obtained in other types of light, due to the mismatch between the flux definition and the action spectrum for leaf photosynthesis. For incandescent light from a quartz-iodine lamp, which is relatively rich in red light, the ratios using the four definitions were: (1) 1.19; (2) 1.19; (3) 1.08; and (4) 1.08. For skylight, which is relatively rich in blue light, the corresponding ratios were: (1) 0.88; (2) 0.86; (3) 0.95; and (4) 0.94. The ratios were slightly smaller for an average growth-chamber-grown leaf than for a field-grown leaf. Non-linearity of the P versus E relationship of the leaf also decreased the deviation; this was shown by experiment. The systematic errors introduced by using the incident quantum flux definition (3) were judged to be acceptable in practice. The paper also includes a table of flux ratios, which can be used (with caution) to convert from one flux definition to another, and a table of “photosynthetic efficacies” showing that the high pressure sodium lamp gives 26% more photosynthetic flux per watt of power consumed than any other lamp tested.

The action spectrum, absorptance and quantum yield of photosynthesis in crop plants

The measurements were made to provide a basis for discussion of the definition of “photosynthetically active radiation”. The action spectrum, absorptance and spectral quantum yield of CO 2 uptake were measured, for leaves of 22 species of crop plant, over the wavelength range 350 to 750 nm. The following factors were varied: species, variety, age of leaf, growth conditions (field or growth chamber), test conditions such as temperature, CO 2 concentration, flux of monochromatic radiation, flux of supplementary white radiation, orientation of leaf (adaxial or abaxial surface exposed). For all species and conditions the quantum yield curve had 2 broad maxima, centered at 620 and 440 nm, with a shoulder at 670 nm. The average height of the blue peak was 70% of that of the red peak. The shortwave cutoff wavelength and the height of the blue peak varied slightly with the growth conditions and with the direction of illumination, but for the practical purpose of defining “photosynthetically active radiation” the differences are probably insignificant. The action spectrum for photosynthesis in wheat, obtained by Hoover in 1937, could be duplicated only with abnormally pale leaves.

The Action Spectrum of Photosynthesis in Euglena Gracilis at Different Stages of Chloroplast Development

A method for measuring the action spectra of photosynthetic oxygen evolution in unicellular algae is described. This involves embedding the cells in a thin strip of agarose gel. These gel strips can then be used for action spectrum measurements, with a bare platinum electrode of the Haxo and Blinks type in the same way as measure� ments are made with a piece of multicellular algal thallus.

Maximum quantum yield and action spectrum of photosynthesis and fluorescence in chlorella

The maximum yield of oxygen production in Chlorella was found, in new, systematic experiments, not to exceed 0.12, under a great variety of conditions. Measurements were made on autospores and other synchronous cultures, at different CO 2 concentrations, at very low light intensities, and in the presence of ‘catalytic’ amounts of blue light. The action spectra (quantum yield as a function of wavelength) of photosynthesis, and of chlorophyll a fluorescence in vivo, were measured on the same Chlorella cell suspensions. In both cases, a decline in the yield was observed in the red beginning at about 675–680 nm. The yield declines to 50% of the maximum, on both curves, at 690–695 nm. A strong dip was observed in the action spectra of both fluorescence and photosynthesis at 660–665 nm.

Relationship between the Absorption and Emission Spectra and the "Red Drop" in the Action Spectra of Fluorescence In Vivo

The Stepanov equation, relating the intensity of emission, f(e)(v), at a given frequency, and that of absorption, k(v), at the same frequency, is applied, in its modified form (see equation 3 in text) to suspensions of Chlorella, Porphyridium, and Anacystis and to chlorophyll solutions. This application can reveal whether the yield of fluorescence, Phi(v), is constant, or changes with frequency. In Chlorella (green alga) a sharp drop of Phi(v) is indicated towards the lower frequencies (longer waves), beginning around v = 1.48 x 10(4)cm(-1) (680 mmu); the Phi(v) function calculated from the Stepanov equation is in fair agreement with the directly determined action spectrum for the excitation of chlorophyll fluorescence in this organism. In Porphyridium (red alga) and Anacystis (blue-green alga) application of the Stepanov equation supports the conclusions, derived from direct measurements, of a much earlier "red drop" of the fluorescence excitation spectra. Direct measurements suggest that the drop in Porphyridium may begin at about 1.53 x 10(4)cm(-1) (654 mmu); in Anacystis, it may begin already above 1.57 x 10(4)cm(-1) (<637mmu). These results confirm the relation, postulated earlier by Duysens and others, between the action spectra of photosynthesis and of chlorophyll a fluorescence in algal cells. The relation of these findings to spectroscopic evidence, suggesting the existence of two main chlorophyll a components in vivo, in green as well as in red and blue-green algae, is discussed.

Ultraviolet Action Spectra of Photosynthesis and Photosynthetic Inhibition in a Green and a Red Alga

Ultraviolet Action Spectra of Photosynthesis and Photosynthetic Inhibition in a Green and a Red Alga

Action spectrum, kinetics and quantum requirement of phosphopyridine nucleotide reduction and cytochrome oxidation in the blue-green alga Anacystis nidulans

By means of fluorescence and absorption-difference spectrophotometry the kinetics were measured of phosphopyridine nucleotide reduction and cytochrome oxidation in intact cells of the blue-green alga Anacytis nidulans upon illumination with light of various wavelengths. The action spectrum of phosphopyridine nucleotide reduction was found to be proportional to that of cytochrome oxidation; both action spectra showed activity of chlorophyll a and of phycocyanin, but a relatively higher activity of chlorophyll a than the action spectrum of photosynthesis. 3-(3,4-Dichlorophenyl)- i,i-dimethylurea, known as a very potent inhibitor of photosynthesis, did only slightly affect the initial rate of phosphopyridine nucleotide reduction upon illumination. The efficiency of cytochrome oxidation was appreciably increased by 3-(3,4-dichlorophenyl)- i,i-dimethylurea in light of 620 mμ, mainly absorbed by phycocyanin, but not or only slightly in light of 680 mμ, mainly absorbed by chlorophyll a. The number of quanta, required for the reduction of a phosphopyridine nucleotide molecule, was found to be about 5 at 620 mμ; the number needed for the oxidation of a molecule of cytochrome was 7–10 at 680 mμ. The results, together with other evidence, support the hypothesis that in algal photosynthesis two different photochemical oxidation-reduction reactions occur, mediated by two different pigment systems. The two systems operate in series: the first one reduces phosphopyridine nucleotide and oxidizes the cytochrome, the other one reduces the cytochrome and produces O 2 by means of the oxidation of water. Possibly in both light reactions one quantum is needed for the transfer of one hydrogen equivalent.