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  • Photosynthesis
  • Springer  (98)
  • American Chemical Society
  • Elsevier
  • 1985-1989  (98)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Recovery of photosynthesis after exposure of intertidal algae to osmotic and temperature stresses: comparative studies of species with differing distributional limits (1986)
    Springer
    Oecologia 70 (1986), S. 6-12 
    Details
    ISSN: 1432-1939
    Keywords: Photosynthesis ; Osmotic stress ; Temperature Stress ; Algae ; Intertidal region ; Porphyra perforata ; Rhodoglossum affine ; Gelidium coulteri ; Smithora naiadum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study examines possible relationships between stress tolerance by marine algae and distributions of these species. The ability to recover photosynthetic activity following dehydration or temperature treatments was the assay used to evaluate stress tolerance, and Porphyra perforata, Rhodoglossum affine, Gelidium coulteri, and Smithora naiadum differed in thresholds of tolerance, even though plants were collected from low tidal sites. Limits of dehydration tolerance were well correlated with limits of tidal distribution for these species. Additionally, other high tidal species tolerated severe dehydration while subtidal and low tidal species were sensitive to dehydration. High tidal individuals of P. perforata were also more tolerant of dehydration than were low tidal thalli of P. perforata. Limits of high or low temperature tolerance were not well correlated with tidal elevation for any groups of algae studied. However, cold-tolerant species had more northerly extensions, and warm-tolerant species had more southerly distributions. Thus, differential tolerance to temperature extremes may be an important influence for latitudinal ranges of species. By comparing the experimentally determined thresholds of stress with distributions of species, we test the role of stress in influencing photosynthesis and ultimately distributions of marine algae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377105
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  • 2
    Electronic Resource
    Electronic Resource
    Denitrification under different cultivated plants: effects of soil moisture tension, nitrate concentration, and photosynthetic activity (1988)
    Springer
    Biology and fertility of soils 6 (1988), S. 271-278 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Soil moisture ; Roots ; Photosynthesis ; Acetylene inhibition method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Plant effects on the denitrification rate were investigated in pot experiments at different soil moisture tensions and nitrate concentrations. Nitrate concentrations and the soil moisture tension were regulated immediately before each measurement. The effects of the plants on denitrification rates were dependent on the soil moisture tension. At a low soil moisture tension (−7 cm H2O), there was a 10-fold increase in the denitrification rate (planted versus unplanted soil). At a medium moisture tension (−30 cm H2O) the plants had practically no effect, and at the highest tension (−60 cm H2O) the effect was slightly negative. Large differences in denitrification rates under different plant species were observed. At a low soil moisture tension, the average denitrification rate (μg N kg−1 soil h−1) was 39–42 under small grains (barley, wheat, and oats), 47–82 under the grasses (cocksfoot, meadow grass, meadow fescue, and timothy) and 18 under red clover. The differences between the monocots were attributable to differences in plant growth rates, rather than to any specific difference in stimulation or inhibition of denitrification, since the variations in photosynthetic activity fairly well predicted the differences in denitrification rates under different monocots. Clover, however, gave much lower denitrification rates than those predicted by the photosynthetic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261011
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  • 3
    Electronic Resource
    Electronic Resource
    Nucleotide sequences of eDNAs encoding the entire precursor polypeptides for subunits II and III of the photosystem I reaction center from spinach (1988)
    Springer
    Current genetics 14 (1988), S. 511-518 
    Details
    ISSN: 1432-0983
    Keywords: Photosynthesis ; Photosystem I ; Subunits II and III ; cDNA nucleotide sequences ; Spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several cDNA clones encoding the complete subunit II and III precursor polypeptides of the photosystem I reaction center were isolated from two spinach lambda gtll expression libraries by immunoscreening and homologous hybridization. The identity of the recombinant cDNAs was verified by an N-terminal amino acid sequence of 14 and 20 residues for the respective mature spinach proteins. The ca. 880 nucleotide long sequence and derived amino acid sequence for subunit II predict a precursor of 23.2 kDa (212 residues) and a positively charged, mature protein of 17.9 kDa (162 residues). The corresponding data for subunit III are ca. 710 nucleotides (cDNA), 13.4 kDa (125 residues, precursor polypeptide) and, again, a positively charged, mature protein of 9.7 kDa (91 residues). Secondary structure predictions indicate that both subunits are extramembraneous components of photosystem I. Subunit II is probably located on the matrix-side, subunit III in the lumen of stroma lamellae which is consistent both with biochemical findings and the proposed roles of these proteins in the electron transition from and to photosystem I, respectively. Major transcripts of 1.1 kb (subunit II) and 0.8 kb (subunit III) have been observed by RNA-DNA hybridization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00521277
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis of cDNA clones encoding the entire precursor-polypeptide for ferredoxin: NADP+ oxidoreductase from spinach (1988)
    Springer
    Current genetics 13 (1988), S. 517-522 
    Details
    ISSN: 1432-0983
    Keywords: Photosynthesis ; Ferredoxin-NADP+ oxidoreductase ; cDNA Nucleotide sequence ; Transit peptide ; Spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this paper, we report the structural characterization of several spinach ferredoxin-NADP+ oxidoreductase (FNR) cDNAs ranging in size from 0.9 to 1.5 kilobases. A comparison of the deduced amino acid sequence with the known amino acid sequence determined for the spinach protein establishes that 1.4–1.5 kpb inserts span the full length of the mature protein (314 amino acid residues; Mr = 35,382). These also include an N-terminal 55 amino acid transit peptide as well as maximally 171 and 214 nucleotide 5′ and 3′ untranslated sequences, respectively. Evidence has been obtained that various forms of FNR arise from at least two similar genes. The FNR precursor (369 amino acid residues) has a calculated molecular mass of 41.2 kDa. Comparison of the transit peptide with transit peptides from two other stromal proteins shows little similarity at the level of primary sequence but some common features in secondary structure predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02427758
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  • 5
    Electronic Resource
    Electronic Resource
    Nucleotide sequences of cDNA clones encoding the entire precursor polypeptide for subunit VI and of the plastome-encoded gene for subunit VII of the photosystem I reaction center from spinach (1989)
    Springer
    Current genetics 16 (1989), S. 99-108 
    Details
    ISSN: 1432-0983
    Keywords: Photosynthesis ; Photosystem I ; Subunits VI and VII ; Nucleotide sequence ; Spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Recombinant phage which encode the entire precursor polypeptide for subunit VI of the photosystem I reaction center have been selected from a lambda gt11 cDNA expression library made from polyadenylated RNA of spinach seedlings. The sequence predicts a precursor polypeptide of 144 amino acids (Mr = 15.3 kDa), a mature protein of 95 residues (Mr = 10.4 kDa) that lacks methionine, histidine and cysteine, and a transit peptide of 49 residues (Mr = 4.9 kDa). The corresponding gene(s) is (are) designated psaH. The gene for subunit VII, psaC, has been located in the small single-copy region of the spinach plastid chromosome using a synthetic oligonucleotide and a heterologous hybridization probe. It is part of a polycistronic transcription unit that is constitutively expressed and processed. Putative processing products include a monocistronic RNA for psaC. The polypeptide chain of 81 (deduced) amino acids is highly conserved and strikingly resembles bacterial-type ferredoxins. It harbours cysteine residues that appear to be involved in the ligation of the two 4Fe4S centres A and B in photosystem I. None of the two subunits appears to be membrane-spanning, and subunit VI, as subunit VII, is located at the reducing (stromal) side of the reaction center. All available information on the major subunits of photosystem I from spinach has been combined into a (revised) topographic model. Evidence that the innermost — plastome-encoded — core of photosystem I represents an old bacterial heritage in present day chloroplasts is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393402
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  • 6
    Electronic Resource
    Electronic Resource
    Plastocyanin is encoded by an uninterrupted nuclear gene in spinach (1986)
    Springer
    Current genetics 11 (1986), S. 171-176 
    Details
    ISSN: 1432-0983
    Keywords: Plastocyanin ; Photosynthesis ; Genomic and cDNA clones ; Sequence analysis ; Transcript ; Spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plastocyanin is a member of photosynthetic electron transport chains that transfers electrons from cytochrome f to the oxidized P700 chlorophyll a pigment of the photosystem I reaction center. We have isolated and characterized cDNA- and genomic clones from spinach (Spinacia oleracea) encoding the complete plastocyanin-precursor polypeptide. The amino acid sequence derived from the nucleotide sequence shows that the precursor consists of 168 amino acid residues including a transit sequence of 69 residues. The precursor polypeptide has a predicted Mr of 16,917, the mature protein of 10,413. The available data indicate that plastocyanin derives probably from a single-copy gene. The coding region contains no intron. The size of the mRNA as determined by S1 nuclease protection experiments is approximately 660 nucleotides, although analysis of different cDNA clones suggests that longer RNA species do exist, approaching the size of the mRNA (850 bases) estimated by Northern blot techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00420603
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  • 7
    Electronic Resource
    Electronic Resource
    Canopy structure, light microclimate and leaf gas exchange of Quercus coccifera L. in a Portuguese macchia: measurements in different canopy layers and simulations with a canopy model (1986)
    Springer
    Trees 1 (1986), S. 25-41 
    Details
    ISSN: 1432-2285
    Keywords: Canopy structure ; Quercus coccifera ; Photosynthesis ; Transpiration ; Simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The structural characteristics of a diverse array of Quercus coccifera canopies were assessed and related to measured and computed light attenuation, proportion of sunlit foliage, foliage temperatures, and photosynthesis and diffusive conductance behavior in different canopy layers. A canopy model incorporating all components of shortwave and longwave radiation, and the energy balance, conductance, and CO2 and H2O exchanges of all leaf layers was developed and compared with measurements of microclimate and gas exchange in canopies in four seasons of the year. In the denser canopies with a leaf area index (LAI) greater than 5, there is little sunlit foliage and the diffuse radiation (400–700 nm) is attenuated to 5% or less of the global radiation (400–700 nm) incident on the top of the canopy. Foliage of this species is nonrandomly distributed with respect to azimuth angle, and within each canopy layer, foliage azimuth and inclination angles are correlated. A detailed version of the model which computed radiation interception and photosynthetic light harvesting according to these nonrandom distributions indicated little difference in whole-canopy gas exchange from calculations of the normal model, which assumes random azimuth orientation. The contributions of different leaf layers to canopy gas exchange are not only a function of the canopy microclimate, but also the degree to which leaves in the lower layers of the canopy exhibit more shade-leaf characteristics, such as low photosynthetic and respiratory capacity and maximal conductance. On cloudless days, the majority of the foliage in a canopy of 5.4 LAI is shaded —70%–90% depending on the time of year. Yet, the shaded foliage under these conditions is calculated to contribute only about one-third of the canopy carbon gain. This contribution is about the same as that of the upper 13% of the canopy foliage. Computed annual whole-canopy carbon gain and water use are, respectively, 60% and 100% greater for a canopy of 5 LAI than for one of 2 LAI. Canopy water-use efficiency is correspondingly less for the canopy of 5 LAI than for that of 2 LAI, but most of this difference is apparent during the cool months of the year, when moisture is more abundant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197022
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  • 8
    Electronic Resource
    Electronic Resource
    Heterosis in hybrid larch (Larix decidua x leptolepis) (1987)
    Springer
    Trees 1 (1987), S. 219-224 
    Details
    ISSN: 1432-2285
    Keywords: Larix ; Heterosis ; Photosynthesis ; Stomatal conductance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Individual 33-year-old forest trees of the deciduous conifer speciesLarix decidua, Larix leptolepis andLarix decidua x leptolepis were investigated with respect to the phenomenon of stem heterosis in hybrid larch; the first part of this study compares the gas exchange responses of leaves. CO2 assimilation per leaf area was similar in the three larch species, but on a dry weight basis the nitrogen content of the needles and maximum CO2 assimilation rate (Amax) were slightly higher in the hybrid. This increase was accompanied by a higher protein content than in the Japanese and a lower specific leaf weight than in the European larch. All three species were similar in terms of the photosynthetic “nitrogen use” and stomatal conductance atA max. The similar slopes of the area-related steady-state responses of gas exchange against irradiance, evaporative demand and internal CO2 concentration led to similar rates of CO2 uptake under ambient conditions. The natural combinations and variability of the environmental factors also reduced the small dry weight-related difference inA max between hybrid larch and the parent species, such that all trees achieved similar daily carbon gains. Thus, the ecological significance of small interspecific differences in the metabolism of leaves has very little effect under the natural habitat conditions of a temperate climate. The second part of the study will investigate the effect of growth characteristics on the heterosis of hybrid larch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01816819
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  • 9
    Electronic Resource
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    Stomatal aperture, photosythesis and water fluxes in mesophyll cells as affected by the abscission of leaves. Simultaneous measurements of gas exchange, light scattering and chlorphyll fluorescence (1986)
    Springer
    Planta 167 (1986), S. 554-562 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Light scattering ; Photosynthesis ; Transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carbon dioxide exchange, transpiration, chlorophyll fluorescence and light scattering of leaves of Lycopersicom esculentum, Helianthus annuus and Arbutus unedo were measured simultaneously before and after abscission of leaves. Scattering of a weak green measuring beam was used to monitor water fluxes across the thylakoid membranes of the mesophyll. When leaves were cut under water, stomata initially closed partially and then occasionally exhibited distinct regulatory oscillations. As stomata closed, light scattering decreased indicating water influx into the mesophyll. Stomatal oscillations were accompanied, with small but noticeable phase shifts, by oscillations of water fluxes at the thylakoid level. These fluxes could be distinguished from the water fluxes accompanying light-dependent ion pumping across the thylakoids by the concomitant chlorophyll fluorescence signals. The latter record energy-dependent ion fluxes in addition to redox changes of the electron-transport chain. As stomata closed partially after cutting a leaf under water, photosynthesis decreased. In Arbutus unedo and Helianthus annuus leaves, transient stomatal closure was insufficient to account for transient inhibition of photosynthesis which appeared to be brought about by transfer of an inhibitory solute through the petiole into the mesophyll. This solute also stimulated respiration in the dark. When leaves were cut in air, stomata opened transiently (Iwanoff effect) before wilting enforced closure. Photosynthesis followed the stomatal responses, increasing during opening and decreasing during closure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391232
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  • 10
    Electronic Resource
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    Stimulation of photosynthesis by 2% oxygen at low temperatures is restored by phosphate (1986)
    Springer
    Planta 168 (1986), S. 84-93 
    Details
    ISSN: 1432-2048
    Keywords: Benson-Calvin cycle ; Phosphate and photosynthesis ; Photosynthesis ; Photorespiration ; Spinacia (photosynthesis)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of phosphate feeding on the influence of low (2%) oxygen on photosynthetic carbon assimilation has been investigated in leaf discs of spinach (Spinacia oleracea L.) at 12°C. The following observations were made. First, after the transition from 20% O2 to 2% O2, the rate of CO2 uptake was inhibited at CO2 concentrations between about 250 and about 800 μl CO2·l-1. Second, phosphate feeding stimulated the rate of CO2 uptake in 20% O2 at higher concentrations of CO2 (500–900 μl·l-1). Third, phosphate feeding stimulated the rate of CO2 uptake in 2% O2 at all but the highest (900 μl·l-1) and lowest 74 (μl·l-1) concentrations of CO2 employed. Phosphate thereby restored the stimulation of photosynthesis by 2% O2 and it did so over a wide range of lower temperatures. Fourth, oscillatory behaviour, however generated, was dampened by phosphate feeding, even at very low concentrations of CO2. Contents of leaf metabolites were measured during the transition to 2% O2 in control and phosphate-fed leaf discs. During this period the ratio glycerate-3-phosphate/triose phosphate rose steeply, but fell again only in the phosphate-treated leaf discs. These data, taken together with measured ATP/ADP ratios, showed that assimilatory power, the ratio [ATP]·[NAD(P)H]/[ADP]·[Pi]·[NAD(P)], decreased when leaves were exposed to 2% O2, but that this decrease was minimised by previous feeding of phosphate. The mechanism of phosphate limitation is discussed in the light of the results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00407013
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  • 11
    Electronic Resource
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    Photosynthetic characteristics of mesophyll cells isolated from cladophylls ofAsparagus officinalis L. (1986)
    Springer
    Planta 169 (1986), S. 38-45 
    Details
    ISSN: 1432-2048
    Keywords: Asparagus (photosynthesis) ; Carbon partitioning ; Mesophyll (isolated cells) ; Photosynthesis ; Sucrose synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intact mesophyll cells can be rapidly isolated from the cladophylls ofAsparagus officinalis by gentle scraping with a plastic card, the yield being higher than 80% on a chlorophyll basis. The cells can be stored for at least 24h without loss of photosynthetic capacity and were found to be stable under a variety of conditions. In contrast to cell preparations from other plant species, photosynthetic activity was little affected by the presence of sorbitol as an osmoticum up to a concentration of 1.5 M. Similarly, the pH value of the medium influenced photosynthesis to only a small extent at a constant [CO2] of 200 μM. The response of the cells' photosynthetic capacity to light, temperature and CO2 concentration was similar to those reported for isolated cells from other plant species. Isolated cells ofA. officinalis can be used under a large range of conditions which gives them a measure of flexibility not possible with most plant cells which have sharply defined optimal conditions for photosynthesis. The isolated cells have a photosynthetic capacity of 40–60% of that of the intact cladophyll. The loss of photosynthetic activity observed upon isolation could not be accounted for by breakage of the cells. Virtually all of the cells were shown to be intact on the basis of Evans Blue exclusion and more than 80% of the cells contained intact chloroplasts and vacuoles. The entire loss of photosynthetic activity could be accounted for by a decrease in sucrose synthesis rather than by an equal decrease in the synthesis in all products. A six- to seven fold increase in the level of14C in hexose phosphates in the isolated cells supports the notion of inhibition of the sucrose-synthesis pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01369773
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  • 12
    Electronic Resource
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    Light and the maintenance of photosynthetic competence in leaves of Populus balsamifera L. during short-term exposures to high concentrations of sulfur dioxide (1989)
    Springer
    Planta 177 (1989), S. 91-97 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Photoinhibition ; Photosynthesis ; Populus ; Sulfur dioxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaves of Populus balsamifera grown under full natural sunlight were treated with 0, 1, or 2 μl SO2·1-1 air under one of four different photon flux densities (PFD). When the SO2 exposures took place in darkness or at 300 μmol photons·m-2·s-1, sulfate accumulated to the levels predicted by measurements of stomatal conductance during SO2 exposure. Under conditions of higher PFD (750 and 1550 μmol·m-2·s-1), however, the predicted levels of accumulated sulfate were substantially higher than those obtained from anion chromatography of the leaf extracts. Light-and CO2-saturated capacity as well as the photon yield of photosynthetic O2 evolution were reduced with increasing concentration of SO2. At 2 μl SO2·1-1 air, the greatest reductions in both photosynthetic, capacity and photon yield occurred when the leaves were exposed to SO2 in the dark, and increasingly smaller reductions in each occurred with increasing PFD during SO2 exposure. This indicates that the inhibition of photosynthesis resulting from SO2 exposure was reduced when the exposure occurred under conditions of higher light. The ratio F v/F M (variable/maximum fluorescence emission) for photosyntem II (PSII), a measure of the photochemical efficiency of PSII, remained unaffected by exposure of leaves to SO2 in the dark and exhibited only moderate reductions with increasing PFD during the exposure, indicating that PSII was not a primary site of damage by SO2. Pretreatment of leaves with SO2 in the dark, however, increased the susceptibility of PSII to photoinhibition, as such pretreated leaves exhibited much greater reductions inF V/F M when transferred to moderate or high light in air than comparable control leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392158
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  • 13
    Electronic Resource
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    Correlations between carbon isotope ratio and microhabitat in desert plants (1988)
    Springer
    Oecologia 76 (1988), S. 562-566 
    Details
    ISSN: 1432-1939
    Keywords: Photosynthesis ; Transpiration ; Stable isotopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Water is usually considered to be the key limiting factor for growth of desert plants, yet there is little information available of the water-use efficiency of species within a desert community. Leaf carbon isotope ratios, an indicator of long-term intercellular carbon dioxide concentrations and thus of water-use efficiency in C3 plants, were measured on species occurring within a Sonoran Desert community, consisting of wash, transition and slope microhabitats. Along a soil moisture gradient from the relatively wetter wash to the relatively drier slope, leaf carbon isotope ratios increased in all species, indicating that water-use efficiency increased as soil water availability decreased. Leaf carbon isotope ratios of long-lived perennials were substantially more positive than in short-lived perennials, even though plants were growing adjacent to each other. Leaf carbon isotope ratio and leaf duration (evergreen versus deciduous) were not correlated with each other. The results are discussed in terms of how the efficiency of water use may affect community structure and composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397870
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  • 14
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    Photosynthesis in epiphytic and rooted Clusia rosea Jacq. (1987)
    Springer
    Oecologia 72 (1987), S. 457-460 
    Details
    ISSN: 1432-1939
    Keywords: Photosynthesis ; Hemiepiphyte ; Crassulacean acid metabolism ; Carbon isotope ratios
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Clusia rosea Jacq. is a hemiepiphyte having Crassulacean Acid Metabolism (CAM). In its natural habitat Clusia begins its life cycle as an epiphyte and eventually becomes a rooted tree. These two stages of the life cycle of Clusia represent markedly different water regimes. Our CO2 exchange, stomatal conductance, titratable acidity, and stable carbon isotope ratio measurements indicate that Clusia has a flexible photosynthetic mode, where CO2 is fixed mostly via CAM during its epiphytic stage, when water availability is low, and via both CAM and C3 during its rooted stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377579
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  • 15
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    Water status related photosynthesis and carbon isotope discrimination in species of the lichen genusPseudocyphellaria with green or blue-green photobionts and in photosymbiodemes (1988)
    Springer
    Oecologia 75 (1988), S. 494-501 
    Details
    ISSN: 1432-1939
    Keywords: Photosymbiodeme ; Phycosymbiodeme ; Delta13C ; Lichen ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Green lichens have been shown to attain positive net photosynthesis in the presence of water vapour while blue-green lichens require liquid water (Lange et al. 1986). This behaviour is confirmed not only for species with differing photobionts in the genusPseudocyphellaria but for green and blue-green photobionts in a single joined thallus (photosymbiodeme), with a single mycobiont, and also when adjacent as co-primary photobionts. The different response is therefore a property of the photobiont. The results are consistent with published photosynthesis/water content response curves. The minimum thallus water content for positive net photosynthesis appears to be much lower in green lichens (15% to 30%, related to dry weight) compared to blue-greens (85% to 100%). Since both types of lichen rehydrate to about 50% water content by water vapour uptake only green lichens will show positive net photosynthesis. It is proposed that the presence of sugar alcohols in green algae allow them to retain a liquid pool (concentrated solution) in their chloroplasts at low water potentials and even to reform it by water vapour uptake after being dried. The previously shown difference in δ13C values between blue-green and green lichens is also retained in a photosymbiodeme and must be photobiont determined. The wide range of δ13C values in lichens can be explained by a C3 carboxylation system and the various effects of different limiting processes for photosynthetic CO2 fixation. If carboxylation is rate limiting, there will be a strong discrimination of13CO2, at high internal CO2 partial pressure. The resulting very low δ13C values (-31 to-35‰) have been found only in green lichens which are able to photosynthesize at low thallus water content by equilibraiton with water vapour. When the liquid phase diffusion of CO2 becomes more and more rate limiting and the internal CO2 pressure decreases, the13C content of the photosynthates increases and less negative δ13C values results, as are found for blue-green lichens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00776410
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  • 16
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    Influence of krummholz mat microclimate on needle physiology and survival (1987)
    Springer
    Oecologia 73 (1987), S. 82-90 
    Details
    ISSN: 1432-1939
    Keywords: Timberline ; Krummholz ; Microclimate ; Picea engelmannii ; Abies lasiocarpa ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microclimate and photosynthesis of krummholz mat growth forms of Picea engelmanii (Parry) and Abies lasiocarpa [Hook.] Nutt. were investigated to determine structural features which may aid survival in alpine environments. The structure of krummholz mats was described in terms of the vertical distribution of leaf area index and leaf area density, which exceeded 50 m-1 (based on total leaf surface area) near the canopy surface and approached zero below 30 cm from the surface in both species. Photosynthetic photon flux density (PPFD, 0.4–0.7 μm wavelengths) and wind decreased by an average of 6 and 50-fold, respectively, between 1 m above and 10 cm below mat surfaces in both species. Needle temperatures on a P. engelmannii krummholz mat during July averaged about 2°C above air temperature during the day, with a maximum overtemperature of greater than 20°C above T air during one sunlit period. At night, needle temperatures averaged 3–4°C below T air. Net photosynthesis in year-old P. engelmannii shoots reached a maximum at 15–20°C during July and August. Surface shoots were light saturated at near 1200 μmoles m-2s-1 PPFD, and had higher photosynthetic rates than subsurface, predominantly shaded shoots above 800 μmoles m-2s-1. Shade shoots had higher photosynthetic rates when PPFD was below 600 μmoles m-2s-1, and at 250 μmoles m-2s-1 shade shoots maintained about 50% of the net photosynthetic rate of sun shoots at light saturation. Shade shoots appeared capable of benefitting photosynthetically from elevated temperatures within krummholz mats despite relatively low light levels. Especially rapid photosynthesis may occur when canopy needles are illuminated by sunflecks and needle temperatures rise by 10° C or more. Snow cover appears crucial for the survival of needles during winter. Snow accumulated within krummholz needle canopies before the sub-canopy zone of unfoliated branches became filled. The concentrated needle growth in the krummholz canopy captured snow in early autumn without support from ground-level snowpack. Early snow cover in both species prevented cuticle abrasion and resulted in high winter needle water contents and viabilities for subsurface compared to surface needles which became abraded, severely dehydrated, and had high mortality between December and February, especially on windward sides of shoots. Extremely high concentrations of needles within krummholz mat canopies created an aerodynamic structure which elevated needle temperatures to more optimal photosynthetic levels in summer and resulted in more efficient snow accumulation in winter. These factors appear crucial for winter needle survival. Thus, krummholz mats appear to be an important adaptation in growth form which provides survival benefits in both summer and winter.
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    URL: http://dx.doi.org/10.1007/BF00376981
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    Stomatal and photosynthetic responses during sun/shade transitions in subalpine plants: influence on water use efficiency (1987)
    Springer
    Oecologia 74 (1987), S. 62-67 
    Details
    ISSN: 1432-1939
    Keywords: Cloudcover ; Photosynthesis ; Stomatal conductance ; Subalpine ; Water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Different response patterns in net photosynthesis (A) leaf conductance (g) and water use efficiency (WUE= a/transpiration) in three subalpine plants occurred during experimental sun/shade transitions that simulated natural cloudcover. In Frasera speciosa Dougl., a large-leaved herb characteristic of open sites, g was relatively insensitive to transitions in irradiance and variations in A. However, large decreases in leaf temperature resulted in reduced transpiration during shade intervals and relatively constant WUE throughout the experimental sun/shade regime. In the understory herb, Arnica cordifolia Hook., patterns of A and g were similar during sun/shade transitions, but WUE was substantially reduced compared to steady-state levels. A third, somewhat intermediate pattern of A, g, and WUE was found in Artemisia tridentata L., an open site shrub. Higher intercellular CO2 values in A. tridentata suggested that internal, cellular limitations to A were high relative to stomatal limitations in this shrub when compared to the herbaceous species.
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    URL: http://dx.doi.org/10.1007/BF00377346
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    Performance of two Picea abies (L.) Karst. stands at different stages of decline (1988)
    Springer
    Oecologia 76 (1988), S. 513-518 
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    ISSN: 1432-1939
    Keywords: Picea abies ; Forest decline ; Stomatal response ; Photosynthesis ; Mg-deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary CO2 assimilation rate (A) and leaf conductance (g) were measured in the field on intact branches of 35-year-old Picea abies (L.) Karst. trees, in five plots each in a healthy and a declining stand. The declining site included trees with yellow needles. In order to separate atmospheric effects on gas exchange from effects of nutrient deficiency, direct effects of atmospheric pollutants were studied on green needles of different age classes in plots of trees at different stages of visible decline. The effects of nutrient deficiency on gas exchange were studied on a different group of trees showing needles of various degrees of yellowing. CO2 assimilation of green needles at the same leaf conductance fell somewhat only when needles had reached 5 years of age, the oldest age examined in this study. Leaf conductance decreased with increasing needle age, but green needles in the declining stand had leaf conductances similar to those of needles in the healthy stand. Stomata of needles with different magnesium concentrations responded to light and air humidity in all age classes. Thus, as long as needles were green, no dese effect was detectable up to 5 years of exposure to atmospheric emissions. Since all needles, green and yellow, were exposed to the same pollution levels, differences in gas exchange between green and yellow needles could not be explained simply in terms of long-term direct effects of air pollution. Needle magnesium contents were correlated with needle yellowing. Neither needle color change nor the magnesium concentration were related to g, but CO2 uptake at ambient CO2 levels declined with lower magnesium concentration and greater degrees of needle yellowing.
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    URL: http://dx.doi.org/10.1007/BF00397862
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    Effect of CO2 enrichment and nitrogen availability on resource acquisition and resource allocation in a grass, Bromus mollis (1988)
    Springer
    Oecologia 77 (1988), S. 544-549 
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    ISSN: 1432-1939
    Keywords: Bromus mollis ; CO2 enrichment ; Biomass partitioning ; Photosynthesis ; Leaf nitrogen concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of CO2 enrichment on the growth, biomass partitioning, photosynthetic rates, and leaf nitrogen concentration of a grass, Bromus mollis (C3), were investigated at a favorable and a low level of nitrogen availability. Despite increases in root: shoot ratios, leaf nitrogen concentrations were decreased under CO2 enrichment at both nitrogen levels. For the low-nitrogen treatment, this resulted in lower photosynthetic rates measured at 650 μl/l for the CO2-enriched plants, compared to photosynthetic rates measured at 350 μl/l for the non-enriched plants. At higher nitrogen availability, photosynthetic rates of plants grown and measured at 650 μl/l were greater than photosynthetic rates of the non-enriched plants measured at 350 μl/l. Water use efficiency, however, was increased in enriched plants at both nitrogen levels. CO2 enrichment stimulated vegetative growth at both high and low nitrogen during most of the vegetative growth phase but, at the end of the experiment, total biomass of the high and low CO2 treatments did not differ for plants grown at low nitrogen availability. While not statistically significant, CO2 tended to stimulate seed production at high nitrogen and to decrease it at low nitrogen.
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    URL: http://dx.doi.org/10.1007/BF00377272
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    The impact of ten years at -20°C on gas exchange in five lichen species (1989)
    Springer
    Oecologia 78 (1989), S. 87-92 
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    ISSN: 1432-1939
    Keywords: Frost resistance ; Freezing stress ; Lichen physiology ; Photosynthesis ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rates of net CO2 exchange in five sympatric species of Umbilicaria were measured after 10 years at-20°C. During that time, the lichens had been at either a high (saturated) or a low (air-dry) water content. The results showed an immediate, return to normal rates of gas exchange for air-dried then frozen U.vellea. Rates returned to normal for air-dried U. deusta within four days. The three other species studied, U. mammulata, U. papulosa and U. muhlenbergii showed intermediate responses. Water saturated then frozen thalli of U. vellea were irreparably damaged after 10 years; even fungal respiration was severely impaired. In U. mammulata, U. papulosa and U. muhlenbergii, photosynthesis was eliminated but fungal respiration rates were not influenced. In contrast to this, water saturated then frozen thalli of U. deusta showed a nearly equal photosynthetic capacity to the original rates following 10 years at -20°C. In all cases the magnitude of the effect of the long-term subzero treatment correlated well with the known distribution patterns of the lichens in the field.
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    URL: http://dx.doi.org/10.1007/BF00377201
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    Photosynthetic kinetics determine the outcome of competition for dissolved inorganic carbon by freshwater microalgae: implications for acidified lakes (1987)
    Springer
    Oecologia 73 (1987), S. 307-311 
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    ISSN: 1432-1939
    Keywords: Algae ; Photosynthesis ; Competition ; pH ; Acidification ; Dissolved inorganic carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Photosynthetic kinetics with respect to dissolved inorganic carbon were used to predict the outcome of competition for DIC between the green alga Selenastrum minutum and the cyanobacterium Synechococcus leopoliensis at pH 6.2, 7.5, and 10. Based on measured values of the maximum rate of photosynthesis, the half-saturation value of photosynthesis with respect to DIC (K 1 2/DIC ), and the DIC compensation point, it was predicted that S. leopoliensis would lower the steady-state DIC concentration below the DIC compensation point of S. minutum. This should result in competitive displacement of the green alga at a rate equivalent to the chemostat dilution rate. This prediction was validated by carrying out competition experiments over the range of pH. These results suggest that the low levels of DIC in air-equilibrated acidified lakes may be an important rate-limiting resource and hence affect phytoplankton community structure. Furthermore, the low levels of DIC in these systems may be below the DIC compensation point for some species, thereby precluding their growth at acid pH solely as a function of DIC limitation. The potential importance of DIC in shaping phytoplankton community structure in acidified systems is discussed.
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    URL: http://dx.doi.org/10.1007/BF00377523
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    The effect of water and nitrogen amendments on photosynthesis, leaf demography, and resource-use efficiency in Larrea tridentata, a desert evergreen shrub (1989)
    Springer
    Oecologia 80 (1989), S. 341-348 
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    ISSN: 1432-1939
    Keywords: Larrea tridentata ; Leaf demography ; Nutrient resorption ; Nutrient-use efficiency ; Photosynthesis ; Water-use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the Chihuahuan Desert of southern New Mexico, both water and nitrogen limit the primary productivity of Larrea tridentata, a xerophytic evergreen shrub. Net photosynthesis was positively correlated to leaf N, but only in plants that received supplemental water. Nutrient-use efficiency, defined as photosynthetic carbon gain per unit N invested in leaf tissue, declined with increasing leaf N. However, water-use efficiency, defined as the ratio of photosynthesis to transpiration, increased with increasing leaf N, and thus these two measures of resource-use efficiency were inversely correlated. Resorption efficiency was not significantly altered over the nutrient gradient, nor was it affected by irrigation treatments. Leaf longevity decreased significantly with fertilization although the absolute magnitude of this decrease was fairly small, in part due to a large background of insect-induced mortality. Age-specific gas exchange measurements support the hypothesis that leaf aging represents a redistribution of resources, rather than actual deterioration or declining resource-use efficiency.
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    URL: http://dx.doi.org/10.1007/BF00379035
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    Ecophysiology of exotic and native shrubs in Southern Wisconsin (1989)
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    Oecologia 80 (1989), S. 356-367 
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    ISSN: 1432-1939
    Keywords: Carbon gain ; Exotic shrubs ; Leaf longevity ; Photosynthesis ; Understory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We compared seasonal trends in photosynthesis of two naturalized exotic shrubs (Rhamnus cathartica and Lonicera X bella) and two native shrubs (Cornus racemosa and Prunus serotina) in open and understory habitats in southern Wisconsin. We examined the relationships between resource availability and leaf photosynthetic performance in these four species. All four species had similar relationships between leaf nitrogen (N) content and photosynthetic rate, but the species differed in absolute leaf N content and therefore in photosynthetic rates. Maximum daily photosynthetic rates of all species were significantly correlated with leaf N content in the open habitat, but not in the understory, where low light availability was the major limitation to photosynthesis. Extended leaf longevity was important in the forest understory because it allowed shrubs to take advantage of high light availability at times when the overstory canopy was leafless. Early leaf emergence was more important than late senescence: from 27% to 35% of the annual carbon gain of P. serotina, R. cathartica, and L. X bella occurred prior to leaf emergence of C. racemosa, the species with the shortest leaf life span. Extended leaf longevity of exotic shrubs may help explain their persistence in the understory habitat, but it contributed relatively less to their annual carbon gain in the open habitat.
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    URL: http://dx.doi.org/10.1007/BF00379037
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    A global survey of carbon isotope discrimination in plants from high altitude (1988)
    Springer
    Oecologia 74 (1988), S. 623-632 
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    ISSN: 1432-1939
    Keywords: Photosynthesis ; δ 13C ; Alpine ecology ; Atmospheric CO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Carbon 13/12 isotope ratios have been determined from leaves of a hundred C3 plant species (or ecotypes) from all major mountain ranges of the globe, avoiding drought stressed areas. A general increase in 13C content was found with increasing altitude, i.e. overall discrimination against the heavy isotope is reduced at high elevation. The steepest decline of discrimination is observed in taxa typically ranging to highest elevations (e.g. the genus Ranunculus). Mean δ 13C for all samples collected between 2500 and 5600 m altitude is-26.15‰ compared to the lowland average of-28.80‰ (P〈0.001). Forbs from highest elevations reach-24‰. According to theory of 13C discrimination this indicates decreasing relative limitation of carbon uptake by carboxylation. In other words, we estimate that the ratio of internal to external partial pressure of CO2 (p i /p a )in leaves of high elevation plants is lower than in leaves of low altitude. These results confirm recent gas exchange analyses in high and low elevation plants.
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    URL: http://dx.doi.org/10.1007/BF00380063
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    Ecophysiology of Zigadenus nuttallii, a toxic spring ephemeral in a warm season grassland: effect of defoliation and fire (1986)
    Springer
    Oecologia 71 (1986), S. 69-74 
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    ISSN: 1432-1939
    Keywords: Photosynthesis ; Carbon storage ; Fire ; Herbivory ; Zigadenus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Zigadenus nuttallii, a highly toxic spring ephemeral in tallgrass prairie, was studied in 1985 to ascertain: 1) several ecophysiological characteristics of the species, 2) seasonal patterns of biomass accumulation, and 3) its response to defoliation and fire. The maximum photosynthetic rate of Z. nuttallii measured in unburned prairie was 13.2 μmoles CO2 m-2 s-1 which occurred at 24–28° C and an incident quantum flux of 0.8–1.0 mmoles m-2 s-1. Maximum stomatal conductance measured was 5.4 mm s-1. Early in the season, belowground storage organs (bulbs) decreased in mass and supplied much of the energy for growth of leaves, even though CO2 uptake was possible. Buld mass did not increase until about 6 weeks after shoot emergence implying that, at this time, leaves had become a source rather than a sink for carbohydrates. The result of a single, severe defoliation event was a decrease in biomass of bulbs, leaves and reproductive structures in Z. nuttallii. Intrinsic compensatory mechanisms were not detected. In contrast, fire, which also defoliated plants, did not result in any biomass decrease at the end of the season. Improved post-fire microclimate and increased nutrient supply (extrinsic factors) may have contributed to higher photosynthetic rates and led to biomass compensation in burned prairie. These data support arguments that intrinsic compensatory mechanisms have evolved in response to chronic herbivory.
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    URL: http://dx.doi.org/10.1007/BF00377323
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    Water vapor uptake and photosynthesis of lichens: performance differences in species with green and blue-green algae as phycobionts (1986)
    Springer
    Oecologia 71 (1986), S. 104-110 
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    ISSN: 1432-1939
    Keywords: Lichens ; Humidity ; Water vapor uptake ; Photosynthesis ; Respiration ; Water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Dry lichen thalli were enclosed in gas exchange chambers and treated with an air stream of high relative humidity (96.5 to near 100%) until water potential equilibrium was reached with the surrounding air (i.e., no further increase of weight through water vapor uptake). They were then sprayed with liquid water. The treatment took place in the dark and was interrupted by short periods of light. CO2 exchange during light and dark respiration was monitored continuously. With no exception water uptake in all of the lichen species with green algae as phycobionts lead to reactivation of the photosynthetic metabolism. Further-more, high rates of CO2 assimilation were attained without the application of liquid water. To date 73 species with different types of Chlorophyceae phycobionts have been tested in this and other studies. In contrast, hydration through high air humidity alone failed to stimulate positive net photosynthesis in any of the lichens with blue-green algae (Cyanobacteria). These required liquid water for CO2 assimilation. So far 33 species have been investigated, and all have behaved similarly. These have included gelatinous as well as heteromerous species, most with Nostoc phycobionts but in addition some with three other Cyanophyceae phycobionts. The same phycobiont performance differences existed even within the same genus (e.g. Lobaria, Peltigera) between species pairs containing green or blue-green phycobionts respectively. Free living algae also seem to behave in a similar manner. Carbon isotope ratios of the lichen thalli suggest that a definite ecological difference exists in water status-dependent photosynthesis of species with green and blue-green phycobionts. The underlying biochemical or biophysical mechanisms are not yet understood. Apparently, a fundamental difference in the structure of the two groups of algae is involved.
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    URL: http://dx.doi.org/10.1007/BF00377327
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    Responses of gas exchange to humidity in populations of three herbs from environments differing in atmospheric water (1986)
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    Oecologia 71 (1986), S. 117-120 
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    ISSN: 1432-1939
    Keywords: Photosynthesis ; Stomatal conductance ; Vapor pressure difference ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Responses to humidity of net photosynthesis and leaf conductance of single attached leaves were examined in populations of herbs from wet soil sites in Beltsville, Maryland and Davis, California, USA. Plants were grown in controlled environments under three conditions which differed in the magnitude of the day-night temperature difference and in daytime air saturation deficit. No population differences in response were found in Abutilon theophrasti. In Amaranthus hybridus stomatal conductance and net photosynthesis were more reduced by increasing leaf to air water vapor pressure difference (VPD) in the population from Beltsville, but only for the growth condition with a constant 25°C temperature. In Chenopodium album, stomatal conductance was more sensitive to VPD in the population from Davis, but only for the growth condition with 28/22°C day/night temperatures. Population differences in the sensitivity to VPD of leaf conductance were associated with differences in leaf area to root weight ratio. The relative reduction of net photosynthesis as VPD increased was greater than, equal to, or less than the relative decrease in substomatal carbon dioxide partial pressure. The pattern depended on species, and on growth condition. From these results one can not conclude that environmental humidity has been a strong selective force in determining sensitivity to humidity of stomatal conductance.
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    Variable HCO 3 - affinity of Elodea canadensis Michaux in response to different HCO 3 - and CO2 concentrations during growth (1986)
    Springer
    Oecologia 70 (1986), S. 426-432 
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    ISSN: 1432-1939
    Keywords: Photosynthesis ; HCO 3 - /CO2 concentration ; Aquatic plants ; Eloded canadensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Elodea canadensis grows over a wide range of inorganic carbon, nutrient, and light conditions in lakes and streams. Affinity for HCO 3 - use during photosynthesis ranged from strong to weak in Elodea collected from seven localities with different HCO 3 - and CO2 concentrations. The response to HCO 3 - was also very plastic in plants grown in the laboratory at high HCO 3 - concentrations and CO2 concentrations varying from 14.8 to 2,200 μM. Bicarbonate affinity was markedly reduced with increasing CO2 concentrations in the growth medium so that ultimately HCO 3 - use was not detectable. High CO2 concentrations also decreased CO2 affinity and induced high CO2 compensation points (360μM CO2) and tenfold higher half-saturation values (∼800 μM CO2). The variable HCO 3 - affinity is probably environmentally based. Elodea is a recently introduced species in Denmark, where it reproduces only vegetatively, leaving little opportunity for genetic variation. More important, local populations in the same water system had different HCO 3 - affinities, and a similar variation was created by exposing one plant collection to different laboratory conditions. Bicarbonate use enabled Elodea to photosynthesize rapidly in waters of high alkalinity and enhanced the carbon-extracting capacity by maintaining photosynthesis above pH 10. On the other hand, use of HCO 3 - represents an investment in transport apparatus and energy which is probably not profitable when CO2 is high and HCO 3 - is low. This explanation is supported by the findings that HCO 3 - affinity was low in field populations where HCO 3 - was low (0.5 and 0.9 m M) or CO2 was locally high, and that HCO 3 - affinity was suppressed in the laboratory by high CO2 concentrations.
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    URL: http://dx.doi.org/10.1007/BF00379507
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    Leaf carbon isotope and mineral composition in subtropical plants along an irradiance cline (1986)
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    Oecologia 70 (1986), S. 520-526 
    Details
    ISSN: 1432-1939
    Keywords: Water-use efficiency ; Nutrient-use efficiency ; Photosynthesis ; Human impact ; 13C/12C ratios
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Leaf carbon isotope ratios and leaf mineral composition (Ca, K, Mg, Mn, N, and P) were measured on the dominant species along an irradiance cline in a subtropical monsoon forest of southern China. This irradiance cline resulted from disturbance caused by fuel-harvesting. Leaf carbon isotope ratios increased from undisturbed to disturbed sites for all species, indicating that leaf intercellular CO2 concentrations decreased and leaf water use efficiencies increased along this cline. Nitrogen and magnesium levels were lower in leaves of species on the disturbed sites, but there were no clear patterns for calcium, potassium, phosphorus or manganese.
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    Photosynthesis in an Australian rainforest tree, Argyrodendron peralatum, during the rapid development and relief of water deficits in the dry season (1987)
    Springer
    Oecologia 74 (1987), S. 441-449 
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    ISSN: 1432-1939
    Keywords: Rainforest ; Photosynthesis ; Transpiration ; Stomatal conductance ; Argyrodendron peralatum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rates of apparent photosynthesis were measured in situ at five positions between the upper crown and a lower branch of a 34 m tall Argyrodendron peralatum (F.M. Bailey) H.L. Edlin ex I.H. Boas tree, and on an understorey sapling of the same species growing in a northern Australian rainforest. At the end of the dry season, rapid reductions in photosynthetic rates occurred in the upper crown within three days after a rain event, but changes in the lower crown and the sapling were less marked. Complete recovery of photosynthesis followed a second rain event. At high photon flux densities, stomatal conductance to water vapour decreased in a curvilinear fashion as the vapour pressure difference between leaf and air increased. Apparent photosynthesis was linearly related to stomatal conductance on the first clear day after each rain event, but there was no relationship between these parameters at the end of a brief natural drying cycle. Under conditions of adequate water supply, stomatal conductances of both upper crown and understorey leaves increased linearly with increasing photon flux density up to about 300 μmol m-2 s-1. During water deficits, stomatal conductances in leaves from the understorey increased much more rapidly at very low photon flux densities than did conductances in leaves from the upper canopy.
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    Maximizing daily canopy photosynthesis with respect to the leaf nitrogen allocation pattern in the canopy (1987)
    Springer
    Oecologia 72 (1987), S. 520-526 
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    ISSN: 1432-1939
    Keywords: Canopy structure ; Nitrogen allocation ; Optimization ; Photosynthesis ; Solidago altissima
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A model of daily canopy photosynthesis was constructed taking light and leaf nitrogen distribution in the canopy into consideration. It was applied to a canopy of Solidago altissima. Both irradiance and nitrogen concentration per unit leaf area decreased exponentially with increasing cumulative leaf area from the top of the canopy. The photosynthetic capacity of a single leaf was evaluated in relation to irradiance and nitrogen concentration. By integration, daily canopy photosynthesis was calculated for various canopy architectures and nitrogen allocation patterns. The optimal pattern of nitrogen distribution that maximizes the canopy photosynthesis was determined. Actual distribution of leaf nitrogen in the canopy was more uniform than the optimal one, but it realized over 20% more photosynthesis than that under uniform distribution and 4.7% less photosynthesis than that under the optimal distribution. Redeployment of leaf nitrogen to the top of the canopy with ageing should be more effective in increasing total canopy photosynthesis in a stand with a dense canopy than in a stand with an open canopy.
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    URL: http://dx.doi.org/10.1007/BF00378977
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    Leaf movement, stress avoidance and photosynthesis in Vitis californica (1989)
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    Oecologia 79 (1989), S. 475-481 
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    ISSN: 1432-1939
    Keywords: Heat stress ; Leaf movement ; Photoinhibition ; Photosynthesis ; Vitis californica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gas exchange and chlorophyll fluorescence techniques were used to evaluate the hypothesis that leaf movement in Vitis californica Benth. (California wild grape) allows a compromise between sunlight interception and stress damage in order to maximize photosynthetic carbon gain over the life of the leaf. Leaves that were restrained horizontally tolerated their increased radiation loads if critical temperatures were not exceeded. Reductions in photosynthetic capacity and the F V/F M fluorescence ratio only occurred in leaves that attained high temperatures. Leaf orientation and canopy position were important determinants of leaf temperature. These results indicate that excessive leaf temperature, not high PFD, can be a principle cause of reduced carbon gain and senescence in this species in the wild. Leaf movement appears to protect photosynthetic components in midsummer.
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    URL: http://dx.doi.org/10.1007/BF00378664
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    Net photosynthetic response patterns of the basidiomycete lichen Cora pavonia (Web.) E. Fries from the tropical volcano La Soufrière (Guadeloupe) (1987)
    Springer
    Oecologia 73 (1987), S. 454-458 
    Details
    ISSN: 1432-1939
    Keywords: Cora pavonia ; Lichens ; Photosynthesis ; Thallus water content ; Tropical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The response of net photosynthesis to temperature, moisture, and light was examined in thalli of the tropical basidiomycete lichen Cora pavonia from recent lahar flows on the volcanic summit La Soufrière (Guadeloupe, French West Indies). Although thalli of C. pavonia are typically exposed to only low light intensities and isothermal temperature conditions under prevailing cloud/shroud conditions on La Soufrière, their photosynthetic response matrix reveals an unexpected breadth of response. The temperature optimum of net photosynthetic uptake in C. pavonia rises from 6°C at a photon flux area density of 25 μmol m−2 s−1 PAR to 27°C at 1000 μmol m−2 s−1 PAR, with rates of maximal net photosynthetic uptake exceeding 25 mg CO2 g−1 h−1. Net photosynthesis was optimal at thallus moisture contents of 250 to 350 percent water content by weight, declining only slightly in fully saturated thalli. These response patterns pose an apparent paradox, as on most days they will act to severely restrict net photosynthetic uptake by thalli of C. pavonia on La Soufrière. This paradox is discussed in context of those selective pressures faced by lichen thalli in later successional stages as well as those imposed by brief periods of atypical weather conditions.
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    URL: http://dx.doi.org/10.1007/BF00385264
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    Influence of cold soil and snowcover on photosynthesis and leaf conductance in two Rocky Mountain conifers (1989)
    Springer
    Oecologia 80 (1989), S. 546-552 
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    ISSN: 1432-1939
    Keywords: Soil temperature ; Photosynthesis ; Picea engelmannii ; Pinus contorta ; Roots ; Snow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The influence of cold soil and snowcover on photosynthesis and conductance of Picea engelmannii and Pinus contorta was investigated early in the growing season in the Medicine Bow Mountains, Wyoming, USA. Trees of both species growing in cold soil (〈1°C) associated with snowpack had 25–40% lower leaf photosynthesis than trees in warm soils (〉10°C). In cold soils leaf conductance of both species was lower, but more so in Pinus, leading to lower intercellular CO2 concentrations and greater stomatal limitation of photosynthesis. Soil temperature had no effect on predawn and midday shoot water potentials of Pinus and Picea and lower photosynthesis and conductance did not appear to be a result of lower bulk shoot water potential. Predawn, as well as midday, water potentials of Pinus were consistently higher than Picea suggesting that Pinus may have deeper roots, although trenching experiments indicated young Picea trees have more extensive lateral root systems than similar sized Pinus trees. Young Picea trees (〈2 m in height) in snowbanks were capable of utilizing warmer soil 4 m from their base. Under similar conditions Pinus in snowbanks had lower photosynthesis and conductance than controls and Pinus did not appear capable of utilizing warmer soils nearby. Under full sunlight, PPFD reflected from the snow surface was 400–1400 μmol m-2 s-1 higher than from snow-free surfaces. This reflected light resulted in a 10%–20% increase in photosynthesis of Picea. The beneficial effect of reflected light was apparent whether or not photosynthesis was reduced by low soil temperatures.
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    URL: http://dx.doi.org/10.1007/BF00380080
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    Potential advantages and disadvantages of germinating early for trees in floodplain forests (1989)
    Springer
    Oecologia 81 (1989), S. 443-449 
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    ISSN: 1432-1939
    Keywords: Bottomland hardwoods ; Photosynthesis ; Stomatal conductance ; Flooding ; Shade tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seedlings of Acer rubrum, Carpinus caroliniana, and Platanus occidentalis were germinated and grown under contrasting light regimes: varied light (59% of the abovecanopy photon flux incrementally decreased to 9%, simulating a forest understory during canopy leaf-out) and low light (constantly less than 10%, simulating an understory after leaf-out). By the time that light in both treatments was equilibrated at 9%, 44 days after the first germination, varied light plants were an order of magnitude larger than low light plants. However, in the remainder of the experiment, during which all plants were kept at 9% light, varied light plants had lower relative growth due to: 1) lower leaf area per unit of plant mass; and 2) lower net productivity per unit of leaf area. A subset of plants were flooded after light equilibration, resulting in reduced growth. Varied and low light plants were equally affected by flooding. Reported differences among species in shade tolerance were poorly correlated with differences in response to light treatment.
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    URL: http://dx.doi.org/10.1007/BF00378950
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    Photosynthesis and water relations and the role of anatomy in Umbilicariaceae (lichenes) from Central Spain (1989)
    Springer
    Oecologia 81 (1989), S. 473-480 
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    ISSN: 1432-1939
    Keywords: Photosynthesis ; Respiration ; Water content ; Umbilicaria ; Anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The response of net photosynthesis and dark respiration in eight species of Umbilicariaceae (lichenes) to temperature (-5, 0, 5, 10, 15, 20, 25, 30°C) and irradiance (55, 110, 220, 400, 620 μmol photons m-2 s-1 PAR) was studied. The samples were collected in montane and alpine localities of the Spanish Sistema Central. The species differed widely in their net photosynthetic rates. The optimal temperature for net photosynthesis in alpine species was significantly lower than in montane species. Montane species were more photophytic than alpine ones. Water saturation and water loss rate were dependent on morphology and particularly anatomy of the thallus. The physiological and structural data are useful in the interpretation of the ecology and altitudinal distribution of the Umbilicariaceae. No adaptation could be linked to particularities of the mediterranean climate.
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    URL: http://dx.doi.org/10.1007/BF00378954
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    Phosotynthesis in hemiepiphytic species of Clusia and Ficus (1987)
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    Oecologia 74 (1987), S. 339-346 
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    ISSN: 1432-1939
    Keywords: Clusia ; Ficus ; Strangler ; CAM ; Photosynthesis ; Hemiepiphyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hemiepiphytic species in the genera Clusia and Ficus were investigated to study their mode of photosynthetic metabolism when growing under natural conditions. Despite growing sympatrically in many areas and having the same growth habit, some Clusia species show Crassulacean acid metabolism (CAM) whereas all species of Ficus investigated are C3. This conclusion is based on diurnal CO2 fixation patterns, diurnal stomatal conductances, diurnal titratable acidity fluctuations, and δ13C isotope ratios. Clusia minor, growing in the savannas adjacent to Barinas, Venezuela, shows all aspects of Crassulacean acid metabolism (CAM) on the basis of nocturnal gas exchange, stomatal conductance, total titratable acidity, and carbon isotope composition when measured during the dry season (February 1986). During the wet season (June 1986), the plants shifted to C3-type gas exchange with all CO2 uptake occurring during the daylight hours. The carbon isotope composition of new growth was-28 to-29‰ typical of C3 plants.
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    URL: http://dx.doi.org/10.1007/BF00378927
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    Field photosynthesis, microclimate and water relations of an exotic temperate liana, Pueraria lobata, kudzu (1987)
    Springer
    Oecologia 71 (1987), S. 262-267 
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    ISSN: 1432-1939
    Keywords: Kudzu ; Photosynthesis ; Water relations ; Microclimate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Kudzu occurs in a variety of habitats in the southeastern United States. It is most common in exposed, forest edge sites and road cuts where it forms an extensive ground canopy as well as a canopy overtopping nearby trees, but it can also be found in completely open fields and deeply shaded sites within a forest. Microclimate, stomatal conductance, leaf water potential and photosynthetic responses to light, temperature and humidity were measured in two contrasting microhabitats on Pueraria lobata, kudzu. Midsummer leaf temperatures and leaf-to-air water vapor deficits for plants growing in an exposed site were significantly greater than for those in a shaded site, exceeding 35° C and 50 mmol mol-1, respectively. Maximum stomatal conductance exceeded 400 mmol m-2 s-1 in exposed leaves during peak vegetative growth. Stomatal conductance in shaded leaves was approximately half the value measured in exposed leaves on any particular dya. Maximum photosynthetic carbon uptake was also higher in leaves growing in exposed sites compared to leaves in shaded sites, exceeding 18.7 and 14.0 μmol m-2 s-1, respectively. Photosynthesis, stomatal conductance and intercellular CO2 concentration decreased dramatically in response to increasing water vapor deficit for leaves from both sites. However, transpiration showed an initial increase at intermediate water vapor deficits, leveling off or even decreasing at higher values. Leaf water potential demonstrated marked diurnal variation, but remained constant over a wide range of transpirational water fluxes. This latter feature, combined with microenvironmental modification through rapid leaf orientation and pronounced stomatal responses to water vapor deficits may represent important adaptive responses in the exploitation of a diverse array of habitats by kudzu.
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    URL: http://dx.doi.org/10.1007/BF00377293
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    Effect of supercooling and freezing on photosynthesis in freezing tolerant leaves of Afroalpine ‘giant rosette’ plants (1987)
    Springer
    Oecologia 72 (1987), S. 366-371 
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    ISSN: 1432-1939
    Keywords: Chlorophyll fluorescence ; Supercooling ; Frozen leaves ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of supercooling and freezing on the photosynthetic capability of representatives of the permanent frost hardy giant rosette plants Dendrosenecio keniodendron, D. brassica and Lobelia telekii, of the tropical alpine regions was investigated with the non-invasive chlorophyll a fluorescence technique. While supercooling, normal chlorophyll a fluorescence kinetics exhibiting the sequence 0, I, (D), P, S, M, were recorded, however with some retardation of both, the fast and the slow characteristics as compared to those obtained at day-time temperature. As long as the leaves remained unfrozen, the rise of the variable fluorescence F ν from the level 0 to P was inversely related to a drop of the temperature from about 0°C to-8°C. The increase of F ν with lower temperature is understood to result from a decrease of the velocity of the quenching reactions while photoreduction of the primary electron acceptor appeared to be unimpeded. The second fluorescence maximum (M), usually interpreted to indicate the commencement of the biochemical reactions of photosynthesis was consistenly to be observed during supercooling. Fluoescence induction kinetics of frozen leaves showed only fast rise to presumably F max which was not followed by a significant decay for as long as 4 min. The lack of substantial quenching indicates that in the freeze-dehydrated state neither reoxidation of the primary acceptor nor energetization of the thylakoid membrane was accomplished. This effect however was immediately and fully reserved upon thawing of the leaves when the usual fluorescence induction kinetics as well as normal rates of CO2-uptake were observed. Thus the permanent frost-hardy afroalpine plants do not exhibit any even short-term memory effect of the nocturnal frost on such a delicate process as is photosynthesis.
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    URL: http://dx.doi.org/10.1007/BF00377565
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    Estimating photosynthetic rate and annual carbon gain in conifers from specific leaf weight and leaf biomass (1986)
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    Oecologia 70 (1986), S. 187-193 
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    ISSN: 1432-1939
    Keywords: Photosynthesis ; Specific leaf weight ; Carbon balance ; Larix ; Picea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Canopy photosynthesis is difficult to measure directly or to predict with complex models demanding knowledge of seasonal variation in environmental and physiological properties of the canopy. Trees in particular offer a challenge with their large, aerodynamically rough and seasonally-changing canopy properties. In this paper we assess the possibility of using specific leaf weight to predict seasonal and annual net photosynthetic rate in deciduous (Larix sp.) and evergreen (Picea abies) conifers. Annual photosynthetic rate and specific leaf weight of different positions of the crown in both species were highly correlated (r 2=0.930). Annual carbon uptake by different segments in a mature P. abies crown was closely related to leaf biomass. The relationship was improved by adjusting the leaf biomass of each segment in regard to its specific leaf weight relative to the maximum found in the canopy. The adjustment accounted for associated differences in photosynthetic activity. This combined structural index (leaf biomassxrelative specific leaf weight) could, when calibrated, predict the total annual carbon uptake by different parts of the crown. If direct measurements of photosynthesis are not available, the combined structural index may still serve as a comparative estimator of annual carbon uptake.
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    URL: http://dx.doi.org/10.1007/BF00379238
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    Photosynthetic light acclimation in two rainforest Piper species with different ecological amplitudes (1987)
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    Oecologia 72 (1987), S. 449-456 
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    ISSN: 1432-1939
    Keywords: Piper auritum ; Piper hispidum ; Tropics ; Photosynthesis ; Dark respiration ; Forest gap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Piper auritum (H.B. & K.), a pioneer tree restricted to open sites and Piper hispidum (Swartz), a shrub common in sites ranging from recent clearings to shaded understory, both adjust photosynthetic characteristics in response to light availability during growth. The sensitivity of photosynthetic capacity to light availability during growth was indistinguishable for the two species growing in their natural habitat. Photosynthetic capacity was strongly correlated with leaf nitrogen in both species, and the relationship was similar between species. Dark respiration and leaf specific mass were more sensitive to light during growth in P. hispidum, the species with the broad habitat ange, than in P. auritum. In general, similarities between the species were more striking than differences between them. The differences in dark respiration could have important implications for carbon balance. The difference in the responsiveness of leaf specific mass to light indicates that the broad-ranging species maintains access to modes of response little utilized by the open-site specialist. We did not and, in the gas exchange characteristics, any evidence that the open site specialist is better suited than the generalist to high-light sites.
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    URL: http://dx.doi.org/10.1007/BF00377578
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    The temperature dependance of photoinhibition in the tropical basidiomycete lichen Cora pavonia E. Fries (1987)
    Springer
    Oecologia 73 (1987), S. 447-453 
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    ISSN: 1432-1939
    Keywords: Cora pavonia ; Lichens ; Photosynthesis ; Oxygen supply ; Photoinhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The response of net photosynthesis (NP) and dark respiration to periods of high insolation exposure was examined in the tropical basidiomycete lichen Cora pavonia. Photoinhibition of NP proved quite dependant on temperature. Rates of light saturated NP were severely impaired immediately after pretreatment high light exposure at temperatures of 10, 20 and 40°C, while similar exposure at 30°C resulted in only minimal photoinhibition. Apparent quantum yield proved an even more sensitive indicator of photoinhibition, reduced in all temperature treatments, although inhibition was again greatest at low and high temperatures. Concurrent exposure to reduced O2 tensions during high light exposure mitigated some of the deleterious effects of high light exposure at 10 and 20°C, suggesting an interaction of O2 with the inactivation of photosynthetic function. This represents the first reported instance of light dependant chilling stress in lichens, and may be an important limitation on the distribution of this and other tropical lichen species. This narrow range of temperatures within which thalli of C. pavonia can withstand periods of high insolation exposure coincides with that faced by hydrated thalli during rare periods of high insolation exposure within the cloud/shroud zone on La Soufrière, and points to the necessity of considering periods of atypical or unusual climatic events when interpreting patterns of net photosynthetic response, both in tropical and in north temperate lichen species.
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    URL: http://dx.doi.org/10.1007/BF00385263
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    Seasonal changes in photosynthetic characteristics of Pachysandra terminalis (Buxaceae), an evergreen woodland chamaephyte, in the cool temperate regions of Japan (1986)
    Springer
    Oecologia 71 (1986), S. 6-11 
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    ISSN: 1432-1939
    Keywords: Photosynthesis ; Leaf conductance ; Mesophyll internal CO2 ; Seasonal course ; Pachysandra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seasonal changes in photosynthetic capacity, and photosynthetic responses to intercellular CO2 concentration and irradiance were investigated under laboratory conditions on intact leaves of Pachysandra terminalis. Photosynthetic capacity and stomatal conductance under saturating light intensity and constant water vapor pressure deficit showed almost the same seasonal trend. They increased from early June just after the expansion of leaves, reached the maximum in late-Septemer, and then decreased to winter. In over-wintering leaves they recovered and increased immediately after snow-melting, reached a first maximum in late April, and then decreased to early July in response to the reduction of light intensity on the forest floor. There-after, they increased from mid August, reached a second maximum in late September, and then decreased to winter. The parallel changes of photosynthesis and stomatal conductane indicate a more or less constant intercellular CO2 concentration throughout the year. The calculated values of relative stomatal limitation of photosynthesis were nearly constant throughout the year, irrespective of leaf age. The results indicate that the seasonal changes in light-saturated photosynthetic capacity are not due to a change of stomatal conductance, but to a change in the photosynthetic capacity of mesophyll. Indeed, carboxylation efficiency assessed by the inital slope of the Ci-photosynthesis curve changed in proportion to seasonal changes of the photosynthetic capacity in both current-year and over-wintered leaves. High photosynthetic capacity in current-year leaves as compared with one-year-old leaves was also due to the high photosynthetic capacity of mesophyll. Nevertheless, stomatal conductance changed in proportion to photosynthetic capacity, indicating that stomatal conductance is regulated by the mesophyll photosynthetic capacity such that the intercellular CO2 concentrations are maintained constant. The quantum yield also changed seasonally parallel with that in the photosynthetic capacity.
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    Seasonal changes in net photosynthesis rates and photosynthetic capacity in leaves of Cistus salvifolius, a European mediterranean semi-deciduous shrub (1987)
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    Oecologia 74 (1987), S. 380-388 
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    ISSN: 1432-1939
    Keywords: Cistus ; Photosynthesis ; Drought deciduous shrubs ; Mediterranean vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During five different periods between Nov. 1982 and Aug. 1983, the diurnal patterns exhibited in photosynthetic CO2 uptake and stomatal conductance were observed under natural conditions on twigs of Cistus salvifolius, a Mediterranean semi-deciduous shrub which retains a significant proportion of its leaves through the summer drought. During the same periods, net photosynthesis at saturating CO2 partial pressure was measured on the same twigs as a function of irradiance at different temperatures. From these data, photosynthetic capacity, defined here as the CO2- and light-saturated net photosynthesis rate, was obtained as a function of leaf temperature. C. salvifolius is a winter growing species, shoot growth being initiated in Nov. and continuing through May. Photosynthetic capacity was quite high in Nov., March and June, exceeding 40 μmol m-2 s-1 at optimum temperature. In Dec., photosynthetic capacity was somewhat reduced, perhaps due to low night-time temperatures (〈5°C) during the measurement period. In Aug., capacity in oversummering shoots at optimum temperature fell to less than 8 μmol m-2 s-1, due to water trees and perhaps leaf aging. Seasonal changes in maximal photosynthetic rates under ambient conditions were similar, and like those found in co-occurring evergreen sclerophylls. Like the evergreens, Cistus demonstrated considerable stomatal control of transpirational water loss, particularly in oversummering leaves. During each measurement period except Aug. when capacity was quite low, the maximum rates of net photosynthesis measured under ambient conditions were less than half the measured photosynthetic capacities at comparable temperatures, suggesting an apparent excess nitrogen investment in the photosynthetic apparatus.
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    Effect of varying environments on photosynthetic parameters of C3, C3-C4 and C4 species of Panicum (1989)
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    Oecologia 79 (1989), S. 168-173 
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    ISSN: 1432-1939
    Keywords: Environment ; Panicum ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary CO2 exchange characteristics and the activity of the carboxylating enzymes phosphoenolpyruvate carboxylase (PEP-C, E.C. 4.1.1.31) and ribulose 1,5-bisphosphate carboxylase (RuBP-C, E.C. 4.1.1.39) during one year in the greenhouse and at two levels of light and temperature in growth chambers were determined in the C3-C4 intermediate species P. milioides Nees ex. Trin. These results were compared with those of P. bisulcatum Thumb. (C3) and P. maximum Jacq. (C4). Under all tested conditions, and even when the influence of leaf surface temperature on photosynthetic rates and CO2 compensation points were measured, the biochemical and physiological behaviour of the C3-C4 intermediate was more similar to that of the C3 plant than the C4 species. The C4 plant P. maximum, however, responded positively, mainly in terms of PEP-C activity and photosynthetic rate, to the regime of high light and temperature. The results presented indicate that in the C3-C4 Panicum grown in high light and temperature no direct relationships between a low CO2 compesation point and superior growth are evident. It has still to be clarified why in nature a photosynthetic-photorespiratory pathway leading to an intermediate CO2 compensation value has evolved in P. milioides.
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    Stem photosynthesis in Psorothamnus spinosus (smoke tree) in the Sonoran desert of California (1989)
    Springer
    Oecologia 79 (1989), S. 193-197 
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    ISSN: 1432-1939
    Keywords: Stem ; Photosynthesis ; Desert ; Plant stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Stem photosynthetic responses to environmental parameters were investigated with Psorothamnus spinosus in the Sonoran Desert of California. Light saturation of stem photosynthesis was equal to maximum midday summer irradance (1600–2000 μmol·m-2·s-1). The optimum temperature for stem photosynthesis was 39°C, and lower stem temperatures (27–35°C) caused significant decreases (up to 50%) in stem photosynthesis. Positive stem photosynthesis was maintained up to 51°C. Stem photosynthesis was relatively insensitive to increasing vpd up to 5 kPa; However, stem conductance decreased by 25% at a vpd of 5 kPa. At vpd greater than 5 kPa stem photosynthesis decreased relatively more than that of stem conductance causing a decrease in water use efficiency and an increase an intercellular carbon dioxide concentration. Maximum stem photosynthetic rates were low (6.2–10.6 μmol·m-2·s-1) on a stem surface area, but, stem photosynthetic rates of young shoots were substantially higher (19.5–33.3 μmol· m-2·s-1) on a projected area basis.
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    Water content effects on photosynthetic response of Sphagnum mosses from the foothills of the Philip Smith Mountains, Alaska (1989)
    Springer
    Oecologia 79 (1989), S. 244-250 
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    ISSN: 1432-1939
    Keywords: Tundra ; Sphagnum ; Photosynthesis ; Water relations ; Microclimate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In tussock tundra areas of the foothills north of the Brooks Range, Alaska, up to two-thirds of annual precipitation may occur during intermittent summer thunderstorms. The seasonal pattern in capitulum water content of Sphagnum spp. depends on the frequency and duration of these precipitation events, on the microtopography of the habitat including depth of thaw, and on morphological characteristics of the individual species. The response of net photosynthesis to varying water content in Sphagnum squarrosum and S. angustifolium growing under willow canopies in a tussock tundra area near the Dalton Highway on the North Slope of Alaska was examined in the field. After a period in June required to develop photosynthetic capability, capitula water content was essentially optimal for photosynthesis in the range from 6 to 10 g H2O/g DW. Above this range, the rate of CO2 uptake was reduced, presumably due to limitations on CO2 diffusion to the photosynthetically active sites. At water contents below the optimum, net photosynthesis fell rapidly until reaching compensation at approximately 1 g H2O/g DW. Dependent on changes in weather conditions, average water content of Sphagnum samples collected in the field occasionally fell below 5 g H2O/g DW. During a particularly dry period, water content of individual Sphagnum hummocks fell below 1 g H2O/g DW, indicating that water stress does limit Sphagnum photosynthetic production in this habitat.
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    Seasonal changes in photosynthetic characteristics of Anemone raddeana, a spring-active geophyte, in the temperate region of Japan (1987)
    Springer
    Oecologia 72 (1987), S. 202-206 
    Details
    ISSN: 1432-1939
    Keywords: Photosynthesis ; Leaf conductance ; Mesophyll internal CO2 ; Seasonal course ; Anemone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seasonal changes in the photosynthetic characteristics of intact involucral leaves of Anemone raddeana were investigated under laboratory conditions. Net photosynthesis and constant water vapor pressure deficit showed almost the same seasonal trend. They increased rapidly from mid-April immediately after unfolding of the leaves and reached the maximum in late-April, before the maximum expansion of the leaves. They retained the maximum values until early-May and then decreased toward late-May with a progress of leaf senescence. The calculated values of intercellular CO2 concentration and relative stomatal limitation of photosynthesis showed no significant change throughout the season. The carboxylation efficiency as assessed by the initial slope of Ci-photosynthesis curve and the net photosynthesis under a high Ci regime varied seasonally in parallel with the change of the light-saturated photosynthesis. The results indicate that the seasonal changes in light-saturated net photosynthesis are not due to a change of stomatal conductance, but to a change in the photosynthetic capacity of mesophyll. Nevertheless, leaf conductance changed concomitantly with photosynthetic capacity, indicating that the seasonal change in stomatal conductance is modulated by the mesophyll photosynthetic capacity such that the intercellular CO2 concentrations is maintained constant. The shape of light-photosynthesis curve was similar to that of sun-leaf type. The quantum yield also changed simultaneously with the photosynthetic capacity throughout the season.
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    Effect of fluctuating rhizosphere redox potential on carbon assimilation ofSpartina alterniflora (1989)
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    Oecologia 80 (1989), S. 132-135 
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    ISSN: 1432-1939
    Keywords: Salt mash ; Soil redox potential ; Photosynthesis ; Spartina alterniflora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spartina alterniflora Lois. plants from a Louisiana salt marsh were subjected to fluctuating levels of soil redox potential under controlled environmental conditions. The experiment was designed to examine the changes in carbon assimilation rates in response to the change in rhizosphere sediment redox condition representing a broad range of reduction normally associated with oxygen deficient environments. Variation in sediment redox potential is frequently encountered by this species in its natural environment in Louisiana's Gulf Coast marshes as a result of tidal patterns. Results indicated some adverse effects of extreme anoxic conditions on carbon assimilation ofS. alterniflora, a possible reflection of this species limited ability for maintaining root oxygenation under rapid, intense reduction in soil redox potential. It was also demonstrated that gas exchange limitations may be temporary and apparently may follow by some recovery. Carbon assimilation rates declined 15 to 21% when soil redox level decreased rapidly to below-200 mV which was followed by substantial recovery. A system for accurate control and measurement of rhizosphere redox potential and simultaneous measurement of plant photosynthetic activity is described.
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    Effects of insect damage on photosynthesis, transpiration and SO2 uptake by sycamore (1989)
    Springer
    Oecologia 80 (1989), S. 136-139 
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    ISSN: 1432-1939
    Keywords: Insect damage ; Water loss ; Photosynthesis ; SO2 uptake ; Acer pseudoplatanus ; Leafhopper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study investigated the effects of damage by the typhlocybine leafhopperOssiannilssonola callosa on the physiology of sycamore seedlings. Feeding by 20 adult leafhoppers for four days produced stippling damage of about 10% of total leaf area. Measurements immediately following removal of the leafhoppers showed a 22% decrease in photosynthesis, 25% decrease in daytime rate of water loss and a 34% increase in night-time rate of water loss, probably due to impaired stomatal function. Sixteen days later control of stomatal function was largely regained with rates of photosynthesis similar to the control plants and slightly higher rates of water loss (6.6% day, 18.0% night) attributable to the still-open feeding punctures of the leafhoppers. Daytime SO2 uptake was similar in damaged and control plants but at night the damaged plants showed a 35% increase in uptake. The hypothesis that leafhopper damage is responsible for this increase is supported by a positive relationship between uptake rate and area of leaf stippled. The physiological effects of leafhopper feeding are greater than the visible damage suggests and the effects are particularly serious when the damage is fresh. Increased rate of air pollutant entry to damaged plants is also a problem, again most marked when damage is fresh.
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    URL: http://dx.doi.org/10.1007/BF00789943
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    Physiological responses in two populations of Andropogon glomeratus Walter B.S.P. to short-term salinity (1988)
    Springer
    Oecologia 75 (1988), S. 78-82 
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    ISSN: 1432-1939
    Keywords: Andropogon glomeratus ; A-Ci curves ; Osmotic adjustment ; Photosynthesis ; Salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Andropogon glomeratus is a C4 nonhalophytic grass which exhibits population differentiation for tolerance to short-term salinity exposure. To investigate possible physiological mechanisms whch enable salt-tolerant individuals to survive short-term inundation, gas exchange and water relations parameters were measured before and during a 5-day watering treatment of half-strength synthetic seawater in plants from a tolerant and a non-tolerant population. Photosynthetic recovery was followed for 10 days after the salinity treatment. Photosynthetic CO2 uptake was substantially inhibited in both populations. Stomatal conductances decreased and intercellular CO2 concentrations increased, indicating non-stomatal factors were primarily responsible for the decrease in CO2 uptake. After termination of the salinity treatment photosynthetic capacity increased more rapidly in the tolerant population and reached the pretreatment level after 6 days, whereas the nontolerant population did not recover fully after 10 days. A-Ci curves measured before and after the salinity treatment indicated a decrease in the carboxylation efficiency, and suggested a proportionately greater metabolic inhibition relative to the increase in the stomatal limitation. Osmotic adjustment occurred in a 2-day period in the tolerant population, but there was no change in the osmotic potentials or the water potential at the point of turgor loss in the nontolerant population. Thus short-term salt tolerance in the marsh population is associated with rapid osmotic adjustment and recovcry of photosynthetic capacity shortly after the end of the salinity exposure, rather than maintenance of greater photosynthesis during the salinity treatment.
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    Physiological determinants of growth rate in response to phosphorus supply in wild and cultivated Hordeum species (1989)
    Springer
    Oecologia 79 (1989), S. 96-105 
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    ISSN: 1432-1939
    Keywords: Allocation ; Growth ; Phosphorus ; Photosynthesis ; Seed size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Under favorable nutrition, accessions of the weedy barleygrass (Hordeum leporinum and H. glaucum) had a higher relative growth rate (RGR) than did accessions of cultivated barley (H. vulgare) or its wild progenitor (H. spontaneum). RGR was not positively correlated with the presumed level of soil fertility at the collection site of an accession either within or among species. RGR was reduced more strongly by low-P supply in the progenitor than in the crop or weed, indicating that selection of cultivars to grow in fertile soils had not reduced their potential to grow effectively under low-P conditions. Seed and embryo masses were more important than RGR in determining plant size. Relative differences among assessions in plant size declined with time, because (1) accessions with small seeds had a higher RGR, and (2) RGR of large-seeded accessions declined with time. Absolute growth rate correlated positively with leaf area and negatively with photosynthetic rate per unit leaf area. Under favorable nutrition, maximum photosynthetic rate correlated negatively with leaf length and therefore was higher in the weeds than in the crop or progenitor accessions. P absorption potential did not differ consistently among species but generally increased in response to P stress. Cultivars produced a few tall tillers, whereas weeds and progenitors produced many small tillers. The cultivar had a larger proportion of reproductive tillers, allocated a larger proportion of biomass to grain, and produced larger grains than did the weedy accession. By contrast, the weed began maturing seeds sooner, produced more reproductive tillers, and produced more grains per car and per plant than did the cultivar. The study suggests two major conclusions: (1) A low RGR is not an adaptation to low P supply in annual Hordeum species. (2) Seed size is the major determinant of early plant size between accessions in these Hordeum species under favorable nutrition. However, large seed size indirectly results in a low RGR because of the inverse relationship between plant size and RGR and results in a low photosynthetic rate because of the inverse relationship between leaf size and photosynthesis.
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    Irradiance and temperature effects on photosynthesis of tussock tundra Sphagnum mosses from the foothills of the Philip Smith Mountains, Alaska (1989)
    Springer
    Oecologia 79 (1989), S. 251-259 
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    ISSN: 1432-1939
    Keywords: Tundra ; Sphagnum ; Photosynthesis ; Irradiance ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Photosynthetic characteristics of three species of Sphagnum common in the foothills of the Brooks Range on the North Slope of Alaska were investigated. Generally, light-saturated rates of net photosynthesis decreased in the order S. squarrosum, S. angustifolium, and S. warnstorfii when plants were grown under common growth chamber conditions. For field-grown S. angustifolium, average light compensation point at 10°C was 37 μmol m-2s-1 photosynthetic photon flux density (PPFD), and light saturation occurred between 250 and 500 μmol m-2 s-1. At 20°C, compensation point increased to 127 μmol m-2s-1 and the PPFD required for light saturation increased to approximately 500 μmol m-2s-1, while maximum rates of CO2 uptake increased only slightly. Light response curves of chamber-grown plants exhibited substantially lower compensation points and higher light-saturated rates of CO2 assimilation than field-grown material, due perhaps to a higher percentage of green, photosynthetically competent tissue. All three species exhibited broad responses to temperature, with optima near 20°C, and maintained at least 75% of maximum assimilation between approx. 13° and 30°C. Rates at 5°C were approx. 50% of maximum. Studies of the microclimate of Sphagnum at the field research site suggest that CO2 uptake should occur at near light-saturated rates during the day in open tussock tundra but that PPFD may often be limiting under Salix and Betula canopies in a water track drainage. Simulations using a simple model provided a seasonal estimate of 0.78 g dry weight (DW) of S. angustifolium produced from each initial g of photosynthetic tissue under willow canopies, assuming no water limitations. Although the simulation model suggests that production would be 66% higher in open tussock tundra, S. angustifolium is rarely found in this potentially more stressful habitat. To explain the relative abundance of Sphagnum in shaded water track areas as compared to open tussock tundra, we postulate that the vascular plant canopies provide protection from adverse effects of high temperatures, excess irradiance and reduced water availability. Under conditions of normal water availability, removal of the vascular plant cover did not affect the tissue water content of S. squarrosum, but resulted in a strong decrease in photosynthetic capacity, accompanied by chlorophyll bleaching. These results suggest that photoinhibition may limit production under certain conditions.
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    Distribution of carbonic anhydrase in British marine macroalgae (1989)
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    Oecologia 81 (1989), S. 534-539 
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    ISSN: 1432-1939
    Keywords: Carbonic anhydrase ; Inorganic carbon ; Marine macroalgae ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thirty-four species of marine macroalgae from around St. Andrews, Scotland, have been assayed for their external activity and thirty-three species for their total activity of carbonic anhydrase. Activity was detected in all the Rhodophyta tested apart from Chondrus crispus, but was absent in Codium fragile, Enteromorpha sp. and Monostroma fuscum (Chlorophyta), and Alaria esculenta, Laminaria digitata, L. saccharina and L. hyperborea (Phaeophyta). Total activity of carbonic anhydrase per unit fresh weight tended to be higher in the Rhodophyta than in the Chlorophyta or Phaeophyta. External activity was present in two of the six Chlorophyta, four of the twelve Phaeophyta and four of the sixteen Rhodophyta tested. On average, when present, external carbonic anhydrase activity represented 2.7% of the total activity. A relationship was found between total carbonic anhydrase activity and habitat. Species from the high intertidal and the low-light subtidal habitats had significantly higher activity than species from the mid and low intertidal, rockpools, or high-light region of the subtidal. External carbonic anhydrase activity did not vary significantly with habitat. There appeared to be no strong relationship between carbonic anhydrase activity and the ability of a species to use HCO - 3 in photosynthesis under water.
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    Role of phosphorus and nitrogen in photosynthetic and whole plant carbon gain and nutrient use efficiency in eastern white pine (1988)
    Springer
    Oecologia 77 (1988), S. 25-33 
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    ISSN: 1432-1939
    Keywords: Photosynthesis ; Nitrogen ; Phosphorus ; Nutrient use efficiency ; Pinus strobus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In white pine (Pinus strobus) seedlings grown in five forest soils from New York State, net photosynthetic capacity (Amax) plant-1 was correlated with total foliar N plant-1 (r 2=0.57), but was more highly correlated with total foliar P plant-1 (r 2=0.82). There was no relationship (r 2〈0.01) between Amax [g leaf]-1 and foliar N [g leaf]-1 for the pooled data set, but there was a significant (P〈0.001), but weak (r 2=0.20) positive relationship between Amax [g leaf]-1 and foliar P [g leaf]-1 across all soils. However, within two of the five soils leaf N concentration was a significant (P〈0.05) determinant of photosynthetic capacity. Due to differences in soil nutrient availabilities a large range in foliar P:N ratio (0.02–0.15) was observed, and the proportion of leaf P:N appeared to control Amax [g leaf N]-1. Whole plant nitrogen (NUE) and phosphorus (PUE) use efficiencies were well correlated with whole plant P:N ratio. In addition, NUE was well correlated with Amax [g leaf N]-1 and PUE was well correlated with Amax [g leaf P]-1. However, NUE was not well correlated with PUE, and Amax [g leaf N]-1 was not well correlated with Amax [g leaf P]-1. These results indicated that P and/or N limitations were important components of photosynthetic nutrient relations in white pine grown in these five soils and suggest that both P and N and their proportions should be considered in analyses of photosynthesis-nutrient relations.
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    Water use efficiency and carbon isotope composition of plants in a cold desert environment (1989)
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    Oecologia 80 (1989), S. 11-18 
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    ISSN: 1432-1939
    Keywords: Water use efficiency ; Carbon isotope composition ; Photosynthesis ; Water availability ; Nitrogen availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of the availabilities of water and nitrogen on water use efficiency (WUE) of plants were investigated in a sagebrush steppe. The four species studied wereArtemisia tridentata (shrub),Ceratoides lanata (suffrutescent shrub),Elymus lanceolatus (rhizomatous grass), andElymus elymoides (tussock grass). Water and nitrogen levels were manipulated in a two-by-two factorial design resulting in four treatments: control (no additions), added water, added nitrogen, and added water and nitrogen. One instantaneous and two long-term indicators of WUE were used to testa priori predictions of the ranking of WUE among treatments. The short-term indicator was the instantaneous ratio of assimilation to transpiration (A/E). The long-term measures were 1) the slope of the relationship between conductance to water vapor and maximum assimilation and 2) the carbon isotope composition (δ13C) of plant material. Additional water decreased WUE, whereas additional nitrogen increased WUE. For both A/E and δ13C, the mean for added nitrogen alone was significantly greater than the mean for added water alone, and means for the control and added water and nitrogen fell in between. This ranking of WUE supported the hypothesis that both water and nitrogen limit plant gas exchange in this semiarid environment. The short- and long-term indicators were in agreement, providing evidence in support of theoretical models concerning the water cost of carbon assimilation.
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    The nutritional status of plants from high altitudes (1989)
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    Oecologia 81 (1989), S. 379-391 
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    ISSN: 1432-1939
    Keywords: Nitrogen ; Specific leaf area ; Partitioning ; Life form ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Are plants at high altitudes short in nutrients? In order to answer this question the mineral nutrient content of leaves from over 150 plant species from 9 different mountain areas of all major climatic zones were analyzed (Kjeldahl nitrogen in all, phosphate in half of the samples, K, Mg, Mn, Ca in the Alps only). The majority of data are from herbaceous perennials, but shrubs and trees were studied as well. N-partitioning was studied in 45 herbaceous species from contrasting altitudes in the Alps. The survey falls into three categories: (1) comparisons of whole communities of species from contrasting altitudes, (2) analysis of altitudinal gradients, and (3) additional collections from high altitude sites alone. Unlike the other mineral nutrients, nitrogen content follows consistent altitudinal and latitudinal trends. The higher altitude sample always had higher N content per unit leaf area, irrespective of life form, wherever comparable plants (the same or related species) were investigated at contrasting altitudes. N content per unit dry weight (%) increased with altitude in herbaceous plants (in some species 〉4%), but was remarkably stable in evergreen woody plants (around 1%). The mean fraction of total plant N allocated to leaves of herbaceous plants in the Alps was the same at low and high altitude (1/3 of total). Leaf N (%) from the regional upper limits of higher plant life reveals a latitudinal decrease from subarctic to equatorial mountains, which may be related to the duration of annual leaf activity. Since mean N content per leaf area hardly differs between the uppermost sites, life span expectation (sink-duration) seems to control carbon investments rather than N input per leaf area. The growth of leaves at high altitude seems to be controlled in a way that leads to comparatively high nutrient contents, which in turn support high metabolic activity. Inherent developmental growth constraints inhibit nutrient dilution in the plant body and thus defy the application of classical concepts of plant-nutrient versus soil-nutrient relations developed for lowlands and in particular for cultivated plants. The results re-emphasize the global significance of links between nitrogen content, leaf sclerophylly, leaf longevity and photosynthetic capacity.
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    Growth consequences of plasticity of plant traits in response to light conditions (1989)
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    Oecologia 78 (1989), S. 508-512 
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    ISSN: 1432-1939
    Keywords: Plasticity ; Growth rate ; Photosynthesis ; Abutilon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We present a method for quantifying the growth advantage, if any, that results from the plasticity of plant traits in response to growth in high vs. low resource levels. The method, which uses two phenotypes and two resource levels, quantifies the average advantage that a phenotype has, in its own set of conditions, over the other phenotype. The method is applied to the growth of two phenotypes of Abutilon theophrasti, induced by high and low light intensity, in response to two levels of incident light intensity. We calculated the growth advantage first using relative growth rate, and second using whole-plant photosynthetic assimilation rate, as the response variable. Then we used the photosynthetic responses to changes in light intensity to calculate changes in growth rates of each phenotype when exposed to a change in light conditions. These three quantifications of growth advantage broadly agree with one another. Despite the great plasticity of its traits induced by growth in high vs. low light intensity, whole-plant plasticity did not allow Abutilon theophrasti to exhibit a significant growth advantage under these conditions. Indeed, the relative growth rate of the low light phenotype greatly exceeded that of the high light phenotype in high incident light conditions. This may have resulted from the higher leaf area ratio of the low light phenotype. Furthermore, the high light phenotype had significantly greater transpiration rate in both light conditions. For these reasons we suggest that light-induced plasticity of traits in Abutilon theophrasti may confer advantage in response to the variation in vapor pressure deficit that is associated with variation in light intensity. Light-induced plasticity may also be advantageous because under high incident light conditions the high-light phenotype has greater reproductive allocation than the low-light phenotype.
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    Proton translocation during denitrification in Rhodopseudomonas sphaeroides f. denitrificans (1985)
    Springer
    Archives of microbiology 140 (1985), S. 358-364 
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    ISSN: 1432-072X
    Keywords: Denitrification ; Proton translocation ; Photosynthesis ; Rhodopseudomonas sphaeroides f. denitrificans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Proton translocation during the reduction of NO 3 - , NO 2 - , N2O and O2, with endogenous substrates, in washed cells of Rhodopseudomonas sphaeroides f. denitrificans was investigated by an oxidant pulse method. On adding NO 2 - to washed cells, anaerobically in the dark, an alkalinization occurred in the reaction mixture followed by acidification. When NO 3 - , N2O or O2 was added to cells in the dark or with these compounds and NO 2 - in light an acidification only was observed. Proton translocation was inhibited by carbonyl cyanide-m-chlorophenyl hydrazone. Valinomycin treated cells produced acid in response to the addition of either NO 3 - , NO 2 - , N2O or O2. The proton extrusion stoichiometry ( $$\vec H^ + /2e^ - $$ ratios) in illuminated cells were as follows: NO 3 - →0.5N2, 4.82; NO 2 - →0.5N2, 5.43; N2O→N2, 6.20; and O2→H2O, 6.43. In the dark the comparable values were 3.99, 4.10, 4.17 and 3.95. Thus, illuminated cells produced higher $$\vec H^ + /2e^ - $$ values than those in the dark, indicating a close link between photosynthesis and denitrification in the generation of proton gradients across the bacterial cell membranes. When reduced benzyl viologen was the electron donor in the presence of 1 mM N-ethylmaleimide and 0.5 mM 2-n-heptyl-4-hydroxyquinoline-N-oxide in the dark, the addition of either NO 3 - , NO 2 - or N2O to washed cells resulted in a rapid alkalinization of the reaction mixture. The stoichiometries for proton consumption, $$\vec H^ + /2e^ - $$ ratios without a permeant ion were NO 3 - →NO 2 - ,-1.95; NO 2 - →0.5 N2O,-3.03 and N2O→N2,-2.02. The data indicate that these reductions occur on the periplasmic side of the cytoplasmic membrane.
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    The Rhodopseudomonas viridis photosynthetic membrane: arrangement in situ (1985)
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    Archives of microbiology 142 (1985), S. 333-339 
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    ISSN: 1432-072X
    Keywords: Photosynthesis ; Membrane structure ; Electron microscopy ; Photosynthetic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization of photosynthetic membranes in the cytoplasm of the photosynthetic bacterium Rh. viridis has been examined by several techniques for electron microscopy. Thin sections of membrane stacks show that the regular lattice of membrane subunits reported in other studies can be observed in thin section. Tilting of sections in the electron microscope shows that the regular lattices of several membranes overlap in a way that suggests they are in register with each other. This observation can be confirmed by freeze-fracture images in which a regular arrangement of membrane lattices can be observed, each perfectly aligned. Analysis of the spacings of membrane pairs shows that the photosynthetic membranes of Rh. viridis are very closely apposed. The mean diameter of two membranes is 160A, and the average space between two such membranes is only 42A. When a recently developed atomic level model of Rh. viridis reaction center is superimposed against these spacings, each reaction center extends from the surface of its respective membrane far enough to make contact with an apposing membrane. The limited free space between membranes and regular alignment of lattices has a number of implications for how this membrane is organized to carry out the process of energy transfer.
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    Active transport of proline into washed cells of Rhodopseudomonas sphaeroides f. sp. denitrificans grown with nitrate (1986)
    Springer
    Archives of microbiology 144 (1986), S. 237-241 
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    ISSN: 1432-072X
    Keywords: Denitrification ; Proline transport ; Photosynthesis ; Chemical potential of proline ; proton motive force ; Rhodopseudomonas sphaeroides f. sp. denitrificans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Washed cells of Rhodopseudomonas sphaeroides f. sp. denitrificans, prepared from cultures grown anaerobically in light with NO 3 - as the terminal acceptor, readily incorporated [14C]-proline both in light and in the dark. The proline uptake was coupled to the reduction of either NO 3 - , NO 2 - , N2O or O2. Light stimulated the accumulation of proline in these cells. The addition of NO 3 - to washed cells in light decreased the K m for proline from 40 μM to 5.7 μM. Proline transport was inhibited by antimycin A, 2-n-heptyl-4-hydroxyquinoline-N-oxide both in light and in the dark with nitrate indicating that electron transfer from both denitrification and photosynthesis are involved in this uptake. Inhibition by carbonyl cyanide-m-chlorophenyl hydrazone and 2.4-dinitrophenol indicate that proline transport is energy dependent. The H+/proline stoichiometry increased from 1 to 2.5 when the external pH was increased from 6.0 to 8.0. Under these conditions Δμpro increased but Δp decreased markedly above pH 7.0.
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    Noncyclic electron transport in chromatophores from photolithotrophically grown Rhodobacter sulfidophilus (1986)
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    Archives of microbiology 145 (1986), S. 295-301 
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    ISSN: 1432-072X
    Keywords: Chromatophores ; Electron transport ; NAD photoreduction ; Photosynthesis ; Phototrophic bacteria ; Rhodobacter sulfidophilus ; Sulfide oxidation ; Ubiquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chromatophores isolated from the marine phototrophic bacterium Rhodobacter sulfidophilus were found to photoreduce NAD with sulfide as the electron donor. The apparent K m for sulfide was 370 μM and the optimal pH was 7.0. The rate of NAD photoreduction in chromatophore suspensions with sulfide as the electron donor (about 7–12 μM/h·μmol Bchl) was approximately onetenth the rate of sulfide oxidation in whole cell suspensions. NAD photoreduction was inhibited by rotenone, carbonyl cyanide-m-chlorophenylhydrazone, and antimycin A. Sulfide reduced ubiquinone in the dark when added to anaerobic chromatophore suspensions. These results suggest that electron transport from sulfide to NAD involves an initial dark reduction of ubiquinone followed by reverse electron transport from ubiquinol to NAD mediated by NADH dehydrogenase.
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    A three dimensional model of the photosynthetic membranes of Ectothiorhodospira halochloris (1986)
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    Archives of microbiology 146 (1986), S. 267-274 
    Details
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Membrane structure ; Electron microscopy ; Ectothiorhodospira ; Serial thin sectioning ; Three dimensional reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous “bridges”. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections.
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    The cytoplasmic pH in photosynthesizing cells of the green alga Chlorella fusca, measured by P-31 NMR spectroscopy (1987)
    Springer
    Archives of microbiology 147 (1987), S. 25-29 
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    ISSN: 1432-072X
    Keywords: Chlorella fusca ; Cyclic photophosphorylation ; Cytoplasmic pH ; Green algae ; P-31 NMR spectroscopy ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract P-31 NMR investigations were performed with the green alga Chlorella fusca under anaerobic conditions in the dark and in the light. In spectra of cells in the dark the signal of intracellular, nonvacuolar Pi indicates a pH in its chemical environment of 7.0–7.2. Upon illumination this signal looses intensity and shifts to lower field, corresponding to a pH of 7.7. Further downfield no other signal that could be attributed to a Pi-pool in more alkaline environment was detected. By the use of 2-deoxyglucose-6-phosphate as an indicator of cytoplasmic pH, this Pi-signal was assigned to the cytoplasm. The pH increase in the cytoplasm upon transfer of cells from the dark to the light is the same as that previously observed upon transfer of cells from anaerobic to aerobic conditions. In cells performing only cyclic photophosphorylation the cytoplasmic pH is lower than in photosynthesizing cells but still 0.2 pH units higher than in the cells in the dark. The reasons for the missing of a signal of stromal Pi and for the difference in cytoplasmic pH in photosynthesizing cells and those capable only of cyclic photophosphorylation are discussed.
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    The response of the filamentous cyanobacterium Spirulina platensis to salt stress (1988)
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    Archives of microbiology 150 (1988), S. 417-420 
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    ISSN: 1432-072X
    Keywords: Cyanobacterium ; Spirulina ; Growth ; Stress ; Photosynthesis ; Respiration ; NaCl, Na+, K+
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The responses of the filamentous cyanobacterium Spirulina platensis to increased NaCl concentrations (0.25–1.0 M) in addition to the concentration of sodium in the growth medium were studied. A two stage response to the salt stress was observed. This consisted of a relatively short shock stage, followed by adaptation process. It was shown that upon exposure to high salt concentrations of 0.5 M and above, immediate inhibition of photosynthesis and respiration, and complete cessation of growth occurred. After a time lag, the energy-yielding processes exhibited restored activity. At 0.5 and 1.0M NaCl photosynthesis reached 80% and 50% that of the control, while respiration was enhanced by 140 and 200%, respectively. The time lags were longer when the cells were exposed to higher NaCl concentrations. The resumption of growth and the establishment of new steady state growth rates were found to be correlated to the recovery in respiration. The relationship between the growth rates after adaptation and the increased NaCl concentrations was found to be inversely linear. The cellular sodium content was maintained at a constant low level, regardless of the external NaCl concentration, while potassium content declined linearly vs. the external NaCl concentration. The carbohydrate content of the cells rose exponentially with the increase in NaCl concentration.
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    Construction of a physical map of the 45 kb photosynthetic gene cluster of Rhodobacter sphaeroides (1989)
    Springer
    Archives of microbiology 151 (1989), S. 454-458 
    Details
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Photosynthetic bacteria ; Evolution ; Bacteriochlorophyll ; Reaction centres ; Light harvesting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1) A number of overlapping clones have been isolated from a Rhodobacter sphaeroides gene bank. Following conjugative gene transfer from Escherichia coli these clones restore a wild type phenotype to several mutants unable to synthesise bacteriochlorophyll. 2) The insert DNA was analysed by restriction mapping and together the clones form the basis of the first restriction map of the 45 kb photosynthetic gene cluster of Rb. sphaeroides. 3) This cluster is bounded on one side by puh A encoding the reaction centre H polypeptide and on the other by the puf operon encoding reaction centre L and M apoproteins and light harvesting LH1 and polypeptides. 4) DNA fragments from the 45 kb cluster were used to probe genomic DNA from other photosynthetic bacteria. Using heterologous hybridisation conditions, a significant degree of homology is shown between Rb. sphaeroides and these other bacteria, suggesting close evolutionary links with Rb. capsulatus in particular.
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    The role of water retaining substrata on the photosynthetic response of three drought tolerant phototrophic micro-organisms isolated from a terrestrial habitat (1989)
    Springer
    Archives of microbiology 152 (1989), S. 458-462 
    Details
    ISSN: 1432-072X
    Keywords: Algal crust ; CO2-fixation ; Matric water potential ; Photosynthesis ; Water activity ; Oscillatoria sp. ; Klebsormidium flaccidum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The water prerequisites of two drought tolerant Oscillatoria type cyanobacteria and one green alga were estimated by their ability to accomplish photosynthesis (carbon dioxide fixation) at conditions of subsaturating water supply. Fixation was zero in desiccated samples. Equilibration with solely water-saturated air did not enable any photosynthesis. However, granted properties of the physical environment of the samples could re-establish photosynthesis activity. These properties were elected by chosing membrane filters with different water retention characteristics as supporting substrata for the test samples in the de-and rehydration steps. Rehydration enabled the recovery of photosynthesis of desiccated samples only on the filters with good water retention, the filters with bad water retention were found ineffective. The Oscillatoria strains showed photosynthesis instantaneously and revealed nearly 100% viability. In contrast, rewetted cells of the green alga showed only 35% viability and the recovery of photosynthesis occurred only after 5 h. These differences reflect the natural environmental conditions: cyanobacteria are the first colonizers in the barren sand, whereas green algae can only start to colonize after progressing improvement of the water retention properties brought about by the pioneering cyanobacteria. The results will be discussed in the light of different specific mechanisms available to organisms which endeavour osmotic and matric water stress.
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    URL: http://dx.doi.org/10.1007/BF00446929
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    Effects of photoperiodicity and light irradiance on phosphate-limited Oscillatoria agardhii in chemostat cultures (1985)
    Springer
    Archives of microbiology 142 (1985), S. 66-71 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacterium ; Adaptation ; Photosynthesis ; Carbohydrate accumulation ; Relative growth rate ; [Light-phosphate] interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacterium Oscillatoria agardhii was grown in continuous culture under various light conditions in order to study the interactions of light on phosphorus-limited growth. Under severe P-limiting (light-saturating) conditions, a low chlorophyll a and C-phycocyanin content was found. In addition, the light-harvesting capacity, reflected in the values of P max (maximum light-saturated oxygen production rate) and α (photosynthetic affinity), were low compared to light-limited cultures. Reduction of the light climate, either by reduction of the length of the photoperiod or light-intensity, resulted in an increase in light-harvesting capacity (higher pigment content, P m and α) during growth under P-limiting conditions. Light-induced changes in P max and α could be related to the relative growth rate, being the actual growth rate as a fraction of the growth rate which would be observed under light-limiting conditions. Under P-limiting conditions, reduction of the light-climate caused a reduction in dry weight of the culture. This decrease was mainly due to a decrease in carbohydrate content of the cells. Under all conditions tested, carbohydrates were found to accumulate during the light-period and to be consumed during the dark-period. Evaluation of carbohydrate consumption in the dark yielded a specific maintenance rate constant of 0.001 h-1. This observation leads to the conclusion that the specific maintenance rate constant is independent on the character of the growth rate limiting nutrient for O. agardhii.
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    Transient state characteristics of adaptation to changes in light conditions for the cyanobacterium Oscillatoria agardhii (1986)
    Springer
    Archives of microbiology 145 (1986), S. 353-357 
    Details
    ISSN: 1432-072X
    Keywords: Transient state ; Light limitation ; Chlorophyll a ; Phycobiliproteins ; Cyanobacteria ; Photosynthesis ; Light-shade adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transitions in growth irradiance level from 92 to 7 μEm-2 s-1 and vice versa caused changes in the pigment contents and photosynthesis of Oscillatoria agardhii. The changes in chlorophyll a and C-phycocyanin contents during the transition from high to low irradiance (H→L) were reflected in photosynthetic parameters. In the L→H transition light utilization efficiencies of the cells changed faster than pigment contents. This appeared to be related to the lowering of light utilization efficiencies of photosynthesis. As a possible explanation it was hypothesized that excess photosynthate production led to feed back inhibition of photosynthesis. Time-scales of changes in the maximal rate of O2 evolution were discussed as changes in the number of reaction centers of photosystem II in relation to photosynthetic electron transport. Parameters that were subject to change during irradiance transitions obeyed first order kinetics, but hysteresis occurred when comparing H→L with L→H transients. Interpretation of first order kinetic analysis was discussed in terms of adaptive response vs changes in growth rate.
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    Transient state characteristics of changes in light conditions for the cyanobacterium Oscillatoria agardhii (1987)
    Springer
    Archives of microbiology 149 (1987), S. 19-23 
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    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Photosynthesis ; Light-shade adaptation ; Reserve polymers ; Carbohydrate accumulation ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacterium Oscillatoria agardhii was subjected to changes in irradiance and to changes in light period. During transient states parameters as growth rate, pigment contents, photosynthetic activities and pool sizes of carbohydrate and proteins were followed. The changes in pigments and photosynthesis were similar for irradiance transitions and transitions in light period length. Carbohydrates served for the supply of carbon and energy during adaptation to low light conditions until a basal level of 125 μg · mg dry wt-1 was reached. After transfer to high light conditions excess carbon fixation led to the storage of carbohydrate reserve polymers up to 600 μg · mg dry wt-1. During adaptation to longer light periods cells showed an overcapacity for carbohydrate accumulation even in the presence of a high carbohydrate content at the start of the light period. A model for the feed back repression of photosynthesis related to carbohydrate accumulation was presented. In all cases protein synthesis was directly maximized under the given conditions. Growth rate defined as specific rate of change in carbon showed the fastest response after a shift in light conditions. It was concluded that adaptation of O. agardhii to changes in light conditions was directed to the optimization of growth. The observation that carbohydrate is used to supply carbon and/or energy during adaptation leads to the conclusion that changes on survival in low light depend on carbohydrate level, the efficiency of its conversion in cell material and the maintenance requirements. Such a survival strategy enables cyanobacteria to cope succesfully with light limiting conditions.
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    Temporal separation of nitrogen fixation and photosynthesis in the filamentous, non-heterocystous cyanobacterium Oscillatoria sp. (1987)
    Springer
    Archives of microbiology 149 (1987), S. 76-80 
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    ISSN: 1432-072X
    Keywords: Photosynthesis ; Respiration ; Nitrogenase ; Light-dark-cycle ; Oxygen-protection ; Cyanobacteria ; Oscillatoria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When growing in laternating light-dark cycles, nitrogenase activity (acetylene reduction) in the filamentous, non-heterocystous cyanobacterium Oscillatoria sp. strain 23 (Oldenburg) is predominantly present during the dark period. Dark respiration followed the same pattern as nitrogenase. Maximum activities of nitrogenase and respiration appeared at the same time and were 3.6 μmol C2H4 and 1.4 mg O2 mg Chl a -1·h-1, respectively. Cultures, adapted to light-dark cycles, but transferred to continuous light, retained their reciprocal rhythm of oxygenic photosynthesis and nitrogen fixation. Moreover, even in the light, oxygen uptake was observed at the same rate as in the dark. Oxygen uptake and nitrogenase activity coincided. However, nitrogenase activity in the light was 6 times as high (22 μmol C2H4 mg Chl a -1·h-1) as compared to the dark activity. Although some overlap was observed in which both oxygen evolution and nitrogenase activity occurred simultaneously, it was concluded that in Oscillatoria nitrogen fixation and photosynthesis are separated temporary. If present, light covered the energy demand of nitrogenase and respiration very probably fulfilled a protective function.
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    The kinetics of photoinhibition and its recovery in the red alga Porphyridium cruentum (1988)
    Springer
    Archives of microbiology 150 (1988), S. 529-533 
    Details
    ISSN: 1432-072X
    Keywords: Photosynthesis ; O2 evolution ; Photoinhibition ; Recovery ; Porphyridium cruentum ; Biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When Porphyridium cruentum cells were illuminated with high fluence rate between 1900 and 4800 μmol photons m-2s-1, a decrease in the photosynthetic activity of the cells was observed. Within the time frame of 20 min, and under the fluence rates studied, the sum of photons to be absorbed by cells (mg of chlorophyll (Chl), sufficient to initiate photoinhibition was calculated to be 9235.8 μmol. The minimal specific light absorption rate to initiate photoinhibition in P. cruentum ranges between 2.29 and 4.26 μmol photons s-1 mg-1 chl.a. There was a linear relationship between the specific rate of photoinhibition and the specific light absorption rate. A photon number of 2.56×104 μmol mg-1 chl.a photoinhibited photosynthesis instantaneously. At 15°C, no photoinhibitory effect was observed at 2300 μmol photons m-2 s-1 even after 45 min of illumination. At the other extreme of 35°C, 84% inhibition of photosynthetic activity was observed within 10 min of exposure to 2300 μmol photons m-2 s-1. Between 20 and 30°C, the photoinhibitory effect was comparable. Photoinhibited P. cruentum cells recovered readily when transferred to low light (90 μmol photons m-2 s-1) and darkness, and the specific rate of recovery was independent of the light intensity to which the cells were exposed, during the photoinhibitory treatment.
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    Photosynthesis and transpiration in the upper crown of a mature spruce in purified and ambient atmosphere in a natural stand (1988)
    Springer
    Trees 2 (1988), S. 213-222 
    Details
    ISSN: 1432-2285
    Keywords: Immission ; Forest decline ; Spruce ; Gas exchange ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study addresses the question of whether gaseous air pollutants are capable of damaging spruce foliage. For this purpose, several twig pairs of an adult tree in a natural stand from the western part of the Bavarian Forest were supplied with pure and ambient air and gas exchange was monitored. With the exception of insignificant and unexplained differences during winter, the gas exchange of the twigs showed no negative deviation due to the influence of gaseous air pollutants. Because visible damage arises only in older needles, the duration of measurement is not sufficient to exclude a long-term influence of gaseous air pollutants.
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    URL: http://dx.doi.org/10.1007/BF00202376
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    Photosynthesis and transpiration of healthy and diseased spruce trees in the course of three vegetation periods (1988)
    Springer
    Trees 2 (1988), S. 223-232 
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    ISSN: 1432-2285
    Keywords: Picea abies ; Novel forest decline ; Photosynthesis ; Transpiration ; Natural habitat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary CO2- and H2O-gas exchange of 20- to 25-year-old spruce trees from a plantation in the Hunsrück mountains were investigated over a period of 3 years. All measurements were made as pair comparisons, i.e., in each case the gas exchange of a damaged tree and of a relatively healthy tree in its immediate vicinity was measured simultaneously. A second plantation in the Westerwald mountains consisted of 18-year-old apparently healthy spruce trees. Pair comparison at this location meant comparison of two healthylooking trees. The investigations at both locations included diurnal course measurements of photosynthesis and transpiration, and light saturation curves and CO2-saturation curves of photosynthesis. The reduced photosynthesis parameters of the phenotypically damaged trees at the Hunsrück location indicates massive damage to the photosynthetic apparatus. Measurements of H2O-gas exchange showed that there are disturbances in stomatal regulation of the needles of damaged trees. As a result, the water use efficiency of these needles proved to be significantly lower. In addition, apparent photorespiration of the damaged trees was decreased, whereas their light- and CO2-compensation points and their dark respiration were increased. In contrast to the Hunsrück plantation, no such effects were detectable when the healthy-looking Westerwald trees were subjected to pair comparison of gas exchange. Reduced photosynthetic capacity and disturbances of the stomatal regulation of the phenotypically damaged Hunsrück trees may be due to damage in the cellular membranes. Furthermore, a comparison of three growing seasons led to the conclusion that the gas exchange of spruce trees in their natural habitat is markedly influenced by climatic conditions.
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    Comparative ecophysiology of two representativeQuercus species appearing in different stages of succession (1986)
    Springer
    Ecological research 1 (1986), S. 129-140 
    Details
    ISSN: 1440-1703
    Keywords: Evergreenness ; Forest succession ; Photosynthesis ; Quercus seedling ; Winter growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ecophysiological comparisons were made of the growth and photosynthetic characteristics between seedlings of deciduousQuercus serrata and evergreenQuercus myrsinaefolia. Q. myrsinaefolia seedlings naturally occurring in secondary coppice forests showed exponential-like growth in height with age, while sympatricQ. serrata seedlings were considerably smaller in height, their growth being limited by shortage of light. The photosynthetic characteristics measured under laboratory conditions showed no bases for the differences in growth between the two species on the forest floor: Light compensation points of the seedlings raised under 5% daylight were almost identical for the two species, being about 6.0 μE·m−2·s−1. Growth analysis of seedlings planted in a coppice forest showed that bothQ. serrata andQ. myrsinaefolia could hardly grow during the summer under the shrub layer, when relative photon flux density (RPFD) was 0.9±0.5%. In the winter, when RPFD under the leafless canopy increased to 29.3±2.7%, the dry matter production of the evergreen seedlings ofQ. myrsinaefolia was much improved. Current-year seedlings of the species showed NAR of 0.102±0.021 g·dm−2·mo−1 during the winter. Temperature dependency of photosynthesis and increment of leaf temperature by direct solar beam also indicated active photosynthesis ofQ. myrsinaefolia on the forest floor during the winter.
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    Control of CO2 fixation regulation of stromal fructose-1,6-bisphosphatase in spinach by pH and Mg2+ concentration (1986)
    Springer
    Planta 168 (1986), S. 536-545 
    Details
    ISSN: 1432-2048
    Keywords: CO2 fixation ; Fructose-1,6-bisphosphatase ; Photosynthesis ; Regulation (fructose-1,6-bisphosphatase) ; Spinacia (chloroplasts)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of pH and of Mg2+ concentration on the light activated form of stromal fructose-1,6-bisphosphatase (FBPase) was studied using the enzyme rapidly extracted from illuminated spinach chloroplasts. The (fructose-1,6-bisphosphate4-)(Mg2+) complex has been identified as the substrate of the enzyme. Therefore, changes of pH and Mg2+ concentrations have an immediate effect on the activity of FBPase by shifting the pH and Mg2+ dependent equilibrium concentration of the substrate. In addition, changes of pH and Mg2+ concentration in the assay medium have a delayed effect on FBPase activity. A correlation of the activities observed using different pH and Mg2+ concentrations indicates, that the effect is not a consequence of the pH and Mg2+ concentration as such, but is caused by a shift in the equilibrium concentration of a hypothetical inhibitor fructose-1,6-bisphosphate3- (uncomplexed), resulting in a change of the activation state of the enzyme. The interplay between a rapid effect on the concentration of the substrate and a delayed effect on the activation state enables a rigid control of stromal FBPase by stromal Mg2+ concentrations and pH. Fructose-1,6-bisphosphatase is allosterically inhibited by fructose-6-phosphate in a sigmoidal fashion, allowing a fine control of the enzyme by its product.
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    Calcium binding by spinach stromal proteins (1987)
    Springer
    Planta 171 (1987), S. 259-265 
    Details
    ISSN: 1432-2048
    Keywords: Calcium (binding proteins) ; Chloroplast (stroma) ; Ionic regulation ; Photosynthesis ; Spinacia (calcium binding)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Calcium binding to spinach (Spinacia oleracea L.) stromal proteins was examined by dual-wavelength spectrophotometry using the metallochromic indicator tetramethylmurexide. The data are consistent with the existence of at least two, probably independent, classes of binding sites. The total number of binding sites varied between 90–155 nmol·mg−1 protein with “average” binding constants of 1.1–2.7·mM−1. Both Mg2+ and La3+ inhibited calcium binding competitively, with “average” inhibitor constants of 0.26·mM−1 and 39.4·mM−1, respectively; an increase in the potassium concentration up to 50 mM had no effect. In a typical experiment a decrease in pH (7.8 to 7.1) resulted in a decrease in the total number of calcium binding sites from 90 to 59 nmol·mg−1 protein, but in an increase of the “average” affinity from 2.7 to 4.5·mM−1. Calculations, using these data and those of Gross and Hess (1974, Biochim. Biophys. Acta 339, 334–346) for binding site I of washed thylakoid membranes, showed that the free-Ca2+ concentration in the stroma under dark conditions, pH 7.1, is higher than under light conditions, pH 7.8. The physiological relevance of the observed calcium binding by stromal proteins is discussed.
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    Rhythms during extended dark periods determine rates of net photosynthesis and accumulation of starch and soluble sugars in subsequent light periods in leaves of Sorghum (1987)
    Springer
    Planta 171 (1987), S. 339-345 
    Details
    ISSN: 1432-2048
    Keywords: Photosynthate partitioning ; Photosynthesis ; Circadian rhythm ; Photoassimilate export ; Carbohydrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthesis and photosynthate partitioning in leaves of Sorghum bicolor (L.) Moench exhibited a cyclic dependence on the duration (10–62 h) of dark periods inserted prior to bright light test periods (550 μmol·s-1·m-2, photosynthetic photon flux). Maximum rates of net photosynthesis and of accumulation of starch and soluble sugars were, in the order given, two-, three- and fourfold greater than minimum values. Between 14 and 53% of photosynthate was retained in leaves depending on the length of the dark period. These changes were sufficient to account for the previously described stimulatory effect of short daylengths (i.e., long nights) on carbohydrate accumulation in leaves (N.J. Chatterton and J.E. Silvius, 1980, Physiol. Plant. 49, 141–144). The freerunning periods for the rhythmic dependence on darkness, determined either directly or by curve fitting, were about 24 h for net photosynthesis, 23 h for starch accumulation, and 26 h for solublesugar cccumulation. The deviation from period lengths of 24 h for carbohydrate accumulation indicates that these rhythms are probably endogenous and circadian. Initial maxima were observed after 14 h of darkness for photosynthesis, after 18–22 h for starch, and after 26 h for soluble sugars. The differences in period length and phase indicate that at least three separate rhythms underlie the dependence of photosynthate partitioning in Sorghum on darkness. Periods of low leaf dry-matter accumulation coincided approximately with periods of high net photosynthesis. As a result, maximum photoassimination and maximum export were synchronized and, furthermore, occurred at about the same time as expected light periods.
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    Photoinhibition of photosynthesis in willow leaves under field conditions (1988)
    Springer
    Planta 175 (1988), S. 229-236 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Photoinhibition ; Photosynthesis ; Quantum yield ; Salix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll fluorescence of leaves of a willow (Salix sp.) stand grown in the field in northern Sweden was measured on several occasions during the growing season of 1987. For leaves that received mostly full daylight, the F V/F P ratio declined roughtly 15% in the afternoon on cloudless days in July (F P is the fluorescence at the peak of the induction curve obtained at the prevailing air temperature after 45 min of dark adaptation, and F V is variable fluoresence, F V=F P-F O, where F O is minimal fluorescence). There was no decrease in the F V/F P ratio on cloudy days, while the effect was intermediate on changeable days. In view of this light dependence, together with the fact that the decline in the F V/F P ratio was paralleled with an equal decline in the corresponding fluorescence ratio F V/F M at 77K, and a similar decline in the maximum quantum yield of O2 evolution, it is suggested that the decline in the F V/F P ratio represents a damage in photosyntem II attributable to photoinhibition. Recovery of the F V/F P ratio in dim light following a decline on a cloudless day took 7–16 h to go to completion; the F V/F P ratio was fully restored the following morning. When all active leaves of a peripheral shoot were compared, the F V/F P ratio in the afternoon of a day of bright light varied greatly from leaf to leaf, though the majority of leaves showed a decline. This variation was matched by a pronounced variation in intercepted photon flux density. When leaves developed in the shade were exposed to full sunlight by trimming of the stand an increased sensitivity to photoinhibition was observed as compared to peripheral leaves. The present study indicates that peripheral willow shoots experienced in the order of 10–20% photoinhibition during an appreciable part of their life. This occurred even though the environmental conditions were within the optimal range of photosynthesis and growth.
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    Coarse control of sucrose-phosphate synthase in leaves: Alterations of the kinetic properties in response to the rate of photosynthesis and the accumulation of sucrose (1988)
    Springer
    Planta 174 (1988), S. 217-230 
    Details
    ISSN: 1432-2048
    Keywords: Hordeum (sucrose-phosphate synthase) ; Photosynthate partitioning Spinacia (sucrosephosphate synthase) ; Photosynthesis ; Rhythm (diurnal) ; Sucrose-phosphate synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It has been investigated whether diurnal rhythms of sucrose-phosphate synthase (SPS) are involved in controlling the rate of photosynthetic sucrose synthesis. Extracts were prepared from spinach (Spinacia oleracea L.) and barley (Hordeum vulgare L.) leaves and assayed for enzyme activity. The activity of SPS increased in parallel with a rising rate of photosynthesis, and was increased by feeding mannose and decreased by supplying inorganic phosphate. In leaf material where sucrose had accumulated during the photoperiod or when sucrose was supplied exogenously, SPS activity decreased. During a diurnal rhythm, SPS activity increased after illumination, declined gradually during the light period, decreased further after darkening and then recovered gradually during the night. These changes did not involve an alteration of the maximal activity, but were caused by changes in the kinetic properties, revealed as a change in sensitivity to inhibition by inorganic phosphate. In experiments which modelled the response of SPS to changing metabolite concentrations, it was shown that these alterations of kinetic properties would strongly modify the activity of SPS in vivo. It is proposed that SPS can exist in kinetically distinct forms in vivo, and that the distribution between these forms can be rapidly altered. As the rate of photosynthesis increases there is an activation of SPS, which may be directly or indirectly linked to changes in the availability of Pi. This activation can be modified by factors related to the accumulation of sucrose. Under normal conditions there is a balance between these factors, and the leaf contains a mixture of the different forms of SPS.
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    Adaptation of photosynthetic electron-transport rate to growth temperature in pea (1986)
    Springer
    Planta 169 (1986), S. 429-436 
    Details
    ISSN: 1432-2048
    Keywords: Chloroplast ; Electron transport ; Photosynthesis ; Pisum (electron transport) ; Temperature adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pea (Pisum sativum L. cv. Feltham First) plants were germinated and grown under two temperature regimes, one chilling (6–8° C) and one non-chilling (16–18° C), which are referred to as “cold-grown” and “warm-grown”, respectively. It was found that: (1) At saturating light intensity and with excess CO2, cold-grown leaves exhibited faster rates of oxygen evolution than warm-grown leaves when measured below 15° C. However when measurements were carried out above this temperature, the reverse relationship was observed. (2) Full-chain electron-transport measurements on thylakoids showed that those isolated from cold-grown plants had greater light-saturated uncoupled rates than their warm-grown equivalents at all temperatures between 3 and 19° C. (3) This difference was apparently not due to a greater activity of photosystem I or II in the thylakoids from cold-grown plants, but rather to a more rapid turnover of a dark step within the electron-transport chain. These results are interpreted in terms of a previously reported apparent homeoviscous adaptation of the pea thylakoid membrane to growth temperature (J. Barber, R.C. Ford, R.A.C. Mitchell, P.A. Millner, 1984, Planta 161, 375–380).
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    Temporal and light control of plastid transcript levels for proteins involved in photosynthesis during mustard (Sinapis alba L.) seedling development (1987)
    Springer
    Planta 172 (1987), S. 393-399 
    Details
    ISSN: 1432-2048
    Keywords: Chloroplast gene expression ; Competence ; Photosynthesis ; Phytochrome ; Sinapis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcript levels of four plastid genes encoding constituents of the photosynthetic apparatus were assessed in cotyledons of developing mustard (Sinapis alba L.) seedlings. These genes, encoding the P700 apoproteins of photosystem I, the alpha subunit of the extrinsic CF1 moiety of the plastid ATP synthase complex, and the cytochromes f and b 6, have been localized and mapped previously on mustard chloroplast DNA (G. Dietrich and G. Link, 1985 Curr. Genet. 9, 683–692). Dot blot and Northern hybridization analysis provides evidence that in dark-grown seedlings transcript levels of all four genes rise between 30 h and 72 h after sowing and thereafter fall again, pointing to the existence of an endogenous, light-independent, developmental program. In light-grown seedlings, an additional enhancement of transcript levels beyond, the dark values becomes noticeable at approx. 30–36 h and then continues throughout the subsequent “light-responsive” phase until 96 h after sowing. This is consistent with a photoregulated modulation mechanism operating once “competence” has been reached. Enhanced transcript accumulation occurs following continuous illumination by either white light or (photosynthetically inefficient) far-red light thought to operate mainly through phytochrome. However, the degree of light enhancement for the transcript specifying the P700 apoprotiens is higher with white light than with far-red light, implying involvement of additional photoreceptor(s) mediating this response. In addition to the endogenous gross regulation and light enhancement, a fine regulation of transcript levels seems to operate, as indicated by temporal variations of two related transcripts originating from the cytochrome-f gene region. The observed developmental and photocontrolled changes in specific transcript levels for photosynthesis proteins are only reflected in part by changes in total RNA content and do not appear due to light-dark differences in plastid-DNA copy number during mustard seedling development.
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    URL: http://dx.doi.org/10.1007/BF00398669
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  • 83
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    Gas-exchange of ears of cereals in response to carbon dioxide and light (1989)
    Springer
    Planta 178 (1989), S. 164-175 
    Details
    ISSN: 1432-2048
    Keywords: Avena (photosynthesis) ; C3−C4 intermediate photosynthesis ; Hordeum (photosynthesis) ; Inflorescence (cereal ear) ; Photosynthesis ; Triticum (photosynthesis)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data for the maximum carboxylation velocity of ribulose-1,5-biosphosphate carboxylase, Vm, and the maximum rate of whole-chain electron transport, Jm, were calculated according to a photosynthesis model from the CO2 response and the light response of CO2 uptake measured on ears of wheat (Triticum aestivum L. cv. Arkas), oat (Avena sativa L. cv. Lorenz), and barley (Hordeum vulgare L. cv. Aramir). The ratio Jm/Vm is lower in glumes of oat and awns of barley than it is in the bracts of wheat and in the lemmas and paleae of oat and barley. Light-microscopy studies revealed, in glumes and lemmas of wheat and in the lemmas of oat and barley, a second type of photosynthesizing cell which, in analogy to the Kranz anatomy of C4 plants, can be designated as a bundle-sheath cell. In wheat ears, the CO2-compensation point (in the absence of dissimilative respiration) is between those that are typical for C3 and C4 plants. A model of the CO2 uptake in C3−C4 intermediate plants proposed by Peisker (1986, Plant Cell Environ. 9, 627–635) is applied to recalculate the initial slopes of the A(pc) curves (net photosynthesis rate versus intercellular partial pressure of CO2) under the assumptions that the Jm/Vm ratio for all organs investigated equals the value found in glumes of oat and awns of barley, and that ribulose-1,5-bisphosphate carboxylase is redistributed from mesophyll to bundle-sheath cells. The results closely match the measured values. As a consequence, all bracts of wheat ears and the inner bracts of oat and barley ears are likely to represent a C3−C4 intermediate type, while glumes of oat and awns of barley represent the C3 type.
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    URL: http://dx.doi.org/10.1007/BF00393191
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  • 84
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    Role of D-genome chromosomes in photosynthesis expression in wheats (1985)
    Springer
    Theoretical and applied genetics 69 (1985), S. 443-446 
    Details
    ISSN: 1432-2242
    Keywords: Triticum ; D-genome ; Photosynthesis ; Flag leaves ; Irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The role of D-genome chromosomes in the expression of net photosynthesis in wheats was analysed with the nullitetrasomic and ditelosomic lines of the bread wheat cultivar ‘Chinese Spring’. The two arms of chromosome 3 D and the short arm of chromosome 6 D control major mechanisms of photosynthesis. The effect of chromosome 6 D can be thoroughly compensated by that of its homoeologues of genomes A or B, contrary to what can be observed for chromosome 3 D. Chromosome 7 D is responsible for the low photosynthesis of flag leaves developed under high irradiances in genotypes possessing the D-genome, as the likely result of ontogeny or of a loss in adaptability to irradiance.
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    URL: http://dx.doi.org/10.1007/BF00570915
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  • 85
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    Complementation analysis of the inorganic carbon concentrating mechanism of Chlamydomonas reinhardtii (1986)
    Springer
    Molecular genetics and genomics 204 (1986), S. 199-203 
    Details
    ISSN: 1617-4623
    Keywords: Chlamydomonas reinhardtii ; Ci concentration mechanism ; Carbonic anhydrase ; Photosynthesis ; High CO2 requiring mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Six independently isolated mutants of Chlamydomonas reinhardtii that require elevated CO2 for photoautotrophic growth were tested by complementation analysis. These mutants are likely to be defective in some aspect of the algal concentrating mechanism for inorganic carbon as they exhibit CO2 fixation and inorganic carbon accumulation properties different from the wild-type. Four of the six mutants defined a single complementation group and appear to be defective in an intracellular carbonic anhydrase. The other two mutations represent two additional complementation groups.
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    URL: http://dx.doi.org/10.1007/BF00425498
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  • 86
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    The complete amino-acid sequence of the rieske FeS-precursor protein from spinach chloroplasts deduced from cDNA analysis (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 171-177 
    Details
    ISSN: 1617-4623
    Keywords: Photosynthesis ; Rieske iron-sulfur precursor protein ; cDNA nucleotide sequence ; Transit peptide ; Spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Summary Several cDNA clones encoding the entire Rieske FeS-precursor protein of the chloroplast cytochrome b 6 f-complex have been isolated by high density plaque immunoscreening of a phage lambda gt11 cDNA expression library, made from poly A+-RNA of spinach seedlings. The identity of the cDNAs has been confirmed by N-terminal amino acid sequencing of the purified protein. The nucleotide sequence indicates a protein of 247 amino acid residues including a putative transit sequence of 68 amino acids corresponding to molecular masses of 26.3 kDa (precursor) and 18.8 kDa (mature protein; 179 amino acid residues). Alignteins of the sequence with sequences from Rieske FeS-proteins of respiratory electron transport chains, two of bacterial and three of mitochondrial origin, shows little sequence homology, but remarkable similarity in secondary structure including a putative N-terminal transmembrane segment of about 25 residues and the peptides CTHLGCV and CPCHGS in the C-terminal region of the protein that are involved in the binding of the Fe2S2-cluster.
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    URL: http://dx.doi.org/10.1007/BF00337775
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  • 87
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    Characterization of the ndhC-psbG-ORF157/159 operon of maize plastid DNA and of the cyanobacterium Synechocystis sp. PCC6803 (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 60-69 
    Details
    ISSN: 1617-4623
    Keywords: Photosynthesis ; Cyanobacterial genes ; DNA sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ndhC and ORF159 genes of the maize plastid DNA (ptDNA) were sequenced and maize ORF159 was used to screen a library of genomic DNA of the blue-green alga Synechocystis sp. PCC 6803. The cyanobacterial gene homologous to ORF159 (ORF157) was isolated and sequenced. In sequencing the region upstream of ORF157, reading frames with homology to the ndhC and psbG genes of maize ptDNA were identified. The ndhC and psbG genes overlap in the ptDNAs of maize, tobacco and Marchantia polymorpha, but are separated by a noncoding spacer in Synechocystis. Northern blot analysis showed that the ndhC, psbG and ORF157/159 genes are cotranscribed in maize and Synechocystis. The three genes occur in the same order in ptDNA of maize, tobacco, and M. polymorpha as in Synechocystis 6803. The amino acid sequences of the NDH-C, PSII-G and the ORF157/159 proteins deduced from the maize genes are 65%, 52% and 53% homologous to those of Synechocystis. However, the cyanobacterial and higher plant NDH-C protein sequences are only 23% homologous to the mitochondrial NDH-3 protein. Protein products of in vitro transcription/translation of the Synechocystis transcription unit had apparent molecular masses of 6 kDa (NDH-C), 25 kDa (PSII-G) and 22 kDa (ORF157) on lithium dodecyl sulfate (LDS) polyacrylamide gel electrophoresis. If these are components of an NADH dehydrogenase, cyanobacteria appear to resemble mitochondria more than they do Escherichia coli and Rhodopseudomonas capsulata with regard to this enzyme complex.
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    URL: http://dx.doi.org/10.1007/BF00332231
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  • 88
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    Physiological properties and cytological features of protoplasts prepared fromChlorella saccharophila (1987)
    Springer
    Protoplasma 139 (1987), S. 153-159 
    Details
    ISSN: 1615-6102
    Keywords: Chlorella ; Protoplasts ; Photosynthesis ; Osmotic properties ; Nonosmotic volume ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplasts were prepared from cells ofChlorella saccharophila by treatment with a mixture of pectinase and cellulase. The yield of protoplasts is dependent upon the culture conditions prior to cell wall digestion. In thin section chemically-fixed protoplasts were without wall remnants at the surface of the plasma membrane. Of particular interest is the relationship between the Golgi apparatus and a nuclear envelope-endoplasmic reticulum continuum. Protoplasts have a photosynthetic capacity lying between 70 and 80% of that of normal cells, but show the same response towards CO2 concentration and DCMU inhibition. Protoplasts also respond to changes in the osmolarity of the surrounding medium in accordance with the Boylevan't Hoff equation as if they are an osmometer. The nonosmotic volume (NOV) was calculated.
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    URL: http://dx.doi.org/10.1007/BF01282286
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  • 89
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    Internal dimorphism of chloroplasts in the leaves ofPeperomia pellucida (L.) H.B.K. (1986)
    Springer
    Protoplasma 134 (1986), S. 73-77 
    Details
    ISSN: 1615-6102
    Keywords: Peperomia pellucida (L.) H.B.K. ; Chloroplast morphology ; Dimorphism ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The large chloroplasts found at the abaxial pole of palisade cells in the leaf ofPeperomia pellucida (L.) H.B.K. exhibit a peculiar ultrastructure, having a marginal and a central zones clearly distinguished from each other. This internal dimorphism may correspond to a functional specialization because starch grains concentrate at the central region, and grana show a much larger number of thylakoids at the marginal zone.
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    URL: http://dx.doi.org/10.1007/BF01275704
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  • 90
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    Are the photosynthetic membranes of cryptophyte algae inside out? (1985)
    Springer
    Protoplasma 129 (1985), S. 1-9 
    Details
    ISSN: 1615-6102
    Keywords: Photosynthesis ; Cryptomonadsk ; Thylakoids ; Freeze-fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cryptomonads are unicellular algae with a unique photosynthetic apparatus, both in structure and pigment composition. A cryptomonad,Rhodomonas lens (R. lens), was studied by conventional electron microscopy, freeze-fracture, and freeze-etch in order to determine whether the thylakoids of this alga are everted with respect to those of other plants, as has been postulated (Gantt et al. 1971,Gantt 1979, 1980) as a means to compensate for the location of the cryptomonad light-harvesting apparatus on the opposite side of the thylakoid membrane from that of related algae. We have characterized the thylakoids of this alga and conclude that they are not everted, but are oriented in the same manner as those of other algae and green plants. Implications for energy transfer are discussed.
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    URL: http://dx.doi.org/10.1007/BF01282300
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  • 91
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    Carbon assimilation in contrasting streamside and inland Spartina alterniflora salt marsh (1988)
    Springer
    Plant ecology 76 (1988), S. 55-61 
    Details
    ISSN: 1573-5052
    Keywords: Anaerobiosis ; Biomass ; Louisiana ; Photosynthesis ; Stomatal conductance ; Stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carbon assimilation and standing crop biomass of Spartina alterniflora were studied in a contrasting streamside and inland salt marsh in Louisiana Gulf coast, USA. A substantially lower leaf dry weight, leaf area index, and standing crop biomass were recorded for inland plants as compared to streamside plants. Net assimilation rates ranged between 8 to 25 μmol m−2 s−1 for streamside and between 4 to 19 μmol m−2 s−1 for inland plants. The average photosynthetic rates were significantly lower for inland plants which were growing in an apparently more stressed environment. In addition, the differences were more profound with progression of the growing season. The reduced photosynthetic activity in the inland marsh was attributed to greater soil waterlogging, increased anaerobic root respiration, plant toxins (sulfide), restricted nutrient uptake or a combination of these factors.
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    URL: http://dx.doi.org/10.1007/BF00047388
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  • 92
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    Growth, mineral nutrition, organic constituents and rate of photosynthesis inSesbania grandiflora L. grown under saline conditions (1986)
    Springer
    Plant and soil 93 (1986), S. 395-404 
    Details
    ISSN: 1573-5036
    Keywords: Mineral nutrition ; Photosynthesis ; Salinity ; Sesbania grandiflora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sesbania showed a luxuriant growth in soil with an electrical conductivity of up to 10 m Scm−1. Under saline conditions Na and Cl accumulated at different rates in the plants. Accumulation of these ions in the leaf rachis compared with leaflets appears to be an adaptive feature of this legume. Maintenance of an optimum K level and accumulation of Ca are also indicative of a salt-tolerance mechanism. Accumulation of Fe in the roots of salt-stressed plants is noteworthy. Organic acids and soluble sugars which accumulated in plants under stress condition may play a role in osmotic adjustment. The level of proline, however, remained unaltered. Though the chlorophyll content of the leaves decreased, the photosynthetic rate was found to be enhanced by saline conditions. The probable relationships between these changes and the salt tolerance mechanism in the plant have been discussed.
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    URL: http://dx.doi.org/10.1007/BF02374290
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  • 93
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    A high molecular weight terminal pigment (“anchor polypeptide”) and a minor blue polypeptide from phycobilisomes of the cyanobacterium Nostoc sp. (MAC): Isolation and characterization (1986)
    Springer
    Photosynthesis research 10 (1986), S. 201-208 
    Details
    ISSN: 1573-5079
    Keywords: Terminal pigment ; Cyanobacteria ; Energy transfer ; Photosynthesis ; Phycobilisome ; Nostoc sp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 94 kD pigment-polypeptide, which is presumed to be involved in anchoring the phycobilisomes to the thylakoids, was isolated from Nostoc phycobilisomes by gel filtration in 63 mM formic acid. The isolation condition did not require detergents or denaturating reagents, as in previous procedures, and enzymatic degradation was not observed at the low pH of 2.5. The “anchor polypeptide” thus obtained had absorption (Abs) and fluorescence maxima (Em) at 658 and 673 nm, respectively, in 63 mM formic acid at room temperature. The maxima shifted to longer wavelengths in 100 mM potassium phosphate (pH 6.8), Abs 665 and Em 683 nm at room temperature, and Abs 665 and Em 684 nm at liquid nitrogen temperature. The fluorescence maxima at both temperatures correspond to the longest wavelength component resolved in phycobilisomes from second derivative spectra. A minor blue polypeptide was also found by this isolation method. The molecular weight of this polypeptide was ca. 18,000 and is probably similar to a polypeptide which has been found in the phycobilisome core of other cyanobacteria.
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    URL: http://dx.doi.org/10.1007/BF00118284
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  • 94
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    Nonstomatal inhibition of photosynthesis by water stress. Reduction in photosynthesis at high transpiration rate without stomatal closure in field-grown tomato (1988)
    Springer
    Photosynthesis research 18 (1988), S. 357-362 
    Details
    ISSN: 1573-5079
    Keywords: Photosynthesis ; stomatal conductance ; substomatal carbon dioxide pressure ; tomato ; transpiration ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Large underestimates of the limitation to photosynthesis imposed by stomata can occur because of an error in the standard method of calculating average substomatal pressures of carbon dioxide when heterogeneity of those pressures occurs across a leaf surface. Most gas exchange data supposedly indicating nonstomatal inhibition of photosynthesis by water stress could have this error. However, if no stomatal closure occurs, any reduction in photosynthesis must be due to nonstomatal inhibition of photosynthesis. Net carbon dioxide exchange rates and conductances to water vapor were measured under field conditions in upper canopy leaves of tomato plants during two summers in Beltsville, Maryland, USA. Comparisons were made near midday at high irradiance between leaflets in air with the ambient water vapor content and in air with a higher water content. The higher water content, which lowered the leaf to air water vapor pressure difference (VPD), was imposed either one half hour or several hours before measurements of gas exchange. In both seasons, and irrespective of the timing of the imposition of different VPDs, net photosynthesis increased 60% after decreasing the VPD from 3 to 1 kPa. There were no differences in leaf conductance between leaves at different VPDs, thus transpiration rates were threefold higher at 3 than at 1 kPa VPD. It is concluded that nonstomatal inhibition of photosynthesis did occur in these leaves at high transpiration rate.
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    URL: http://dx.doi.org/10.1007/BF00034840
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  • 95
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    The mechanism of photosynthetic water oxidation (1985)
    Springer
    Photosynthesis research 6 (1985), S. 33-55 
    Details
    ISSN: 1573-5079
    Keywords: Photosynthesis ; Water oxidation ; Manganese ; Plastoquinone ; Polypeptides ; Cytochrome c oxidase ; (Plants)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetie water oxidation is unique to plants and cyanobacteria, it occurs in thylakoid membranes. The components associated with this process include: a reaction center polypeptide, having a molecular weight (Mr) of 47–50 kilodaltons (kDa), containing a reaction center chlorophyll a labeled as P680, a plastoquinol(?)-electron donor Z, a primary electron acceptor pheophytin, and a quinone electron acceptor QA; three ‘extrinsic’ polypeptides having Mr of approximately 17 kDa, 23 kDa, and 33 kDa; and, in all likelihood, an approximately 34 kDa ‘intrinsic’ polypeptide associated with manganese (Mn) atoms. In addition, chloride and calcium ions appear to be essential components for water oxidation. Photons, absorbed by the so-called photosystem II, provide the necessary energy for the chemical oxidation-reduction at P680; the oxidized P680 (P680+), then, oxidizes Z, which then oxidizes the water-manganese system contained, perhaps, in a protein matrix. The oxidation of water, leading to O2 evolution and H+ release, requires four such independent acts, i.e., there is a charge accumulating device (the so-called S-states). In this minireview, we have presented our current understanding of the reaction center P680, the chemical nature of Z, a possible working model for water oxidation, and the possible roles of manganese atoms, chloride ions, and the various polypeptides, mentioned above. A comparison with cytochrome c oxidase, which is involved in the opposite process of the reduction of O2 to H2O, is stressed. This minireview is a prelude to the several minireviews, scheduled to be published in the forthcoming issues of Photosynthesis Research, including those on photosystem II (by H.J. van Gorkom); polypeptides of the O2-evolving system (by D.F. Ghanotakis and C.F. Yocum); and the role of chloride in O2 evolution (by S. Izawa).
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    URL: http://dx.doi.org/10.1007/BF00029045
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  • 96
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    Analytical studies on the responses of sunflower (Helianthus annuus) to various defoliation treatments (1987)
    Springer
    Ecological research 2 (1987), S. 1-17 
    Details
    ISSN: 1440-1703
    Keywords: Defoliation ; Dry matter distribution ; Growth parameter ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of defoliation treatments on plant growth in sunflower (Helianthus annuus) were studied in the field. Four defoliation treatments, 0 (control), 37.4, 56.1 and 93.4% of the total leaf dry weight, were applied to plants that had small third leaves. Decreased leaf weight/whole plant weight (F/W) ratios in defoliated plants rapidly recovered to almost the same ratio as that observed in the control within 12 to 16 days after defoliation according to the degree of defoliation. The mechanism involved in the recovery of the F/W ratio in defoliated plants mainly consisted of three parameters: enhancement of (1) carbon distribution ratios in the leaves, (2) photosynthetic activity in the remaining leaves, and (3) retranslocation of carbon from the stem and/or roots to leaves. Inhibitive effects of defoliation on relative growth rate and net assimilation rate were seen at an early stage, but subsequently both rates became larger in defoliated plants than in controls. Defoliated plants tended to show rapid development and expansion of new leaves, and to show increased specific leaf area and protein synthesis in individual leaves. The sugar content of leaves in defoliated plants was higher than that in controls, while the content in both stem and roots was lower. These responses seem to be advantageous for development of the photosynthetic system. Heights of defoliated plants were clearly depressed according to the degree of defoliation, and this was attributed largely to differences in the elongation rates of the internodes resulting from defoliation.
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    URL: http://dx.doi.org/10.1007/BF02348615
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  • 97
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    Influence of magnetic fields on the P-870 triplet state in Rps. sphaeroides reaction centers (1986)
    Springer
    Photosynthesis research 10 (1986), S. 347-354 
    Details
    ISSN: 1573-5079
    Keywords: Photosynthesis ; Purple bacteria ; Reaction center ; Magnetic field ; Quinone reduction ; Triplet state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Magnetic fields influence two properties of the P-870 triplet state observed in Rps. sphaeroides reaction centers: the yield of formation and the kinetics of decay. These effects have been studied in reaction centers which were prepared in three different states: state QA −, state QA 2− and state (− QA) (QA depleted). The triplet yields decrease with increasing magnetic fields, with B1/2's of about 140, 41 and 57 Gauss, respectively. The half-time of 3P-870 decay is not influenced by the field in state QA −; it increases at increasing fields, in state QA 2− and state (− QA), with the same B1/2 as the triplet yield. These results are discussed in the framework of current theories of the radical-pair dynamics and of the mechanism of triplet decay.
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    URL: http://dx.doi.org/10.1007/BF00118300
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  • 98
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    Interference by luteolin, quercetin, and taxifolin with chloroplast-mediated electron transport and phosphorylation (1987)
    Springer
    Plant and soil 98 (1987), S. 145-159 
    Details
    ISSN: 1573-5036
    Keywords: Electron transport ; Flavonoids ; Luteolin ; Photophosphorylation ; Photosynthesis ; Quercetin ; Spinach ; Taxifolin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of luteolin, quercetin, and taxifolin on light induced phosphorylation and electron transport in isolated, greenhouse-grown, spinach (Spinacia oleracea L.) thylakoids were investigated. Luteolin and quercetin interacted with components associated with both the ATP-generating pathway and the electron-transport pathway. However, the action of taxifolin involved only the phosphorylation pathway. Interference with the phosphorylation pathway was evidenced by the greater sensitivity of phosphorylation than oxygen uptake in coupled whole-chain electron transport, inhibition of the light-activated Mg2+-ATPase, and inhibition of the Ca2+-ATPase associated with CF1. The following order of decreasing inhibitory effectiveness was exhibited: luteolin 〉 quercetin 〉〉〉 taxifolin. On the electron-transport pathway, luteolin and quercetin interfered with the activity of the QB-protein complex as evidenced by inhibition of the partial reaction with diphenylcarbazide as the electron donor and 2,6-dichlorophenolindophenol as electron acceptor; alteration of the chlorophyll fluorescence transients; and competitive displacement of radiolabeled atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine].
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    URL: http://dx.doi.org/10.1007/BF02381735
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