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1

Digitale Medien

The effect of growth at elevated CO2 concentrations on photosynthesis in wheat (1994)

McKEE, I. F. ; WOODWARD, F. I.

Oxford, UK : Blackwell Publishing Ltd

Plant, cell & environment 17 (1994), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Rising levels of atmospheric CO2 will have profound, direct effects on plant carbon metabolism. In this study we used gas exchange measurements, models describing the instantaneous response of leaf net CO2 assimilation rate (A) to intercellular CO2 partial pressure (Ci), in vitro enzyme activity assay, and carbohydrate assay in order to investigate the photosynthetic responses of wheat (Triticum aestivum L., cv. Wembley) to growth under elevated partial pressures of atmospheric CO2 (Ca). At flag leaf ligule emergence, the modelled, in vivo, maximum carboxylation velocity for RuBisCO was significantly lower in plants grown at elevated Ca than in plants grown at ambient Ca (70 Pa compared with 40 Pa). By 12 d after ligule emergence, no significant difference in this parameter was detectable. At ligule emergence, plants grown at elevated Ca exhibited reduced in vitro initial activities and activation states of RuBisCO. At their respective growth Ci values, the photosynthesis of 40-Pa-grown plants was sensitive to p(O2) and to p(CO2) whereas that of 70-Pa-grown plants was insensitive. Both sucrose and starch accumulated more rapidly in the leaves of plants grown at 70 Pa. At flag leaf ligule emergence, modelled non-photorespiratory respiration in the light (Rd) was significantly higher in 70-Pa-grown plants than in 40-Pa-grown plants. By 12 d after ligule emergence no significant differences in Rd were detectable.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-3040.1994.tb00180.x

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2

Digitale Medien

Will elevated CO2 concentrations protect the yield of wheat from O3 damage? (1997)

MCKEE, I. F. ; BULLIMORE, J. F. ; LONG, S. P.

Oxford, UK : Blackwell Publishing Ltd

Plant, cell & environment 20 (1997), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: This study investigated the interacting effects of carbon dioxide and ozone concentrations on the growth and yield of spring whet (Triticum aestivum L. cv. Wembley). Plants were exposed from time of sowing to harvest to reciprocal combinations of two carbon dioxide and two ozone treatments: [CO2] at 350 or 700 μmol mol−1, and [O3] at 〈 5 or 60 nmol mol−1. Records of leaf emergence, leaf duration and tillering were taken throughout leaf development. At harvest, biomass, yield and partitioning were analysed. Our data showed that elevated [CO2] fully protected against the detrimental effect of elevated [O3] on biomass, but not yield.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1046/j.1365-3040.1997.d01-1.x

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3

Digitale Medien

Analysis of limitations to CO2 assimilation on exposure of leaves of two Brassica napus cultivars to UV-B (1997)

ALLEN, D. J. ; MCKEE, I. F. ; FARAGE, P. K. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Plant, cell & environment 20 (1997), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Apex and Bristol cultivars of oilseed rape (Brassica napus) were irradiated with 0.63 W m−2 of UV-B over 5 d. Analyses of the response of net leaf carbon assimilation to intercellular CO2 concentration were used to examine the potential limitations imposed by stomata, carboxylation velocity and capacity for regeneration of ribulose 1,5-bis-phosphate on leaf photosynthesis. Simultaneous measurements of chlorophyll fluorescence were used to estimate the maximum quantum efficiency of photosystem II (PSII) photochemistry, the quantum efficiency of linear electron transport at steady-state photosynthesis, and the light and CO2-saturated rate of linear electron transport. Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) content and activities were assayed in vitro. In both cultivars the UV-B treatment resulted in decreases in the light-saturated rate of CO2 assimilation, which were accompanied by decreases in carboxylation velocity and Rubisco content and activity. No major effects of UV-B were observed on end-product inhibition and stomatal limitation of photosynthesis or the rate of photorespiration relative to CO2 assimilation. In the Bristol cultivar, photoinhibition of PSII and loss of linear electron transport activity were observed when CO2 assimilation was severely inhibited. However, the Apex cultivar exhibited no major inhibition of PSII photochemistry or linear electron transport as the rate of CO2 assimilation decreased. It is concluded that loss of Rubisco is a primary factor in UV-B inhibition of CO2 assimilation.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-3040.1997.00093.x

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4

Digitale Medien

The interactive effects of elevated CO2 and O3 concentration on photosynthesis in spring wheat (1995)

McKee, I. F. ; Farage, P. K. ; Long, S. P.

Springer

Photosynthesis research 45 (1995), S. 111-119

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ISSN: 1573-5079

Schlagwort(e): carbon dioxide ; gas exchange ; ozone ; RuBisCO ; stomata ; Triticum aestivum L.

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract This study investigated the interacting effects of carbon dioxide and ozone on photosynthetic physiology in the flag leaves of spring wheat (Triticum aestivum L. cv. Wembley), at three stages of development. Plants were exposed throughout their development to reciprocal combinations of two carbon dioxide and two ozone treatments: [CO2] at 350 or 700 μmol mol−1, [O3] at 〈 5 or 60 nmol mol−1. Gas exchange analysis, coupled spectrophotometric assay for RuBisCO activity, and SDS-PAGE, were used to examine the relative importance of pollutant effects on i) stomatal conductance, ii) quantum yield, and iii) RuBisCO activity, activation, and concentration. Independently, both elevated [CO2] and elevated [O3] caused a loss of RuBisCO protein and Vcmax. In combination, elevated [CO2] partially protected against the deleterious effects of ozone. It did this partly by reducing stomatal conductance, and thereby reducing the effective ozone dose. Elevated [O3] caused stomatal closure largely via its effect on photoassimilation.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00032582

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5

Digitale Medien

Can photosynthesis respond to short-term fluctuations in atmospheric carbon dioxide? (1997)

Hendrey, G. R. ; Long, S. P. ; McKee, I. F. ; [weitere]

Springer

Photosynthesis research 51 (1997), S. 179-184

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ISSN: 1573-5079

Schlagwort(e): chlorophyll fluorescence ; FACE ; global change ; photosynthesis ; Photosystem II ; quantum yield ; quenching analysis ; rising CO2 concentration ; wheat

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Rapid and irregular variations of atmospheric CO2 concentrations (ca) occur in nature but are often very much more pronounced and frequent when artificially enriching CO2 concentrations in simulating the future atmosphere. Therefore, there is the danger that plant responses at elevated CO2 in fumigation experiments might reflect the increased frequency and amplitude of fluctuation in concentration as well as the increase in average concentration. Tests were conducted to determine whether the photosynthetic process could sense such fluctuations in ca. Instantaneous chlorophyll fluorescence (Ft) was monitored for wheat leaves (Triticum aestivum cv. Hereward) exposed to ca oscillating symmetrically by 225 μmol mol-1 about a ca set point concentration of 575 or 650 μmol mol-1. No Ft response was detected to half-cycle step changes in ca lasting less than two seconds, but at half-cycles of two seconds or longer, the response of Ft was pronounced. In order to determine the in vivo linear electron transport rate (J) the O2 concentration was maintained at 21 mmol mol-1 to eliminate photorespiration. J which is directly proportional to the rate of CO2 uptake under these conditions, was not significantly changed at half-cycles of 30 s or less but was decreased by half-cycles of 60 s or longer. It was inferred that if duration of an oscillation is less than 1 minute and is symmetrical with respect to mean CO2 concentration, then there is no effect on current carbon uptake, but oscillations of 1 minute or more decrease photosynthetic CO2 uptake in wheat.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1005804203928

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