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  • Chlorophyll fluorescence  (4)
  • Springer  (4)
  • American Chemical Society
  • American Institute of Physics (AIP)
  • 1985-1989  (4)
  • 1955-1959
  • 1935-1939
  • 1915-1919
Collection
Keywords
Publisher
  • Springer  (4)
  • American Chemical Society
  • American Institute of Physics (AIP)
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Studies on the limitations to photosynthesis in leaves of the atrazine-resistant mutant ofSenecio vulgaris L. (1988)
    Springer
    Planta 173 (1988), S. 459-467 
    Details
    ISSN: 1432-2048
    Keywords: Atrazine ; Carbon assimilation ; Chlorophyll fluorescence ; Herbicide resistance ; Mutant (atrazine resistant) ; Photosynthesis in atrazine resistant mutant ; Senecio (atrazine, mutant)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In leaves of an atrazine-resistant mutant ofSenecio vulgaris the quantum efficiency of CO2 assimilation was reduced by 21% compared to the atrazine-susceptible wild type, and at a light level twice that required to saturate photosynthesis in the wild type the CO2 fixation rate in the mutant was decreased by 15%. In leaves at steady-state photosynthesis there was a measurable increase in the reduction state of the photosystem II (PSII) primary quinone acceptor,Q A. Although this would lead to a decreased rate of PSII electron transport and may thus explain the decrease in quantum efficiency, this cannot account for the fall in the maximum rate of CO2 fixation. The atrazine-resistant mutant showed an appreciably longer photosynthetic induction time which indicates an effect on carbon metabolism; however, the response of CO2-fixation rate to intercellular CO2 concentration revealed no differences in carboxylation efficiency. There were also no differences in the ability to perform a State 1–State 2 transition between the atrazine-resistant and susceptible biotypes and no difference in the profiles of phosphorylated thylakoid polypeptides. It is concluded that the alteration of the redox equilibrium between PSII quinone electron acceptors in the atrazine-resistant biotype limits appreciably the photosynthetic efficiency in non-saturating light. Additionally, there is a further, as yet unidentified, limitation which decreases photosynthesis in the resistant mutant under light-saturating conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00958958
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of ionic stress on photosynthesis in Dunaliella tertiolecta (1985)
    Springer
    Planta 163 (1985), S. 250-256 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Dunaliella (osmoregulation) ; Osmoregulation ; Photosynthesis (ionic stress)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparison of the effects of ionic stress and an uncoupler on long-term fluorescence transients (the ‘Kautsky effect’) in the green alga Dunaliella tertiolecta indicated that the large quenching induced by ionic stress was caused by a pH gradient across the thylakoid membrane. This possiblity was given support by the increase in the slow phase of 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea-induced fluorescence relaxation in algae subjected to ionic stress. Low-temperature fluorescence emission spectra indicated that salt stress enhanced photosystem-I emission in the dark, and a comparison of simultaneous emissions at 695 and 720 nm at room temperature indicated a further increase in photosystem-I emission during the fluorescence transients. Taken together with the decrease in the fast phase of 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea-induced fluorescence relaxation in stressed algae, our results indicate that ionic stress stimulates cyclic electron flow, and that non-cyclic flow is inhibited. The effect of sucrose-induced osmotic stress was similar to, but less marked than, the effects of NaCl and KCl; the effect of decreasing the external salinity was small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393515
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  • 3
    Electronic Resource
    Electronic Resource
    Some effects of 4-chloro-5-(dimethylamino)-2-phenyl-3(2H)-pyridazinone (San 9785) on the development of chloroplast thylakoid membranes in Hordeum vulgare L. (1985)
    Springer
    Planta 165 (1985), S. 277-283 
    Details
    ISSN: 1432-2048
    Keywords: 4-Chloro-5-(dimethylamino)-2-phenyl-3(2H)-pyridazinone ; Chlorophyll fluorescence ; Hordeum (thylakoids) ; Linolenic acid ; San 9785 ; Thylakoid (organisation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chloroplast ultrastructural and photochemical features were examined in 6-d-old barley (Hordeum vulgare L. cv. Sundance) plants which had developed in the presence of 4-chloro-5-(dimethylamino)-2-phenyl-3(2H)-pyridazinone (San 9785). In spite of a substantial modification of the fatty-acid composition of thylakoid lipids there were no gross abnormalities in chloroplast morphology, and normal amounts of membrane and chlorophyll were present. Fluorescence kinetics at 77K demonstrated considerable energetic interaction of photosystem (PS)I and PSII chlorophylls within the altered lipid environment. An interference with electron transport was indicated from altered room-temperature fluorescence kinetics at 20°C. Subtle changes in the arrangements of chloroplast membranes were consistently evident and the overall effects of these changes was to increase the proportion of appressed to nonappressed membranes. This correlated with a lower chlorophyll a/b ratio, an increase in the amount of light-harvesting chlorophylls as determined by gel electrophoresis and fluorescence emission spectra, and an increase in excitation-energy transfer from PSII to PSI, as predicted from current ideas on the organisation of photosystems in appressed and non-appressed thylakoid membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395051
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  • 4
    Electronic Resource
    Electronic Resource
    The role of carbon dioxide and oxygen in determining chlorophyll fluorescence quenching during leaf development (1985)
    Springer
    Planta 165 (1985), S. 477-485 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Leaf development (photosynthesis) ; Photoinhibition ; Triticum ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll fluorescence emission at 680 nm (F680) and the rate of CO2 fixation were measured simultaneously in sections along the length of wheat and maize leaves. These leaves possess a basal meristem and show a gradation in development towards the leaf tip. The redox state of the primary electron acceptor, Q, of photosystem II was estimated using a non-invasive method. Distal mature leaf sections displayed typical F680 induction curves which were generally anti-parallel with CO2 fixation and during which Q became gradually oxidised. In leaf-base sections net assimilation of CO2 was not detectable, F680 quenched slowly and monotonously without displaying any of the oscillations typical of mature tissue and Q remained relatively reduced. Sections cut from mid-regions of the leaf showed intermediate characteristics. There were no major differences between the wheat and maize leaf in the parameters measured. The results support the hypothesis that generation of the transthylakoid proton gradient and associated ATP production is not a major limitation to photosynthesis during leaf development in either C3 or C4 plants. Removal of CO2 from the mature leaf sections caused little change in steady-state F680 and produced about 50% reduction of Q. When O2 was then removed, F680 rose sharply and Q became almost totally reduced. In immature tissue unable to assimilate CO2, removal of O2 alone caused a similar large rise in F680 and reduction of Q whilst removal of CO2 had negligible effects on F680 and the redox state of Q. It is concluded that in leaf tissue unable to assimilate CO2, either because CO2 is absent or the tissue is immature, O2 acts as an electron acceptor and maintains Q in a partially oxidised state. The important implication that O2 may have a role in the prevention of photoinhibition of the photochemical apparatus in the developing leaf is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398092
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