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Photosynthesis and photorespiratory CO2 evolution of water-stressed sunflower leaves

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Rates of true photosynthesis (TPS), apparent photosynthesis (APS) and photorespiration (PR) of sunflower (Helianthus annuus L., Var. Mennonite) leaves were measured in air (21% O2, 300 vpm CO2) at 25° C and 400 μEinsteins m-2 s-1 radiant flux density. The plants were water stressed by application of osmoticum (polyethylene glycol 4000) to the root system. TPS and APS decreased linearly from maxima at-4 bar leaf-water potential (ψ) to become very small and zero respectively at about-18 bar ψ; at smaller potential CO2 was evolved from the leaf. Statistical analysis shows that TPS and APS were more closely correlated with ψ than stomatal conductance (r s -1), because r s -1 changed only in the range-4 to-13 bar but ψ exerted an effect at smaller potential. Photorespiration decreased linearly with stress and at-18 bar was 30% of the control plant rate; ψ and TPS accounted for only part of the variance in PR, both independently and in combination, and r s -1 accounted for little of the variance. Tricarboxylic acid cycle respiration of leaves placed for 20 min in darkness, remained almost constant with changing ψ and r s -1. It was one-third of photorespiration in control plants but increased as a proportion in severely stressed plants. The relative specific activity (RSA) of the CO2 released by PR of wellwatered plants was 90% after 20 min photosynthesis in 14CO2 but decreased to 18% at-18 bar ψ. Therefore, under stress mpre CO2 was derived by respiration from reserve materials and less from immediate photosynthate. Elimination of CO2 production by the glycollate pathway with small oxygen concentration (1.5%), showed that the contribution of TCA cycle respiration to photorespiration was small in unstressed plants but increased at small ψ to almost the same rate as photorespiration. It is concluded that desiccation decreased photosynthesis by decreasing the stomatal conductance to CO2 diffusion and by changing the balance between CO2 assimilation and production of the leaf. As a consequence carbon flux through the glycollate pathway decreased as did the rate of CO2 produced by it. However, TCA cycle respiration in the light increased with stress, so that total photorespiration remained large. The importance of maintaining carbon flux through the glycollate pathway and TCA cycle is discussed.

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Ribulose diphosphate


Tricarboxylic acid cycle

TPS cycle:

true or gross photosynthesis


apparent or net photosynthesis




  1. Andrews, T. J., Lorimer, G. H., Tolbert, N. E.: Ribulose diphosphate oxygenase. I. Synthesis of phosphoglycollate by fraction-1 protein of leaves. Biochemistry (Wash.) 12, 11–18 (1973)

  2. Arnon, D. I., Hoagland, D. R.: Crop prodution in artificial culture solutions and in soil with special reference to factors influencing yields and absorption of inorganic nutrients. Soil Sci. 50, 463–484 (1940)

  3. Atkins, C. A., Canvin, D. T.: Photosynthesis and CO2 evolution by leaf discs: gas exchange, extraction and ion exchange fractionation of 14C labelled products. Canad. J. Bot. 49, 1225–1234 (1971)

  4. Bird, I. F., Cornelius, M. J., Keys, A. J., Whittingham, C. P.: Oxidation and phosphorylation association with the conversion of glycine to serine. Phytochemistry 11, 1587–1594 (1972)

  5. Bird, I. F., Cornelius, M. J., Keys, A. J., Whittingham, C. P.: Intracellular site of sucrose synthesis in leaves. Phytochemistry 13, 59–64 (1974)

  6. Boyer, J. S., Bowen, B. L.: Inhibition of oxygen evolution in chloroplasts isolated from leaves with low water potential. Plant Physiol. 45, 612–615 (1970)

  7. Chapman, E. A., Graham, D.: The effect of light on the tricarboxylic acid cycle in green leaves. I. Relative rates of the cycle in the dark and light. Plant Physiol. 53, 879–885 (1974)

  8. D'Aoust, A. L., Canvin, D. T.: The specific activity of 14CO2 evolved into CO2-free air in the light and darkness by sunflower leaves following periods of photosynthesis in 14CO2. Photosynthetica 6, 150–157 (1972)

  9. Fock, H., Schaub, H., Hilgenberg, W.: Über den Sauerstoff- und Kohlendioxidgaswechsel von Chlorella und Conocephalum während der Lichtphase. Z. Pflanzenphysiol. 60, 56–63 (1968)

  10. Fry, K. E.: Some factors affecting Hill reaction activity in cotton chloroplasts. Plant Physiol. 45, 465–469 (1970)

  11. Graham, D., Walker, D. A.: Some effects of light on the interconversion of metabolites in green leaves. Biochem J. 82, 554 (1962)

  12. Heber, U.: Conformational changes of chloroplasts induced by illumination of leaves in vivo. Biochim. biophys. Acta (Amst.) 180, 302–319 (1969)

  13. Hew, C. S., Krotkov, G., Canvin, D. T.: Determination of the rate of CO2 evolution by green leaves in light. Plant Physiol. 43, 464–466 (1969)

  14. Jackson, W. A., Volk, R. J.: Photorespiration. Ann. Rev. Plant Physiol. 21, 385–432 (1970)

  15. Kandler, O., Haberer-Liesenkötter, I. L.: Über den Zusammenhang zwischen Phosphathaushalt und Photosynthese. V. Regulation der Glykolyse durch die Lichtphosphorylierung bei Chlorella. Z. Naturforsch. 18b, 718–730 (1963)

  16. Keck, R. W., Boyer, J. S.: Chloroplast response to low leaf water potentials. III. Differing inhibition of electron transport and photophosphorylation. Plant Physiol. 53, 474–479 (1974)

  17. Lawlor, D. W.: Absorption of polyethylene glycols by plants and their effects on plant groth. New Phytol. 69, 501–513 (1970)

  18. Lawlor, D. W.: An automatic multichannel thermocouple psychrometer based on an operational amplifier. J. appl. Ecol. 9, 581–588 (1972)

  19. Lorimer, G. H., Andrews, T. J.: Plant photorespiration—an inevitable consequence of the existence of atmospheric oxygen. Nature (Lond.) New Biol. 243, 359–360 (1973)

  20. Ludwig, L. J., Canvin, D. T.: An open gas exchange system for the simultaneous measurements of the CO2 and 14CO2 fluxes from leaves. Canad. J. Bot. 49, 1299–1313 (1971a)

  21. Ludwig, L. J., Canvin, D. T.: The rate of photorespiration during photosynthesis and the relationship of the substrate of light respiration to the products of photosynthesis in sunflower leaves. Plant Physiol. 48, 712–719 (1971b)

  22. Mahon, J. D., Fock, H., Höhler, T., Canvin, D. T.: Changes in specific radioactivities of corn leaf metabolites during photosynthesis in 14CO2 and 12CO2 at normal and low oxygen. Planta (Berl.) 120, 113–123 (1974a)

  23. Mohon, J. D., Fock, H., Canvin, D. T.: Changes in specific radioactivity of sunflower leaf metabolites during photosynthesis in 14CO2 and 12CO2 at three concentrations of CO2. Planta (Berl.) 120, 245–254 (1974b)

  24. Ogren, W. L., Bowes, G.: Ribulose diphosphate carboxylase regulation of soybean respiration. Nature (Lond.) New Biol. 230, 159–160 (1971)

  25. Raven, I. A.: Endogenous inorganic carbon sources in plant photosynthesis. II. Comparison of total CO2 production in the light with measured CO2 evolution in the light. New Phytol. 71, 995–1014 (1972)

  26. Redshaw, A. J., Meidner, H.: Effects of water stress on the resistance to uptake of carbon dioxide in tobacco. J. exp. Bot. 23, 229–240 (1972)

  27. Samish, Y., Koller, D.: Photorespiration in green plants during photosynthesis estimated by the use of isotopic CO2. Plant Physiol. 43, 1129–1132 (1968)

  28. Samish, Y., Pallas, J. E., Dornhoff, G. M., Shibles, R. M.: A re-evaluation of soybean leaf photorespiration. Plant Physiol. 50, 28–30 (1972)

  29. Santarius, K. A., Heber, U.: Changes in the intracellular levels of ATP, ADP, AMP and P1 and regulatory functions of the adenylate system in leaf cells during photosynthesis. Biochim. biophys. Acta. (Amst.) 102, 39–54 (1965)

  30. Schaub, H., Hilgenberg, W., Fock, H.: Eine neue Meßordnung zur gleichzeitigen Messung von Sauerstoff und Kohlendioxid im offenen Gasstrom. Z. Pflanzenphysiol. 60, 64–71 (1968)

  31. Scholander, P. F., Hammel, H. T., Bradstreet, E. D., Hemmingsen, E. A.: Sap pressure in vascular plants. Science 148, 339–346 (1965)

  32. Shimshi, D.: Effects of soil moisture and phenylmercuric acetate upon stomatal aperture, transpiration and photosynthesis. Plant Physiol. 38, 713–721 (1963)

  33. Slayter, R. O.: Plant water relationships. New York: Academic Press 1967

  34. Slayter, R. O.: Effects of short periods of water stress on leaf photosynthesis. In: Plant response to climatic factors. Proc. Uppsala Symp. 1970. UNESCO, PARIS (1973)

  35. Tolbert, N. E.: Leaf peroxisomes and photorespiration. In: Photosynthesis and photorespiration. (M. D. Hatch, C. B. Osmond, R. O. Slayter, eds.), p. 458–471. New York: Wiley-Interscience 1971

  36. Tregunna, E. B., Krotkov, G., Nelson, C. D.: Effect of oxygen on the rate of photorespiration in detached tobacco leaves. Physiol. Plant. 19, 723–733 (1966)

  37. Troughton, J. H., Slayter, R. O.: Plant water status, leaf temperature and the calculated mesophyll resistance to carbon dioxide of cotton leaves. Aust. J. biol. Sci. 22, 815–827 (1969)

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Lawlor, D.W., Fock, H. Photosynthesis and photorespiratory CO2 evolution of water-stressed sunflower leaves. Planta 126, 247–258 (1975). https://doi.org/10.1007/BF00388966

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  • Photosynthesis
  • Stomatal Conductance
  • Polyethylene Glycol 4000
  • Carbon Flux
  • Polyethylene Glycol