Effect of oxygen concentration on leaf photosynthesis and resistances to carbon dioxide diffusion

Planta ◽  
1970 ◽  
Vol 91 (4) ◽  
pp. 285-290 ◽  
Author(s):  
M. M. Ludlow
1929 ◽  
Vol 13 (1) ◽  
pp. 27-45 ◽  
Author(s):  
Charles S. Shoup

1. The respiration of luminous bacteria has been studied by colorimetric and manometric methods. 2. Limulus oxyhaemocyanin has been used as a colorimetric indicator of oxygen consumption and indicator dyes were used for colorimetric determination of carbon dioxide production. 3. The Thunberg-Winterstein microrespirometer has been used for the measurement of the rate of oxygen consumption by luminous bacteria at different partial pressures of oxygen. 4. The effect of oxygen concentration upon oxygen consumption has been followed from equilibrium with air to low pressures of oxygen. 5. Luminous bacteria consume oxygen and produce carbon dioxide independent of oxygen pressures from equilibrium with air (152 mm.) to approximately 22.80 mm. oxygen or 0.03 atmosphere. 6. Dimming of a suspension of luminous bacteria occurs when oxygen tension is lowered to approximately 2 mm. Hg (0.0026 atmosphere) and when the rate of respiration becomes diminished one-half. 7. Pure nitrogen stops respiratory activity and pure oxygen irreversibly inhibits oxygen consumption. 8. The curve for rate of oxygen consumption with oxygen concentration is similar to curves for adsorption of gasses at catalytic surfaces, and agrees with the Langmuir equation for the expression of the amount of gas adsorbed in unimolecular layer at catalytic surfaces with gas pressure. 9. A constant and maximum rate of oxygen consumption occurs in small cells when oxygen concentration becomes sufficient to entirely saturate the surface of the oxidative catalyst of the cell.


1973 ◽  
Vol 51 (2) ◽  
pp. 457-464 ◽  
Author(s):  
A. L. D'Aoust ◽  
D. T. Canvin

Carbon dioxide gas exchange of leaf material was studied in the light at different oxygen tensions for two CO2 concentrations, using an isotope technique. With bean, radish, and tobacco leaves in the leaf chamber, increasing the oxygen tension resulted in a significant alteration in the 14CO2/CO2 ratio of the gas mixture leaving the leaf chamber as compared to that offered to the leaf material. On estimating the rates of “true’ and apparent photosynthesis it was found that below 5% oxygen concentration the rates were not significantly different. However, increasing the oxygen concentration of the gas mixture resulted in a proportional decrease in the rates of true and of apparent photosynthesis. The increasing oxygen tension also resulted in proportional increases in the CO2 evolution (true photosynthesis minus apparent photosynthesis). The percentage inhibition of apparent photosynthesis was greater at low carbon dioxide concentration, while the inhibition of true photosynthesis was not as sensitive to the carbon dioxide level. The inhibition of apparent photosynthesis was not entirely attributable to the increased photorespiration but was roughly equally divided between an inhibition of true photosynthesis and a stimulation of CO2 evolution in the light.However, with corn leaf material, there was no effect of oxygen concentration on both the rates of true and apparent photosynthesis; also, no large CO2 evolution could be detected as emerging from leaf in the light at any of the oxygen concentrations tested.


1975 ◽  
Vol 2 (3) ◽  
pp. 367 ◽  
Author(s):  
WJS Downton ◽  
E Torokfalvy

The gas exchange characteristics of asparagus shoots at various stages of development are described. Reassimilation in spears conserved 50-100% of the carbon dioxide produced in respiration. Refixation was influenced by light intensity and CO2 concentration in the surrounding air, but not by oxygen concentration. The absence of an inhibitory effect of oxygen on refixation is attributed to suppression by high levels of CO2 inside the spear. Assimilation of radioactive CO2 in both the spear and fern forms of asparagus was by the C3 pathway. Fern forms displayed more usual C3 properties, with photosynthesis and CO2 compensation points showing sensitivity to oxygen concentration.


1974 ◽  
Vol 2 (3) ◽  
pp. 214-219 ◽  
Author(s):  
W A Crosbie ◽  
J P Warren ◽  
L A Smith

The performance of a new mask (Mix-O-Mask) for giving supplementary oxygen in clinical situations was compared with three other methods in a patient with cor pulmonale. Measurements were made of the intra-tracheal gas concentrations and arterial blood levels of oxygen and carbon dioxide. The new mask was as reliable as Ventimasks in delivering a claimed oxygen concentration and did not cause rebreathing of expired air. The mask proved durable when worn for sixteen hours in a day and was preferred for comfort by the patient.


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