Photosynthesis in Developing Asparagus Plants

1975 ◽  
Vol 2 (3) ◽  
pp. 367 ◽  
Author(s):  
WJS Downton ◽  
E Torokfalvy
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Light Intensity ◽  
Oxygen Concentration ◽  
Co2 Concentration ◽  
Inhibitory Effect ◽  
Stages Of Development ◽  
Gas Exchange Characteristics ◽  
Effect Of Oxygen

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.

scholarly journals Differential responses between mature and young leaves of sunflower plants to oxidative stress caused by water deficit

2010 ◽  
Vol 40 (6) ◽  
pp. 1290-1294 ◽  
Author(s):  
Inês Cechin ◽  
Natália Corniani ◽  
Terezinha de Fátima Fumis ◽  
Ana Catarina Cataneo
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Intercellular Co2 Concentration ◽  
Leaf Age ◽  
Co2 Concentration ◽  
Mature Leaves ◽  
Young Leaves ◽  
Mda Content ◽  
Gas Exchange Characteristics

The effects of water stress and rehydration on leaf gas exchange characteristics along with changes in lipid peroxidation and pirogalol peroxidase (PG-POD) were studied in mature and in young leaves of sunflower (Helianthus annuus L.), which were grown in a greenhouse. Water stress reduced photosynthesis (Pn), stomatal conductance (g s), and transpiration (E) in both young and mature leaves. However, the amplitude of the reduction was dependent on leaf age. The intercellular CO2 concentration (Ci) was increased in mature leaves but it was not altered in young leaves. Instantaneous water use efficiency (WUE) in mature stressed leaves was reduced when compared to control leaves while in young stressed leaves it was maintained to the same level as the control. After 24h of rehydration, most of the parameters related to gas exchange recovered to the same level as the unstressed plants except gs and E in mature leaves. Water stress did not activated PG-POD independently of leaf age. However, after rehydration the enzyme activity was increased in mature leaves and remained to the same as the control in young leaves. Malondialdehyde (MDA) content was increased by water stress in both mature and young leaves. The results suggest that young leaves are more susceptible to water stress in terms of gas exchange characteristics than mature leaves although both went through oxidative estresse.

The behaviour of plants in various gas mixtures

1971 ◽  
Vol 179 (1056) ◽  
pp. 177-188
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Higher Plants ◽  
Dry Mass ◽  
Carbon Dioxide Partial Pressure ◽  
Ambient Oxygen ◽  
Leaf Dry Mass ◽  
Rate Of Photosynthesis ◽  
Effect Of Oxygen

The effects of the composition and pressure of the ambient gas mixture on the diffusive gas exchange of leaves, and the effects of carbon dioxide and oxygen on respiration and photosynthesis are described. When photosynthesis is limited by the rate at which carbon dioxide reaches the chloroplasts, the net rate of photosynthesis of many (but not all) plant species depends on the ambient oxygen partial pressure. The effect of oxygen may be principally to stimulate a respiratory process rather than to inhibit carboxylation. However, when photosynthesis is not limited by the carbon dioxide supply, this respiratory process seems to be suppressed. The gas exchange of plant communities responds to the aerial environment in the way expected from measurements on single leaves, but the growth response to a given difference in gas composition is smaller than expected because of adaptation, notably in the ratio of leaf dry mass to leaf area. It is concluded that the growth rate of higher plants in given illumination will be independent of the partial pressure of oxygen and of other gases likely to be used to dilute it, provided that the carbon dioxide partial pressure is so adjusted (probably to not more than 2 mbar (200 Pa)) that the rate of photosynthesis is not limited by the rate of diffusion to the chloroplasts.

scholarly journals THE RESPIRATION OF LUMINOUS BACTERIA AND THE EFFECT OF OXYGEN TENSION UPON OXYGEN CONSUMPTION

1929 ◽  
Vol 13 (1) ◽  
pp. 27-45 ◽  
Author(s):  
Charles S. Shoup
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Small Cells ◽  
Pure Oxygen ◽  
Catalytic Surfaces ◽  
Rate Of Oxygen Consumption ◽  
Luminous Bacteria ◽  
Effect Of Oxygen

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.

Effect of oxygen concentration on the rates of photosynthesis and photorespiration of some higher plants

1973 ◽  
Vol 51 (2) ◽  
pp. 457-464 ◽  
Author(s):  
A. L. D'Aoust ◽  
D. T. Canvin
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Higher Plants ◽  
Carbon Dioxide Concentration ◽  
Gas Mixture ◽  
Low Carbon ◽  
Leaf Material ◽  
Leaf Chamber ◽  
Effect Of Oxygen

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.

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