Species-specific responses to water stress of gas exchange parameters mimicked by applied abscisic acid

1987 ◽  
Vol 65 (1) ◽  
pp. 103-106 ◽  
Author(s):  
James A. Bunce
Keyword(s):  
Carbon Dioxide ◽  
Abscisic Acid ◽  
Water Stress ◽  
Partial Pressure ◽  
Photosynthetic Rate ◽  
Carbon Dioxide Partial Pressure ◽  
Initial Slope ◽  
Gas Exchange Parameters ◽  
Amaranthus Hypochondriacus ◽  
Relative Decrease

Net photosynthetic rates and leaf conductances to water vapor were measured in Abutilon theophrasti, Amaranthus hypochondriacus, and Glycine max after injecting abscisic acid into petioles of attached leaves. Changes in substomatal carbon dioxide partial pressure were measured in air in each species for various degrees of inhibition of the photosynthetic rate. Changes in the initial slope of photosynthesis versus substomatal carbon dioxide partial pressure were also characterised in two of the species. Responses to abscisic acid were compared with responses to water stress. Abscisic acid reduced photosynthetic rate and conductance in air in proportion to the amount applied. In no case was the relative decrease in substomatal carbon dioxide partial pressure as large as the relative decrease in photosynthesis. This indicated that nonstomatal inhibition of photosynthesis occurred. The changes in substomatal carbon dioxide partial pressure as photosynthesis was progressively inhibited and the changes in initial slope of photosynthesis versus substomatal carbon dioxide partial pressure were distinct for each species and were the same for abscisic acid and for water stress. The data strongly suggest that the reductions of both photosynthetic capacity and conductance by water stress are mediated by abscisic acid in these species.

Volume and osmotic potential changes in relation to inhibition of photosynthesis by water stress in intact leaves

1986 ◽  
Vol 64 (3) ◽  
pp. 557-560 ◽  
Author(s):  
James A. Bunce
Keyword(s):  
Carbon Dioxide ◽  
Water Stress ◽  
Partial Pressure ◽  
Osmotic Potential ◽  
Relative Volume ◽  
Carbon Dioxide Partial Pressure ◽  
Initial Slope ◽  
Water Potentials ◽  
Intact Leaves ◽  
Stressed Leaf

It has been reported that for osmotically stressed leaf slices of a wide range of species, carbon dioxide saturated photosynthesis is uniformly inhibited by stress when water status is expressed as relative volume. Comparable data for intact leaves of a range of species are lacking. It is also unknown whether the same pattern of response applies to carbon dioxide limited photosynthesis. For these reasons responses of photosynthesis to carbon dioxide partial pressure were determined at 21% oxygen at high irradiance in intact leaves of five species as water deficits developed slowly in intact plants. Relative water content (volume) and total and osmotic water potentials were measured at each level of water stress. Three species adjusted osmotically such that volume remained unchanged over a range of water potentials. Regardless of whether volume was maintained, carbon dioxide saturated photosynthesis decreased as water potentials decreased. In contrast to the data for osmotically stressed leaf slices, relative volume, relative osmotic potential, and total water potential did not indicate a uniform level of inhibition of either carbon dioxide saturated or carbon dioxide limited photosynthesis across species. In some species the carbon dioxide compensation point increased with stress. The initial slope of photosynthesis versus substomatal carbon dioxide partial pressure was relatively less inhibited by stress than was the saturated rate. This difference was greater in some species than in others.

Temperature-carbon dioxide partial pressure trends in confined aquifers

1998 ◽  
Vol 145 (1-2) ◽  
pp. 73-89 ◽  
Author(s):  
Anne Coudrain-Ribstein ◽  
Philippe Gouze ◽  
Ghislain de Marsily
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Carbon Dioxide Partial Pressure ◽  
Confined Aquifers

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.

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