Abstract
The effect of long-term (weeks to months) CO(2) enhancement on (a) the gas-exchange characteristics, (b) the content and activation state of ribulose-1,5-bisphosphate carboxylase (rubisco), and (c) leaf nitrogen, chlorophyll, and dry weight per area were studied in five C(3) species (Chenopodium album, Phaseolus vulgaris, Solanum tuberosum, Solanum melongena, and Brassica oleracea) grown at CO(2) partial pressures of 300 or 900 to 1000 microbars. Long-term exposure to elevated CO(2) affected the CO(2) response of photosynthesis in one of three ways: (a) the initial slope of the CO(2) response was unaffected, but the photosynthetic rate at high CO(2) increased (S. tuberosum); (b) the initial slope decreased but the CO(2)-saturated rate of photosynthesis was little affected (C. album, P. vulgaris); (c) both the initial slope and the CO(2)-saturated rate of photosynthesis decreased (B. oleracea, S. melongena). In all five species, growth at high CO(2) increased the extent to which photosynthesis was stimulated following a decrease in the partial pressure of O(2) or an increase in measurement CO(2) above 600 microbars. This stimulation indicates that a limitation on photosynthesis by the capacity to regenerate orthophosphate was reduced or absent after acclimation to high CO(2). Leaf nitrogen per area either increased (S. tuberosum, S. melongena) or was little changed by CO(2) enhancement. The content of rubisco was lower in only two of the five species, yet its activation state was 19% to 48% lower in all five species following long-term exposure to high CO(2). These results indicate that during growth in CO(2)-enriched air, leaf rubisco content remains in excess of that required to support the observed photosynthetic rates.
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Claims 12
Claim · model-written summary
In S. tuberosum, elevated carbon dioxide increased high CO2 photosynthetic rate while the initial response slope was unchanged.
- Taxon
- S. tuberosum
Solanum tuberosume0 - Treatment
- CO(2)e1
- Outcome
- photosynthetic rate at high CO(2)e0
- Direction
- increasede0
- Qualifier
- initial slope of the CO(2) response was unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the initial slope of the CO(2) response was unaffected, but the photosynthetic rate at high CO(2) increased (S. tuberosum)”
e1“Long-term exposure to elevated CO(2)”
Claim · model-written summary
Elevated CO2 decreased the initial response slope in C. album.
- Taxon
- C. album
Chenopodium albume0 - Treatment
- CO(2)e1
- Outcome
- initial slopee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the initial slope decreased but the CO(2)-saturated rate of photosynthesis was little affected (C. album, P. vulgaris)”
e1“Long-term exposure to elevated CO(2)”
Claim · model-written summary
Elevated CO2 decreased the initial response slope in P. vulgaris.
- Taxon
- P. vulgaris
Phaseolus vulgarise0 - Treatment
- CO(2)e1
- Outcome
- initial slopee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the initial slope decreased but the CO(2)-saturated rate of photosynthesis was little affected (C. album, P. vulgaris)”
e1“Long-term exposure to elevated CO(2)”
Claim · model-written summary
Elevated CO2 decreased both the initial slope and saturated photosynthesis rate in B. oleracea.
- Taxon
- B. oleracea
Brassica oleraceae0 - Treatment
- CO(2)e1
- Outcome
- initial slope and the CO(2)-saturated rate of photosynthesise0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both the initial slope and the CO(2)-saturated rate of photosynthesis decreased (B. oleracea, S. melongena)”
e1“Long-term exposure to elevated CO(2)”
Claim · model-written summary
Elevated CO2 decreased both the initial slope and saturated photosynthesis rate in S. melongena.
- Taxon
- S. melongena
Solanum melongenae0 - Treatment
- CO(2)e1
- Outcome
- initial slope and the CO(2)-saturated rate of photosynthesise0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both the initial slope and the CO(2)-saturated rate of photosynthesis decreased (B. oleracea, S. melongena)”
e1“Long-term exposure to elevated CO(2)”
Claim · model-written summary
In all five species, high CO2 growth increased photosynthetic stimulation after lowering oxygen or increasing measurement CO2.
- Taxon
- five speciese0
- Treatment
- growth at high CO(2)e0
- Outcome
- extent to which photosynthesis was stimulatede0
- Direction
- increasede0
- Qualifier
- following a decrease in the partial pressure of O(2) or an increase in measurement CO(2) above 600 microbarse0
Not reportedComparator
Verbatim
e0“In all five species, growth at high CO(2) increased the extent to which photosynthesis was stimulated following a decrease in the partial pressure of O(2) or an increase in measurement CO(2) above 600 microbars”
Claim · model-written summary
The stimulation suggests reduced or absent orthophosphate regeneration limitation after acclimation.
Verbatim
e0“This stimulation indicates that a limitation on photosynthesis by the capacity to regenerate orthophosphate was reduced or absent after acclimation to high CO(2)”
e1“five C(3) species”
Claim · model-written summary
Leaf nitrogen per area increased in S. tuberosum under CO2 enrichment.
- Taxon
- S. tuberosumSolanum tuberosume0
- Treatment
- CO(2) enhancemente0
- Outcome
- Leaf nitrogen per areae0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf nitrogen per area either increased (S. tuberosum, S. melongena) or was little changed by CO(2) enhancement”
Claim · model-written summary
Leaf nitrogen per area increased in S. melongena under CO2 enrichment.
- Taxon
- S. melongenaSolanum melongenae0
- Treatment
- CO(2) enhancemente0
- Outcome
- Leaf nitrogen per areae0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf nitrogen per area either increased (S. tuberosum, S. melongena) or was little changed by CO(2) enhancement”
Claim · model-written summary
Rubisco content was lower in two of the five species.
- Taxon
- five speciese0
- Treatment
- high CO(2)e0
- Outcome
- content of rubiscoe0
- Direction
- lowere0
- Value
- two of the five speciese0
Not reportedComparator
Verbatim
e0“The content of rubisco was lower in only two of the five species, yet its activation state was 19% to 48% lower in all five species following long-term exposure to high CO(2)”
Claim · model-written summary
Rubisco activation state was 19% to 48% lower in all five species after prolonged high CO2.
Not reportedComparator
Verbatim
e0“The content of rubisco was lower in only two of the five species, yet its activation state was 19% to 48% lower in all five species following long-term exposure to high CO(2)”
Claim · model-written summary
The authors infer that rubisco content remained above that needed for the observed photosynthesis in CO2 enriched air.
Verbatim
e0“during growth in CO(2)-enriched air, leaf rubisco content remains in excess of that required to support the observed photosynthetic rates”
e1“five C(3) species”
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See all 15 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.