Abstract
Five cool-season C3 pasture species ( Bromus willdenowii Kunth, Festuca arundinacea Schreb, Lolium multiflorum Lam., Lolium perenne L. and Trifolium repens L.) were grown at a constant temperature of 12°C to assess effects of elevated CO2 on growth and photosynthesis. Plants were grown at either 350 or 700 μmol mol–1 CO2 for 42-56 d, after which they were destructively harvested to assess biomass. At the same time, leaf gas exchange was measured at 12°C for each species at both CO2 concentrations. Photosynthetic response to CO2, that is the A / C i curve, was also measured. Results showed all species responded to elevated CO2 at low temperature by increasing total biomass, relative to that at ambient CO2, from 105 to 158%. T. repens and B. willdenowii had the smallest response, and the two Lolium species had the greatest response. Photosynthesis also responded strongly to elevated CO2 at low temperature, increasing on average by 40%. Only small growth CO2 effects occurred with the A / C i curves, with lower CO2-saturated photosynthesis only for L. perenne and T. repens grown at elevated CO2. The photosynthetic response to CO2 was not correlated with the growth response. However, the product of photosynthesis and leaf area, that is carbon supply, was highly correlated with the growth rate, and growth CO2 had a marked effect. Results suggest T. repens responded poorly to elevated CO2 at low temperature because of a low capacity to fix carbon, while both Lolium species responded strongly at low temperature because of a high capacity to fix CO2. Changes to photosynthetic model parameters are now required to account for growth temperature effects on the CO2 response.
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Claims 13
Claim · model-written summary
Elevated CO2 increased total biomass of all five pasture species by 105 to 158% relative to ambient CO2.
Verbatim
e0“Results showed all species responded to elevated CO2 at low temperature by increasing total biomass, relative to that at ambient CO2, from 105 to 158%.”
t0“Five cool-season C3 pasture species”
Claim · model-written summary
T. repens had the smallest response to elevated CO2.
- Taxon
- T. repens
Trifolium repense0 - Outcome
- smallest responsee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“T. repens and B. willdenowii had the smallest response, and the two Lolium species had the greatest response.”
Claim · model-written summary
B. willdenowii had the smallest response to elevated CO2.
- Taxon
- B. willdenowii
Bromus catharticuse0 - Outcome
- smallest responsee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“T. repens and B. willdenowii had the smallest response, and the two Lolium species had the greatest response.”
Claim · model-written summary
Lolium species had the greatest response to elevated CO2.
- Outcome
- greatest responsee0
LoliumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“T. repens and B. willdenowii had the smallest response, and the two Lolium species had the greatest response.”
Claim · model-written summary
Photosynthesis increased by an average 40% under elevated CO2 at low temperature.
- Taxon
- Five cool-season C3 pasture speciest0
- Treatment
- elevated CO2e0
- Outcome
- Photosynthesise0
- Direction
- increasinge0
- Value
- 40%e0
Not reportedComparator
Verbatim
e0“Photosynthesis also responded strongly to elevated CO2 at low temperature, increasing on average by 40%.”
t0“Five cool-season C3 pasture species”
Claim · model-written summary
L. perenne grown at elevated CO2 had lower CO2-saturated photosynthesis.
- Taxon
- L. perenne
Lolium perennee0 - Treatment
- elevated CO2e0
- Outcome
- CO2-saturated photosynthesise0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only small growth CO2 effects occurred with the A / C i curves, with lower CO2-saturated photosynthesis only for L. perenne and T. repens grown at elevated CO2.”
Claim · model-written summary
T. repens grown at elevated CO2 had lower CO2-saturated photosynthesis.
- Taxon
- T. repensTrifolium repense0
- Treatment
- elevated CO2e0
- Outcome
- CO2-saturated photosynthesise0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only small growth CO2 effects occurred with the A / C i curves, with lower CO2-saturated photosynthesis only for L. perenne and T. repens grown at elevated CO2.”
Claim · model-written summary
Photosynthetic response to CO2 was not correlated with growth response.
- Taxon
- Five cool-season C3 pasture speciest0
- Outcome
- photosynthetic response to CO2e0
- Comparator
- growth responsee0
Not reportedDirection
Verbatim
e0“The photosynthetic response to CO2 was not correlated with the growth response.”
t0“Five cool-season C3 pasture species”
Claim · model-written summary
Carbon supply was highly correlated with growth rate.
Not reportedDirection
Verbatim
e0“the product of photosynthesis and leaf area, that is carbon supply, was highly correlated with the growth rate”
t0“Five cool-season C3 pasture species”
Claim · model-written summary
Growth CO2 markedly affected carbon supply.
Not reportedComparatorDirection
Verbatim
e0“the product of photosynthesis and leaf area, that is carbon supply, was highly correlated with the growth rate, and growth CO2 had a marked effect.”
t0“Five cool-season C3 pasture species”
Claim · model-written summary
The authors attributed weak T. repens response to low carbon-fixation capacity.
- Taxon
- T. repensTrifolium repense0
- Outcome
- responded poorly to elevated CO2e0
- Qualifier
- low capacity to fix carbone0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Results suggest T. repens responded poorly to elevated CO2 at low temperature because of a low capacity to fix carbon”
Claim · model-written summary
The authors attributed strong Lolium response to high CO2-fixation capacity.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both Lolium species responded strongly at low temperature because of a high capacity to fix CO2”
Claim · model-written summary
The authors recommend changing photosynthetic model parameters for growth temperature effects on CO2 response.
Verbatim
e0“Changes to photosynthetic model parameters are now required to account for growth temperature effects on the CO2 response.”
t0“Five cool-season C3 pasture species”
The same questions in other papers
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1 paper in the same direction as this paper · 6 in the opposite direction
- positive
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See all 8 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.