Abstract
We studied the effects of CO2 elevation on leaf and canopy photosynthesis and optimal leaf area index (LAI) for stands of the annual species Abutilon theophrasti and Ambrosia artemisiifolia. Leaf photosynthesis was modeled as a function of photosyn- thetic photon flux density (PPFD) and nitrogen content per unit leaf area (NL). There was a curvilinear relationship between the light-saturated rates of leaf photosynthesis (Pmax) and NL. CO2 elevation significantly increased Pmax as a function of NL in both species. Dark respiration (Rd) was linearly correlated with NL. CO2 elevation slightly but significantly increased Rd in Abutilon, while it had no significant effect on Rd in Ambrosia. The initial slope of a light-response curve was determined from quantum yield (4gabs) multiplied by leaf absorptance and then calibrated against NL. Daily canopy photosynthesis, calculated by integration of leaf photosynthesis with the actual distribution of leaf area, leaf N, and PPFD within a canopy, showed fairly good agreement with the canopy photosynthesis estimated from growth analysis. CO2 elevation increased canopy photosynthesis by 30- 50%. Based on the leaf photosynthesis model for Abutilon, we calculated daily canopy photosynthesis for a given LAI and N availability, in which N was assumed to be distributed optimally within a leaf canopy to maximize daily canopy photosynthesis. An optimal LAI to maximize daily canopy photosynthesis was obtained for each level of N availability and this optimum increased with increasing N availability. Contrary to the often predicted increase in LAI with CO2 elevation, the optimum LAI did not increase at high CO2 when N availability was limited. Two factors were suggested to be involved in counteracting the increase in LAI in a high-CO2 world. One is the higher 4abs of plants grown in elevated C02, which makes leaves in the canopy more N limited, favors higher NL and thus lowers optimal LAI. The other is the higher Rd in elevated C02, which leads to higher light compensation points, and lowers optimal LAI.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 11
Claim · model-written summary
Light-saturated leaf photosynthesis had a curvilinear relationship with leaf nitrogen per area.
- Taxon
- Abutilon theophrasti and Ambrosia artemisiifolia
Abutilon theophrasti
Ambrosia artemisiifoliae1 - Organ / stage
- leafe0
- Outcome
- light-saturated rates of leaf photosynthesise0
- Qualifier
- NLe0
Not reportedCompoundDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a curvilinear relationship between the light-saturated rates of leaf photosynthesis (Pmax) and NL.”
e1“annual species Abutilon theophrasti and Ambrosia artemisiifolia”
Claim · model-written summary
CO2 elevation significantly increased Pmax as a function of leaf nitrogen in both species.
- Taxon
- Abutilon theophrasti and Ambrosia artemisiifoliaAbutilon theophrastiAmbrosia artemisiifoliae1
- Treatment
- CO2 elevatione0
- Outcome
- Pmaxe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO2 elevation significantly increased Pmax as a function of NL in both species.”
e1“annual species Abutilon theophrasti and Ambrosia artemisiifolia”
Claim · model-written summary
Dark respiration was linearly correlated with leaf nitrogen per area.
- Taxon
- Abutilon theophrasti and Ambrosia artemisiifoliaAbutilon theophrastiAmbrosia artemisiifoliae1
- Outcome
- Dark respiratione0
- Comparator
- NLe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Dark respiration (Rd) was linearly correlated with NL.”
e1“annual species Abutilon theophrasti and Ambrosia artemisiifolia”
Claim · model-written summary
CO2 elevation slightly but significantly increased dark respiration in Abutilon.
AbutilonNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO2 elevation slightly but significantly increased Rd in Abutilon”
Claim · model-written summary
CO2 elevation had no significant effect on dark respiration in Ambrosia.
AmbrosiaNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it had no significant effect on Rd in Ambrosia”
e1“CO2 elevation slightly but significantly increased Rd in Abutilon”
Claim · model-written summary
Modeled daily canopy photosynthesis agreed fairly well with growth-analysis estimates.
- Taxon
- Abutilon theophrasti and Ambrosia artemisiifoliaAbutilon theophrastiAmbrosia artemisiifoliae1
- Outcome
- Daily canopy photosynthesise0
- Direction
- fairly good agreemente0
- Comparator
- canopy photosynthesis estimated from growth analysise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Daily canopy photosynthesis, calculated by integration of leaf photosynthesis with the actual distribution of leaf area, leaf N, and PPFD within a canopy, showed fairly good agreement with the canopy photosynthesis estimated from growth analysis.”
e1“annual species Abutilon theophrasti and Ambrosia artemisiifolia”
Claim · model-written summary
CO2 elevation increased canopy photosynthesis by 30- 50%.
- Taxon
- Abutilon theophrasti and Ambrosia artemisiifoliaAbutilon theophrastiAmbrosia artemisiifoliae1
- Treatment
- CO2 elevatione0
- Outcome
- canopy photosynthesise0
- Direction
- increasede0
- Value
- 30- 50%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO2 elevation increased canopy photosynthesis by 30- 50%.”
e1“annual species Abutilon theophrasti and Ambrosia artemisiifolia”
Claim · model-written summary
Optimal LAI increased as nitrogen availability increased in the Abutilon model.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“An optimal LAI to maximize daily canopy photosynthesis was obtained for each level of N availability and this optimum increased with increasing N availability.”
e1“leaf photosynthesis model for Abutilon”
Claim · model-written summary
Under limited nitrogen availability, elevated CO2 did not increase optimal LAI.
- Treatment
- high CO2e0
- Outcome
- optimum LAIe0
- Direction
- did not increasee0
- Qualifier
- N availability was limitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the optimum LAI did not increase at high CO2 when N availability was limited.”
e1“leaf photosynthesis model for Abutilon”
Claim · model-written summary
Higher leaf absorptance under elevated CO2 was proposed to lower optimal LAI through nitrogen limitation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher 4abs of plants grown in elevated C02, which makes leaves in the canopy more N limited, favors higher NL and thus lowers optimal LAI.”
e1“leaf photosynthesis model for Abutilon”
Claim · model-written summary
Higher dark respiration under elevated CO2 was proposed to lower optimal LAI through higher light compensation points.
- Treatment
- elevated C02e0
- Outcome
- optimal LAIe0
- Direction
- lowerse0
- Qualifier
- higher light compensation pointse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher Rd in elevated C02, which leads to higher light compensation points, and lowers optimal LAI.”
e1“leaf photosynthesis model for Abutilon”
The same questions in other papers
co2 · growth · AbutilonPositive and negative results
1 in the opposite direction
- positive
altitude · physiology: photosynthesis · Abutilon theophrasti (velvetleaf)Results agree
1 paper in the same direction as this paper
- positive
co2 · physiology: photosynthesis · Ambrosia artemisiifolia (common ragweed)Results agree
1 paper in the same direction as this paper
- positive
altitude · physiology: photosynthesis · Ambrosia artemisiifolia (common ragweed)Results agree
1 paper in the same direction as this paper
- positive
co2 · physiology: photosynthesis · Abutilon theophrasti (velvetleaf)Results agree
2 papers in the same direction as this paper
- positive
- positive
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.