Abstract
ABSTRACT Photosynthesis is commonly stimulated in grasslands with experimental increases in atmospheric CO 2 concentration ([CO 2 ]), a physiological response that could significantly alter the future carbon cycle if it persists in the long term. Yet an acclimation of photosynthetic capacity suggested by theoretical models and short‐term experiments could completely remove this effect of CO 2 . Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE ), with two contrasting nitrogen levels and abrupt changes in the source : sink ratio following periodic harvests. More than 3000 measurements characterized the response of leaf photosynthesis and stomatal conductance to elevated [CO 2 ] across each growing season for the duration of the experiment. Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake. Photosynthetic stimulation was maintained despite a 30% decrease in stomatal conductance and significant decreases in both the apparent, maximum carboxylation velocity ( V c,max ) and the maximum rate of electron transport ( J max ). Immediately prior to the periodic (every 4–8 weeks) cuts of the L. perenne stands, V c,max and J max, were significantly lower in elevated than in ambient [CO 2 ] in the low‐nitrogen treatment. This difference was smaller after the cut, suggesting a dependence upon the balance between the sources and sinks for carbon. In contrast with theoretical expectations and the results of shorter duration experiments, the present results provide no significant change in photosynthetic stimulation across a 10‐year period, nor greater acclimation in V c,max and J max in the later years in either nitrogen treatment.
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 10
Claim · model-written summary
Over 10 years, elevated CO2 gave a 43% higher rate of light-saturated leaf photosynthesis in Lolium perenne.
- Taxon
- Lolium perenne
Lolium perennee2 - Material
- Bastione2
- Treatment
- elevated [CO 2 ]e1
- Outcome
- rate of light‐saturated leaf photosynthesise1
- Direction
- highere1
- Value
- 43%e1
- Qualifier
- Over the 10 years as a wholee1
- Setting
- FACEe2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake”
e2“Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE )”
Claim · model-written summary
Over 10 years, elevated CO2 gave a 36% increase in daily integral of leaf CO2 uptake in Lolium perenne.
- Taxon
- Lolium perenneLolium perennee2
- Treatment
- elevated [CO 2 ]e1
- Outcome
- daily integral of leaf CO 2 uptakee1
- Direction
- increasee1
- Value
- 36%e1
- Setting
- FACEe2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake”
e2“Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE )”
Claim · model-written summary
Elevated CO2 decreased stomatal conductance by 30% in Lolium perenne while photosynthetic stimulation was maintained.
- Taxon
- Lolium perenneLolium perennee2
- Treatment
- elevated [CO 2 ]e1
- Outcome
- stomatal conductancee3
- Direction
- decreasee3
- Value
- 30%e3
- Setting
- FACEe2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake”
e2“Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE )”
e3“Photosynthetic stimulation was maintained despite a 30% decrease in stomatal conductance and significant decreases in both the apparent, maximum carboxylation velocity ( V c,max ) and the maximum rate of electron transport ( J max )”
Claim · model-written summary
Elevated CO2 significantly decreased the maximum carboxylation velocity (Vc,max) in Lolium perenne.
- Taxon
- Lolium perenneLolium perennee2
- Treatment
- elevated [CO 2 ]e1
- Outcome
- maximum carboxylation velocitye3
- Direction
- decreasese3
- Setting
- FACEe2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake”
e2“Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE )”
e3“Photosynthetic stimulation was maintained despite a 30% decrease in stomatal conductance and significant decreases in both the apparent, maximum carboxylation velocity ( V c,max ) and the maximum rate of electron transport ( J max )”
Claim · model-written summary
Elevated CO2 significantly decreased the maximum rate of electron transport (Jmax) in Lolium perenne.
- Taxon
- Lolium perenneLolium perennee2
- Treatment
- elevated [CO 2 ]e1
- Outcome
- maximum rate of electron transporte3
- Direction
- decreasese3
- Setting
- FACEe2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake”
e2“Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE )”
e3“Photosynthetic stimulation was maintained despite a 30% decrease in stomatal conductance and significant decreases in both the apparent, maximum carboxylation velocity ( V c,max ) and the maximum rate of electron transport ( J max )”
Claim · model-written summary
Immediately before cutting, elevated CO2 lowered Vc,max and Jmax in the low-nitrogen treatment of Lolium perenne.
- Taxon
- Lolium perenneLolium perennee2
- Treatment
- elevated [CO 2 ]e1
- Outcome
- V c,max and J maxe5
- Direction
- lowere5
- Qualifier
- low‐nitrogen treatmente5
- Comparator
- ambient [CO 2 ]e5
- Setting
- FACEe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake”
e2“Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE )”
e5“Immediately prior to the periodic (every 4–8 weeks) cuts of the L. perenne stands, V c,max and J max, were significantly lower in elevated than in ambient [CO 2 ] in the low‐nitrogen treatment”
Claim · model-written summary
The elevated versus ambient difference in Vc,max and Jmax was smaller after cutting in L. perenne.
- Taxon
- L. perenneLolium perennee5
- Treatment
- after the cute6
- Outcome
- differencee6
- Direction
- smallere6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Immediately prior to the periodic (every 4–8 weeks) cuts of the L. perenne stands, V c,max and J max, were significantly lower in elevated than in ambient [CO 2 ] in the low‐nitrogen treatment”
e6“This difference was smaller after the cut, suggesting a dependence upon the balance between the sources and sinks for carbon”
Claim · model-written summary
The smaller difference after cutting suggests that Vc,max and Jmax depend on the source-sink carbon balance.
- Taxon
- L. perenneLolium perennee5
- Outcome
- differencee6
- Qualifier
- a dependence upon the balance between the sources and sinks for carbone6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Immediately prior to the periodic (every 4–8 weeks) cuts of the L. perenne stands, V c,max and J max, were significantly lower in elevated than in ambient [CO 2 ] in the low‐nitrogen treatment”
e6“This difference was smaller after the cut, suggesting a dependence upon the balance between the sources and sinks for carbon”
Claim · model-written summary
Over 10 years, elevated CO2 caused no significant change in photosynthetic stimulation in Lolium perenne.
- Taxon
- Lolium perenneLolium perennee2
- Treatment
- elevated [CO 2 ]e1
- Outcome
- photosynthetic stimulatione7
- Direction
- no significant changee7
- Qualifier
- across a 10‐year periode7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake”
e2“Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE )”
e7“the present results provide no significant change in photosynthetic stimulation across a 10‐year period, nor greater acclimation in V c,max and J max in the later years in either nitrogen treatment”
Claim · model-written summary
Elevated CO2 gave no greater acclimation of Vc,max and Jmax in later years in either nitrogen treatment.
- Taxon
- Lolium perenneLolium perennee2
- Treatment
- elevated [CO 2 ]e1
- Outcome
- acclimation in V c,max and J maxe7
- Direction
- nor greatere7
- Qualifier
- in either nitrogen treatmente7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Over the 10 years as a whole, growth at elevated [CO 2 ] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO 2 uptake”
e2“Perennial ryegrass ( Lolium perenne L. cv. Bastion) was grown under an elevated [CO 2 ] of 600 µ mol mol −1 for 10 years using F ree A ir C O 2 E nrichment ( FACE )”
e7“the present results provide no significant change in photosynthetic stimulation across a 10‐year period, nor greater acclimation in V c,max and J max in the later years in either nitrogen treatment”
The same questions in other papers
co2 · nutrient: content · Lolium perenne (perennial ryegrass)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- no effect
- negative
- positive
co2 · physiology: photosynthesis · Lolium perenne (perennial ryegrass)Positive and negative results
3 papers in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- negative
3 papers more in this group
See all 7 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.