Abstract
Effects of atmospheric CO2 enrichment to a level above 600 parts 10−6 on leaf and canopy gas exchange characteristics were investigated in Trifolium repens, using an open system for gas exchange measurement. The cuvettes of the system served as growth chambers, allowing continuous measurement in a semi-controlled environment of ±350 and ±600 parts 10−6 CO2, respectively. Carbon balance data were compared with crop yield and effects on the canopy level were compared with measured leaf responses of photosynthesis and stomatal behaviour. Photosynthetic stimulation by high CO2 was stronger at the canopy level (103% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development. The latter increased absolute water consumption by 16%, despite strong stomatal closure. The overall result was a 63% improvement in canopy water use efficiency (WUE), while leaf WVE increased almost 3-fold in saturating light. The stomatal response was such that, while the internal CO2 concentration in the leaf, ch increased with rising atmospherical CO2 concentration, ca, ci/ca was somewhat decreased. Total canopy resistance, Rc, was generally lower at high CO2 levels, despite higher leaf resistance. Higher canopy CO2 loss at night and faster light extinction in a larger-sized high CO2 canopy were major drawbacks which prevented a further increase in dry matter production (the harvest index was increased by a factor 1.83).
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 12
Claim · model-written summary
High CO2 stimulated canopy photosynthesis by 103% on average, more strongly than leaf photosynthesis.
- Taxon
- Trifolium repens
Trifolium repense0 - Material
- Blancat0
- Organ / stage
- canopy levele1
- Treatment
- high CO2e1
- Outcome
- Photosynthetic stimulatione1
- Direction
- strongere1
- Value
- 103% on averagee1
- Comparator
- leavese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
t0“cv. Blanca”
e1“Photosynthetic stimulation by high CO2 was stronger at the canopy level (103% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development”
Claim · model-written summary
High CO2 stimulated leaf photosynthesis by 90% in full light, less than at canopy level.
- Taxon
- Trifolium repensTrifolium repense0
- Material
- Blancat0
- Organ / stage
- leavese1
- Treatment
- high CO2e1
- Outcome
- Photosynthetic stimulatione1
- Direction
- lowerinferrede1
- Value
- 90% in full lighte1
- Comparator
- canopy levele1
- Setting
- full lighte1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
t0“cv. Blanca”
e1“Photosynthetic stimulation by high CO2 was stronger at the canopy level (103% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development”
Claim · model-written summary
The canopy photosynthetic stimulation by high CO2 is attributed to accelerated foliage area development (author interpretation).
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- high CO2e1
- Outcome
- Photosynthetic stimulatione1
- Qualifier
- accelerated foliage area developmente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e1“Photosynthetic stimulation by high CO2 was stronger at the canopy level (103% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development”
Claim · model-written summary
High CO2 increased absolute canopy water consumption by 16% despite strong stomatal closure.
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- high CO2e1
- Outcome
- absolute water consumptione2
- Direction
- increasede2
- Value
- 16%e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e1“Photosynthetic stimulation by high CO2 was stronger at the canopy level (103% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development”
e2“The latter increased absolute water consumption by 16%, despite strong stomatal closure”
Claim · model-written summary
High CO2 gave a 63% improvement in canopy water use efficiency.
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- high CO2e1
- Outcome
- canopy water use efficiency (WUE)e3
- Direction
- improvemente3
- Value
- 63%e3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e1“Photosynthetic stimulation by high CO2 was stronger at the canopy level (103% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development”
e3“The overall result was a 63% improvement in canopy water use efficiency (WUE)”
Claim · model-written summary
Leaf water use efficiency increased almost 3-fold in saturating light under high CO2.
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- high CO2e1
- Outcome
- leaf WVEe4
- Direction
- increasede4
- Value
- almost 3-folde4
- Setting
- saturating lighte4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e1“Photosynthetic stimulation by high CO2 was stronger at the canopy level (103% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development”
e4“while leaf WVE increased almost 3-fold in saturating light”
Claim · model-written summary
Internal CO2 concentration in the leaf increased with rising atmospheric CO2 concentration.
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- rising atmospherical CO2 concentratione5
- Outcome
- internal CO2 concentration in the leafe5
- Direction
- increasede5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e5“The stomatal response was such that, while the internal CO2 concentration in the leaf, ch increased with rising atmospherical CO2 concentration, ca, ci/ca was somewhat decreased”
Claim · model-written summary
The ratio ci/ca decreased somewhat with rising atmospheric CO2 concentration.
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- rising atmospherical CO2 concentratione5
- Outcome
- ci/cae5
- Direction
- decreasede5
- Qualifier
- somewhate5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e5“The stomatal response was such that, while the internal CO2 concentration in the leaf, ch increased with rising atmospherical CO2 concentration, ca, ci/ca was somewhat decreased”
Claim · model-written summary
Total canopy resistance was generally lower at high CO2 levels.
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- high CO2 levelse6
- Outcome
- Total canopy resistance, Rce6
- Direction
- lowere6
- Qualifier
- generallye6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e6“Total canopy resistance, Rc, was generally lower at high CO2 levels, despite higher leaf resistance”
Claim · model-written summary
Leaf resistance was higher under high CO2 levels.
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- high CO2 levelse6
- Outcome
- leaf resistancee6
- Direction
- highere6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e6“Total canopy resistance, Rc, was generally lower at high CO2 levels, despite higher leaf resistance”
Claim · model-written summary
Higher night-time canopy CO2 loss and faster light extinction in the high CO2 canopy prevented a further increase in dry matter production (author interpretation).
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- high CO2e7
- Outcome
- a further increase in dry matter productione7
- Qualifier
- Higher canopy CO2 loss at night and faster light extinctione7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e7“Higher canopy CO2 loss at night and faster light extinction in a larger-sized high CO2 canopy were major drawbacks which prevented a further increase in dry matter production”
Claim · model-written summary
High CO2 increased the harvest index by a factor of 1.83.
- Taxon
- Trifolium repensTrifolium repense0
- Treatment
- high CO2e1
- Outcome
- harvest indexe2
- Direction
- increasede2
- Value
- by a factor 1.83e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in Trifolium repens”
e1“Photosynthetic stimulation by high CO2 was stronger at the canopy level (103% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development”
e2“the harvest index was increased by a factor 1.83”
The same questions in other papers
co2 · yield · Trifolium repens (white clover)Positive and negative results
4 papers in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
- positive
2 papers more in this group
See all 6 papers →co2 · physiology: photosynthesis · Trifolium repens (white clover)Positive and negative results
5 papers in the same direction as this paper · 2 in the opposite direction
- no effect
- negative
- positive
4 papers more in this group
See all 8 papers →co2 · physiology: water · Trifolium repens (white clover)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.