Abstract
The objective of this investigation was to examine the effect of an elevated atmospheric CO 2 partial pressure ( p CO 2 ) on the N‐sink strength and performance of symbiotic N 2 fixation in Trifolium repens L. cv. Milkanova. After initial growth under ambient p CO 2 in a nitrogen‐free nutrient solution, T. repens in the exponential growth stage was exposed to ambient and elevated p CO 2 (35 and 60 Pa) and two levels of mineral N (N‐free and 7·5 mol m –3 N) for 36 d in single pots filled with silica sand in growth chambers. Elevated p CO 2 evoked a significant increase in biomass production from day 12 after the start of CO 2 enrichment. For plants supplied with 7·5 mol m –3 N, the relative contribution of symbiotically fixed N (%N sym ) as opposed to N assimilated from mineral sources ( 15 N‐isotope‐dilution method), dropped to 40%. However, in the presence of this high level of mineral N, %N sym was unaffected by atmospheric p CO 2 over the entire experimental period. In plants fully dependent on N 2 fixation, the increase in N yield reflects a stimulation of symbiotic N 2 fixation that was the result of the formation of more nodules rather than of higher specific N 2 fixation. These results are discussed with regard to physiological processes governing symbiotic N 2 fixation and to the response of symbiotic N 2 fixation to elevated p CO 2 in field‐grown T. repens .
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Claims 5
Claim · model-written summary
Elevated CO2 significantly increased biomass production from day 12.
- Taxon
- Trifolium repens L.
Trifolium repenst0 - Treatment
- Elevated p CO 2e0
- Outcome
- biomass productione0
- Direction
- increasee0
- Qualifier
- from day 12e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated p CO 2 evoked a significant increase in biomass production from day 12 after the start of CO 2 enrichment”
t0“Trifolium repens L.”
Claim · model-written summary
At high mineral N, symbiotic N contribution dropped to 40%.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- 7·5 mol m –3 Ne0
- Outcome
- relative contribution of symbiotically fixed Ne0
- Direction
- droppede0
- Value
- 40%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For plants supplied with 7·5 mol m –3 N, the relative contribution of symbiotically fixed N (%N sym ) as opposed to N assimilated from mineral sources ( 15 N‐isotope‐dilution method), dropped to 40%”
t0“Trifolium repens L.”
Claim · model-written summary
At high mineral N, atmospheric CO2 did not affect symbiotic N contribution.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- atmospheric p CO 2e0
- Outcome
- %N syme0
- Direction
- unaffectede0
- Qualifier
- in the presence of this high level of mineral Ne0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the presence of this high level of mineral N, %N sym was unaffected by atmospheric p CO 2 over the entire experimental period”
t0“Trifolium repens L.”
Claim · model-written summary
For plants dependent on N2 fixation, increased N yield reflected stimulated symbiotic fixation.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Outcome
- N yielde0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In plants fully dependent on N 2 fixation, the increase in N yield reflects a stimulation of symbiotic N 2 fixation”
t0“Trifolium repens L.”
Claim · model-written summary
Stimulation of fixation resulted from more nodules, not higher specific fixation.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Organ / stage
- nodulese0
- Outcome
- stimulation of symbiotic N 2 fixatione0
- Qualifier
- formation of more nodules rather than of higher specific N 2 fixatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stimulation of symbiotic N 2 fixation that was the result of the formation of more nodules rather than of higher specific N 2 fixation”
t0“Trifolium repens L.”
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 →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.