Abstract
Trifolium repens L. was grown to test the following hypotheses: when P is deficient (i) N 2 fixation decreases as a result of the plant's adaptation to the low N demand, regulated by an N feedback mechanism, and (ii) the decrease in the photosynthetic capacity of the leaves does not limit N 2 fixation. Severe P deficiency prevented nodulation or stopped nodule growth when the P deficiency occurred after the plants had formed nodules. At low P, the proportion of whole‐plant‐N derived from symbiotic N 2 fixation decreased, whereas specific N 2 fixation increased and compensated partially for poor nodulation. Leaf photosynthesis was reduced under P deficiency due to low Vc,max and Jmax . Poor growth or poor performance of the nodules was not due to C limitation, because (i) the improved photosynthetic performance at elevated p CO 2 had no effect on the growth and functioning of the nodules, (ii) starch accumulated in the leaves, particularly under elevated p CO 2 , and (iii) the concentration of WSC in the nodules was highest under P deficiency. Under severe P deficiency, the concentrations of whole‐plant‐N and leaf‐N were the highest, indicating that the assimilation of N exceeded the amount of N required by the plant for growth. This was clearly demonstrated by a strong increase in asparagine concentrations in the roots and nodules under low P supply. This indicates that nodulation and the proportion of N derived from symbiotic N 2 fixation are down‐regulated by an N feedback mechanism.
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Claims 13
Claim · model-written summary
Severe phosphorus deficiency prevented nodulation.
- Taxon
- Trifolium repens L.
Trifolium repenst0 - Treatment
- Severe P deficiencye0
- Outcome
- nodulatione0
- Direction
- preventede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Severe P deficiency prevented nodulation or stopped nodule growth when the P deficiency occurred after the plants had formed nodules.”
t0“Trifolium repens L.”
Claim · model-written summary
Severe phosphorus deficiency stopped growth of established nodules.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- Severe P deficiencye0
- Outcome
- nodule growthe0
- Direction
- stoppede0
- Qualifier
- after the plants had formed nodulese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Severe P deficiency prevented nodulation or stopped nodule growth when the P deficiency occurred after the plants had formed nodules.”
t0“Trifolium repens L.”
Claim · model-written summary
Low phosphorus reduced the proportion of whole plant nitrogen derived from symbiotic fixation.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- low Pe0
- Outcome
- proportion of whole‐plant‐N derived from symbiotic N 2 fixatione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At low P, the proportion of whole‐plant‐N derived from symbiotic N 2 fixation decreased, whereas specific N 2 fixation increased and compensated partially for poor nodulation.”
t0“Trifolium repens L.”
Claim · model-written summary
Low phosphorus increased specific nitrogen fixation, partly compensating for poor nodulation.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- low Pe0
- Outcome
- specific N 2 fixatione0
- Direction
- increasede0
- Qualifier
- compensated partially for poor nodulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At low P, the proportion of whole‐plant‐N derived from symbiotic N 2 fixation decreased, whereas specific N 2 fixation increased and compensated partially for poor nodulation.”
t0“Trifolium repens L.”
Claim · model-written summary
Phosphorus deficiency reduced leaf photosynthesis.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- P deficiencye0
- Outcome
- Leaf photosynthesise0
- Direction
- reducede0
- Qualifier
- due to low Vc,max and Jmaxe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf photosynthesis was reduced under P deficiency due to low Vc,max and Jmax .”
t0“Trifolium repens L.”
Claim · model-written summary
Elevated carbon dioxide improved photosynthetic performance.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- elevated p CO 2e0
- Outcome
- photosynthetic performancee0
- Direction
- improvede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the improved photosynthetic performance at elevated p CO 2 had no effect on the growth and functioning of the nodules”
t0“Trifolium repens L.”
Claim · model-written summary
Elevated carbon dioxide did not affect nodule growth or function.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- elevated p CO 2e0
- Outcome
- growth and functioning of the nodulese0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the improved photosynthetic performance at elevated p CO 2 had no effect on the growth and functioning of the nodules”
t0“Trifolium repens L.”
Claim · model-written summary
Starch accumulated in leaves, particularly under elevated carbon dioxide.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Outcome
- starch accumulated in the leavese0
- Direction
- accumulatede0
- Qualifier
- particularly under elevated p CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“starch accumulated in the leaves, particularly under elevated p CO 2”
t0“Trifolium repens L.”
Claim · model-written summary
Nodule WSC concentration was highest under phosphorus deficiency.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- P deficiencye0
- Outcome
- concentration of WSC in the nodulese0
- Direction
- higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the concentration of WSC in the nodules was highest under P deficiency.”
t0“Trifolium repens L.”
Claim · model-written summary
Under severe phosphorus deficiency, whole plant nitrogen concentration was highest.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- severe P deficiencye0
- Outcome
- concentrations of whole‐plant‐Ne0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under severe P deficiency, the concentrations of whole‐plant‐N and leaf‐N were the highest”
t0“Trifolium repens L.”
Claim · model-written summary
Under severe phosphorus deficiency, leaf nitrogen concentration was highest.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- severe P deficiencye0
- Outcome
- leaf‐Ne0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under severe P deficiency, the concentrations of whole‐plant‐N and leaf‐N were the highest”
t0“Trifolium repens L.”
Claim · model-written summary
Low phosphorus supply strongly increased asparagine in roots and nodules.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Treatment
- low P supplye0
- Outcome
- asparagine concentrations in the roots and nodulese0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a strong increase in asparagine concentrations in the roots and nodules under low P supply.”
t0“Trifolium repens L.”
Claim · model-written summary
Nitrogen feedback down regulates nodulation and the symbiotically derived nitrogen proportion.
- Taxon
- Trifolium repens L.Trifolium repenst0
- Outcome
- nodulation and the proportion of N derived from symbiotic N 2 fixatione0
- Direction
- down‐regulatede0
- Qualifier
- N feedback mechanisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nodulation and the proportion of N derived from symbiotic N 2 fixation are down‐regulated by an N feedback mechanism.”
t0“Trifolium repens L.”
The same questions in other papers
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This paper is about lacking the nutrient, so it counts the other way round here.
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See all 9 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.