Abstract
Gas exchange measurements and noninvasive leghemoglobin (Lb) spectrophotometry (nodule oximetry) were used to monitor nodule responses to shoot removal in alfalfa (Medicago sativa L. cv Weevlchek) and birdsfoot trefoil (Lotus corniculatus L. cv Fergus). In each species, total nitrogenase activity, measured as H(2) evolution in Ar:O(2) (80:20), decreased to <50% of the initial rate within 1 hour after detopping, and net CO(2) production decreased to about 65% of the initial value. In a separate experiment in which nodule oximetry was used, nodule O(2) permeability decreased 50% within 5 hours in each species. A similar decrease in the O(2)-saturated respiration rate (V(max)) for the nodule central zone occurred within 5 hours in birdsfoot trefoil, but only after 24 hours in alfalfa. Lb concentration, also measured by oximetry, decreased after 48 to 72 hours. The decrease in permeability preceded the decrease in V(max) in each species. V(max) may depend mainly on carbohydrate availability in the nodule. If so, then the decrease in permeability could not have been triggered by decreasing carbohydrate availability. Both oximetry and gas exchange data were consistent with the hypothesis that, for the cultivars tested, carbohydrate availability decreased more rapidly in birdsfoot trefoil than in alfalfa nodules. Fractional Lb oxygenation (initially about 0.15) decreased during the first 24 hours after detopping but subsequently increased to >0.65 for a majority of nodules of each species. This increase could lead to O(2) inactivation of nitrogenase.
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Claims 16
Claim · model-written summary
Detopping reduced nitrogenase activity below half its initial rate within one hour in alfalfa.
- Taxon
- alfalfa
Medicago sativae1 - Material
- Weevlcheke1
- Treatment
- detoppinge0
- Outcome
- total nitrogenase activitye0
- Direction
- decreasede0
- Value
- <50%e0
- Qualifier
- within 1 houre0
- Comparator
- initial ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In each species, total nitrogenase activity, measured as H(2) evolution in Ar:O(2) (80:20), decreased to <50% of the initial rate within 1 hour after detopping”
e1“alfalfa (Medicago sativa L. cv Weevlchek)”
Claim · model-written summary
Detopping reduced nitrogenase activity below half its initial rate within one hour in birdsfoot trefoil.
Verbatim
e0“In each species, total nitrogenase activity, measured as H(2) evolution in Ar:O(2) (80:20), decreased to <50% of the initial rate within 1 hour after detopping”
e1“birdsfoot trefoil (Lotus corniculatus L. cv Fergus)”
Claim · model-written summary
Detopping reduced net CO2 production to about 65% of its initial value in alfalfa.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- shoot removale2
- Outcome
- net CO(2) productione0
- Direction
- decreasede0
- Value
- about 65%e0
- Comparator
- initial valuee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“net CO(2) production decreased to about 65% of the initial value”
e1“alfalfa (Medicago sativa L. cv Weevlchek)”
e2“shoot removal”
Claim · model-written summary
Detopping reduced net CO2 production to about 65% of its initial value in birdsfoot trefoil.
Verbatim
e0“net CO(2) production decreased to about 65% of the initial value”
e1“birdsfoot trefoil (Lotus corniculatus L. cv Fergus)”
e2“shoot removal”
Claim · model-written summary
Nodule oxygen permeability decreased 50% within five hours after detopping in alfalfa.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- shoot removale2
- Outcome
- nodule O(2) permeabilitye0
- Direction
- decreasede0
- Value
- 50%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nodule O(2) permeability decreased 50% within 5 hours in each species”
e1“alfalfa (Medicago sativa L. cv Weevlchek)”
e2“shoot removal”
Claim · model-written summary
Nodule oxygen permeability decreased 50% within five hours after detopping in birdsfoot trefoil.
- Taxon
- birdsfoot trefoile1
- Treatment
- shoot removale2
- Outcome
- nodule O(2) permeabilitye0
- Direction
- decreasede0
- Value
- 50%e0
Not reportedComparator
Verbatim
e0“nodule O(2) permeability decreased 50% within 5 hours in each species”
e1“birdsfoot trefoil (Lotus corniculatus L. cv Fergus)”
e2“shoot removal”
Claim · model-written summary
Nodule central-zone maximum respiration decreased within five hours after detopping in birdsfoot trefoil.
- Taxon
- birdsfoot trefoile0
- Treatment
- shoot removale1
- Outcome
- O(2)-saturated respiration rate (V(max))e0
- Direction
- decreasee0
- Qualifier
- within 5 hourse0
Not reportedComparator
Verbatim
e0“A similar decrease in the O(2)-saturated respiration rate (V(max)) for the nodule central zone occurred within 5 hours in birdsfoot trefoil”
e1“shoot removal”
Claim · model-written summary
Nodule central-zone maximum respiration decreased only after 24 hours following detopping in alfalfa.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- shoot removale1
- Outcome
- O(2)-saturated respiration rate (V(max))e0
- Direction
- decreasee0
- Qualifier
- only after 24 hourse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A similar decrease in the O(2)-saturated respiration rate (V(max)) for the nodule central zone occurred within 5 hours in birdsfoot trefoil, but only after 24 hours in alfalfa.”
e1“shoot removal”
Claim · model-written summary
Leghemoglobin concentration decreased 48 to 72 hours after detopping in both species.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- shoot removale2
- Outcome
- Lb concentratione0
- Direction
- decreasede0
- Qualifier
- after 48 to 72 hourse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lb concentration, also measured by oximetry, decreased after 48 to 72 hours.”
e1“alfalfa (Medicago sativa L. cv Weevlchek) and birdsfoot trefoil (Lotus corniculatus L. cv Fergus)”
e2“shoot removal”
Claim · model-written summary
The permeability decline preceded the maximum respiration decline in both species.
- Taxon
- alfalfaMedicago sativae1
- Outcome
- decrease in permeability preceded the decrease in V(max)e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The decrease in permeability preceded the decrease in V(max) in each species.”
e1“alfalfa (Medicago sativa L. cv Weevlchek) and birdsfoot trefoil (Lotus corniculatus L. cv Fergus)”
Claim · model-written summary
Evidence was consistent with faster loss of nodule carbohydrate availability in birdsfoot trefoil than alfalfa.
Verbatim
e0“carbohydrate availability decreased more rapidly in birdsfoot trefoil than in alfalfa nodules”
e1“Both oximetry and gas exchange data were consistent with the hypothesis that, for the cultivars tested,”
Claim · model-written summary
Fractional leghemoglobin oxygenation decreased in the first 24 hours after detopping in alfalfa.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- detoppinge0
- Outcome
- Fractional Lb oxygenatione0
- Direction
- decreasede0
- Qualifier
- first 24 hourse0
- Comparator
- initially about 0.15e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fractional Lb oxygenation (initially about 0.15) decreased during the first 24 hours after detopping”
e1“alfalfa (Medicago sativa L. cv Weevlchek)”
Claim · model-written summary
Fractional leghemoglobin oxygenation later rose above 0.65 in most alfalfa nodules.
- Taxon
- alfalfaMedicago sativae2
- Outcome
- Fractional Lb oxygenatione1
- Direction
- increasede0
- Value
- >0.65e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“subsequently increased to >0.65 for a majority of nodules of each species”
e1“Fractional Lb oxygenation”
e2“alfalfa (Medicago sativa L. cv Weevlchek)”
Claim · model-written summary
Fractional leghemoglobin oxygenation decreased in the first 24 hours after detopping in birdsfoot trefoil.
Verbatim
e0“Fractional Lb oxygenation (initially about 0.15) decreased during the first 24 hours after detopping”
e1“birdsfoot trefoil (Lotus corniculatus L. cv Fergus)”
Claim · model-written summary
Fractional leghemoglobin oxygenation later rose above 0.65 in most birdsfoot trefoil nodules.
Verbatim
e0“subsequently increased to >0.65 for a majority of nodules of each species”
e1“Fractional Lb oxygenation”
e2“birdsfoot trefoil (Lotus corniculatus L. cv Fergus)”
Claim · model-written summary
The later rise in nodule oxygenation could inactivate nitrogenase.
- Taxon
- alfalfaMedicago sativae1
- Outcome
- O(2) inactivation of nitrogenasee0
- Qualifier
- This increasee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This increase could lead to O(2) inactivation of nitrogenase.”
e1“alfalfa (Medicago sativa L. cv Weevlchek) and birdsfoot trefoil (Lotus corniculatus L. cv Fergus)”
The same questions in other papers
pruning · physiology: enzyme activity · Medicago sativa (alfalfa)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
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.