Abstract
Symbiotic nitrogen fixation of two field grown soybean [ Glycine max (L.) Merr.] varieties, ‘Chippewa 64’ and ‘Clay,’ was measured at 7 to 10 day intervals starting at flowering, using the acetylene reduction assay. At he end of flowering, treatments were applied which were designed to alter the relationship between the photosynthetic source and sink components in the plants. The treatments were supplemental light, 25% shade, 50% depodding, 60% defoliation, and control. Total acetylene reduction activity per plant increased in both varieties during the flowering period, reached a maximum near the end of flowering, and then declined markedly during the early podfilling stage. The activity decline was due to a decline in the specific activity of the nodules, and occurred immediately prior to the time when the growth rate of the pods (including seed) exceeded that of the total plant tops in the respective varieties. Treatments designed to enhance he photosynthetic source/sink ratio (supplemental light and depodding) maintained nodule activity well above the control in both varieties. Conversely, treatments designed to reduce the source/sink ratio (shading and defoliation) decreased nodule activity below the level of the control. Treatment effects on total plant protein recovered at maturity closely reflected the treatment effects on total nodule activity. The results of this study are interpreted as evidence that symbiotic nitrogen fixation in these varieties declined during podfilling as the result of inadequate assimilate supply to the nodules.
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Claims 8
Claim · model-written summary
Acetylene reduction activity rose during flowering, peaked near its end, then declined in early podfilling.
- Taxon
- soybean
Glycine maxt0 - Organ / stage
- flowering periode0
- Outcome
- Total acetylene reduction activity per plante0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total acetylene reduction activity per plant increased in both varieties during the flowering period, reached a maximum near the end of flowering, and then declined markedly during the early podfilling stage.”
t0“Soybeans”
Claim · model-written summary
Specific nodule activity declined before pod growth outpaced total tops growth.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- nodulese0
- Outcome
- specific activity of the nodulese0
- Direction
- declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The activity decline was due to a decline in the specific activity of the nodules, and occurred immediately prior to the time when the growth rate of the pods (including seed) exceeded that of the total plant tops in the respective varieties.”
t0“Soybeans”
Claim · model-written summary
Supplemental light maintained nodule activity above control in both varieties.
- Taxon
- soybeanGlycine maxt0
- Treatment
- supplemental lighte0
- Outcome
- nodule activitye0
- Direction
- well abovee0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“supplemental light and depodding) maintained nodule activity well above the control in both varieties.”
t0“Soybeans”
Claim · model-written summary
Depodding maintained nodule activity above control in both varieties.
- Taxon
- soybeanGlycine maxt0
- Treatment
- depoddinge0
- Outcome
- nodule activitye0
- Direction
- well abovee0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“supplemental light and depodding) maintained nodule activity well above the control in both varieties.”
t0“Soybeans”
Claim · model-written summary
Shading reduced nodule activity below control.
- Taxon
- soybeanGlycine maxt0
- Treatment
- shadinge0
- Outcome
- nodule activitye0
- Direction
- decreasede0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“shading and defoliation) decreased nodule activity below the level of the control.”
t0“Soybeans”
Claim · model-written summary
Defoliation reduced nodule activity below control.
- Taxon
- soybeanGlycine maxt0
- Treatment
- defoliatione0
- Outcome
- nodule activitye0
- Direction
- decreasede0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“shading and defoliation) decreased nodule activity below the level of the control.”
t0“Soybeans”
Claim · model-written summary
Treatment effects on mature plant protein closely reflected nodule activity effects.
- Taxon
- soybeanGlycine maxt0
- Treatment
- Treatment effectse0
- Outcome
- total plant protein recovered at maturitye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment effects on total plant protein recovered at maturity closely reflected the treatment effects on total nodule activity.”
t0“Soybeans”
Claim · model-written summary
The authors interpret the podfilling fixation decline as caused by inadequate assimilate to nodules.
- Taxon
- soybeanGlycine maxt0
- Outcome
- symbiotic nitrogen fixatione0
- Direction
- declinede0
- Qualifier
- inadequate assimilate supply to the nodulese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“symbiotic nitrogen fixation in these varieties declined during podfilling as the result of inadequate assimilate supply to the nodules.”
t0“Soybeans”
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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.