Abstract
The symbiosis of the root-nodules of Bragg soybean [Glycine max (L.) Merrill] and the relative dependence of the plants on symbiotic and soil sources of N were evaluated in an experiment conducted on a vertisol which was high in organic- and mineral-N, free of Rhizobium japonicum, and where poor nodulation was characteristic of inoculated, new sowings. Effective inoculant containing R. japonicum strain CB 1809 was sprayed into the seed bed at three rates of application (10-fold intervals). Increasing rates of inoculant led to greater numbers of rhizobia in the rhizosphere and in the soil, and to improved nodulation. Uninoculated plants did not nodulate. High soil NO-3 (30 ¦g N/g, top 30 cm) did not prevent prompt, abundant colonization of rhizospheres by the bacteria from the inoculant, but nodule initiation was delayed and nodule development was retarded until 42 days after sowing. There was an acceleration in nodule formation and development between 42 and 62 days which coincided with a depletion of NO-3 from the top 60 cm of the soil profile. Nodulated and unnodulated soybeans took up NO-3 at similar times and rates to a soil depth of 90 cm; only unnodulated plants utilized soil NO-3 below 90 cm. Vacuum-extracted stem (xylem) exudate was sampled from plants throughout growth and analysed for nitrogenous solutes. The proportion of ureide-N relative to total-solutes-N in xylem sap was used as an index of symbiotic N2-fixation. The initial increase in concentrations of ureides coincided with the period of accelerated nodule formation and development between 42 and 62 days. Thereafter, there was a progressive increase in ureide concentrations in nodulated plants, and the levels were related to rate of inoculation, extent of nodulation, and to the decline in concentrations of soil NO-3. Ureide concentrations in unnodulated plants remained low throughout. The quantities of NO-3-N and ß-NH2- N in xylem sap were not related to nodulation. The differences between treatments in terms of whole-plant N and grain N were less than predicted from the symbiotic parameters. This indicated that soybeans compensated for symbiotic deficiencies by more efficient exploitation of soil N and/or by more efficient redistribution of vegetative N into grain N, and that nodulation and soil NO-3 were interactive and complementary in meeting the N requirements of the crop.
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Claims 15
Claim · model-written summary
Increasing inoculant rates gave greater numbers of rhizobia in the rhizosphere and in the soil.
- Taxon
- soybean
Glycine maxt0 - Treatment
- Increasing rates of inoculante1
- Interactor
- rhizobiae1symbiont
- Outcome
- numbers of rhizobia in the rhizosphere and in the soile1
- Direction
- greatere1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“Increasing rates of inoculant led to greater numbers of rhizobia in the rhizosphere and in the soil, and to improved nodulation”
Claim · model-written summary
Increasing inoculant rates improved nodulation of soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- Increasing rates of inoculante1
- Interactor
- rhizobiae1symbiont
- Outcome
- nodulatione1
- Direction
- improvede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“Increasing rates of inoculant led to greater numbers of rhizobia in the rhizosphere and in the soil, and to improved nodulation”
Claim · model-written summary
Uninoculated soybean plants did not nodulate.
- Taxon
- soybeanGlycine maxt0
- Outcome
- did not nodulatee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“Uninoculated plants did not nodulate”
Claim · model-written summary
High soil nitrate (30 ug N/g, top 30 cm) did not prevent prompt, abundant colonization of rhizospheres by the inoculant bacteria.
- Taxon
- soybeanGlycine maxt0
- Treatment
- High soil NO-3e1
- Outcome
- colonization of rhizospherese1
- Direction
- did not prevente1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“High soil NO-3 (30 ¦g N/g, top 30 cm) did not prevent prompt, abundant colonization of rhizospheres”
Claim · model-written summary
High soil nitrate delayed nodule initiation and retarded nodule development until 42 days after sowing.
- Taxon
- soybeanGlycine maxt0
- Treatment
- High soil NO-3e1
- Outcome
- nodule initiatione2
- Direction
- delayede2
- Qualifier
- until 42 days after sowinge2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“High soil NO-3”
e2“nodule initiation was delayed and nodule development was retarded until 42 days after sowing”
Claim · model-written summary
Nodule formation and development accelerated between 42 and 62 days, coinciding with depletion of soil nitrate from the top 60 cm.
- Taxon
- soybeanGlycine maxt0
- Compound
- NO-3e1
- Outcome
- nodule formation and developmente1
- Direction
- acceleratione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“There was an acceleration in nodule formation and development between 42 and 62 days which coincided with a depletion of NO-3 from the top 60 cm of the soil profile”
Claim · model-written summary
Nodulated and unnodulated soybeans took up nitrate at similar times and rates to a soil depth of 90 cm.
- Taxon
- soybeansGlycine maxe1
- Outcome
- took up NO-3 at similar times and ratese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Nodulated and unnodulated soybeans took up NO-3 at similar times and rates to a soil depth of 90 cm”
Claim · model-written summary
Only unnodulated soybean plants used soil nitrate below 90 cm.
- Taxon
- soybeanGlycine maxt0
- Outcome
- only unnodulated plants utilized soil NO-3 below 90 cme1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“only unnodulated plants utilized soil NO-3 below 90 cm”
Claim · model-written summary
The initial increase in xylem ureide concentrations coincided with the period of accelerated nodule formation between 42 and 62 days.
- Taxon
- soybeanGlycine maxt0
- Outcome
- initial increase in concentrations of ureidese1
- Qualifier
- coincided with the period of accelerated nodule formation and development between 42 and 62 dayse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“The initial increase in concentrations of ureides coincided with the period of accelerated nodule formation and development between 42 and 62 days”
Claim · model-written summary
In nodulated plants ureide concentrations increased progressively and were related to inoculation rate, extent of nodulation and the decline in soil nitrate.
- Taxon
- soybeanGlycine maxt0
- Treatment
- rate of inoculatione1
- Outcome
- ureide concentrationse1
- Direction
- progressive increasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“there was a progressive increase in ureide concentrations in nodulated plants, and the levels were related to rate of inoculation, extent of nodulation, and to the decline in concentrations of soil NO-3”
Claim · model-written summary
Ureide concentrations in unnodulated plants remained low throughout.
- Taxon
- soybeanGlycine maxt0
- Outcome
- Ureide concentrations in unnodulated plants remained lowe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“Ureide concentrations in unnodulated plants remained low throughout”
Claim · model-written summary
Amounts of nitrate-N and beta-amino-N in xylem sap were not related to nodulation.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- xylem sape1
- Outcome
- quantities of NO-3-N and ß-NH2- Ne1
- Direction
- no_changeinferrede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“The quantities of NO-3-N and ß-NH2- N in xylem sap were not related to nodulation”
Claim · model-written summary
Differences between treatments in whole-plant N and grain N were less than predicted from the symbiotic parameters.
- Taxon
- soybeanGlycine maxt0
- Outcome
- whole-plant N and grain Ne1
- Qualifier
- less than predicted from the symbiotic parameterse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“The differences between treatments in terms of whole-plant N and grain N were less than predicted from the symbiotic parameters”
Claim · model-written summary
The authors infer that soybeans compensated for symbiotic deficiencies by more efficient exploitation of soil N and/or more efficient redistribution of vegetative N into grain N.
- Taxon
- soybeansGlycine maxe1
- Outcome
- compensated for symbiotic deficienciese1
- Qualifier
- more efficient exploitation of soil N and/or by more efficient redistribution of vegetative N into grain Ne1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“soybeans compensated for symbiotic deficiencies by more efficient exploitation of soil N and/or by more efficient redistribution of vegetative N into grain N”
Claim · model-written summary
The authors conclude that nodulation and soil nitrate were interactive and complementary in meeting the crop nitrogen requirements.
- Taxon
- soybeanGlycine maxt0
- Outcome
- interactive and complementary in meeting the N requirementse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“soybean”
e1“nodulation and soil NO-3 were interactive and complementary in meeting the N requirements of the crop”
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