Abstract
Biological nitrogen fixation (BNF) is crucial for enhancing soybean productivity while reducing reliance on mineral nitrogen fertilizers. The accurate estimation of BNF via the δ15N natural abundance method depends on reliable B-values, which represent plants that derive all their nitrogen from fixation. This study aimed to assess the B-values and symbiotic efficiency of Bradyrhizobium-inoculated soybean varieties using δ15N natural abundance techniques. Eight strains and five soybean varieties were evaluated in sterilized sand culture using a factorial completely randomized design under lath-house conditions. Plants were analyzed for δ15N, shoot N concentration, shoot N content, and symbiotic efficiency (SE). The applied treatments showed highly significant effects with strong interactions, reflecting substantial genotypic variation in symbiotic performance. Strain SD-53 produced the lowest δ15N values (−0.24 to 0.14‰) and the highest SE, with several strain–variety combinations surpassing N-fertilized controls. Shoot N concentration and content ranged from 0.96–3.16% and 9.90–52.73 mg plant−1, respectively, and SE varied from 29.07 to 136.29%. δ15N showed strong negative correlations with SE and plant N traits. The study identified SD-53 as a promising inoculant candidate and generated the first regional soybean B-values (−0.24 to 0.14‰ for each tested variety and a mean of −0.08 ± 0.14‰) for Ethiopia. These values provide an important baseline for %Ndfa calculations and support future field validation and inoculant formulation.
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Claims 11
Claim · model-written summary
Strain–variety treatments had significant interacting effects on symbiotic performance.
- Taxon
- soybean
Glycine maxt0 - Interactor
- Bradyrhizobium
Bradyrhizobiumt0symbiont - Outcome
- symbiotic performancee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The applied treatments showed highly significant effects with strong interactions, reflecting substantial genotypic variation in symbiotic performance.”
t0“Bradyrhizobium-Inoculated Soybean Varieties”
Claim · model-written summary
SD-53 produced the lowest δ15N values.
- Taxon
- soybeanGlycine maxt0
- Material
- Strain SD-53e0
- Interactor
- BradyrhizobiumBradyrhizobiumt0symbiont
- Outcome
- δ15N valuese0
- Direction
- loweste0
- Value
- −0.24 to 0.14‰e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Strain SD-53 produced the lowest δ15N values (−0.24 to 0.14‰) and the highest SE, with several strain–variety combinations surpassing N-fertilized controls.”
t0“Bradyrhizobium-Inoculated Soybean Varieties”
Claim · model-written summary
SD-53 had the highest symbiotic efficiency.
- Taxon
- soybeanGlycine maxt0
- Material
- Strain SD-53e0
- Interactor
- BradyrhizobiumBradyrhizobiumt0symbiont
- Outcome
- SEe0
- Direction
- higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Strain SD-53 produced the lowest δ15N values (−0.24 to 0.14‰) and the highest SE, with several strain–variety combinations surpassing N-fertilized controls.”
t0“Bradyrhizobium-Inoculated Soybean Varieties”
Claim · model-written summary
Several inoculated strain–variety combinations surpassed N-fertilized controls.
- Taxon
- soybeanGlycine maxt0
- Interactor
- BradyrhizobiumBradyrhizobiumt0symbiont
- Outcome
- SEe0
- Direction
- surpassinge0
- Comparator
- N-fertilized controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Strain SD-53 produced the lowest δ15N values (−0.24 to 0.14‰) and the highest SE, with several strain–variety combinations surpassing N-fertilized controls.”
t0“Bradyrhizobium-Inoculated Soybean Varieties”
Claim · model-written summary
Shoot nitrogen concentration ranged from 0.96 to 3.16%.
- Taxon
- soybeanGlycine maxt0
- Outcome
- Shoot N concentratione0
- Value
- 0.96–3.16%e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot N concentration and content ranged from 0.96–3.16% and 9.90–52.73 mg plant−1, respectively, and SE varied from 29.07 to 136.29%.”
t0“Bradyrhizobium-Inoculated Soybean Varieties”
Claim · model-written summary
Shoot nitrogen content ranged from 9.90 to 52.73 mg per plant.
- Taxon
- soybeanGlycine maxt0
- Outcome
- contente0
- Value
- 9.90–52.73 mg plant−1e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot N concentration and content ranged from 0.96–3.16% and 9.90–52.73 mg plant−1, respectively, and SE varied from 29.07 to 136.29%.”
t0“Bradyrhizobium-Inoculated Soybean Varieties”
Claim · model-written summary
Symbiotic efficiency ranged from 29.07 to 136.29%.
- Taxon
- soybeanGlycine maxt0
- Outcome
- SEe0
- Value
- 29.07 to 136.29%e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot N concentration and content ranged from 0.96–3.16% and 9.90–52.73 mg plant−1, respectively, and SE varied from 29.07 to 136.29%.”
t0“Bradyrhizobium-Inoculated Soybean Varieties”
Claim · model-written summary
δ15N correlated negatively with symbiotic efficiency and plant N traits.
- Taxon
- soybeanGlycine maxt0
- Outcome
- SE and plant N traitse0
- Direction
- negativee0
- Comparator
- δ15Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“δ15N showed strong negative correlations with SE and plant N traits.”
t0“Bradyrhizobium-Inoculated Soybean Varieties”
Claim · model-written summary
SD-53 was identified as a promising inoculant.
- Taxon
- soybeanGlycine maxe0
- Interactor
- SD-53e0symbiont
- Outcome
- SD-53 as a promising inoculant candidatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The study identified SD-53 as a promising inoculant candidate and generated the first regional soybean B-values (−0.24 to 0.14‰ for each tested variety and a mean of −0.08 ± 0.14‰) for Ethiopia.”
Claim · model-written summary
The study generated regional soybean B-values for Ethiopia.
- Taxon
- soybeanGlycine maxe0
- Outcome
- soybean B-valuese0
- Value
- −0.24 to 0.14‰e0
- Setting
- Ethiopiae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The study identified SD-53 as a promising inoculant candidate and generated the first regional soybean B-values (−0.24 to 0.14‰ for each tested variety and a mean of −0.08 ± 0.14‰) for Ethiopia.”
Claim · model-written summary
Mean regional soybean B-value was −0.08 ± 0.14‰.
- Taxon
- soybeanGlycine maxe0
- Outcome
- soybean B-valuese0
- Value
- −0.08 ± 0.14‰e0
- Setting
- Ethiopiae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The study identified SD-53 as a promising inoculant candidate and generated the first regional soybean B-values (−0.24 to 0.14‰ for each tested variety and a mean of −0.08 ± 0.14‰) for Ethiopia.”