Abstract
Efficient biological nitrogen fixation (BNF) is crucial for sustainable soybean productivity. Current strategies involve the use of Bradyrhizobium diazoefficiens and co-inoculation with plant growth-promoting bacteria like Azospirillum brasilense. To further optimize BNF and plant performance, we investigated the effect of co-inoculation with A. brasilense and B. diazoefficiens combined with the strategic application of the micronutrients Molybdenum (Mo), Cobalt (Co), and Nickel (Ni) on soybean grown under greenhouse conditions. We evaluated plant growth, photosynthetic parameters, accumulation of N, nitrate reductase activity, and nifH gene expression at the R1 reproductive stage. Our main finding was that the co-inoculation combined with the simultaneous application of Mo, Co, and Ni significantly maximized vegetative growth, photochemical efficiency, and BNF. Specifically, this triple supplementation increased nifH gene expression (0.22) compared to the inoculated control (0.003), leading to a substantial enhancement of photosynthetic parameters, including photosystem II (PSII) efficiency and net carbon assimilation (A). For example, the total dry mass was 14.36 g in the Mo + Co + Ni + AZO + BRADY combination and 6.50 g in the non-inoculated and non-micronutrient-treated plants. The total N content was also higher in the plants treated with Mo + Co + Ni + AZO + BRADY (73.20 g kg−1). Crucially, the data also demonstrated that excessive levels of Co impaired the symbiosis, underscoring the necessity of precise dose management. These results confirm the strong synergistic potential of combining microbial co-inoculation with targeted mineral nutrition as a high-impact, sustainable strategy for boosting soybean productivity.
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Claims 6
Claim · model-written summary
Combined co-inoculation and Mo, Co and Ni maximized vegetative growth, photochemical efficiency and BNF.
- Taxon
- soybean
Glycine maxe1 - Treatment
- co-inoculation combined with the simultaneous application of Mo, Co, and Nie0
- Outcome
- vegetative growth, photochemical efficiency, and BNFe0
- Direction
- maximizede0
- Setting
- greenhouse conditionse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the co-inoculation combined with the simultaneous application of Mo, Co, and Ni significantly maximized vegetative growth, photochemical efficiency, and BNF”
e1“on soybean grown under greenhouse conditions”
Claim · model-written summary
Triple supplementation raised nifH expression relative to the inoculated control.
- Taxon
- soybeanGlycine maxe1
- Treatment
- this triple supplementatione0
- Gene
- nifHe0
- Outcome
- nifH gene expressione0
- Direction
- increasede0
- Value
- 0.22e0
- Comparator
- inoculated controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this triple supplementation increased nifH gene expression (0.22) compared to the inoculated control (0.003)”
e1“on soybean grown under greenhouse conditions”
Claim · model-written summary
The combined treatment enhanced PSII efficiency and net carbon assimilation.
- Taxon
- soybeanGlycine maxe2
- Treatment
- co-inoculation combined with the simultaneous application of Mo, Co, and Nie1
- Outcome
- photosystem II (PSII) efficiency and net carbon assimilation (A)e0
- Direction
- enhancemente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“substantial enhancement of photosynthetic parameters, including photosystem II (PSII) efficiency and net carbon assimilation (A)”
e1“co-inoculation combined with the simultaneous application of Mo, Co, and Ni”
e2“on soybean grown under greenhouse conditions”
Claim · model-written summary
Combined treatment produced 14.36 g dry mass versus 6.50 g without inoculation or micronutrients.
- Taxon
- soybeanGlycine maxe1
- Treatment
- Mo + Co + Ni + AZO + BRADY combinatione0
- Outcome
- total dry masse0
- Value
- 14.36 ge0
- Qualifier
- 6.50 ge0
- Comparator
- non-inoculated and non-micronutrient-treated plantse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total dry mass was 14.36 g in the Mo + Co + Ni + AZO + BRADY combination and 6.50 g in the non-inoculated and non-micronutrient-treated plants”
e1“on soybean grown under greenhouse conditions”
Claim · model-written summary
Total nitrogen content was higher under the combined treatment, reaching 73.20 g kg−1.
- Taxon
- soybeanGlycine maxe1
- Treatment
- Mo + Co + Ni + AZO + BRADYe0
- Outcome
- total N contente0
- Direction
- highere0
- Value
- 73.20 g kg−1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The total N content was also higher in the plants treated with Mo + Co + Ni + AZO + BRADY (73.20 g kg−1)”
e1“on soybean grown under greenhouse conditions”
Claim · model-written summary
Excessive Co impaired symbiosis.
- Taxon
- soybeanGlycine maxe1
- Treatment
- excessive levels of Coe0
- Outcome
- symbiosise0
- Direction
- impairede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“excessive levels of Co impaired the symbiosis”
e1“on soybean grown under greenhouse conditions”
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