Abstract
Abstract The form of nitrogen (N) supply has a significant impact on rhizosphere chemistry and root growth responses of higher plants. The respective effects are also employed as management options to improve nutrient acquisition and to minimize nutrient losses in cropping systems. However, surprisingly little is known concerning the interactions with rhizosphere biota. In this study, we investigated the effects of selected bacterial and fungal inoculants with proven plant growth‐promoting and phosphate (P)‐solubilizing potential (plant growth‐promoting microorganisms, PGPM) in maize with nitrate or stabilized ammonium supply, on soils with limited P availability and sparingly soluble rock phosphate (Rock‐P) applied as P fertilizer. The combination of the bacterial inoculants Pseudomonas sp. DSMZ 13134 (Proradix) and Bacillus amyloliquefaciens FZB42 with ammonium sulphate fertilization, stabilized with the nitrification inhibitor 3,4‐dimethylpyrazole‐phosphate (DMPP), resulted in a superior shoot biomass production (79–111%) and shoot P accumulation (109–235%) as compared with nitrate supply. This effect could be partially attributed to (1) ammonium‐induced rhizosphere acidification via increased root extrusion of protons, (2) promotion of root hair elongation, and (3) increased shoot concentrations of hormonal growth regulators (indole‐3‐acetic acid, zeatin, gibberellic acid). The effects, induced by the microbial inoculants were mainly related to increased root length development (43–44%), associated with a 60% increase in auxin production potential. No inoculant effects were detected on root hair elongation or on chemical modifications of the rhizosphere involved in P solubilisation, such as rhizosphere acidification, release of carboxylates or secretory phosphohydrolases. However, the ammonium‐induced stimulation of root hair elongation increased preferential sites for root colonization by the selected inoculants, which may explain the increase in rhizosphere abundance of PGPMs, exemplarily recorded for the fungal inoculant Trichoderma harzianum OMG16 (210%). The presented data suggest a network of positive interactions between stabilized ammonium fertilization and plant growth‐promoting functions of various bacterial and fungal PGPM inoculants. This offers perspectives to increase the efficiency and the reproducibility of PGPM‐assisted fertilization strategies.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 12
Claim · model-written summary
Bacterial inoculants with stabilized ammonium raised maize shoot biomass by 79–111% versus nitrate.
- Treatment
- ammonium sulphate fertilizatione0
- Interactor
- Pseudomonas sp. DSMZ 13134 (Proradix)e0symbiont
- Second interactor
- Bacillus amyloliquefaciens FZB42Bacillus velezensis FZB42e0symbiont
- Outcome
- shoot biomass productione0
- Direction
- superiore0
- Value
- 79–111%e0
- Comparator
- nitrate supplye0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“The combination of the bacterial inoculants Pseudomonas sp. DSMZ 13134 (Proradix) and Bacillus amyloliquefaciens FZB42 with ammonium sulphate fertilization, stabilized with the nitrification inhibitor 3,4‐dimethylpyrazole‐phosphate (DMPP), resulted in a superior shoot biomass production (79–111%) and shoot P accumulation (109–235%) as compared with nitrate supply.”
Claim · model-written summary
Bacterial inoculants with stabilized ammonium raised maize shoot P accumulation by 109–235% versus nitrate.
- Treatment
- ammonium sulphate fertilizatione0
- Interactor
- Pseudomonas sp. DSMZ 13134 (Proradix)e0symbiont
- Second interactor
- Bacillus amyloliquefaciens FZB42Bacillus velezensis FZB42e0symbiont
- Outcome
- shoot P accumulatione0
- Direction
- superiore0
- Value
- 109–235%e0
- Comparator
- nitrate supplye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“The combination of the bacterial inoculants Pseudomonas sp. DSMZ 13134 (Proradix) and Bacillus amyloliquefaciens FZB42 with ammonium sulphate fertilization, stabilized with the nitrification inhibitor 3,4‐dimethylpyrazole‐phosphate (DMPP), resulted in a superior shoot biomass production (79–111%) and shoot P accumulation (109–235%) as compared with nitrate supply.”
Claim · model-written summary
Ammonium-associated shoot responses were partly attributed to rhizosphere acidification by root proton extrusion.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“This effect could be partially attributed to (1) ammonium‐induced rhizosphere acidification via increased root extrusion of protons”
Claim · model-written summary
Ammonium-associated shoot responses were partly attributed to root hair elongation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“This effect could be partially attributed to (1) ammonium‐induced rhizosphere acidification via increased root extrusion of protons, (2) promotion of root hair elongation”
Claim · model-written summary
Ammonium-associated shoot responses were partly attributed to higher shoot hormonal growth regulators.
- Compound
- indole‐3‐acetic acid, zeatin, gibberellic acide0
- Outcome
- increased shoot concentrations of hormonal growth regulatorse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“(3) increased shoot concentrations of hormonal growth regulators (indole‐3‐acetic acid, zeatin, gibberellic acid).”
Claim · model-written summary
Microbial inoculants increased maize root length development by 43–44%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“The effects, induced by the microbial inoculants were mainly related to increased root length development (43–44%), associated with a 60% increase in auxin production potential.”
Claim · model-written summary
Microbial inoculant effects were associated with a 60% increase in auxin production potential.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“The effects, induced by the microbial inoculants were mainly related to increased root length development (43–44%), associated with a 60% increase in auxin production potential.”
Claim · model-written summary
Inoculants had no detected effect on maize root hair elongation.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“No inoculant effects were detected on root hair elongation or on chemical modifications of the rhizosphere involved in P solubilisation, such as rhizosphere acidification, release of carboxylates or secretory phosphohydrolases.”
Claim · model-written summary
Inoculants had no detected effects on rhizosphere acidification, carboxylate release or secretory phosphohydrolases.
- Treatment
- inoculante0
- Outcome
- rhizosphere acidification, release of carboxylates or secretory phosphohydrolasese0
- Direction
- No inoculant effectse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“No inoculant effects were detected on root hair elongation or on chemical modifications of the rhizosphere involved in P solubilisation, such as rhizosphere acidification, release of carboxylates or secretory phosphohydrolases.”
Claim · model-written summary
Ammonium-stimulated root hair elongation increased sites for inoculant root colonization.
- Outcome
- preferential sites for root colonizatione0
- Qualifier
- ammonium‐induced stimulation of root hair elongatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“the ammonium‐induced stimulation of root hair elongation increased preferential sites for root colonization by the selected inoculants”
Claim · model-written summary
Trichoderma harzianum OMG16 rhizosphere abundance increased 210%.
- Interactor
- Trichoderma harzianum OMG16
Trichoderma harzianume0symbiont - Outcome
- rhizosphere abundance of PGPMse0
- Direction
- increasee0
- Value
- 210%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“increase in rhizosphere abundance of PGPMs, exemplarily recorded for the fungal inoculant Trichoderma harzianum OMG16 (210%).”
Claim · model-written summary
The authors suggest positive interactions between stabilized ammonium fertilization and growth-promoting inoculant functions.
- Treatment
- stabilized ammonium fertilizatione0
- Outcome
- plant growth‐promoting functionse0
- Direction
- positivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“The presented data suggest a network of positive interactions between stabilized ammonium fertilization and plant growth‐promoting functions of various bacterial and fungal PGPM inoculants.”
The same questions in other papers
ammonium sulfate · yield · Zea mays (maize)Results differ
30 papers in the same direction as this paper · 5 in the opposite direction · 1 reporting no difference from an alternative
- no effect
- negative
- negative
33 papers more in this group
See all 37 papers →ammonium sulfate · nutrient: content · Zea mays (maize)Positive and negative results
12 papers in the same direction as this paper · 2 in the opposite direction
- negative
- negative
- positive
11 papers more in this group
See all 15 papers →inoculation · molecular: metabolites · Zea mays (maize)Positive and negative results
11 papers in the same direction as this paper · 117 in the opposite direction
- positive
- positive
- positive
125 papers more in this group
See all 129 papers →inoculation · growth · Zea mays (maize)Positive and negative results
634 papers in the same direction as this paper · 61 in the opposite direction · 3 reporting no difference from an alternative
- positive
- negative
- no effect
695 papers more in this group
See all 699 papers →fertilization · nutrient: content · Zea mays (maize)Positive and negative results
1,025 papers in the same direction as this paper · 127 in the opposite direction · 11 reporting no difference from an alternative
- negative
- positive
- negative
1,160 papers more in this group
See all 1,164 papers →fertilization · yield · Zea mays (maize)Positive and negative results
3,484 papers in the same direction as this paper · 338 in the opposite direction · 85 reporting no difference from an alternative
- negative
- positive
- positive
3,904 papers more in this group
See all 3,908 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.