Abstract
A hundred of bacterial strains, belonging to the genera Azotobacter, Azospirillum, Bacillus, Enterobacter and Pseudomonas, were isolated from the rhizosphere of various crops. They were characterized as to the ability of directly enhancing plant growth, root colonizing, and growth using root exudates as the only energy and carbon source. In vitro bacterial inoculation on maize seedlings resulted in changes of average yield ranging from a 50% decrease to a 70% increase over controls. Most isolates were found to grow on nutrients exuded by roots of both maize and wheat. On the contrary, colonization ability varied greatly with crop. The occurrence and distribution of some bacterial properties, which could be involved in plant-growth stimulation, was investigated in fifty-one non-deleterious strains. Nitrogenase activity, and production of siderophore, indole-3-acetic acid and pectinolytic enzymes were measured under pure culture conditions. A significant nitrogen fixation rate was detectable only with Azotobacter and Azospirillum isolates. Siderophore and pectinase production was found to be restricted to Enterobacter and Bacillus strains, respectively. More widespread resulted the synthesis of the phytohormone indoleacetic acid. A total or partial replacement of the carbon source in the culture medium with root exudates failed to stimulate these bacterial activities.
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Claims 8
Claim · model-written summary
Bacterial inoculation changed maize seedling average yield from a 50% decrease to a 70% increase versus controls.
- Treatment
- bacterial inoculatione0
- Interactor
- bacteriale0symbiont
- Outcome
- average yielde0
- Value
- 50% decrease to a 70% increasee0
- Comparator
- controlse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In vitro bacterial inoculation on maize seedlings resulted in changes of average yield ranging from a 50% decrease to a 70% increase over controls.”
Claim · model-written summary
Most isolates grew on nutrients exuded by maize and wheat roots.
- Taxon
- maize and wheat
Triticum aestivum
Zea mayse0 - Interactor
- isolatese0symbiont
- Outcome
- isolates were found to grow on nutrients exuded by rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Most isolates were found to grow on nutrients exuded by roots of both maize and wheat.”
Claim · model-written summary
Bacterial colonization ability varied greatly by crop.
Not reportedDirection
Verbatim
e0“colonization ability varied greatly with crop.”
t0“plant-associated bacteria”
e1“from the rhizosphere of various crops”
Claim · model-written summary
Significant nitrogen fixation was detectable only in Azotobacter and Azospirillum isolates.
- Taxon
- various cropse1
- Interactor
- Azotobacter and Azospirillum
Azospirillum
Azotobactere0symbiont - Outcome
- nitrogen fixation ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A significant nitrogen fixation rate was detectable only with Azotobacter and Azospirillum isolates.”
t0“plant-associated bacteria”
e1“from the rhizosphere of various crops”
Claim · model-written summary
Siderophore production was restricted to Enterobacter.
- Taxon
- various cropse1
- Interactor
- Enterobacter
Enterobactere0symbiont - Outcome
- siderophoree2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Siderophore and pectinase production was found to be restricted to Enterobacter and Bacillus strains, respectively.”
t0“plant-associated bacteria”
e1“from the rhizosphere of various crops”
e2“production of siderophore”
Claim · model-written summary
Pectinase production was restricted to Bacillus.
Verbatim
e0“Siderophore and pectinase production was found to be restricted to Enterobacter and Bacillus strains, respectively.”
t0“plant-associated bacteria”
e1“from the rhizosphere of various crops”
Claim · model-written summary
Indoleacetic acid synthesis was more widespread.
Verbatim
e0“More widespread resulted the synthesis of the phytohormone indoleacetic acid.”
t0“plant-associated bacteria”
e1“from the rhizosphere of various crops”
Claim · model-written summary
Root exudates did not stimulate the measured bacterial activities.
Verbatim
e0“A total or partial replacement of the carbon source in the culture medium with root exudates failed to stimulate these bacterial activities.”
t0“plant-associated bacteria”
e1“from the rhizosphere of various crops”