Abstract
Plant-growth-promoting rhizobacteria (PGPR) are used on crops most often as seed treatments; however, an alternative application method for transplanted vegetables is mixing PGPR into the soilless medium in which the transplants are grown. Studies were undertaken to compare root colonization and persistence of rifampicin-resistant mutants of PGPR strains Bacillus pumilus SE34 and Pseudomonas fluorescens 89B61, SE34r and 89B61r, on tomato as a function of application method. When the bacteria were incorporated into Promix soilless medium at log 6, 7, and 8 colony- forming units/g, populations of strain SE34r per gram of medium maintained the initial inoculum densities, while populations of 89B61r decreased approximately one to two orders of magnitude by 4 weeks after planting. The populations of each PGPR strain colonizing roots after application into the soilless medium showed a similar pattern at 6 weeks as that at 4 weeks after planting, with higher populations on the whole roots and lateral roots than on the taproots. Strain SE34r but not 89B61r moved upwards and colonized the phyllosphere when incorporated into the soilless medium. Following application as seed treatment, populations of SE34r were significantly higher on upper roots and on the taproot than were populations following application through the soilless medium. Conversely, populations were higher on lower roots and lateral roots following application through the soilless medium than were populations following application as seed treatment. While strain SE34 enhanced plant growth with application both to the medium and as seed treatment, the level of growth promotion was significantly greater with application in the soilless medium. The results indicate that PGPR can be successfully incorporated into soilless media in vegetable transplant production systems.
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Claims 9
Claim · model-written summary
SE34r maintained its initial medium population density.
- Taxon
- tomato
Solanum lycopersicumt0 - Interactor
- SE34re0symbiont
- Outcome
- populations of strain SE34r per gram of mediume0
- Direction
- maintainede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“populations of strain SE34r per gram of medium maintained the initial inoculum densities”
t0“tomato transplant system”
Claim · model-written summary
89B61r populations in medium fell by one to two orders of magnitude after four weeks.
- Taxon
- tomatoSolanum lycopersicumt0
- Interactor
- 89B61re0symbiont
- Outcome
- populations of 89B61re0
- Direction
- decreasede0
- Value
- one to two orders of magnitudee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“populations of 89B61r decreased approximately one to two orders of magnitude by 4 weeks after planting.”
t0“tomato transplant system”
Claim · model-written summary
Both strains colonized whole and lateral roots more densely than taproots at four and six weeks.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- rootse0
- Outcome
- populations on the whole roots and lateral rootse0
- Direction
- highere0
- Comparator
- taprootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The populations of each PGPR strain colonizing roots after application into the soilless medium showed a similar pattern at 6 weeks as that at 4 weeks after planting, with higher populations on the whole roots and lateral roots than on the taproots.”
t0“tomato transplant system”
Claim · model-written summary
SE34r colonized the phyllosphere after medium incorporation.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- phyllospheree0
- Interactor
- SE34re0symbiont
- Outcome
- colonized the phyllospheree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Strain SE34r but not 89B61r moved upwards and colonized the phyllosphere when incorporated into the soilless medium.”
t0“tomato transplant system”
Claim · model-written summary
89B61r did not colonize the phyllosphere under medium incorporation.
- Taxon
- tomatoSolanum lycopersicumt0
- Interactor
- 89B61re0symbiont
- Outcome
- not 89B61r moved upwards and colonized the phyllospheree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Strain SE34r but not 89B61r moved upwards and colonized the phyllosphere when incorporated into the soilless medium.”
t0“tomato transplant system”
Claim · model-written summary
Seed treatment produced higher SE34r populations on upper roots and taproot than medium application.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- application as seed treatmente0
- Interactor
- SE34re0symbiont
- Outcome
- populations of SE34re0
- Direction
- highere0
- Comparator
- application through the soilless mediume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Following application as seed treatment, populations of SE34r were significantly higher on upper roots and on the taproot than were populations following application through the soilless medium.”
t0“tomato transplant system”
Claim · model-written summary
Medium application produced higher bacterial populations on lower and lateral roots than seed treatment.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- lower roots and lateral rootse0
- Treatment
- application through the soilless mediume0
- Outcome
- populationse0
- Direction
- highere0
- Comparator
- application as seed treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“populations were higher on lower roots and lateral roots following application through the soilless medium than were populations following application as seed treatment.”
t0“tomato transplant system”
Claim · model-written summary
SE34 promoted tomato growth through both application routes.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- strain SE34e0
- Interactor
- SE34e0symbiont
- Outcome
- plant growthe0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“strain SE34 enhanced plant growth with application both to the medium and as seed treatment”
t0“tomato transplant system”
Claim · model-written summary
Medium application promoted growth more than seed treatment.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- application in the soilless mediume0
- Outcome
- growth promotione0
- Direction
- greatere0
- Comparator
- seed treatmente2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the level of growth promotion was significantly greater with application in the soilless medium.”
t0“tomato transplant system”
e2“both to the medium and as seed treatment”
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