Abstract
The present study deals with the isolation of plant growth promoting rhizobacteria (PGPR) from rice (variety NIAB IRRI-9) and the beneficial effects of these inoculants on two Basmati rice varieties. Nitrogen-fixing activity (acetylene-reduction activity) was detected in the roots and submerged shoots of field-grown rice variety NIAB IRRI-9. Estimation of the population size of diazotrophic bacteria by ARA-based MPN (acetylene reduction assay-based most probable number) in roots and shoots indicated about 10(5)-10(6) counts/g dry weight at panicle initiation and grain filling stages. Four bacterial isolates from rice roots and shoots were obtained in pure culture which produced phytohormone indoleacetic acid (IAA) in the growth medium. Among these, three isolates S1, S4, and R3 reduced acetylene to ethylene in nitrogen-free semi-solid medium. Morphological and physiological characteristics of the isolates indicated that three nitrogen-fixing isolates S1, S4, and R3 belonged to the genus Enterobacter, while the non-fixing isolate R8 belonged to the genus Aeromonas. 16S rRNA sequence of one isolate from root (R8) and one isolate from shoot (S1) was obtained which confirmed identification of the isolates as Aeromonas veronii and Enterobacter cloacae, respectively. The 1517-nucleotide-long sequence of the isolate R8 showed 99% similarity with Aeromonas veronii (accession No. AF099023) while partial 16S rRNA sequence (two stretches of total 1271 nucleotide length) of S1 showed 97% similarity with the sequence of Enterobacter cloacae (accession No. AJ251469). The seedlings of two rice varieties Basmati 385 and Super Basmati were inoculated with the four bacterial isolates from rice and one Azospirillum brasilense strain Wb3, which was isolated from wheat. In the rice variety Basmati 385, maximum increase in root area and plant biomass was obtained in plants inoculated with Enterobacter S1 and Azospirillum Wb3, whereas in the rice variety Super Basmati, inoculation with Enterobacter R3 resulted in maximum increase of root area and plant biomass. Nitrogen fixation was quantified by using 15N isotopic dilution method. Maximum fixation was observed in Basmati 385 with the inoculants Azospirillum Wb3 and Enterobacter S1 where nearly 46% and 41% of the nitrogen was derived from atmosphere (%Ndfa), respectively. In general, higher nitrogen fixation was observed in variety Basmati 385 than in Super Basmati, and different bacterial strains were found more effective as inoculants for the rice varieties Basmati 385 and Super Basmati.
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Claims 14
Claim · model-written summary
Nitrogen fixing activity was detected in roots and submerged shoots of field grown NIAB IRRI-9 rice.
- Taxon
- rice
Oryza sativae0 - Material
- NIAB IRRI-9e0
- Organ / stage
- roots and submerged shootse0
- Outcome
- Nitrogen-fixing activitye0
- Setting
- field-growne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen-fixing activity (acetylene-reduction activity) was detected in the roots and submerged shoots of field-grown rice variety NIAB IRRI-9.”
Claim · model-written summary
Diazotrophic bacterial populations in rice roots and shoots were about 10(5)-10(6) counts/g dry weight.
- Taxon
- riceOryza sativae1
- Organ / stage
- roots and shootse0
- Outcome
- counts/g dry weighte0
- Value
- 10(5)-10(6) counts/g dry weighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in roots and shoots indicated about 10(5)-10(6) counts/g dry weight at panicle initiation and grain filling stages.”
e1“field-grown rice variety NIAB IRRI-9”
Claim · model-written summary
Four bacterial isolates from rice roots and shoots produced IAA in culture.
- Taxon
- riceOryza sativae0
- Interactor
- bacterial isolatese0symbiont
- Outcome
- produced phytohormone indoleacetic acid (IAA)e0
- Value
- Foure0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Four bacterial isolates from rice roots and shoots were obtained in pure culture which produced phytohormone indoleacetic acid (IAA) in the growth medium.”
Claim · model-written summary
Isolates S1, S4 and R3 reduced acetylene to ethylene in nitrogen free medium.
- Taxon
- riceOryza sativae1
- Interactor
- isolates S1, S4, and R3e0symbiont
- Outcome
- reduced acetylene to ethylenee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“three isolates S1, S4, and R3 reduced acetylene to ethylene in nitrogen-free semi-solid medium.”
e1“rice roots and shoots”
Claim · model-written summary
Nitrogen fixing isolates S1, S4 and R3 were identified as Enterobacter.
- Taxon
- riceOryza sativae1
- Interactor
- Enterobacter
Enterobactere0symbiont - Outcome
- belonged to the genus Enterobactere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“three nitrogen-fixing isolates S1, S4, and R3 belonged to the genus Enterobacter”
e1“rice roots and shoots”
Claim · model-written summary
The nonfixing isolate R8 was identified as Aeromonas.
- Taxon
- riceOryza sativae1
- Outcome
- belonged to the genus Aeromonase0
AeromonasOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the non-fixing isolate R8 belonged to the genus Aeromonas.”
e1“rice roots and shoots”
Claim · model-written summary
Root isolate R8 was identified by 16S rRNA sequence as Aeromonas veronii with 99% similarity.
- Taxon
- riceOryza sativae1
- Interactor
- Aeromonas veronii
Aeromonas veroniie0symbiont - Outcome
- similarity with Aeromonas veroniie0
- Value
- 99%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The 1517-nucleotide-long sequence of the isolate R8 showed 99% similarity with Aeromonas veronii”
e1“rice roots and shoots”
Claim · model-written summary
Shoot isolate S1 was identified as Enterobacter cloacae with 97% sequence similarity.
- Taxon
- riceOryza sativae1
- Interactor
- Enterobacter cloacaeEnterobacter cloacaee0symbiont
- Outcome
- similarity with the sequence of Enterobacter cloacaee0
- Value
- 97%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“S1 showed 97% similarity with the sequence of Enterobacter cloacae”
e1“rice roots and shoots”
Claim · model-written summary
In Basmati 385, Enterobacter S1 inoculation produced maximum root area and biomass increases.
- Taxon
- riceOryza sativae0
- Material
- Basmati 385e0
- Treatment
- inoculated with Enterobacter S1e0
- Interactor
- Enterobacter S1e0symbiont
- Outcome
- root area and plant biomasse0
- Direction
- maximum increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the rice variety Basmati 385, maximum increase in root area and plant biomass was obtained in plants inoculated with Enterobacter S1 and Azospirillum Wb3”
Claim · model-written summary
In Basmati 385, Azospirillum Wb3 inoculation produced maximum root area and biomass increases.
- Taxon
- riceOryza sativae0
- Material
- Basmati 385e0
- Treatment
- inoculated with Enterobacter S1 and Azospirillum Wb3e0
- Interactor
- Azospirillum Wb3e0symbiont
- Outcome
- root area and plant biomasse0
- Direction
- maximum increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the rice variety Basmati 385, maximum increase in root area and plant biomass was obtained in plants inoculated with Enterobacter S1 and Azospirillum Wb3”
Claim · model-written summary
In Super Basmati, Enterobacter R3 inoculation produced maximum root area and biomass increases.
- Taxon
- riceOryza sativae0
- Material
- Super Basmatie0
- Treatment
- inoculation with Enterobacter R3e0
- Interactor
- Enterobacter R3e0symbiont
- Outcome
- root area and plant biomasse0
- Direction
- maximum increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the rice variety Super Basmati, inoculation with Enterobacter R3 resulted in maximum increase of root area and plant biomass.”
Claim · model-written summary
Azospirillum Wb3 yielded nearly 46% nitrogen derived from atmosphere in Basmati 385.
- Taxon
- riceOryza sativae1
- Material
- Basmati 385e0
- Treatment
- inoculants Azospirillum Wb3e0
- Interactor
- Azospirillum Wb3e0symbiont
- Outcome
- nitrogen was derived from atmosphere (%Ndfa)e0
- Direction
- Maximume0
- Value
- 46%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximum fixation was observed in Basmati 385 with the inoculants Azospirillum Wb3 and Enterobacter S1 where nearly 46% and 41% of the nitrogen was derived from atmosphere (%Ndfa), respectively.”
e1“rice variety Basmati 385”
Claim · model-written summary
Enterobacter S1 yielded nearly 41% nitrogen derived from atmosphere in Basmati 385.
- Taxon
- riceOryza sativae1
- Material
- Basmati 385e0
- Treatment
- Enterobacter S1e0
- Interactor
- Enterobacter S1e0symbiont
- Outcome
- nitrogen was derived from atmosphere (%Ndfa)e0
- Direction
- Maximume0
- Value
- 41%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximum fixation was observed in Basmati 385 with the inoculants Azospirillum Wb3 and Enterobacter S1 where nearly 46% and 41% of the nitrogen was derived from atmosphere (%Ndfa), respectively.”
e1“rice variety Basmati 385”
Claim · model-written summary
Basmati 385 generally had higher nitrogen fixation than Super Basmati.
- Taxon
- riceOryza sativae1
- Material
- Basmati 385e0
- Outcome
- nitrogen fixatione0
- Direction
- highere0
- Comparator
- Super Basmatie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher nitrogen fixation was observed in variety Basmati 385 than in Super Basmati”
e1“rice varieties Basmati 385 and Super Basmati were inoculated”
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