Abstract
The practice of inoculating forage legumes with rhizobia strains is widespread. It is assumed that the inoculated strain determines the performance of the symbiosis and nitrogen fixation rates. However, native-naturalized strains can be competitive, and actual nodule occupancy is often scarcely investigated. In consequence, failures in establishment and low productivity attributed to poor performance of the inoculant may merely reflect the absence of the inoculated strain in the nodules. This study lays out a strategy followed for selecting a Rhizobium leguminosarum sv. trifolii strain for white clover (Trifolium repens) with competitive nodule occupancy. First, the competitiveness of native-naturalized rhizobia strains selected for their efficiency to fix N2 in clover and tagged with gusA was evaluated in controlled conditions with different soils. Second, three of these experimental strains with superior nodule occupancy plus the currently recommended commercial inoculant, an introduced strain, were tested in the field in two years and at two sites. Plant establishment, herbage productivity, fixation of atmospheric N2 (15N natural abundance), and nodule occupancy (ERIC-PCR genomic fingerprinting) were measured. In both years and sites, nodule occupancy of the native-naturalized experimental strains was either higher or similar to that of the commercial inoculant in both primary and secondary roots. The difference was even greater in stolon roots nodules, where nodule occupancy of the native-naturalized experimental strains was at least five times greater. The amount of N fixed per unit plant mass was consistently higher with native-naturalized experimental strains, although the proportion of N derived from atmospheric fixation was similar for all strains. Plant establishment and herbage production, as well as clover contribution in oversown native grasslands, were either similar or higher in white clover inoculated with the native-naturalized experimental strains. These results support the use of our implemented strategy for developing a competitive inoculant from native-naturalized strains.
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Claims 7
Claim · model-written summary
Nodule occupancy of native-naturalized experimental strains was higher or similar to that of the commercial inoculant in primary and secondary roots
- Taxon
- white clover
Trifolium repense1 - Organ / stage
- primary and secondary rootse3
- Treatment
- native-naturalized experimental strainse3
- Interactor
- rhizobiae2symbiont
- Outcome
- nodule occupancye3
- Direction
- either higher or similare3
- Comparator
- commercial inoculante3
- Setting
- both years and sitese3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“for white clover (Trifolium repens)”
e2“native-naturalized rhizobia strains selected for their efficiency to fix N2 in clover”
e3“In both years and sites, nodule occupancy of the native-naturalized experimental strains was either higher or similar to that of the commercial inoculant in both primary and secondary roots”
Claim · model-written summary
Nodule occupancy in stolon root nodules of native-naturalized experimental strains was at least five times greater than with the commercial inoculant
- Taxon
- white cloverTrifolium repense1
- Organ / stage
- stolon roots nodulese4
- Treatment
- native-naturalized experimental strainse4
- Interactor
- rhizobiae2symbiont
- Outcome
- nodule occupancye4
- Direction
- greatere4
- Value
- at least five timese4
- Comparator
- commercial inoculante3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“for white clover (Trifolium repens)”
e2“native-naturalized rhizobia strains selected for their efficiency to fix N2 in clover”
e3“In both years and sites, nodule occupancy of the native-naturalized experimental strains was either higher or similar to that of the commercial inoculant in both primary and secondary roots”
e4“The difference was even greater in stolon roots nodules, where nodule occupancy of the native-naturalized experimental strains was at least five times greater”
Claim · model-written summary
The amount of N fixed per unit plant mass was higher with native-naturalized experimental strains
- Taxon
- white cloverTrifolium repense1
- Treatment
- native-naturalized experimental strainse5
- Outcome
- amount of N fixed per unit plant masse5
- Direction
- highere5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“for white clover (Trifolium repens)”
e5“The amount of N fixed per unit plant mass was consistently higher with native-naturalized experimental strains”
Claim · model-written summary
The proportion of N derived from atmospheric fixation was similar for all strains
- Taxon
- white cloverTrifolium repense1
- Treatment
- all strainse6
- Outcome
- proportion of N derived from atmospheric fixatione6
- Direction
- similare6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“for white clover (Trifolium repens)”
e6“although the proportion of N derived from atmospheric fixation was similar for all strains”
Claim · model-written summary
Plant establishment and herbage production were similar or higher in white clover inoculated with native-naturalized experimental strains
- Taxon
- white cloverTrifolium repense7
- Treatment
- inoculated with the native-naturalized experimental strainse7
- Outcome
- Plant establishment and herbage productione7
- Direction
- either similar or highere7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“for white clover (Trifolium repens)”
e7“Plant establishment and herbage production, as well as clover contribution in oversown native grasslands, were either similar or higher in white clover inoculated with the native-naturalized experimental strains”
Claim · model-written summary
Clover contribution in oversown native grasslands was similar or higher in white clover inoculated with native-naturalized experimental strains
- Taxon
- white cloverTrifolium repense7
- Treatment
- inoculated with the native-naturalized experimental strainse7
- Outcome
- clover contributione7
- Direction
- either similar or highere7
- Setting
- oversown native grasslandse7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“for white clover (Trifolium repens)”
e7“Plant establishment and herbage production, as well as clover contribution in oversown native grasslands, were either similar or higher in white clover inoculated with the native-naturalized experimental strains”
Claim · model-written summary
The implemented strategy supports developing a competitive inoculant from native-naturalized strains
- Taxon
- white cloverTrifolium repense1
- Outcome
- developing a competitive inoculant from native-naturalized strainse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“for white clover (Trifolium repens)”
e2“These results support the use of our implemented strategy for developing a competitive inoculant from native-naturalized strains”
The same questions in other papers
inoculation · yield · Trifolium repens (white clover)Positive and negative results
7 papers in the same direction as this paper · 2 in the opposite direction
- no effect
- positive
- no effect
6 papers more in this group
See all 10 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.