Abstract
Due to changing cropping practices in perennial grass seed crops in western Oregon, USA, alternative rotation systems are being considered to reduce weed infestations. Information is generally lacking regarding the effects of alternative agronomic operations and herbicide inputs on soil weed seed bank composition during this transition. Six crop rotation systems were imposed in 1992 on a field that had historically produced monoculture perennial ryegrass (Lolium perenne L.) seeds. Each system plot was 20 x 30 m, arranged in a randomized complete block design, replicated four times. Twenty to thirty soil cores were sampled in June 1997 from each plot. The weed species composition of the cores was determined by successive greenhouse grow-out assays. In addition to seed density, heterogeneity indices for species evenness, richness, and diversity were determined. The most abundant species were Juncus bufonius L. and Poa annua L. Changes in seed bank composition were due to the different herbicides used for the rotation crop components. Compared to the other rotation systems, no-tillage, spring-planted wheat (Triticum aestivum L.) and oat (Avena sativa L.) reduced overall weed seed density and richness, but did not affect weed species evenness or diversity. When meadowfoam (Limnanthes alba Hartweg ex Benth.) succeeded wheat in rotation, weed species richness was unaffected, but evenness and diversity were reduced, compared to the other rotation systems. For meadowfoam in sequence after white clover (Trifolium repens L.), crop establishment method (no-tillage and conventional tillage) had no effect on weed seed species density, evenness, or diversity.
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Claims 7
Claim · model-written summary
Juncus bufonius and Poa annua were the most abundant weed species.
- Taxon
- perennial ryegrass
Lolium perennet0 - Interactor
- Juncus bufonius L.
Juncus bufoniuse0weed - Outcome
- The most abundant species were Juncus bufonius L. and Poa annua L.e0
Poa annuaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The most abundant species were Juncus bufonius L. and Poa annua L.”
t0“perennial ryegrass (Lolium perenne L.)”
Claim · model-written summary
Different herbicides caused changes in weed seed bank composition.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- different herbicidese0
- Outcome
- seed bank compositione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Changes in seed bank composition were due to the different herbicides used for the rotation crop components.”
t0“perennial ryegrass (Lolium perenne L.)”
Claim · model-written summary
No-tillage spring wheat and oat rotations reduced overall weed seed density and richness versus other systems.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- no-tillage, spring-planted wheat (Triticum aestivum L.) and oat (Avena sativa L.)e0
- Outcome
- weed seed density and richnesse0
- Direction
- reducede0
- Comparator
- other rotation systemse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to the other rotation systems, no-tillage, spring-planted wheat (Triticum aestivum L.) and oat (Avena sativa L.) reduced overall weed seed density and richness”
Claim · model-written summary
Those rotations did not affect weed evenness or diversity.
- Taxon
- perennial ryegrassLolium perennet0
- Outcome
- but did not affect weed species evenness or diversity.e0
- Direction
- did not affecte0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but did not affect weed species evenness or diversity.”
t0“perennial ryegrass (Lolium perenne L.)”
Claim · model-written summary
Meadowfoam after wheat did not affect weed richness versus other rotations.
- Taxon
- meadowfoame0
- Treatment
- meadowfoam (Limnanthes alba Hartweg ex Benth.) succeeded wheate0
- Outcome
- weed species richnesse0
- Direction
- unaffectede0
Not reportedComparator
Verbatim
e0“When meadowfoam (Limnanthes alba Hartweg ex Benth.) succeeded wheat in rotation, weed species richness was unaffected”
Claim · model-written summary
Meadowfoam after wheat reduced weed evenness and diversity versus other rotations.
Verbatim
e0“evenness and diversity were reduced, compared to the other rotation systems.”
t0“When meadowfoam (Limnanthes alba Hartweg ex Benth.)”
Claim · model-written summary
Tillage method did not affect weed seed species density, evenness or diversity for meadowfoam after white clover.
- Taxon
- meadowfoame0
- Treatment
- no-tillage and conventional tillagee0
- Outcome
- weed seed species density, evenness, or diversitye0
- Direction
- no effecte0
Not reportedComparator
Verbatim
e0“For meadowfoam in sequence after white clover (Trifolium repens L.), crop establishment method (no-tillage and conventional tillage) had no effect on weed seed species density, evenness, or diversity.”
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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.