Abstract
Abstract Mixtures and monocultures of wheat ( Triticum aestivum ) and wild oat ( Avena fatua ), a common weedy competitor of wheat, were exposed to enhanced solar UV‐B radiation simulating a 20% reduction in stratospheric ozone to assess the timing and seasonal development of the UV‐B effects on light competition in these species. Results from two years of field study revealed that UV‐B enhancement had no detectable effect on the magnitude or timing of seedling emergence in either species. End‐of‐season measurements showed significant UV‐B inhibition of leaf insertion height in wild oat in mixture and monoculture in the second year (irrigated year) but not in the first year (drought year). Leaf insertion height of wheat was not affected by UV‐B in either year. The UV‐B treatment had no detectable effect on monoculture or total (combined species) mixture LAI but did significantly increase (5–7%) the fractional contribution of wheat to the mixture LAI after four weeks of growth in both years. In addition, the UV‐B treatment had subtle effects on LAI height profiles with early season mixtures showing significant reductions in wild oat LAI in lower canopy layers in both years while midseason Year 2 mixtures showed significant reductions in wild oat LAI in upper canopy layers. The changes in canopy structure were found to significantly increase (6–7%) the proportional simulated clear sky canopy photosynthesis and light interception of wheat in mixture. These findings, and others, indicate that the effects of UV‐B enhancement on competition are realized very early in canopy development and provide additional support for the hypothesis that UV‐B enhancement may shift the balance of competition between these species indirectly by altering competitive interactions for light.
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Claims 10
Claim · model-written summary
UV-B enhancement had no detectable effect on wheat seedling emergence.
- Taxon
- wheat
Triticum aestivume1 - Treatment
- UV‐B enhancemente0
- Outcome
- magnitude or timing of seedling emergencee0
- Direction
- no detectable effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UV‐B enhancement had no detectable effect on the magnitude or timing of seedling emergence in either species”
e1“wheat ( Triticum aestivum )”
Claim · model-written summary
UV-B enhancement had no detectable effect on wild oat seedling emergence.
- Taxon
- wild oate1
- Treatment
- UV‐B enhancemente0
- Outcome
- magnitude or timing of seedling emergencee0
- Direction
- no detectable effecte0
Not reportedComparator
Verbatim
e0“UV‐B enhancement had no detectable effect on the magnitude or timing of seedling emergence in either species”
e1“wild oat ( Avena fatua )”
Claim · model-written summary
UV-B significantly inhibited wild oat leaf insertion height in the irrigated second year.
- Taxon
- wild oate0
- Treatment
- UV‐Be0
- Outcome
- leaf insertion heighte0
- Direction
- inhibitione0
- Qualifier
- in the second year (irrigated year)e0
Not reportedComparator
Verbatim
e0“significant UV‐B inhibition of leaf insertion height in wild oat in mixture and monoculture in the second year (irrigated year) but not in the first year (drought year)”
Claim · model-written summary
Wild oat leaf insertion height was not inhibited in the drought first year.
- Taxon
- wild oate0
- Treatment
- UV‐Be0
- Outcome
- leaf insertion heighte0
- Direction
- note0
- Qualifier
- first year (drought year)e0
Not reportedComparator
Verbatim
e0“significant UV‐B inhibition of leaf insertion height in wild oat in mixture and monoculture in the second year (irrigated year) but not in the first year (drought year)”
Claim · model-written summary
Wheat leaf insertion height was unaffected by UV-B in either year.
- Taxon
- wheatTriticum aestivume0
- Treatment
- UV‐Be0
- Outcome
- Leaf insertion heighte0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf insertion height of wheat was not affected by UV‐B in either year”
Claim · model-written summary
UV-B had no detectable effect on monoculture or total mixture LAI.
- Treatment
- UV‐B treatmente0
- Outcome
- monoculture or total (combined species) mixture LAIe0
- Direction
- no detectable effecte0
Not reportedTaxonComparator
Verbatim
e0“The UV‐B treatment had no detectable effect on monoculture or total (combined species) mixture LAI”
Claim · model-written summary
UV-B increased wheat contribution to mixture LAI by 5–7%.
- Taxon
- wheatTriticum aestivume0
- Outcome
- fractional contribution of wheat to the mixture LAIe0
- Direction
- increasee0
- Value
- 5–7%e0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significantly increase (5–7%) the fractional contribution of wheat to the mixture LAI after four weeks of growth in both years”
Claim · model-written summary
UV-B reduced wild oat LAI in lower canopy layers in early mixtures.
Not reportedTreatmentComparator
Verbatim
e0“early season mixtures showing significant reductions in wild oat LAI in lower canopy layers in both years”
Claim · model-written summary
UV-B reduced wild oat LAI in upper canopy layers in midseason year-two mixtures.
Not reportedTreatmentComparator
Verbatim
e0“midseason Year 2 mixtures showed significant reductions in wild oat LAI in upper canopy layers”
Claim · model-written summary
Canopy structure changes increased simulated wheat photosynthesis and light interception by 6–7%.
- Taxon
- wheatTriticum aestivume0
- Treatment
- changes in canopy structuree0
- Outcome
- proportional simulated clear sky canopy photosynthesis and light interception of wheate0
- Direction
- increasee0
- Value
- 6–7%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The changes in canopy structure were found to significantly increase (6–7%) the proportional simulated clear sky canopy photosynthesis and light interception of wheat in mixture”
The same questions in other papers
uv · growth · Triticum aestivum (wheat)Results differ
25 papers in the same direction as this paper · 19 in the opposite direction
- positive
- positive
- positive
41 papers more in this group
See all 45 papers →uv · growth · Avena sativa (oats)Results agree
4 papers in the same direction as this paper
- negative
- negative
- negative
1 paper more in this group
See all 5 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.