Abstract
SUMMARY Four experiments conducted over three seasons (2002–05) at the Crops Research Unit, University of Reading, investigated effects of canopy management of autumn sown oilseed rape ( Brassica napus L. ssp. oleifera var. biennis (DC.) Metzg.) on competition with grass weeds. Emphasis was placed on the effect of the crop on the weeds. Rape canopy size was manipulated using sowing date, seed rate and the application of autumn fertilizer. Lolium multiflorum Lam., L .× boucheanum Kunth and Alopecurus myosuroides Huds. were sown as indicative grass weeds. The effects of sowing date, seed rate and autumn nitrogen on crop competitive ability were correlated with rape biomass and fractional interception of photosynthetically active radiation (PAR) by the rape floral layer, to the extent that by spring there was good evidence of crop: weed replacement. An increase in seed rate up to the highest plant densities tested increased both rape biomass and competitiveness, e.g. in 2002/3, L. multiflorum head density was reduced from 539 to 245 heads/m 2 and spikelet density from 13 170 to 5960 spikelets/m 2 when rape plant density was increased from 16 to 81 plants/m 2 . Spikelets/head of Lolium spp. was little affected by rape seed rate, but the length of heads of A. myosuroides was reduced by 9% when plant density was increased from 29–51 plants/m 2 . Autumn nitrogen increased rape biomass and reduced L. multiflorum head density (415 and 336 heads/m 2 without and with autumn nitrogen, respectively) and spikelet density (9990 and 8220 spikelets/m 2 without and with autumn nitrogen, respectively). The number of spikelets/head was not significantly affected by autumn nitrogen. Early sowing could increase biomass and competitiveness, but poor crop establishment sometimes overrode the effect. Where crop and weed establishment was similar for both sowing dates, a 2-week delay (i.e. early September to mid-September) increased L. multiflorum head density from 226 to 633 heads/m 2 and spikelet density from 5780 to 15 060 spikelets/m 2 .
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Claims 9
Claim · model-written summary
Increasing seed rate increased rape biomass and competitiveness.
- Taxon
- winter oilseed rape
_Brassica_napus_-_Habit.jpg?width=60)
Brassica napust0 - Treatment
- An increase in seed ratee1
- Outcome
- rape biomass and competitivenesse1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Brassica_napus_-_Habit.jpg?width=500)
Verbatim
t0“winter oilseed rape”
e1“An increase in seed rate up to the highest plant densities tested increased both rape biomass and competitiveness”
Claim · model-written summary
Rape density from 16 to 81 plants/m2 reduced L. multiflorum head density from 539 to 245 heads/m2 in 2002/3.
- Taxon
- winter oilseed rapeBrassica napust0
- Treatment
- rape plant density was increased from 16 to 81 plants/m 2e2
- Interactor
- L. multiflorum
Lolium multiflorume2weed - Outcome
- L. multiflorum head densitye2
- Direction
- reducede2
- Value
- 539 to 245 heads/m 2e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter oilseed rape”
e2“in 2002/3, L. multiflorum head density was reduced from 539 to 245 heads/m 2 and spikelet density from 13 170 to 5960 spikelets/m 2 when rape plant density was increased from 16 to 81 plants/m 2”
Claim · model-written summary
Rape density from 16 to 81 plants/m2 reduced L. multiflorum spikelet density from 13 170 to 5960 spikelets/m2 in 2002/3.
- Taxon
- winter oilseed rapeBrassica napust0
- Treatment
- rape plant density was increased from 16 to 81 plants/m 2e2
- Interactor
- L. multiflorumLolium multiflorume2weed
- Outcome
- spikelet densitye2
- Direction
- reducede2
- Value
- 13 170 to 5960 spikelets/m 2e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter oilseed rape”
e2“in 2002/3, L. multiflorum head density was reduced from 539 to 245 heads/m 2 and spikelet density from 13 170 to 5960 spikelets/m 2 when rape plant density was increased from 16 to 81 plants/m 2”
Claim · model-written summary
Autumn nitrogen increased rape biomass.
- Taxon
- winter oilseed rapeBrassica napust0
- Treatment
- Autumn nitrogene3
- Outcome
- rape biomasse3
- Direction
- increasede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter oilseed rape”
e3“Autumn nitrogen increased rape biomass and reduced L. multiflorum head density (415 and 336 heads/m 2 without and with autumn nitrogen, respectively)”
Claim · model-written summary
Autumn nitrogen reduced L. multiflorum head density to 336 heads/m2 with autumn nitrogen versus 415 without.
- Taxon
- winter oilseed rapeBrassica napust0
- Treatment
- Autumn nitrogene3
- Interactor
- L. multiflorumLolium multiflorume3weed
- Outcome
- L. multiflorum head densitye3
- Direction
- reducede3
- Value
- 415 and 336 heads/m 2e3
- Comparator
- withoute3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter oilseed rape”
e3“Autumn nitrogen increased rape biomass and reduced L. multiflorum head density (415 and 336 heads/m 2 without and with autumn nitrogen, respectively)”
Claim · model-written summary
Autumn nitrogen did not significantly affect the number of spikelets per head.
- Taxon
- winter oilseed rapeBrassica napust0
- Treatment
- autumn nitrogene4
- Outcome
- number of spikelets/heade4
- Direction
- not significantly affectede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter oilseed rape”
e4“The number of spikelets/head was not significantly affected by autumn nitrogen”
Claim · model-written summary
Early sowing could increase rape biomass and competitiveness.
- Taxon
- winter oilseed rapeBrassica napust0
- Treatment
- Early sowinge5
- Outcome
- biomass and competitivenesse5
- Direction
- increasee5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter oilseed rape”
e5“Early sowing could increase biomass and competitiveness”
Claim · model-written summary
A 2-week sowing delay increased L. multiflorum head density from 226 to 633 heads/m2.
- Taxon
- winter oilseed rapeBrassica napust0
- Treatment
- a 2-week delay (i.e. early September to mid-September)e6
- Interactor
- L. multiflorumLolium multiflorume6weed
- Outcome
- L. multiflorum head densitye6
- Direction
- increasede6
- Value
- from 226 to 633 heads/m 2e6
- Comparator
- early Septembere6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter oilseed rape”
e6“a 2-week delay (i.e. early September to mid-September) increased L. multiflorum head density from 226 to 633 heads/m 2 and spikelet density from 5780 to 15 060 spikelets/m 2”
Claim · model-written summary
A 2-week sowing delay increased L. multiflorum spikelet density from 5780 to 15 060 spikelets/m2.
- Taxon
- winter oilseed rapeBrassica napust0
- Treatment
- a 2-week delay (i.e. early September to mid-September)e6
- Interactor
- L. multiflorumLolium multiflorume6weed
- Outcome
- spikelet densitye6
- Direction
- increasede6
- Value
- from 5780 to 15 060 spikelets/m 2e6
- Comparator
- early Septembere6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter oilseed rape”
e6“a 2-week delay (i.e. early September to mid-September) increased L. multiflorum head density from 226 to 633 heads/m 2 and spikelet density from 5780 to 15 060 spikelets/m 2”
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See all 239 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.