Abstract
Simulated mixed swards of perennial ryegrass (Lolium perenne L. cv. S23) and white clover (Trifolium repens L. cv. S100) were grown from seed under a constant 10°C day/8°C night temperature regime and their growth, and carbon and nitrogen economies examined. The swards received a nutrient solution, every second day, which contained either high (220 μg g−1) or low (40 μg g−1) nitrate N. The High-N swards had rates of canopy photosynthesis and dry matter production (over the linear phase of growth) similar to those previously shown by mixed swards at high temperature. The Low-N swards grew more slowly; canopy photosynthesis, at a given LAI, was similar to that at High-N but lower LAI's were sustained. Clover increased its contribution to total carbon uptake and total dry weight throughout the period in the Low-N treatment and, despite the fact that grass took up most of the available nitrate, clover maintained a consistently higher N content by virtue of N2-fixation. At High-N, grass dominated throughout the measurement period. Earlier, when plants grew as spaced individuals, clover grew less well than grass, but once the canopy was closed it had a similar relative growth rate and thus maintained a steady proportion of total sward dry weight. It is proposed that early in the development of the crop, leaf area production is the limiting factor for growth, and that in this respect clover is adversely affected by low temperature relative to grass. Later, as the LAI of the crop builds up, and the canopy becomes fully light intercepting, net canopy photosynthesis plays a more dominant role and here the higher photosynthetic rate per unit leaf area of the clover is crucial.
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Claims 13
Claim · model-written summary
High-N swards had canopy photosynthesis and dry matter production similar to those previously shown by mixed swards at high temperature.
- Taxon
- perennial ryegrass
Lolium perennee0 - Treatment
- High-Ne1
- Outcome
- rates of canopy photosynthesis and dry matter productione1
- Direction
- similare1
- Comparator
- those previously shown by mixed swards at high temperaturee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simulated mixed swards of perennial ryegrass (Lolium perenne L. cv. S23) and white clover (Trifolium repens L. cv. S100)”
e1“The High-N swards had rates of canopy photosynthesis and dry matter production (over the linear phase of growth) similar to those previously shown by mixed swards at high temperature”
Claim · model-written summary
Low-N swards grew more slowly than swards under high nitrogen.
- Taxon
- perennial ryegrassLolium perennee0
- Treatment
- Low-Ne2
- Outcome
- grewe2
- Direction
- more slowlye2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simulated mixed swards of perennial ryegrass (Lolium perenne L. cv. S23) and white clover (Trifolium repens L. cv. S100)”
e2“The Low-N swards grew more slowly”
Claim · model-written summary
At a given LAI, canopy photosynthesis of Low-N swards was similar to that of High-N swards.
- Taxon
- perennial ryegrassLolium perennee0
- Treatment
- Low-Ne2
- Outcome
- canopy photosynthesis, at a given LAIe3
- Direction
- similare3
- Comparator
- High-Ne3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simulated mixed swards of perennial ryegrass (Lolium perenne L. cv. S23) and white clover (Trifolium repens L. cv. S100)”
e2“The Low-N swards grew more slowly”
e3“canopy photosynthesis, at a given LAI, was similar to that at High-N but lower LAI's were sustained”
Claim · model-written summary
Low-N swards sustained lower LAIs.
- Taxon
- perennial ryegrassLolium perennee0
- Treatment
- Low-Ne2
- Outcome
- LAI'se3
- Direction
- lowere3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simulated mixed swards of perennial ryegrass (Lolium perenne L. cv. S23) and white clover (Trifolium repens L. cv. S100)”
e2“The Low-N swards grew more slowly”
e3“canopy photosynthesis, at a given LAI, was similar to that at High-N but lower LAI's were sustained”
Claim · model-written summary
Clover increased its contribution to total carbon uptake and total dry weight throughout the period in the Low-N treatment.
- Taxon
- white clover
Trifolium repense0 - Material
- Trifolium repens L. cv. S100e0
- Treatment
- Low-Ne4
- Outcome
- total carbon uptake and total dry weighte4
- Direction
- increasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simulated mixed swards of perennial ryegrass (Lolium perenne L. cv. S23) and white clover (Trifolium repens L. cv. S100)”
e4“Clover increased its contribution to total carbon uptake and total dry weight throughout the period in the Low-N treatment”
Claim · model-written summary
Clover maintained a consistently higher N content than grass, by virtue of N2-fixation.
- Taxon
- white cloverTrifolium repense0
- Outcome
- N contente5
- Direction
- highere5
- Qualifier
- by virtue of N2-fixatione5
- Comparator
- grasse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simulated mixed swards of perennial ryegrass (Lolium perenne L. cv. S23) and white clover (Trifolium repens L. cv. S100)”
e5“despite the fact that grass took up most of the available nitrate, clover maintained a consistently higher N content by virtue of N2-fixation”
Claim · model-written summary
At High-N, grass dominated throughout the measurement period.
Verbatim
e6“At High-N, grass dominated throughout the measurement period”
Claim · model-written summary
When plants grew as spaced individuals, clover grew less well than grass.
TrifoliumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“Earlier, when plants grew as spaced individuals, clover grew less well than grass, but once the canopy was closed it had a similar relative growth rate and thus maintained a steady proportion of total sward dry weight”
Claim · model-written summary
Once the canopy was closed, clover had a similar relative growth rate to grass.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“Earlier, when plants grew as spaced individuals, clover grew less well than grass, but once the canopy was closed it had a similar relative growth rate and thus maintained a steady proportion of total sward dry weight”
Claim · model-written summary
Once the canopy was closed, clover maintained a steady proportion of total sward dry weight.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“Earlier, when plants grew as spaced individuals, clover grew less well than grass, but once the canopy was closed it had a similar relative growth rate and thus maintained a steady proportion of total sward dry weight”
Claim · model-written summary
It is proposed that early in crop development, leaf area production limits growth of the mixed sward.
- Taxon
- perennial ryegrassLolium perennee0
- Outcome
- growthe1
- Qualifier
- leaf area production is the limiting factore1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simulated mixed swards of perennial ryegrass (Lolium perenne L. cv. S23) and white clover (Trifolium repens L. cv. S100)”
e1“It is proposed that early in the development of the crop, leaf area production is the limiting factor for growth, and that in this respect clover is adversely affected by low temperature relative to grass”
Claim · model-written summary
Clover is proposed to be adversely affected by low temperature relative to grass in growth.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“It is proposed that early in the development of the crop, leaf area production is the limiting factor for growth, and that in this respect clover is adversely affected by low temperature relative to grass”
Claim · model-written summary
Net canopy photosynthesis plays a more dominant role later, when the canopy is fully light intercepting, and the higher photosynthetic rate per unit leaf area of clover is crucial.
- Outcome
- net canopy photosynthesise1
- Qualifier
- higher photosynthetic rate per unit leaf area of the clovere1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Later, as the LAI of the crop builds up, and the canopy becomes fully light intercepting, net canopy photosynthesis plays a more dominant role and here the higher photosynthetic rate per unit leaf area of the clover is crucial”
The same questions in other papers
nitrogen · physiology: photosynthesis · Lolium perenne (perennial ryegrass)Positive and negative results
3 reporting no difference from an alternative
- positive
- positive
- positive
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.