Abstract
Abstract Atmospheric carbon dioxide (CO2) levels are increasing. In a glasshouse experiment with wheat grown at 5 levels of nitrate (NO3) supply, CO2 enrichment (1500 cm3/m3) substantially decreased critical concentrations of N03‐N and total‐N in stem bases and leaves. For example, critical NO3‐N concentrations in stem bases at Feekes Stages 1.5, 5, and 10.3, were 4.5, 2.0, and 2.0 mg/g dry wt, respectively, for CO2‐enriched plants, compared with 7.5, 6.2 and 6.4 mg/g dry wt, respectively, for control plants grown at the ambient level of CO2. However, concentrations of NO3‐N in the rooting medium required to produce maximum dry matter accumulation by CO2‐enriched plants were similar to those of control plants at the three growth stages. Critical concentrations of NO3‐N and total‐N declined with time in stem bases and leaves of plants grown at both ambient and elevated CO2 levels, but the decline was greater for CO2‐enriched plants. It was concluded that diagnostic criteria based on current critical N concentrations may become invalid as the atmospheric level of CO2 increases.
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Claims 8
Claim · model-written summary
CO2 enrichment decreased critical nitrate-N and total-N concentrations in wheat stem bases and leaves.
- Taxon
- wheat
Triticum aestivume0 - Organ / stage
- stem bases and leavese0
- Treatment
- CO2 enrichment (1500 cm3/m3)e0
- Outcome
- critical concentrations of N03‐N and total‐Ne0
- Direction
- decreasede0
- Setting
- glasshousee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In a glasshouse experiment with wheat grown at 5 levels of nitrate (NO3) supply, CO2 enrichment (1500 cm3/m3) substantially decreased critical concentrations of N03‐N and total‐N in stem bases and leaves.”
Claim · model-written summary
At Feekes Stage 1.5, enriched wheat stem bases had critical nitrate-N of 4.5 mg/g dry wt versus 7.5 mg/g dry wt in ambient controls.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- stem basese0
- Treatment
- CO2‐enrichede0
- Outcome
- critical NO3‐N concentrationse0
- Direction
- lowerinferrede0
- Value
- 4.5e0
- Qualifier
- 1.5e0
- Comparator
- control plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For example, critical NO3‐N concentrations in stem bases at Feekes Stages 1.5, 5, and 10.3, were 4.5, 2.0, and 2.0 mg/g dry wt, respectively, for CO2‐enriched plants, compared with 7.5, 6.2 and 6.4 mg/g dry wt, respectively, for control plants grown at the ambient level of CO2.”
t0“wheat”
Claim · model-written summary
At Feekes Stage 5, enriched wheat stem bases had critical nitrate-N of 2.0 mg/g dry wt versus 6.2 mg/g dry wt in ambient controls.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- stem basese0
- Treatment
- CO2‐enrichede0
- Outcome
- critical NO3‐N concentrationse0
- Direction
- lowerinferrede0
- Value
- 2.0e0
- Qualifier
- Feekes Stages 1.5, 5, and 10.3e0
- Comparator
- control plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For example, critical NO3‐N concentrations in stem bases at Feekes Stages 1.5, 5, and 10.3, were 4.5, 2.0, and 2.0 mg/g dry wt, respectively, for CO2‐enriched plants, compared with 7.5, 6.2 and 6.4 mg/g dry wt, respectively, for control plants grown at the ambient level of CO2.”
t0“wheat”
Claim · model-written summary
At Feekes Stage 10.3, enriched wheat stem bases had critical nitrate-N of 2.0 mg/g dry wt versus 6.4 mg/g dry wt in ambient controls.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- stem basese0
- Treatment
- CO2‐enrichede0
- Outcome
- critical NO3‐N concentrationse0
- Direction
- lowerinferrede0
- Value
- 2.0 mg/g dry wte0
- Qualifier
- 10.3e0
- Comparator
- control plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For example, critical NO3‐N concentrations in stem bases at Feekes Stages 1.5, 5, and 10.3, were 4.5, 2.0, and 2.0 mg/g dry wt, respectively, for CO2‐enriched plants, compared with 7.5, 6.2 and 6.4 mg/g dry wt, respectively, for control plants grown at the ambient level of CO2.”
t0“wheat”
Claim · model-written summary
Rooting-medium nitrate-N concentrations needed for maximum wheat dry matter accumulation were similar under enriched and ambient CO2 at all three stages.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- CO2‐enrichede0
- Outcome
- concentrations of NO3‐N in the rooting mediume0
- Direction
- similare0
- Qualifier
- at the three growth stagese0
- Comparator
- control plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, concentrations of NO3‐N in the rooting medium required to produce maximum dry matter accumulation by CO2‐enriched plants were similar to those of control plants at the three growth stages.”
t0“wheat”
Claim · model-written summary
Critical nitrate-N and total-N concentrations declined with time in wheat stem bases and leaves at both ambient and elevated CO2.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- stem bases and leavese0
- Treatment
- both ambient and elevated CO2 levelse0
- Outcome
- Critical concentrations of NO3‐N and total‐Ne0
- Direction
- declinede0
- Qualifier
- with timee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Critical concentrations of NO3‐N and total‐N declined with time in stem bases and leaves of plants grown at both ambient and elevated CO2 levels, but the decline was greater for CO2‐enriched plants.”
t0“wheat”
Claim · model-written summary
The temporal decline in wheat critical nitrate-N and total-N concentrations was greater under CO2 enrichment.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- stem bases and leavese0
- Treatment
- CO2‐enrichede0
- Outcome
- declinee0
- Direction
- greatere0
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Critical concentrations of NO3‐N and total‐N declined with time in stem bases and leaves of plants grown at both ambient and elevated CO2 levels, but the decline was greater for CO2‐enriched plants.”
t0“wheat”
Claim · model-written summary
Current critical nitrogen diagnostic criteria may become invalid as atmospheric CO2 increases.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- diagnostic criteria based on current critical N concentrations may become invalide0
- Qualifier
- as the atmospheric level of CO2 increasese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It was concluded that diagnostic criteria based on current critical N concentrations may become invalid as the atmospheric level of CO2 increases.”
t0“wheat”
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co2 · growth · Triticum aestivum (wheat)Positive and negative results
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