Abstract
The hypothesis that growth of rice ( Oryza sativa L. cv. Jarrah) at elevated atmospheric CO2 partial pressure alters leaf nitrogen (N) concentrations required to support maximum dry mass production and photosynthetic rates during the period of rapid tiller initiation was tested by growing plants for 30 days in unstirred sand/hydroponic culture with N concentrations of 5, 20, 40, 60 and 100 mg N L–1. Maximum growth and photosynthetic potential was greater at 70 than 36 Pa CO2 at all N concentrations in the solution. Elevated CO2 reduced leaf N concentrations required to support 90% of maximum growth and photosynthetic rates (critical concentration) from 40 to 27 g kg–1 for growth and from 45 to 30 g kg–1 for photosynthesis. Morphological changes at elevated CO2 included increased tiller numbers and reduced leaf area ratio. The latter could be explained by lower plant N concentrations which occurred at high CO2 at each N concentration in the solution, primarily due to lower leaf blade and root N concentrations. Changes in tiller numbers at high CO2 were unrelated to leaf or plant N but were strongly correlated with leaf soluble carbohydrate concentrations. We conclude that elevated CO2 alters the nutritional physiology of rice during the rapid tillering phase in a way that increases the efficiency of N utilisation for growth and photosynthesis.
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Claims 9
Claim · model-written summary
Maximum growth was greater at 70 than 36 Pa CO2 across nitrogen concentrations.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximum growth and photosynthetic potential was greater at 70 than 36 Pa CO2 at all N concentrations in the solution.”
t0“rice, Oryza sativa L. cv. Jarrah”
Claim · model-written summary
Photosynthetic potential was greater at 70 than 36 Pa CO2 across nitrogen concentrations.
- Taxon
- rice
Oryza sativat0 - Treatment
- 70e0
- Outcome
- photosynthetic potentiale0
- Direction
- greatere0
- Comparator
- 36 Pa CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximum growth and photosynthetic potential was greater at 70 than 36 Pa CO2 at all N concentrations in the solution.”
t0“rice, Oryza sativa L. cv. Jarrah”
Claim · model-written summary
Elevated CO2 reduced critical leaf N concentration for growth from 40 to 27 g kg–1.
- Taxon
- riceOryza sativat0
- Treatment
- Elevated CO2e0
- Outcome
- leaf N concentrations required to support 90% of maximum growthe0
- Direction
- reducede0
- Value
- from 40 to 27 g kg–1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated CO2 reduced leaf N concentrations required to support 90% of maximum growth and photosynthetic rates (critical concentration) from 40 to 27 g kg–1 for growth and from 45 to 30 g kg–1 for photosynthesis.”
t0“rice, Oryza sativa L. cv. Jarrah”
Claim · model-written summary
Elevated CO2 reduced critical leaf N concentration for photosynthesis from 45 to 30 g kg–1.
- Taxon
- riceOryza sativat0
- Treatment
- Elevated CO2e0
- Outcome
- photosynthetic ratese0
- Direction
- reducede0
- Value
- from 45 to 30 g kg–1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated CO2 reduced leaf N concentrations required to support 90% of maximum growth and photosynthetic rates (critical concentration) from 40 to 27 g kg–1 for growth and from 45 to 30 g kg–1 for photosynthesis.”
t0“rice, Oryza sativa L. cv. Jarrah”
Claim · model-written summary
Elevated CO2 increased tiller numbers.
- Taxon
- riceOryza sativat0
- Treatment
- elevated CO2e0
- Outcome
- tiller numberse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Morphological changes at elevated CO2 included increased tiller numbers and reduced leaf area ratio.”
t0“rice, Oryza sativa L. cv. Jarrah”
Claim · model-written summary
Elevated CO2 reduced leaf area ratio.
- Taxon
- riceOryza sativat0
- Treatment
- elevated CO2e0
- Outcome
- leaf area ratioe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Morphological changes at elevated CO2 included increased tiller numbers and reduced leaf area ratio.”
t0“rice, Oryza sativa L. cv. Jarrah”
Claim · model-written summary
High CO2 lowered leaf-blade and root nitrogen concentration.
- Taxon
- riceOryza sativat0
- Treatment
- high CO2e0
- Outcome
- leaf blade and root N concentrationse0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lower plant N concentrations which occurred at high CO2 at each N concentration in the solution, primarily due to lower leaf blade and root N concentrations.”
t0“rice, Oryza sativa L. cv. Jarrah”
Claim · model-written summary
Tiller number changes under high CO2 were unrelated to leaf or plant N.
- Taxon
- riceOryza sativat0
- Compound
- leaf or plant Ne0
- Outcome
- Changes in tiller numberse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Changes in tiller numbers at high CO2 were unrelated to leaf or plant N but were strongly correlated with leaf soluble carbohydrate concentrations.”
t0“rice, Oryza sativa L. cv. Jarrah”
Claim · model-written summary
Tiller number changes were strongly correlated with leaf soluble carbohydrate concentration.
- Taxon
- riceOryza sativat0
- Compound
- leaf soluble carbohydrate concentrationse0
- Outcome
- Changes in tiller numberse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Changes in tiller numbers at high CO2 were unrelated to leaf or plant N but were strongly correlated with leaf soluble carbohydrate concentrations.”
t0“rice, Oryza sativa L. cv. Jarrah”
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