Abstract
Long-term exposure of plants to elevated partial pressures of CO2 (pCO2) often depresses photosynthetic capacity. The mechanistic basis for this photosynthetic acclimation may involve accumulation of carbohydrate and may be promoted by nutrient limitation. However, our current knowledge is inadequate for making reliable predictions concerning the onset and extent of acclimation. Many studies have sought to investigate the effects of N supply but the methodologies used generally do not allow separation of the direct effects of limited N availability from those caused by a N dilution effect due to accelerated growth at elevated pCO2. To dissociate these interactions, wheat (Triticum aestivum L.) was grown hydroponically and N was added in direct proportion to plant growth. Photosynthesis did not acclimate to elevated pCO2 even when growth was restricted by a low-N relative addition rate. Ribulose-1, 5-bisphosphate carboxylase/oxygenase activity and quantity were maintained, there was no evidence for triose phosphate limitation of photosynthesis, and tissue N content remained within the range recorded for healthy wheat plants. In contrast, wheat grown in sand culture with N supplied at a fixed concentration suffered photosynthetic acclimation at elevated pCO2 in a low-N treatment. This was accompanied by a significant reduction in the quantity of active ribulose-1, 5-bisphosphate carboxylase/oxygenase and leaf N content.
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Claims 7
Claim · model-written summary
Hydroponic wheat did not acclimate photosynthesis to elevated pCO2 under growth-proportional nitrogen, even at a low rate.
- Taxon
- wheat
Triticum aestivumt0 - Treatment
- elevated pCO2e0
- Outcome
- Photosynthesise0
- Direction
- did not acclimatee0
- Qualifier
- low-N relative addition ratee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthesis did not acclimate to elevated pCO2 even when growth was restricted by a low-N relative addition rate”
t0“wheat (Triticum aestivum L.) was grown hydroponically”
Claim · model-written summary
Rubisco activity and quantity were maintained in hydroponic wheat.
- Taxon
- wheatTriticum aestivumt0
- Gene
- Ribulose-1, 5-bisphosphate carboxylase/oxygenasee0
- Outcome
- Ribulose-1, 5-bisphosphate carboxylase/oxygenase activity and quantitye0
- Direction
- maintainede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ribulose-1, 5-bisphosphate carboxylase/oxygenase activity and quantity were maintained”
t0“wheat (Triticum aestivum L.) was grown hydroponically”
Claim · model-written summary
Hydroponic wheat showed no triose phosphate limitation of photosynthesis.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- triose phosphate limitation of photosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was no evidence for triose phosphate limitation of photosynthesis”
t0“wheat (Triticum aestivum L.) was grown hydroponically”
Claim · model-written summary
Hydroponic wheat tissue nitrogen remained in the healthy range.
- Taxon
- wheatTriticum aestivume0
- Outcome
- tissue N contente0
- Direction
- remained within the rangee0
- Comparator
- healthy wheat plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“tissue N content remained within the range recorded for healthy wheat plants”
Claim · model-written summary
Sand-grown low-nitrogen wheat suffered photosynthetic acclimation at elevated pCO2.
- Taxon
- wheatTriticum aestivume0
- Treatment
- low-N treatmente0
- Outcome
- photosynthetic acclimatione0
- Setting
- sand culturee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat grown in sand culture with N supplied at a fixed concentration suffered photosynthetic acclimation at elevated pCO2 in a low-N treatment”
Claim · model-written summary
The sand-culture response included significantly reduced active Rubisco quantity.
- Taxon
- wheatTriticum aestivumt0
- Gene
- ribulose-1, 5-bisphosphate carboxylase/oxygenasee0
- Outcome
- quantity of active ribulose-1, 5-bisphosphate carboxylase/oxygenasee0
- Direction
- reductione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a significant reduction in the quantity of active ribulose-1, 5-bisphosphate carboxylase/oxygenase and leaf N content”
t0“wheat (Triticum aestivum L.) was grown hydroponically”
Claim · model-written summary
The sand-culture response included significantly reduced leaf nitrogen content.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- leaf N contente0
- Direction
- reductione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a significant reduction in the quantity of active ribulose-1, 5-bisphosphate carboxylase/oxygenase and leaf N content”
t0“wheat (Triticum aestivum L.) was grown hydroponically”
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