Abstract
Plants grown at elevated CO 2 often acclimate such that their photosynthetic capacities are reduced relative to ambient CO 2 ‐grown plants. Reductions in synthesis of photosynthetic enzymes could result either from reduced photosynthetic gene expression or from reduced availability of nitrogen‐containing substrates for enzyme synthesis. Increased carbohydrate concentrations resulting from increased photosynthetic carbon fixation at elevated CO 2 concentrations have been suggested to reduce the expression of photosynthetic genes. However, recent studies have also suggested that nitrogen uptake may be depressed by elevated CO 2 , or at least that it is not increased enough to keep pace with increased carbohydrate production. This response could induce a nitrogen limitation in elevated‐CO 2 plants that might account for the reduction in photosynthetic enzyme synthesis. If CO 2 acclimation were a response to limited nitrogen uptake, the effects of elevated CO 2 and limiting nitrogen supply on photosynthesis and nitrogen allocation should be similar. To test this hypothesis we grew non‐nodulating soybeans at two levels each of nitrogen and CO 2 concentration and measured leaf nitrogen contents, photosynthetic capacities and Rubisco contents. Both low nitrogen and elevated CO 2 reduced nitrogen as a percentage of total leaf dry mass but only low nitrogen supply produced significant decreases in nitrogen as a percentage of leaf structural dry mass. The primary effect of elevated CO 2 was to increase non‐structural carbohydrate storage rather than to decrease nitrogen content. Both low nitrogen supply and elevated CO 2 also decreased carboxylation capacity ( V cmax ) and Rubisco content per unit leaf area. However, when V cmax and Rubisco content were expressed per unit nitrogen, low nitrogen supply generally caused them to increase whereas elevated CO 2 generally caused them to decrease. Finally, elevated CO 2 significantly increased the ratio of RuBP regeneration capacity to V cmax whereas neither nitrogen supply nor plant age had a significant effect on this parameter. We conclude that reductions in photosynthetic enzyme synthesis in elevated CO 2 appear not to result from limited nitrogen supply but instead may result from feedback inhibition by increased carbohydrate contents.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 11
Claim · model-written summary
Low nitrogen supply reduced nitrogen as a percentage of total leaf dry mass in soybean.
- Taxon
- soybean
Glycine maxt0 - Treatment
- low nitrogene1
- Outcome
- nitrogen as a percentage of total leaf dry masse1
- Direction
- reducede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e1“Both low nitrogen and elevated CO 2 reduced nitrogen as a percentage of total leaf dry mass but only low nitrogen supply produced significant decreases in nitrogen as a percentage of leaf structural dry mass”
Claim · model-written summary
Elevated CO2 reduced nitrogen as a percentage of total leaf dry mass in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- elevated CO 2e1
- Outcome
- nitrogen as a percentage of total leaf dry masse1
- Direction
- reducede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e1“Both low nitrogen and elevated CO 2 reduced nitrogen as a percentage of total leaf dry mass but only low nitrogen supply produced significant decreases in nitrogen as a percentage of leaf structural dry mass”
Claim · model-written summary
Low nitrogen supply significantly decreased nitrogen as a percentage of leaf structural dry mass in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- low nitrogen supplye1
- Outcome
- nitrogen as a percentage of leaf structural dry masse1
- Direction
- decreasese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e1“Both low nitrogen and elevated CO 2 reduced nitrogen as a percentage of total leaf dry mass but only low nitrogen supply produced significant decreases in nitrogen as a percentage of leaf structural dry mass”
Claim · model-written summary
Elevated CO2 mainly increased non-structural carbohydrate storage rather than decreasing leaf nitrogen content in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- elevated CO 2e2
- Outcome
- carbohydrate storagee2
- Direction
- increasee2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e2“The primary effect of elevated CO 2 was to increase non‐structural carbohydrate storage rather than to decrease nitrogen content”
Claim · model-written summary
Low nitrogen supply decreased carboxylation capacity and Rubisco content per unit leaf area in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- low nitrogen supplye3
- Outcome
- carboxylation capacity ( V cmax ) and Rubisco content per unit leaf areae3
- Direction
- decreasede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e3“Both low nitrogen supply and elevated CO 2 also decreased carboxylation capacity ( V cmax ) and Rubisco content per unit leaf area”
Claim · model-written summary
Elevated CO2 decreased carboxylation capacity and Rubisco content per unit leaf area in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- elevated CO 2e3
- Outcome
- carboxylation capacity ( V cmax ) and Rubisco content per unit leaf areae3
- Direction
- decreasede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e3“Both low nitrogen supply and elevated CO 2 also decreased carboxylation capacity ( V cmax ) and Rubisco content per unit leaf area”
Claim · model-written summary
Low nitrogen supply increased carboxylation capacity and Rubisco content when expressed per unit nitrogen in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- low nitrogen supplye4
- Outcome
- V cmax and Rubisco contente4
- Direction
- increasee4
- Qualifier
- expressed per unit nitrogene4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e4“However, when V cmax and Rubisco content were expressed per unit nitrogen, low nitrogen supply generally caused them to increase whereas elevated CO 2 generally caused them to decrease”
Claim · model-written summary
Elevated CO2 decreased carboxylation capacity and Rubisco content when expressed per unit nitrogen in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- elevated CO 2e4
- Outcome
- V cmax and Rubisco contente4
- Direction
- decreasee4
- Qualifier
- expressed per unit nitrogene4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e4“However, when V cmax and Rubisco content were expressed per unit nitrogen, low nitrogen supply generally caused them to increase whereas elevated CO 2 generally caused them to decrease”
Claim · model-written summary
Elevated CO2 significantly increased the ratio of RuBP regeneration capacity to Vcmax in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- elevated CO 2e5
- Outcome
- ratio of RuBP regeneration capacity to V cmaxe5
- Direction
- increasede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e5“Finally, elevated CO 2 significantly increased the ratio of RuBP regeneration capacity to V cmax whereas neither nitrogen supply nor plant age had a significant effect on this parameter”
Claim · model-written summary
Neither nitrogen supply nor plant age had a significant effect on the ratio of RuBP regeneration capacity to Vcmax in soybean.
- Taxon
- soybeanGlycine maxt0
- Treatment
- neither nitrogen supply nor plant agee5
- Outcome
- ratio of RuBP regeneration capacity to V cmaxe5
- Direction
- no_changeinferrede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e5“Finally, elevated CO 2 significantly increased the ratio of RuBP regeneration capacity to V cmax whereas neither nitrogen supply nor plant age had a significant effect on this parameter”
Claim · model-written summary
Reduced photosynthetic enzyme synthesis under elevated CO2 may reflect feedback inhibition by increased carbohydrate contents rather than limited nitrogen supply.
- Taxon
- soybeanGlycine maxt0
- Outcome
- reductions in photosynthetic enzyme synthesise6
- Qualifier
- feedback inhibition by increased carbohydrate contentse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in soybean”
e6“We conclude that reductions in photosynthetic enzyme synthesis in elevated CO 2 appear not to result from limited nitrogen supply but instead may result from feedback inhibition by increased carbohydrate contents”
The same questions in other papers
stage · growth · Glycine max (soybean)Positive and negative results
18 papers in the same direction as this paper · 20 in the opposite direction
- positive
- positive
- positive
35 papers more in this group
See all 39 papers →nitrogen · growth · Glycine max (soybean)Positive and negative results
35 papers in the same direction as this paper · 117 in the opposite direction
- positive
- positive
- positive
149 papers more in this group
See all 153 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.