Abstract
Attempts to identify crop genetic material with larger growth stimulation at projected elevated atmospheric CO2 concentrations are becoming more common. The probability of reductions in photosynthesis and yield caused by short-term variation in CO2 concentration within elevated CO2 treatments in the free-air CO2 enrichment plots raises the question of whether similar effects occur in glasshouse or indoor chamber experiments. These experiments were designed to test whether even the normal, modest, cyclic variation in CO2 concentration typical of indoor exposure systems have persistent impacts on photosynthesis and growth, and to explore mechanisms underlying the responses observed. Wheat, cotton, soybeans, and rice were grown from seed in indoor chambers at a mean CO2 concentration of 560 μmol mol−1, with “triangular” cyclic variation with standard deviations of either 4.5 or 18.0 μmol mol−1 measured with 0.1 s sampling periods with an open path analyzer. Photosynthesis, stomatal conductance, and above ground biomass at 20 to 23 days were reduced in all four species by the larger variation in CO2 concentration. Tests of rates of stomatal opening and closing with step changes in light and CO2, and tests of responses to square-wave cycling of CO2 were also conducted on individual leaves of these and three other species, using a leaf gas exchange system. Reduced stomatal conductance due to larger amplitude cycling of CO2 during growth occurred even in soybeans and rice, which had equal rates of opening and closing in response to step changes in CO2. The gas exchange results further indicated that reduced mean stomatal conductance was not the only cause of reduced photosynthesis in variable CO2 conditions.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. 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 4
Claim · model-written summary
Larger cyclic variation in CO2 concentration reduced photosynthesis, stomatal conductance and above ground biomass at 20 to 23 days in wheat, cotton, soybeans and rice grown in indoor chambers.
- Taxon
- Wheat, cotton, soybeans, and rice
Gossypium hirsutum
Glycine max
Oryza sativa
Triticum aestivume0 - Treatment
- the larger variation in CO2 concentratione1
- Outcome
- Photosynthesis, stomatal conductance, and above ground biomasse1
- Direction
- reducede1
- Qualifier
- at 20 to 23 dayse1
- Setting
- indoor chamberse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wheat, cotton, soybeans, and rice were grown from seed in indoor chambers”
e1“Photosynthesis, stomatal conductance, and above ground biomass at 20 to 23 days were reduced in all four species by the larger variation in CO2 concentration”
Claim · model-written summary
Reduced stomatal conductance due to larger amplitude cycling of CO2 during growth occurred in soybeans and rice.
- Taxon
- soybeans and riceGlycine maxOryza sativae0
- Treatment
- larger amplitude cycling of CO2e0
- Outcome
- stomatal conductancee0
- Direction
- Reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduced stomatal conductance due to larger amplitude cycling of CO2 during growth occurred even in soybeans and rice”
Claim · model-written summary
Soybeans and rice had equal rates of stomatal opening and closing in response to step changes in CO2.
- Taxon
- soybeans and riceGlycine maxOryza sativae0
- Outcome
- equal rates of opening and closinge0
- Qualifier
- in response to step changes in CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“soybeans and rice, which had equal rates of opening and closing in response to step changes in CO2”
Claim · model-written summary
The gas exchange results indicated that reduced mean stomatal conductance was not the only cause of reduced photosynthesis in variable CO2 conditions.
- Treatment
- variable CO2 conditionse0
- Outcome
- reduced photosynthesise0
- Qualifier
- reduced mean stomatal conductance was not the only causee0
Not reportedTaxon
Verbatim
e0“The gas exchange results further indicated that reduced mean stomatal conductance was not the only cause of reduced photosynthesis in variable CO2 conditions”
The same questions in other papers
co2 · physiology: photosynthesis · Oryza sativa (rice)Results differ
16 papers in the same direction as this paper · 45 in the opposite direction
- positive
- positive
- positive
58 papers more in this group
See all 62 papers →co2 · physiology: photosynthesis · Glycine max (soybean)Results differ
13 papers in the same direction as this paper · 50 in the opposite direction
- positive
- positive
- positive
60 papers more in this group
See all 64 papers →co2 · physiology: gas exchange · Glycine max (soybean)Positive and negative results
7 papers in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- positive
7 papers more in this group
See all 11 papers →co2 · physiology: gas exchange · Oryza sativa (rice)Positive and negative results
8 papers in the same direction as this paper · 2 in the opposite direction
- negative
- positive
- positive
7 papers more in this group
See all 11 papers →co2 · physiology: photosynthesis · Gossypium hirsutum (cotton)Positive and negative results
2 papers in the same direction as this paper · 9 in the opposite direction
- negative
- positive
- positive
8 papers more in this group
See all 12 papers →co2 · physiology: photosynthesis · Triticum aestivum (wheat)Positive and negative results
27 papers in the same direction as this paper · 69 in the opposite direction
- positive
- negative
- positive
93 papers more in this group
See all 97 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.