Abstract
We studied photosynthetic and stomatal responses of grain sorghum ( Sorghum bicolor [L.] Moench cv. Pioneer 8500), soybean ( Glycine max L. cv. Flyer) and eastern gamagrass ( Tripsacum dactyloides L.) during experimental sun and shade periods simulating summer cloud cover. Leaf gas exchange measurements of field plants showed that short‐term (5 min) shading of leaves to 300–400 μmol m −2 s −1 photosynthetic photon flux density reduced photosynthesis, leaf temperature, stomatal conductance, transpiration and water use efficiency and increased intercellular CO 2 partial pressure. In all species, photosynthetic recovery was delayed when leaves were reilluminated, apparently by stomatal closure. The strongest stomatal response was in soybean. Photosynthetic recovery was studied further with soybeans grown indoors (maximum photosynthetic photon flux density 1 200 μmol m −2 s −1 ). Plants grown indoors had responses to shade similar to those of field plants, except for brief nonstomatal limitation immediately after reillumination. These responses indicated the importance of the light environment during leaf development on assimilation responses to variable light, and suggested different limitations on carbon assimilation in different parts of the soybean canopy. Photosynthetic oxygen evolution recovered immediately upon reillumination, indicating that the light reactions did not limit soybean photosynthetic recovery. While shade periods caused stomatal closure and reduced carbon gain and water loss in all species, the consequences for carbon gain/water loss were greatest in soybean. The occurrence of stomatal closure in all three species may arise from their shared phenologies and herbaceous growth forms.
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Claims 8
Claim · model-written summary
Short shading reduced photosynthesis, leaf temperature and stomatal conductance in the three species.
- Treatment
- short‐term (5 min) shading of leaves to 300–400 μmol m −2 s −1 photosynthetic photon flux densitye0
- Outcome
- photosynthesis, leaf temperature, stomatal conductancee0
- Direction
- reducede0
SorghumNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“short‐term (5 min) shading of leaves to 300–400 μmol m −2 s −1 photosynthetic photon flux density reduced photosynthesis, leaf temperature, stomatal conductance, transpiration and water use efficiency and increased intercellular CO 2 partial pressure.”
t0“sorghum”
Claim · model-written summary
Short shading reduced transpiration and water use efficiency.
- Taxon
- soybean
Glycine maxt0 - Treatment
- short‐term (5 min) shading of leaves to 300–400 μmol m −2 s −1 photosynthetic photon flux densitye0
- Outcome
- transpiration and water use efficiencye0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“short‐term (5 min) shading of leaves to 300–400 μmol m −2 s −1 photosynthetic photon flux density reduced photosynthesis, leaf temperature, stomatal conductance, transpiration and water use efficiency and increased intercellular CO 2 partial pressure.”
t0“soybean”
Claim · model-written summary
Short shading increased intercellular CO2 partial pressure.
- Taxon
- eastern gamagrass
Tripsacum dactyloidest0 - Treatment
- short‐term (5 min) shading of leaves to 300–400 μmol m −2 s −1 photosynthetic photon flux densitye0
- Outcome
- intercellular CO 2 partial pressuree0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“short‐term (5 min) shading of leaves to 300–400 μmol m −2 s −1 photosynthetic photon flux density reduced photosynthesis, leaf temperature, stomatal conductance, transpiration and water use efficiency and increased intercellular CO 2 partial pressure.”
t0“eastern gamagrass”
Claim · model-written summary
Photosynthetic recovery after reillumination was delayed in all species.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In all species, photosynthetic recovery was delayed when leaves were reilluminated, apparently by stomatal closure.”
t0“sorghum”
Claim · model-written summary
Soybean showed the strongest stomatal response.
- Taxon
- soybeanGlycine maxe0
- Outcome
- stomatal responsee0
- Direction
- strongeste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The strongest stomatal response was in soybean.”
Claim · model-written summary
Indoor soybeans responded to shade similarly to field plants, except for brief nonstomatal limitation after reillumination.
- Taxon
- soybeanGlycine maxt0
- Outcome
- responses to shadee0
- Comparator
- field plantse0
- Setting
- indoorse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plants grown indoors had responses to shade similar to those of field plants, except for brief nonstomatal limitation immediately after reillumination.”
t0“soybean”
Claim · model-written summary
Soybean photosynthetic oxygen evolution recovered immediately upon reillumination.
- Taxon
- soybeanGlycine maxt0
- Outcome
- Photosynthetic oxygen evolutione0
- Direction
- recoverede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthetic oxygen evolution recovered immediately upon reillumination”
t0“soybean”
Claim · model-written summary
Shade had the greatest consequences for carbon gain relative to water loss in soybean.
- Taxon
- soybeanGlycine maxe0
- Outcome
- carbon gain/water losse0
- Direction
- greateste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the consequences for carbon gain/water loss were greatest in soybean.”
The same questions in other papers
light · physiology: photosynthesis · SorghumPositive and negative results
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See all 6 papers →light · physiology: gas exchange · Glycine max (soybean)Positive and negative results
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See all 8 papers →shade · physiology: photosynthesis · SorghumResults agree
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- no effect
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shade · physiology: gas exchange · Glycine max (soybean)Results agree
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- negative
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See all 7 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.