Abstract
Soybean plants (Glycine max var. Ransom) were grown at light intensities of 850 and 250 mueinsteins m(-2) sec(-1) of photosynthetically active radiation. A group of plants was shifted from each environment into the other environment 24 hours before the beginning of the experiment. Net photosynthetic rates and stomatal conductances were measured at 2,000 and 100 mueinsteins m(-2) sec(-1) photosynthetically active radiation on the 1st, 2nd, and 5th days of the experiment to determine the time course of photosynthetic light adaptation. The following factors were also measured: dark respiration, leaf water potential, leaf thickness, internal surface area per external surface area, chlorophyll content, photosynthetic unit size and number, specific leaf weight, and activities of malate dehydrogenase, and glycolate oxidase. Comparisons were made with plants maintained in either 850 or 250 mueinsteins m(-2) sec(-1) environments. Changes in photosynthesis, stomatal conductance, leaf anatomy, leaf water potential, photosynthetic unit size, and glycolate oxidase activity occurred upon altering the light environment, and were complete within 1 day, whereas chlorophyll content, numbers of photosynthetic units, specific leaf weight, and malate dehydrogenase activity showed slower changes. Differences in photosynthetic rates at high light were largely accounted for by internal surface area differences with low environmental light associated with low internal area and low photosynthetic rate. An exception to this was the fact that plants grown at 250 mueinsteins m(-2) sec(-1) then switched to 850 mueinsteins m(-2) sec(-1) showed lower photosynthesis at high light than any other treatment. This was associated with higher glycolate oxidase and malate dehydrogenase activity. Photosynthesis at low light was higher in plants kept at or switched to the lower light environment. This increased rate was associated with larger photosynthetic unit size, and lower dark respiration and malate dehydrogenase activity. Both anatomical and physiological changes with environmental light occurred even after leaf expansion was complete and both were important in determining photosynthetic response to light.
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Claims 8
Claim · model-written summary
Photosynthesis, stomatal conductance, anatomy, water potential, unit size and glycolate oxidase activity changed within one day of a light shift.
- Taxon
- Soybean
Glycine maxe1 - Treatment
- altering the light environmente0
- Outcome
- photosynthesis, stomatal conductance, leaf anatomye0
- Value
- within 1 daye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Changes in photosynthesis, stomatal conductance, leaf anatomy, leaf water potential, photosynthetic unit size, and glycolate oxidase activity occurred upon altering the light environment, and were complete within 1 day”
e1“Soybean plants”
Claim · model-written summary
Chlorophyll content, photosynthetic unit numbers, leaf weight and malate dehydrogenase activity changed more slowly.
- Taxon
- SoybeanGlycine maxe1
- Treatment
- altering the light environmente2
- Outcome
- chlorophyll content, numbers of photosynthetic units, specific leaf weighte0
- Direction
- slower changese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“chlorophyll content, numbers of photosynthetic units, specific leaf weight, and malate dehydrogenase activity showed slower changes”
e1“Soybean plants”
e2“altering the light environment”
Claim · model-written summary
Low growth light was associated with low internal surface area and low high-light photosynthesis.
- Taxon
- SoybeanGlycine maxe1
- Treatment
- low environmental lighte0
- Outcome
- photosynthetic ratee0
- Direction
- lowe0
- Qualifier
- low internal areae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“low environmental light associated with low internal area and low photosynthetic rate”
e1“Soybean plants”
Claim · model-written summary
Plants shifted from 250 to 850 light units had the lowest high-light photosynthesis.
- Taxon
- SoybeanGlycine maxe1
- Treatment
- switched to 850 mueinsteins m(-2) sec(-1)e0
- Outcome
- photosynthesis at high lighte0
- Direction
- lowere0
- Comparator
- any other treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plants grown at 250 mueinsteins m(-2) sec(-1) then switched to 850 mueinsteins m(-2) sec(-1) showed lower photosynthesis at high light than any other treatment”
e1“Soybean plants”
Claim · model-written summary
The 250-to-850 group had higher glycolate oxidase and malate dehydrogenase activity.
- Taxon
- SoybeanGlycine maxe2
- Treatment
- switched to 850 mueinsteins m(-2) sec(-1)e1
- Outcome
- glycolate oxidase and malate dehydrogenase activitye0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This was associated with higher glycolate oxidase and malate dehydrogenase activity”
e1“plants grown at 250 mueinsteins m(-2) sec(-1) then switched to 850 mueinsteins m(-2) sec(-1)”
e2“Soybean plants”
Claim · model-written summary
Low-light photosynthesis was higher for plants kept or shifted to lower light.
- Taxon
- SoybeanGlycine maxe1
- Treatment
- switched to the lower light environmente0
- Outcome
- Photosynthesis at low lighte0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthesis at low light was higher in plants kept at or switched to the lower light environment”
e1“Soybean plants”
Claim · model-written summary
Higher low-light photosynthesis was associated with larger photosynthetic units and lower dark respiration and malate dehydrogenase activity.
- Taxon
- SoybeanGlycine maxe2
- Treatment
- switched to the lower light environmente3
- Outcome
- Photosynthesis at low lighte1
- Direction
- highere1
- Qualifier
- larger photosynthetic unit size, and lower dark respiration and malate dehydrogenase activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This increased rate was associated with larger photosynthetic unit size, and lower dark respiration and malate dehydrogenase activity”
e1“Photosynthesis at low light was higher”
e2“Soybean plants”
e3“switched to the lower light environment”
Claim · model-written summary
Anatomical and physiological light responses occurred even after leaf expansion was complete.
- Taxon
- SoybeanGlycine maxe1
- Organ / stage
- leaf expansione0
- Outcome
- anatomical and physiological changese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both anatomical and physiological changes with environmental light occurred even after leaf expansion was complete”
e1“Soybean plants”
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See all 43 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.