Abstract
Abstract The application of a leaf disc electrode to the measurement of the quantum yield of photosynthetic oxygen evolution (in saturating carbon dioxide concentrations) is described. The technique was also used to characterize the light-saturation curves for photosynthesis in leaves of spinach plants grown in relatively low (‘shade’) and high (‘sun’) light intensities. It was found that the flux of a blue excitation light required to elicit oscillations in chlorophyll a fluorescence corresponded, approximately, to the flux of (white) light required to saturate photosynthetic oxygen evolution. The requirement was higher for leaves of sun-grown plants (approximately 800 μmol m-2 s-1) than for shade-grown plants (approximately 200 μmol m-2 s-1). Brief pretreatment of leaf discs from sun-grown plants with D-mannose did not change the quantum yield, but lowered the light saturated rate and the photon flux density required to saturate photosynthesis. Oscillations in fluorescence could then be observed at lower fluxes of blue excitation light, similar to those required by leaves from shade-grown plants. Photoinhibition of shade-grown plants (exposed to full sunlight for 5 h) reduced quantum yield and increased the light flux required for saturation of photosynthesis. Oscillations in fluorescence, normally observed at low fluxes of blue light in these leaves, could not be detected after photoinhibition. These correlations are interpreted and applications of the techniques described are discussed.
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 9
Claim · model-written summary
Blue light flux required for chlorophyll fluorescence oscillations approximately matched white light flux required to saturate photosynthetic oxygen evolution.
- Taxon
- spinach plants
Spinacia oleraceae1 - Outcome
- flux of a blue excitation light required to elicit oscillations in chlorophyll a fluorescencee0
- Comparator
- flux of (white) light required to saturate photosynthetic oxygen evolutione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the flux of a blue excitation light required to elicit oscillations in chlorophyll a fluorescence corresponded, approximately, to the flux of (white) light required to saturate photosynthetic oxygen evolution.”
e1“leaves of spinach plants”
Claim · model-written summary
The light flux requirement was higher in sun-grown leaves at approximately 800 μmol m-2 s-1 than in shade-grown leaves at approximately 200 μmol m-2 s-1.
- Taxon
- spinach plantsSpinacia oleraceae1
- Treatment
- sun-growne0
- Outcome
- requiremente0
- Direction
- highere0
- Value
- approximately 800 μmol m-2 s-1e0
- Qualifier
- approximately 200 μmol m-2 s-1e0
- Comparator
- shade-grown plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The requirement was higher for leaves of sun-grown plants (approximately 800 μmol m-2 s-1) than for shade-grown plants (approximately 200 μmol m-2 s-1).”
e1“leaves of spinach plants”
Claim · model-written summary
D-mannose pretreatment did not change quantum yield in sun-grown spinach leaf discs.
- Taxon
- spinach plantsSpinacia oleraceae1
- Treatment
- Brief pretreatment of leaf discs from sun-grown plants with D-mannosee0
- Outcome
- quantum yielde0
- Direction
- did not changee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Brief pretreatment of leaf discs from sun-grown plants with D-mannose did not change the quantum yield”
e1“leaves of spinach plants”
Claim · model-written summary
D-mannose pretreatment lowered the light saturated photosynthetic rate in sun-grown leaf discs.
- Taxon
- spinach plantsSpinacia oleraceae1
- Treatment
- Brief pretreatment of leaf discs from sun-grown plants with D-mannosee0
- Outcome
- light saturated ratee0
- Direction
- lowerede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Brief pretreatment of leaf discs from sun-grown plants with D-mannose did not change the quantum yield, but lowered the light saturated rate and the photon flux density required to saturate photosynthesis.”
e1“leaves of spinach plants”
Claim · model-written summary
D-mannose pretreatment lowered photon flux density required to saturate photosynthesis.
- Taxon
- spinach plantsSpinacia oleraceae1
- Treatment
- Brief pretreatment of leaf discs from sun-grown plants with D-mannosee0
- Outcome
- photon flux density required to saturate photosynthesise0
- Direction
- lowerede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Brief pretreatment of leaf discs from sun-grown plants with D-mannose did not change the quantum yield, but lowered the light saturated rate and the photon flux density required to saturate photosynthesis.”
e1“leaves of spinach plants”
Claim · model-written summary
Following D-mannose pretreatment, fluorescence oscillations occurred at lower blue light fluxes, similar to shade-grown leaves.
- Taxon
- spinach plantsSpinacia oleraceae2
- Treatment
- Brief pretreatment of leaf discs from sun-grown plants with D-mannosee1
- Outcome
- fluxes of blue excitation lighte0
- Direction
- lowere0
- Comparator
- leaves from shade-grown plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oscillations in fluorescence could then be observed at lower fluxes of blue excitation light, similar to those required by leaves from shade-grown plants.”
e1“Brief pretreatment of leaf discs from sun-grown plants with D-mannose”
e2“leaves of spinach plants”
Claim · model-written summary
Photoinhibition reduced quantum yield in shade-grown spinach leaves.
- Taxon
- spinach plantsSpinacia oleraceae1
- Treatment
- Photoinhibition of shade-grown plants (exposed to full sunlight for 5 h)e0
- Outcome
- quantum yielde0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photoinhibition of shade-grown plants (exposed to full sunlight for 5 h) reduced quantum yield”
e1“leaves of spinach plants”
Claim · model-written summary
Photoinhibition increased light flux required to saturate photosynthesis in shade-grown spinach leaves.
- Taxon
- spinach plantsSpinacia oleraceae1
- Treatment
- Photoinhibition of shade-grown plants (exposed to full sunlight for 5 h)e0
- Outcome
- light flux required for saturation of photosynthesise0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photoinhibition of shade-grown plants (exposed to full sunlight for 5 h) reduced quantum yield and increased the light flux required for saturation of photosynthesis.”
e1“leaves of spinach plants”
Claim · model-written summary
Fluorescence oscillations could not be detected after photoinhibition in shade-grown spinach leaves.
- Taxon
- spinach plantsSpinacia oleraceae1
- Outcome
- Oscillations in fluorescence, normally observed at low fluxes of blue light in these leaves, could not be detected after photoinhibitione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oscillations in fluorescence, normally observed at low fluxes of blue light in these leaves, could not be detected after photoinhibition.”
e1“leaves of spinach plants”
The same questions in other papers
(1S)-isoindoline-1-carboxylic acid · physiology: photosynthesis · Spinacia oleracea (spinach)Positive and negative results
1 in the opposite direction
- positive
light · physiology: photosynthesis · Spinacia oleracea (spinach)Positive and negative results
12 papers in the same direction as this paper · 15 in the opposite direction
- positive
- positive
- positive
24 papers more in this group
See all 28 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.