Abstract
The mechanisms of photosynthetic adaptation to different combinations of temperature and irradiance during growth, and especially the consequences of exposure to high light (2000 micro mol m(-2) s(-1) PPFD) for 5 min, simulating natural sunflecks, was studied in bean plants (Phaseolus vulgaris L.). A protocol using only short (3 min) dark pre-treatment was introduced to maximize the amount of replication possible in studies of chlorophyll fluorescence. High light at low temperature (10 degrees C) significantly down-regulated photosynthetic electron transport capacity [as measured by the efficiency of photosystem II (PSII)], with the protective acclimation allowing the simulated sunflecks to be used more effectively for photosynthesis by plants grown in low light. The greater energy dissipation by thermal processes (lower F(v)'/F(m)' ratio) at low temperature was related to increased xanthophyll de-epoxidation and to the fact that photosynthetic carbon fixation was more limiting at low than at high temperatures. A key objective was to investigate the role of photorespiration in acclimation to irradiance and temperature by comparing the effect of normal (21 kPa) and low (1.5 kPa) O(2) concentrations. Low [O(2)] decreased F(v)/F(m) and the efficiency of PSII (Phi(PSII)), related to greater PSII down-regulation in cold pre-treated plants, but minimized further inhibition by the mild 'sunfleck' treatment used. Results support the hypothesis that photorespiration provides a 'safety-valve' for excess energy.
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Claims 7
Claim · model-written summary
High light at 10 degrees C significantly down-regulated photosynthetic electron transport capacity.
- Taxon
- bean plantst0
- Treatment
- High light at low temperature (10 degrees C)e0
- Outcome
- photosynthetic electron transport capacitye0
- Direction
- down-regulatede0
Not reportedComparator
Verbatim
e0“High light at low temperature (10 degrees C) significantly down-regulated photosynthetic electron transport capacity [as measured by the efficiency of photosystem II (PSII)]”
t0“bean plants (Phaseolus vulgaris L.)”
Claim · model-written summary
Protective acclimation allowed low-light-grown plants to use simulated sunflecks more effectively for photosynthesis.
Verbatim
e0“with the protective acclimation allowing the simulated sunflecks to be used more effectively for photosynthesis by plants grown in low light”
t0“bean plants (Phaseolus vulgaris L.)”
Claim · model-written summary
Thermal energy dissipation at low temperature was greater and related to increased xanthophyll de-epoxidation.
Verbatim
e0“The greater energy dissipation by thermal processes (lower F(v)'/F(m)' ratio) at low temperature was related to increased xanthophyll de-epoxidation”
t0“bean plants (Phaseolus vulgaris L.)”
Claim · model-written summary
Photosynthetic carbon fixation was more limiting at low than high temperatures.
Verbatim
e0“photosynthetic carbon fixation was more limiting at low than at high temperatures”
t0“bean plants (Phaseolus vulgaris L.)”
Claim · model-written summary
Low oxygen decreased F(v)/F(m).
Not reportedComparator
Verbatim
e0“Low [O(2)] decreased F(v)/F(m)”
t0“bean plants (Phaseolus vulgaris L.)”
Claim · model-written summary
Low oxygen decreased PSII efficiency.
Not reportedComparator
Verbatim
e0“Low [O(2)] decreased F(v)/F(m) and the efficiency of PSII (Phi(PSII))”
t0“bean plants (Phaseolus vulgaris L.)”
Claim · model-written summary
Low oxygen minimized further inhibition by the mild sunfleck treatment.
- Taxon
- bean plantst0
- Treatment
- mild 'sunfleck' treatmente0
- Outcome
- further inhibitione0
- Direction
- minimizede0
Not reportedComparator
Verbatim
e0“but minimized further inhibition by the mild 'sunfleck' treatment used”
t0“bean plants (Phaseolus vulgaris L.)”
The same questions in other papers
light · physiology: photosynthesis · Phaseolus vulgaris (common bean)Positive and negative results
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See all 14 papers →cold · physiology: photosynthesis · Phaseolus vulgaris (common bean)Results agree
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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.