Abstract
Plants are often exposed to fluctuating light under natural conditions, but the effects of changing frequency of fluctuating light on photosynthesis and related mechanism are not clear. In order to study the photosynthetic mechanism under fluctuating light, the changes of morphology, chlorophyll content, gas exchange, chlorophyll a fluorescence and enzymatic antioxidant system were compared in cucumber seedlings grown under different light regimes. Results showed that the plant height, biomass, leaf area and specific leaf weight were significantly higher under high light treatment (T1, T2 and T3) than those of low light treatment (T4), and these values decreased with the frequency of fluctuating light increasing (T2 and T3). Compared with low light treatment, the total chlorophyll content decreased under high light, and enhancing the frequency of fluctuating light resulted in the decrease in the chlorophyll content slightly. Photosynthetic rate and stomatal conductance in leaves grown under high light were higher than those under low light, and the levels of both parameters decreased slightly with the changing frequency of fluctuating light increasing. The results of chlorophyll a fluorescence induction kinetics showed that although there was no significant difference in the maximum quantum yield of photosystem II (PSII), the electron transport activity of PSII in cucumber leaves decreased with the increase of the changing frequency of fluctuating light. Increasing the changing frequency of fluctuating light led to an obvious decrease in antenna conversion efficiency of PSII (Fv′/Fm′) and rapid increase in non-photochemical quenching (NPQ). In addition, the activities of the major antioxidant enzymes in cucumber leaves grown under high light was higher than that under low light, yet the increase of the frequency of fluctuating light reduced their activities. Therefore, enhancing the changing frequency of fluctuating light leads to a decrease in photosynthetic rate and the activities of major antioxidant enzymes in cucumber seedlings, the enhanced thermal dissipation may play a very important role in copying with excessive excited energy under fluctuating light. In addition, the difference in acclimative mechanism between fluctuating and steady-state high light in cucumber seedlings were also discussed.
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Claims 10
Claim · model-written summary
Plant height, biomass and leaf area were significantly higher under high than low light, and declined as fluctuation frequency increased.
- Taxon
- cucumber seedlings
Cucumis sativust0 - Treatment
- high light treatment (T1, T2 and T3)e0
- Outcome
- plant height, biomass, leaf areae0
- Direction
- highere0
- Comparator
- low light treatment (T4)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plant height, biomass, leaf area and specific leaf weight were significantly higher under high light treatment (T1, T2 and T3) than those of low light treatment (T4), and these values decreased with the frequency of fluctuating light increasing (T2 and T3).”
t0“cucumber seedlings”
Claim · model-written summary
Specific leaf weight was significantly higher under high than low light and declined with higher fluctuation frequency.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- high light treatment (T1, T2 and T3)e0
- Outcome
- specific leaf weighte0
- Direction
- highere0
- Comparator
- low light treatment (T4)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plant height, biomass, leaf area and specific leaf weight were significantly higher under high light treatment (T1, T2 and T3) than those of low light treatment (T4), and these values decreased with the frequency of fluctuating light increasing (T2 and T3).”
t0“cucumber seedlings”
Claim · model-written summary
Total chlorophyll content fell under high light and fell slightly further with increasing fluctuation frequency.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- high lighte0
- Outcome
- total chlorophyll contente0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total chlorophyll content decreased under high light, and enhancing the frequency of fluctuating light resulted in the decrease in the chlorophyll content slightly.”
t0“cucumber seedlings”
Claim · model-written summary
Photosynthetic rate and stomatal conductance were higher under high than low light and declined slightly as fluctuation frequency increased.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- high lighte0
- Outcome
- Photosynthetic rate and stomatal conductancee0
- Direction
- highere0
- Comparator
- low lighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthetic rate and stomatal conductance in leaves grown under high light were higher than those under low light, and the levels of both parameters decreased slightly with the changing frequency of fluctuating light increasing.”
t0“cucumber seedlings”
Claim · model-written summary
Maximum PSII quantum yield did not differ significantly among light regimes.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- fluctuating lightt0
- Outcome
- maximum quantum yield of photosystem II (PSII)e0
- Direction
- no significant differencee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was no significant difference in the maximum quantum yield of photosystem II (PSII)”
t0“fluctuating light on photosynthesis in cucumber seedlings”
Claim · model-written summary
PSII electron transport activity declined with increasing fluctuation frequency.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- increase of the changing frequency of fluctuating lighte0
- Outcome
- electron transport activity of PSIIe0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the electron transport activity of PSII in cucumber leaves decreased with the increase of the changing frequency of fluctuating light.”
Claim · model-written summary
Increasing fluctuation frequency decreased PSII antenna conversion efficiency.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- Increasing the changing frequency of fluctuating lighte0
- Outcome
- antenna conversion efficiency of PSII (Fv′/Fm′)e0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing the changing frequency of fluctuating light led to an obvious decrease in antenna conversion efficiency of PSII (Fv′/Fm′)”
t0“cucumber seedlings”
Claim · model-written summary
Increasing fluctuation frequency rapidly increased non-photochemical quenching.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- fluctuating lightt0
- Outcome
- non-photochemical quenching (NPQ)e0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“rapid increase in non-photochemical quenching (NPQ)”
t0“fluctuating light on photosynthesis in cucumber seedlings”
Claim · model-written summary
Major antioxidant enzyme activity was higher under high than low light but decreased as fluctuation frequency rose.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- high lighte0
- Outcome
- activities of the major antioxidant enzymese0
- Direction
- highere0
- Comparator
- low lighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the activities of the major antioxidant enzymes in cucumber leaves grown under high light was higher than that under low light, yet the increase of the frequency of fluctuating light reduced their activities.”
Claim · model-written summary
Enhanced thermal dissipation may help cope with excess excitation under fluctuating light.
- Taxon
- cucumber seedlingsCucumis sativust0
- Outcome
- copying with excessive excited energye0
- Qualifier
- enhanced thermal dissipatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the enhanced thermal dissipation may play a very important role in copying with excessive excited energy under fluctuating light.”
t0“cucumber seedlings”
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See all 61 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.