Abstract
Senescence-induced changes in the xanthophyll cycle activity and chlorophyll (Chl) fluorescence parameters were compared in detached barley (Hordeum vulgare L.) leaf segments kept for 6 d in darkness or under continuous " white light" (90 μmol m-2 s-1). Before detachment of the leaf segments, the plants were grown at periodic regime [12 h light (90 μmol m-2 s-1)/12 h dark]. The de-epoxidation state of the xanthophyll cycle pigments (DEPS) in the leaf samples was determined immediately (the actual DEPS), after 1 h of dark-adaptation (the residual DEPS), and during 14 min of a high-irradiance (HI) exposure (500 μmol m-2 s-1) (HI-induced DEPS). In the light-senescing segments, senescence was delayed pronouncedly compared to dark-senescing ones as the Chl content, the photosystem 2 photochemistry, and electron transport processes were highly maintained. Further, the actual DEPS increased, probably due to the increased mean photon dose. The HI-induced increase in the DEPS was stimulated in the light-senescing segments, whereas it was slowed down in the dark-senescing ones. However, after the 14 min HI-exposure of the dark-senescing segments the HI-induced DEPS was not markedly lower than in the mature leaves, which indicated the maintenance of the xanthophyll cycle operation.
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Claims 5
Claim · model-written summary
Light delayed senescence relative to darkness and maintained chlorophyll content, photosystem 2 photochemistry and electron transport.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaret0 - Treatment
- light-senescinge0
- Outcome
- Chl content, the photosystem 2 photochemistry, and electron transport processese0
- Direction
- highly maintainede0
- Comparator
- dark-senescing onese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“In the light-senescing segments, senescence was delayed pronouncedly compared to dark-senescing ones as the Chl content, the photosystem 2 photochemistry, and electron transport processes were highly maintained.”
t0“barley”
Claim · model-written summary
Actual DEPS increased in light-senescing leaf segments.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- actual DEPSe0
- Direction
- increasede0
- Qualifier
- probably due to the increased mean photon dosee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the actual DEPS increased, probably due to the increased mean photon dose”
t0“barley”
Claim · model-written summary
The high-irradiance-induced DEPS increase was stimulated in light-senescing segments.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- HI-induced increase in the DEPSe0
- Direction
- stimulatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The HI-induced increase in the DEPS was stimulated in the light-senescing segments”
t0“barley”
Claim · model-written summary
The high-irradiance-induced DEPS increase slowed in dark-senescing segments.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- ite0
- Direction
- slowed downe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it was slowed down in the dark-senescing ones”
t0“barley”
Claim · model-written summary
After 14 minutes of high irradiance, dark-senescing leaves had HI-induced DEPS not markedly lower than mature leaves.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- HI-induced DEPSe0
- Direction
- not markedly lowere0
- Comparator
- mature leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“after the 14 min HI-exposure of the dark-senescing segments the HI-induced DEPS was not markedly lower than in the mature leaves”
t0“barley”
The same questions in other papers
light · physiology: photosynthesis · Hordeum vulgare (barley)Positive and negative results
6 papers in the same direction as this paper · 11 in the opposite direction
- no effect
- negative
- negative
14 papers more in this group
See all 18 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.