Abstract
Greenhouse grown tobacco plants were exposed to supplemental ultraviolet irradiation (280-400 nm, UV-B centered) for 6 days and changes in their photosynthesis (gas exchange and electron transport) and general and specific antioxidant activities were measured. UV irradiation corresponded to 8.95 kJ m-2 d-1 biologically effective dose and was supplemented to below ambient (200 μmol m-2 s-1 photon flux density) photosynthetic photon flux density (PPFD, 400-700 nm). Two groups of plants, which were different in their leaf antioxidant capacities due to one of them having been acclimated to high irradiance (1000 μmol m-2 s-1 PPFD) before the UV treatment, responded differently. High light pretreated leaves lost approximately 25% of photosynthetic activity during the UV exposure and showed no change either in the amounts of UV-absorbing pigments or antioxidant levels. On the other hand, leaves which were exposed to UV irradiation without the preceding high light acclimation had 60% lower photosynthesis by the end of the treatment, and increased antioxidant activities. Our results emphasize the importance of base antioxidant levels over inducible pools in leaf responses to low doses of UV irradiation and may also contribute to hypotheses on acclimation under field conditions.
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Claims 4
Claim · model-written summary
High-light-pretreated tobacco leaves lost approximately 25% of photosynthetic activity during UV exposure.
- Taxon
- tobacco plants
Nicotiana tabacume1 - Organ / stage
- leavese0
- Treatment
- UV exposuree0
- Outcome
- photosynthetic activitye0
- Direction
- loste0
- Value
- approximately 25%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“High light pretreated leaves lost approximately 25% of photosynthetic activity during the UV exposure”
e1“tobacco plants”
Claim · model-written summary
High-light-pretreated leaves showed no change in UV-absorbing pigments or antioxidant levels during UV exposure.
- Taxon
- tobacco plantsNicotiana tabacume1
- Organ / stage
- leavese0
- Treatment
- UV exposuree0
- Outcome
- amounts of UV-absorbing pigments or antioxidant levelse0
- Direction
- no changee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“High light pretreated leaves lost approximately 25% of photosynthetic activity during the UV exposure and showed no change either in the amounts of UV-absorbing pigments or antioxidant levels”
e1“tobacco plants”
Claim · model-written summary
Without preceding high-light acclimation, UV-exposed leaves had 60% lower photosynthesis by treatment end.
- Taxon
- tobacco plantsNicotiana tabacume1
- Organ / stage
- leavese0
- Treatment
- UV irradiatione0
- Outcome
- photosynthesise0
- Direction
- lowere0
- Value
- 60%e0
- Qualifier
- without the preceding high light acclimatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaves which were exposed to UV irradiation without the preceding high light acclimation had 60% lower photosynthesis by the end of the treatment”
e1“tobacco plants”
Claim · model-written summary
Without preceding high-light acclimation, UV-exposed leaves increased antioxidant activities.
- Taxon
- tobacco plantsNicotiana tabacume1
- Organ / stage
- leavese0
- Treatment
- UV irradiatione0
- Outcome
- antioxidant activitiese0
- Direction
- increasede0
- Qualifier
- without the preceding high light acclimatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaves which were exposed to UV irradiation without the preceding high light acclimation had 60% lower photosynthesis by the end of the treatment, and increased antioxidant activities”
e1“tobacco plants”
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See all 9 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.