Abstract
ABSTRACT Mature pea (Pisum sativum L., cv. Meteor) leaves were exposed to two levels of UV‐B radiation, with and without supplementary UV‐C radiation, during 15 h photoperiods. Simultaneous measurements of CO 2 assimilation and modulated chlorophyll fluorescence parameters demonstrated that irradiation with UV‐B resulted in decreases in CO 2 assimilation that are not accompanied by decreases in the maximum quantum efficiency of photosystem II (PSII) primary photochemistry. Increased exposure to UV‐B resulted in a further loss of CO 2 assimilation and decreases in the maximum quantum efficiency of PSII primary photochemistry, which were accompanied by a loss of the capacity of thylakoids isolated from the leaves to bind atrazine, thus demonstrating that photodamage to PSII reaction centres had occurred. Addition of UV‐C to the UV‐B treatments increased markedly the rate of inhibition of photosynthesis, but the relationships between CO 2 assimilation and PSII characteristics remained the same, indicating that UV‐B and UV‐C inhibit leaf photosynthesis by a similar mechanism. It is concluded that PSII is not the primary target site involved in the onset of the inhibition of photosynthesis in pea leaves induced by irradiation with UV‐B.
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Claims 8
Claim · model-written summary
UV-B lowered CO2 assimilation.
- Taxon
- pea
Lathyrus oleraceust0 - Treatment
- UV‐Be0
- Outcome
- CO 2 assimilatione0
- Direction
- decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“pea”
e0“irradiation with UV‐B resulted in decreases in CO 2 assimilation”
Claim · model-written summary
Initial UV-B exposure did not decrease maximum PSII quantum efficiency.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- UV‐Be0
- Outcome
- maximum quantum efficiency of photosystem II (PSII) primary photochemistrye0
- Direction
- not accompanied by decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“pea”
e0“irradiation with UV‐B resulted in decreases in CO 2 assimilation that are not accompanied by decreases in the maximum quantum efficiency of photosystem II (PSII) primary photochemistry”
Claim · model-written summary
Increased UV-B exposure further reduced CO2 assimilation.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- Increased exposure to UV‐Be0
- Outcome
- CO 2 assimilatione0
- Direction
- further losse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“pea”
e0“Increased exposure to UV‐B resulted in a further loss of CO 2 assimilation”
Claim · model-written summary
Increased UV-B exposure reduced maximum PSII quantum efficiency.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- Increased exposure to UV‐Be0
- Outcome
- maximum quantum efficiency of PSII primary photochemistrye0
- Direction
- decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“pea”
e0“Increased exposure to UV‐B resulted in a further loss of CO 2 assimilation and decreases in the maximum quantum efficiency of PSII primary photochemistry”
Claim · model-written summary
Increased UV-B exposure reduced atrazine binding capacity of leaf thylakoids.
- Taxon
- peaLathyrus oleraceust0
- Outcome
- capacity of thylakoids isolated from the leaves to bind atrazinee0
- Direction
- losse0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“pea”
e0“a loss of the capacity of thylakoids isolated from the leaves to bind atrazine”
Claim · model-written summary
Adding UV-C to UV-B markedly accelerated photosynthesis inhibition.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- Addition of UV‐C to the UV‐B treatmentse0
- Outcome
- rate of inhibition of photosynthesise0
- Direction
- increased markedlye0
- Comparator
- UV‐B treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“pea”
e0“Addition of UV‐C to the UV‐B treatments increased markedly the rate of inhibition of photosynthesis”
Claim · model-written summary
UV-C addition left the relation between assimilation and PSII characteristics unchanged.
- Taxon
- peaLathyrus oleraceust0
- Outcome
- relationships between CO 2 assimilation and PSII characteristicse0
- Direction
- remained the samee0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“pea”
e0“the relationships between CO 2 assimilation and PSII characteristics remained the same”
Claim · model-written summary
The authors conclude that PSII is not the primary initial target of UV-B inhibition.
- Taxon
- peaLathyrus oleraceust0
- Outcome
- inhibition of photosynthesise0
- Qualifier
- PSII is not the primary target sitee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“pea”
e0“PSII is not the primary target site involved in the onset of the inhibition of photosynthesis in pea leaves induced by irradiation with UV‐B”
The same questions in other papers
uv · physiology: photosynthesis · Lathyrus oleraceus (pea)Results differ
17 papers in the same direction as this paper · 3 in the opposite direction
- no effect
- negative
- no effect
17 papers more in this group
See all 21 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.