Abstract
Abstract Sensitivity of plants to UV‐B radiation (280–315 nm) is often reduced at high background irradiance. Interpretation of plant responses to potential increases in solar UV‐B requires improved understanding of interactions between UV‐B and other environmental parameters. In this study, photosynthetically active radiation (PAR, 400–700 nm) was kept approximately constant (38 mol m‐ 2 per day) while the daily blue light fluence (BL, 400–500 nm) was varied between 0.23 and 2.68 mol m‐ 2 . Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared. At low BL, 3 days of UV‐B treatment (21 kJ m‐ 2 biologically effective radiation per 10 h per day) caused severe inhibition of growth in a developing leaf in both cultivars. Growth effects were detectable sooner and were accompanied by chlorotic lesions in the sensitive cultivar (cv Poinsett). Supplemental BL progressively reduced symptoms, consistent with an important role for BL photoreceptor(s) in prevention or repair of UV‐B damage. Ultraviolet‐induced increases in UV‐absorbing compounds on an a rea basis were significant within 24 h of the start of the treatment but were independent of BL fluence over the range tested, suggesting that bulk accumulation of screening pigments did not contribute to BL‐dependent amelioration of UV damage. However, BL did stimulate net increases in extractable UV‐absorbing compounds on a total leaf busis , while high‐performance liquid chromatography analysis indicated that BL and UV‐B acted synergistically to increase specific components. Thus, the data do not necessarily exclude UV‐absorbing compounds from an important role in overall UV‐B protection nor do they rule out some more specific function for these compounds ( e.g . antioxidants). Finally, BL effects on UV‐B alteration of leaf growth and accumulation of UV‐absorbing compounds were not saturated under the conditions used here, suggesting that BL may contribute to interactions between UV‐B and natural levels of background irradiance. Caution is urged in the interpretation of data on UV‐B effects obtained under conditions of low BL irradiance.
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Claims 9
Claim · model-written summary
Three days of UV-B treatment severely inhibited growth of a developing leaf in both cucumber cultivars at low blue light.
- Taxon
- cucumber
Cucumis sativuse1 - Material
- cvs Ashley and Poinsette1
- Organ / stage
- developing leafe3
- Treatment
- 3 days of UV‐B treatmente2
- Outcome
- growthe3
- Direction
- inhibitione3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e2“At low BL, 3 days of UV‐B treatment”
e3“caused severe inhibition of growth in a developing leaf in both cultivars”
Claim · model-written summary
UV-B damage in the sensitive cultivar Poinsett appeared sooner and was accompanied by chlorotic lesions.
- Taxon
- cucumberCucumis sativuse1
- Material
- cv Poinsette4
- Outcome
- chlorotic lesionse4
- Qualifier
- Growth effects were detectable soonere4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e4“Growth effects were detectable sooner and were accompanied by chlorotic lesions in the sensitive cultivar (cv Poinsett). Supplemental BL progressively reduced symptoms”
Claim · model-written summary
Supplemental blue light progressively reduced UV-B symptoms compared with low blue light.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- Supplemental BLe4
- Outcome
- symptomse4
- Direction
- reducede4
- Comparator
- low BLe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e2“At low BL, 3 days of UV‐B treatment”
e4“Growth effects were detectable sooner and were accompanied by chlorotic lesions in the sensitive cultivar (cv Poinsett). Supplemental BL progressively reduced symptoms”
Claim · model-written summary
UV-B treatment increased UV-absorbing compounds significantly within 24 h of treatment start.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- UV‐B treatmente2
- Outcome
- increases in UV‐absorbing compoundse5
- Direction
- increasese5
- Qualifier
- within 24 h of the start of the treatmente5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e2“At low BL, 3 days of UV‐B treatment”
e5“increases in UV‐absorbing compounds on an a rea basis were significant within 24 h of the start of the treatment but were independent of BL fluence over the range tested”
Claim · model-written summary
The UV-B-induced increase in UV-absorbing compounds was independent of blue light fluence over the range tested.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- BL fluencee5
- Outcome
- UV‐absorbing compoundse5
- Direction
- no_changeinferrede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e5“increases in UV‐absorbing compounds on an a rea basis were significant within 24 h of the start of the treatment but were independent of BL fluence over the range tested”
Claim · model-written summary
Blue light stimulated net increases in extractable UV-absorbing compounds on a total leaf basis.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- BLe6
- Outcome
- net increases in extractable UV‐absorbing compoundse6
- Direction
- increasese6
- Qualifier
- on a total leaf busise6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e6“BL did stimulate net increases in extractable UV‐absorbing compounds on a total leaf busis , while high‐performance liquid chromatography analysis indicated that BL and UV‐B acted synergistically to increase specific components”
Claim · model-written summary
Blue light and UV-B acted synergistically to increase specific UV-absorbing components.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- BL and UV‐Be6
- Outcome
- specific componentse6
- Direction
- increasee6
- Qualifier
- synergisticallye6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e6“BL did stimulate net increases in extractable UV‐absorbing compounds on a total leaf busis , while high‐performance liquid chromatography analysis indicated that BL and UV‐B acted synergistically to increase specific components”
Claim · model-written summary
The blue light effects on UV-B alteration of leaf growth and on UV-absorbing compound accumulation were not saturated under the conditions used.
- Taxon
- cucumberCucumis sativuse1
- Outcome
- BL effects on UV‐B alteration of leaf growthe7
- Qualifier
- were not saturated under the conditions used heree7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e7“BL effects on UV‐B alteration of leaf growth and accumulation of UV‐absorbing compounds were not saturated under the conditions used here”
Claim · model-written summary
The authors urge caution in interpreting UV-B effects obtained under low blue light irradiance.
- Taxon
- cucumberCucumis sativuse1
- Outcome
- Caution is urged in the interpretation of data on UV‐B effectse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Two lines of cucumber (cvs Ashley and Poinsett) with differential sensitivity to UV‐B were compared”
e0“Caution is urged in the interpretation of data on UV‐B effects obtained under conditions of low BL irradiance”
The same questions in other papers
uv · growth · Cucumis sativus (cucumber)Results differ
28 papers in the same direction as this paper · 10 in the opposite direction
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