Abstract
The inhibition of stem elongation in dark-grown seedlings by blue light was studied with marking techniques and with a high-resolution, growth-measuring apparatus. Blue light rapidly suppresses growth in a variety of cultivated species. In some species, the inhibition persists only during the period of irradiation, after which time growth quickly returns to the high dark rate, whereas, in other species, the light response has an additional long-term component which lasts for at least several hours in the dark. The long-term inhibition may be mediated by phytochrome, whereas the rapid, short-term component is specific to a blue-light receptor.The rapid inhibition of growth in cucumber (Cucumis sativus L.) requires high-energy blue irradiation, which is perceived directly by the growing region of the hypocotyl and inhibits all regions below the hook to the same extent. Detailed investigation of the kinetics of the inhibition in cucumber and in sunflower (Helianthus annuus L.) shows that, after a short lag period (20 to 30 seconds in cucumber, 60 to 70 seconds in sunflower), the growth rate declines in an exponential fashion to a lower rate, with a half-time of 15 to 25 seconds in cucumber and 90 to 150 seconds in sunflower. Excision of the hypocotyl greatly reduces the sensitivity of the growth rate to blue-light inhibition. Because of the rapid kinetics, the blue-light photoreceptor cannot affect cell enlargement by altering the supply of growth hormone or the sensitivity to hormones but probably operates more directly either on the biochemical process which loosens cell walls or on cell turgor.
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Claims 8
Claim · model-written summary
Blue light rapidly suppresses growth in a variety of cultivated species.
Not reportedComparator
Verbatim
e0“Blue light rapidly suppresses growth in a variety of cultivated species.”
Claim · model-written summary
In some species, growth inhibition lasts only during irradiation and growth then returns quickly to the dark rate.
Verbatim
e0“In some species, the inhibition persists only during the period of irradiation, after which time growth quickly returns to the high dark rate”
Claim · model-written summary
In other species, blue-light growth inhibition lasts for at least several hours in darkness.
Verbatim
e0“in other species, the light response has an additional long-term component which lasts for at least several hours in the dark”
Claim · model-written summary
Rapid growth inhibition in cucumber requires high-energy blue irradiation perceived by the growing hypocotyl region and affects all regions below the hook equally.
- Taxon
- cucumber
Cucumis sativuse0 - Organ / stage
- hypocotyle0
- Treatment
- high-energy blue irradiatione0
- Outcome
- growthe0
- Direction
- inhibitione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rapid inhibition of growth in cucumber (Cucumis sativus L.) requires high-energy blue irradiation, which is perceived directly by the growing region of the hypocotyl and inhibits all regions below the hook to the same extent.”
Claim · model-written summary
After a 20 to 30 second lag, cucumber growth rate declines exponentially with a 15 to 25 second half-time.
- Taxon
- cucumberCucumis sativuse0
- Outcome
- growth ratee0
- Direction
- declinese0
- Value
- 15 to 25 secondse0
- Qualifier
- 20 to 30 seconds in cucumbere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“after a short lag period (20 to 30 seconds in cucumber, 60 to 70 seconds in sunflower), the growth rate declines in an exponential fashion to a lower rate, with a half-time of 15 to 25 seconds in cucumber and 90 to 150 seconds in sunflower”
Claim · model-written summary
After a 60 to 70 second lag, sunflower growth rate declines exponentially with a 90 to 150 second half-time.
- Taxon
- sunflower
Helianthus annuuse0 - Outcome
- growth ratee0
- Direction
- declinese0
- Value
- 90 to 150 secondse0
- Qualifier
- 60 to 70 seconds in sunflowere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“after a short lag period (20 to 30 seconds in cucumber, 60 to 70 seconds in sunflower), the growth rate declines in an exponential fashion to a lower rate, with a half-time of 15 to 25 seconds in cucumber and 90 to 150 seconds in sunflower”
Claim · model-written summary
Hypocotyl excision greatly reduces growth-rate sensitivity to blue-light inhibition.
- Treatment
- Excision of the hypocotyle0
- Outcome
- sensitivity of the growth rate to blue-light inhibitione0
- Direction
- reducese0
Not reportedTaxonComparator
Verbatim
e0“Excision of the hypocotyl greatly reduces the sensitivity of the growth rate to blue-light inhibition.”
Claim · model-written summary
The authors infer that rapid blue-light growth inhibition probably acts on cell-wall loosening or cell turgor.
Not reportedTaxon
Verbatim
e0“the blue-light photoreceptor cannot affect cell enlargement by altering the supply of growth hormone or the sensitivity to hormones but probably operates more directly either on the biochemical process which loosens cell walls or on cell turgor”
The same questions in other papers
radiation · growth · Cucumis sativus (cucumber)Positive and negative results
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See all 19 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.