Abstract
ABSTRACT The biophysical mechanism underlying photoinhibition of radish ( Raphanus sativus L.) seed germination was investigated using three cultivars differing in sensitivity to continuous irradiation with far‐red light (high‐irradiance reaction of phytochrome). Sensitivity of germination to the inhibitory action of light was assessed by probing germination under osmotic stress (incubation in media of low water potentials adjusted with polyethylene glycol 6000) and expressed in terms of ‘germination potential’ (positive value of the water potential at which germination is inhibited by 50%). Far‐red light decreases the germination potential to various degrees in the different cultivars, reflecting the light‐sensitivity of germination in water. Removal of the seed coat increases the germination potential by a constant amount in darkness and light. It is concluded that germination depends on the expansive force of the embryo which can be drastically diminished by far‐red light. Seed‐coat constraint and expansive force of the embryo interact additively on the level of the germination potential. Photoinhibition of germination was accompanied by an inhibition of water uptake into the seed. Analysis of seed water relations showed that osmotic pressure and turgor assumed higher levels in photoinhibited seeds, compared to seeds germinating in darkness, while the water potential was close to zero under both conditions. Far‐red light produced a shift (to less negative values) in the curve relating water‐uptake rate to external water potential, i.e. a reduction in the driving force for water uptake. It is concluded that photoinhibition of germination results from the maintenance of a high threshold of cell‐wall extensibility in the embryo.
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Claims 9
Claim · model-written summary
Far-red light decreased germination potential of radish seeds in the cultivars tested, in water.
- Taxon
- radish
Raphanus sativust0 - Material
- different cultivarse0
- Treatment
- Far‑red lighte0
- Outcome
- germination potentiale0
- Direction
- decreasese0
- Qualifier
- in watere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e0“Far‑red light decreases the germination potential to various degrees in the different cultivars, reflecting the light‑sensitivity of germination in water”
Claim · model-written summary
Removal of the seed coat increased germination potential by a constant amount in darkness and light.
- Taxon
- radishRaphanus sativust0
- Treatment
- Removal of the seed coate1
- Outcome
- germination potentiale1
- Direction
- increasese1
- Value
- a constant amounte1
- Qualifier
- in darkness and lighte1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e1“Removal of the seed coat increases the germination potential by a constant amount in darkness and light”
Claim · model-written summary
The seed coat constraint and embryo expansive force interact additively on germination potential.
- Taxon
- radishRaphanus sativust0
- Treatment
- expansive force of the embryoe2
- Outcome
- germination potentiale2
- Direction
- interact additivelye2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e2“Seed‑coat constraint and expansive force of the embryo interact additively on the level of the germination potential”
Claim · model-written summary
Photoinhibition of germination was associated with reduced water uptake into the seed.
- Taxon
- radishRaphanus sativust0
- Treatment
- Photoinhibition of germinatione3
- Outcome
- water uptake into the seede3
- Direction
- inhibitione3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e3“Photoinhibition of germination was accompanied by an inhibition of water uptake into the seed”
Claim · model-written summary
Osmotic pressure and turgor were higher in photoinhibited seeds than in seeds germinating in darkness.
- Taxon
- radishRaphanus sativust0
- Outcome
- osmotic pressure and turgore4
- Direction
- highere4
- Comparator
- seeds germinating in darknesse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e4“Analysis of seed water relations showed that osmotic pressure and turgor assumed higher levels in photoinhibited seeds, compared to seeds germinating in darkness, while the water potential was close to zero under both conditions”
Claim · model-written summary
Seed water potential was close to zero under both photoinhibited and dark conditions.
- Taxon
- radishRaphanus sativust0
- Outcome
- water potentiale4
- Value
- close to zeroe4
- Qualifier
- under both conditionse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e4“Analysis of seed water relations showed that osmotic pressure and turgor assumed higher levels in photoinhibited seeds, compared to seeds germinating in darkness, while the water potential was close to zero under both conditions”
Claim · model-written summary
Far-red light reduced the driving force for water uptake, shifting the water uptake curve to less negative water potentials.
- Taxon
- radishRaphanus sativust0
- Treatment
- Far‑red lighte5
- Outcome
- driving force for water uptakee5
- Direction
- reductione5
- Qualifier
- shift (to less negative values) in the curvee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e5“Far‑red light produced a shift (to less negative values) in the curve relating water‑uptake rate to external water potential, i.e. a reduction in the driving force for water uptake”
Claim · model-written summary
Photoinhibition of germination results from maintaining a high threshold of cell-wall extensibility in the embryo.
- Taxon
- radishRaphanus sativust0
- Outcome
- photoinhibition of germinatione6
- Qualifier
- a high threshold of cell‑wall extensibilitye6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e6“It is concluded that photoinhibition of germination results from the maintenance of a high threshold of cell‑wall extensibility in the embryo”
Claim · model-written summary
Germination depends on the embryo expansive force, which far-red light can drastically diminish.
- Taxon
- radishRaphanus sativust0
- Treatment
- far‑red lighte7
- Outcome
- germinatione7
- Qualifier
- expansive force of the embryoe7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“radish (Raphanus sativus L)”
e7“It is concluded that germination depends on the expansive force of the embryo which can be drastically diminished by far‑red light”
The same questions in other papers
light · growth · Raphanus sativus (radish)Positive and negative results
17 papers in the same direction as this paper · 12 in the opposite direction
- negative
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26 papers more in this group
See all 30 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.