Abstract
Growth and flowering of shoots of `Mercedes' rose was investigated as a function of the level and spectral quality of photosynthetic photon flux (PPF). Experiments were performed with single-shoot plants decapitated above the two most basal leaves with five leaflets. The development of the two lateral shoots emerging from the axillary buds of these leaves was studied for 4 to 6 weeks. To discriminate between the effects of irradiance and light quality, plants were grown in growth chambers in which PPF and its spectral composition could be controlled. At a photoperiod of 12 hours, the length, weight, and flowering of the shoots strongly increased with irradiance. The growth and number of flowering shoots were always higher for the uppermost than for the second shoot. At the highest PPF (270 μmol·m -2 ·s -1 ), flowering occurred in 89% and 33% of the uppermost and second shoots, respectively. At an irradiance level of 90 μmol·m -2 ·s -1 , these percentages were 6% and 0%. Although length and dry weight of both types of shoots were significantly increased by reducing the amount of blue light at constant PPF, flower development was not affected. In a second experiment, plants grown in white light (12 h/day) received a short treatment with low-intensity red or far-red `light at the end of each photoperiod. An end-of-day treatment with red light resulted in significantly more flowering shoots than far-red. The red far-red reversibility of this flowering response indicates the involvement of the photoreceptor phytochrome.
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Claims 10
Claim · model-written summary
Shoot length, weight and flowering increased with irradiance.
- Taxon
- Rosa hybridst0
- Material
- Mercedest0
- Treatment
- irradiancee0
- Outcome
- length, weight, and flowering of the shootse0
- Direction
- increasede0
- Qualifier
- photoperiod of 12 hourse0
Not reportedComparator
Verbatim
e0“At a photoperiod of 12 hours, the length, weight, and flowering of the shoots strongly increased with irradiance”
t0“Rosa hybrids `Mercedes'”
Claim · model-written summary
Uppermost shoots had more growth and flowering than second shoots.
Verbatim
e0“The growth and number of flowering shoots were always higher for the uppermost than for the second shoot”
t0“Rosa hybrids”
Claim · model-written summary
At the highest PPF, 89% of uppermost shoots flowered.
Verbatim
e0“At the highest PPF (270 μmol·m -2 ·s -1 ), flowering occurred in 89% and 33% of the uppermost and second shoots, respectively”
t0“Rosa hybrids”
Claim · model-written summary
At the highest PPF, 33% of second shoots flowered.
Verbatim
e0“At the highest PPF (270 μmol·m -2 ·s -1 ), flowering occurred in 89% and 33% of the uppermost and second shoots, respectively”
t0“Rosa hybrids”
Claim · model-written summary
At 90 PPF, 6% of uppermost shoots flowered.
Verbatim
e0“At an irradiance level of 90 μmol·m -2 ·s -1 , these percentages were 6% and 0%”
t0“Rosa hybrids”
Claim · model-written summary
At 90 PPF, 0% of second shoots flowered.
Verbatim
e0“At an irradiance level of 90 μmol·m -2 ·s -1 , these percentages were 6% and 0%”
t0“Rosa hybrids”
Claim · model-written summary
Reduced blue light increased shoot length and dry weight.
- Taxon
- Rosa hybridst0
- Treatment
- reducing the amount of blue lighte0
- Outcome
- length and dry weight of both types of shootse0
- Direction
- increasede0
- Qualifier
- constant PPFe0
Not reportedComparator
Verbatim
e0“length and dry weight of both types of shoots were significantly increased by reducing the amount of blue light at constant PPF”
t0“Rosa hybrids”
Claim · model-written summary
Reduced blue light did not change flower development.
- Taxon
- Rosa hybridst0
- Treatment
- reducing the amount of blue lighte1
- Outcome
- flower developmente0
- Direction
- not affectede0
Not reportedComparator
Verbatim
e0“flower development was not affected”
e1“reducing the amount of blue light at constant PPF”
t0“Rosa hybrids”
Claim · model-written summary
End-of-day red light produced significantly more flowering shoots than far-red.
Verbatim
e0“An end-of-day treatment with red light resulted in significantly more flowering shoots than far-red”
t0“Rosa hybrids”
Claim · model-written summary
The red far-red reversible flowering response indicates phytochrome involvement.
Verbatim
e0“The red far-red reversibility of this flowering response indicates the involvement of the photoreceptor phytochrome”
t0“Rosa hybrids”
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