Abstract
To produce uniform, compact, and high-quality annual bedding plant seedlings in late winter through early spring, growers in northern latitudes must use supplemental lighting (SL) to achieve a photosynthetic daily light integral (DLI) of 10 to 12 mol·m −2 ·d −1 . Alternatively, new lighting technologies may be used for sole-source photosynthetic lighting (SSL) to grow seedlings in an indoor high-density multilayer controlled environment. The objective of this study was to compare seedlings grown under low greenhouse ambient light (AL) to those grown under SL or SSL with a similar DLI. On hypocotyl emergence, seedlings of vinca ( Catharanthus roseus ), impatiens ( Impatiens walleriana ), geranium ( Pelargonium × hortorum ), petunia ( Petunia × hybrida ), and French marigold ( Tagetes patula ) were placed in a greenhouse under AL or AL plus SL delivering a photosynthetic photon flux ( PPF ) of 70 µmol·m −2 ·s –1 for 16 hours, or under multilayer SSL delivering a PPF of 185 µmol·m −2 ·s –1 for 16 hours in a walk-in growth chamber. Supplemental lighting consisted of high-pressure sodium (HPS) lamps or high-intensity light-emitting diode (LED) arrays with a red:blue light ratio (400–700 nm; %) of 87:13, and SSL consisted of LED arrays providing a red:blue light ratio (%) of 87:13 or 70:30. Root and shoot dry mass, stem diameter, relative chlorophyll content, and the quality index (a quantitative measurement of quality) of most species were generally greater under SSL and SL than under AL. In addition, height of geranium, petunia, and marigold was 5% to 26%, 62% to 79%, and 7% to 19% shorter, respectively, for seedlings grown under SSL compared with those under AL and SL. With the exception of impatiens, time to flower was similar or hastened for all species grown under SL or SSL compared with AL. Seedlings grown under SSL were of similar or greater quality compared with those under SL; indicating that LED SSL could be used as an alternative to traditional greenhouse seedling production.
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Claims 7
Claim · model-written summary
Under supplemental or sole-source lighting, most species had greater root and shoot dry mass, stem diameter, relative chlorophyll content, and quality index than under ambient light.
Verbatim
e0“Root and shoot dry mass, stem diameter, relative chlorophyll content, and the quality index (a quantitative measurement of quality) of most species were generally greater under SSL and SL than under AL”
t0“Bedding Plant Seedlings”
Claim · model-written summary
Geranium seedlings under sole-source lighting were 5% to 26% shorter than under ambient or supplemental lighting.
GeraniumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“height of geranium, petunia, and marigold was 5% to 26%, 62% to 79%, and 7% to 19% shorter, respectively, for seedlings grown under SSL compared with those under AL and SL”
Claim · model-written summary
Petunia seedlings under sole-source lighting were 62% to 79% shorter than under ambient or supplemental lighting.
_flowers_in_Westgate_Gardens%2C_Canterbury.jpg?width=60){kind=small}
PetuniaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
_flowers_in_Westgate_Gardens%2C_Canterbury.jpg?width=500)
Verbatim
e0“height of geranium, petunia, and marigold was 5% to 26%, 62% to 79%, and 7% to 19% shorter, respectively, for seedlings grown under SSL compared with those under AL and SL”
Claim · model-written summary
Marigold seedlings under sole-source lighting were 7% to 19% shorter than under ambient or supplemental lighting.
Verbatim
e0“height of geranium, petunia, and marigold was 5% to 26%, 62% to 79%, and 7% to 19% shorter, respectively, for seedlings grown under SSL compared with those under AL and SL”
Claim · model-written summary
Except for impatiens, supplemental or sole-source lighting left time to flower similar or hastened relative to ambient light.
Verbatim
e0“With the exception of impatiens, time to flower was similar or hastened for all species grown under SL or SSL compared with AL”
t0“Bedding Plant Seedlings”
Claim · model-written summary
Sole-source lighting gave seedlings similar or greater quality than supplemental lighting.
Verbatim
e0“Seedlings grown under SSL were of similar or greater quality compared with those under SL”
t0“Bedding Plant Seedlings”
Claim · model-written summary
The authors propose LED sole-source lighting as an alternative for greenhouse seedling production.
Verbatim
e0“LED SSL could be used as an alternative to traditional greenhouse seedling production”
t0“Bedding Plant Seedlings”
The same questions in other papers
light · growth · GeraniumPositive and negative results
6 papers in the same direction as this paper · 1 in the opposite direction · 1 reporting no difference from an alternative
- no effect
- negative
- positive
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See all 9 papers →light · growth · Petunia (petunia)Positive and negative results
19 papers in the same direction as this paper · 4 in the opposite direction
- negative
- negative
- negative
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See all 24 papers →light · growth · Tagetes (marigolds)Results agree
6 papers in the same direction as this paper
- positive
- positive
- positive
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See all 7 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.