Abstract
Annual bedding plants make up the largest sector of the U.S. floriculture industry. High-quality annual bedding plant seedlings are compact, fully rooted transplants with a large stem caliper and high root dry mass. However, production usually occurs in late winter or early spring when the daily light integral (DLI) is as low as 1 to 5 mol·m–2·d –1 in northern latitudes. Therefore, supplemental lighting (SL) is often used to increase the DLI to a recommended 10 to 12 mol·m –2·d–1. The objectives of this study were to: 1) quantify the effects of SL from three light-emitting diode (LED) sources of different light qualities and high-pressure sodium (HPS) lamps; 2) quantify the effects of end-of-day (EOD) light from incandescent and compact fluorescent lamps, LEDs of low, medium, and high red:far-red light ratios, or mixed red:blue:far-red ratios (Expt. 2); and 3) quantify the effects of ambient light and SL from LEDs, HPS, and plasma (PL) lamps in a greenhouse, and the effects of sole-source light (SS) from LEDs with two different light qualities in a growth chamber vertical production system (Expt. 3) on seedling growth, morphology, quality, and subsequent flowering. Supplemental light proportions (%) from LEDs (Expt. 1 and 3) ranged from 100:0 to 70:30 red:blue light, and EOD (Expt. 2) LED light proportions ranged from 100:0 to 50:50 red:far-red or 100:0:0 to 0:100:0 and 62:33:5 red:blue:far-red light. In Expt. 1, stem elongation of Catharanthus, Celosia, Impatiens, Petunia, Tagetes, Salvia, andViola seedlings was reduced 9%-55% under 85:15 red:blue LEDs compared to HPS lamps. In Expt. 2, stem elongation of Petunia seedlings after 21 d of EOD light was reduced up to 48% under LEDs providing a red:far-red light ratio ≥4.5 compared to ≈0.9; and 10%-11% under 100:0:0, 75:25:0, and 25:75:0 red:blue:far-red LEDs compared to 62:33:5 red:blue:far-red LEDs. In Expt. 3, stem elongation of Pelargonium, Petunia, and Tagetes was reduced up to 79% under SS compared to HPS lamps. Quality index, a quantitative measurement of quality, of Petunia was 44%–129% greater for seedlings grown under all light treatments compared to ambient solar light (control). Additionally, with the exception of Impatiens, time to flower was similar or reduced for seedlings propagated under light treatments compared to the control. Overall, the results obtained from these experiments indicate that SL, EOD lighting, and SS can be used to enhance seedling growth, morphology, and quality without substantially delaying subsequent flowering of the annual bedding plant species tested.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 6
Claim · model-written summary
Red:blue LED supplemental lighting reduced stem elongation of seven bedding plant genera by 9%-55% relative to HPS lamps.
Verbatim
e0“stem elongation of Catharanthus, Celosia, Impatiens, Petunia, Tagetes, Salvia, andViola seedlings was reduced 9%-55% under 85:15 red:blue LEDs compared to HPS lamps”
Claim · model-written summary
Petunia stem elongation fell by up to 48% with end-of-day LEDs at red:far-red ratio ≥4.5 versus ≈0.9.
- Organ / stage
- seedlingse0
- Treatment
- LEDs providing a red:far-red light ratio ≥4.5e0
- Outcome
- stem elongatione0
- Direction
- reducede0
- Value
- up to 48%e0
- Qualifier
- after 21 d of EOD lighte0
- Comparator
- ≈0.9e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_flowers_in_Westgate_Gardens%2C_Canterbury.jpg?width=500)
Verbatim
e0“stem elongation of Petunia seedlings after 21 d of EOD light was reduced up to 48% under LEDs providing a red:far-red light ratio ≥4.5 compared to ≈0.9”
Claim · model-written summary
Three red:blue:far-red LED ratios reduced Petunia stem elongation by 10%-11% relative to 62:33:5 LEDs.
- Treatment
- 100:0:0, 75:25:0, and 25:75:0 red:blue:far-red LEDse0
- Outcome
- stem elongatione0
- Direction
- reducede0
- Value
- 10%-11%e0
- Comparator
- 62:33:5 red:blue:far-red LEDse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stem elongation of Petunia seedlings after 21 d of EOD light was reduced up to 48% under LEDs providing a red:far-red light ratio ≥4.5 compared to ≈0.9; and 10%-11% under 100:0:0, 75:25:0, and 25:75:0 red:blue:far-red LEDs compared to 62:33:5 red:blue:far-red LEDs”
Claim · model-written summary
Sole-source lighting reduced stem elongation of Pelargonium, Petunia, and Tagetes by up to 79% relative to HPS.
- Taxon
- Pelargonium, Petunia, and Tagetes
.jpg?width=60)
Pelargonium_flowers_in_Westgate_Gardens%2C_Canterbury.jpg?width=60)
Petunia.jpg?width=60)
Tagetese0 - Treatment
- SSe0
- Outcome
- stem elongatione0
- Direction
- reducede0
- Value
- up to 79%e0
- Comparator
- HPS lampse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
.jpg?width=500)
Verbatim
e0“stem elongation of Pelargonium, Petunia, and Tagetes was reduced up to 79% under SS compared to HPS lamps”
Claim · model-written summary
Petunia seedling quality index was 44%–129% greater under all light treatments than ambient solar light.
- Treatment
- all light treatmentse0
- Outcome
- Quality indexe0
- Direction
- greatere0
- Value
- 44%–129%e0
- Comparator
- ambient solar light (control)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Quality index, a quantitative measurement of quality, of Petunia was 44%–129% greater for seedlings grown under all light treatments compared to ambient solar light (control)”
Claim · model-written summary
For species other than Impatiens, lighting produced similar or shorter time to flower than control.
- Treatment
- light treatmentse0
- Outcome
- time to flowere0
- Direction
- similar or reducede0
- Qualifier
- with the exception of Impatiense0
- Comparator
- the controle0
ImpatiensOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with the exception of Impatiens, time to flower was similar or reduced for seedlings propagated under light treatments compared to the control”
The same questions in other papers
light · quality: general · Petunia (petunia)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- negative
- positive
light · growth · PelargoniumPositive and negative results
3 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
1 paper more in this group
See all 5 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
20 papers more in this group
See all 24 papers →light · growth · Tagetes (marigolds)Results agree
6 papers in the same direction as this paper
- positive
- positive
- positive
3 papers more in this group
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.