Comparing Flowering Responses of Long-day Plants under Incandescent and Two Commercial Light-emitting Diode Lamps

When the natural daylength is short, commercial growers of ornamental long-day plants (LDP) often provide low-intensity lighting to more rapidly and uniformly induce flowering. Incandescent (INC) lamps have been traditionally used for photoperiodic lighting because their spectrum, rich in red [R (600 to 700 nm)] and far-red [FR (700 to 800 nm)] light, is effective and they are inexpensive to purchase and install. Light-emitting diodes (LEDs) are much more energy efficient, can emit wavelengths of light that specifically regulate flowering, and last at least 20 times longer. We investigated the efficacy of two new commercial LED products developed for flowering applications on the LDP ageratum (Ageratum houstonianum), calibrachoa (Calibrachoa ×hybrida), two cultivars of dianthus (Dianthus chinensis), and two cultivars of petunia (Petunia ×hybrida). Plants were grown under a 9-hour short day without or with a 4-hour night interruption (NI) delivered by one of three lamp types: INC lamps (R:FR = 0.59), LED lamps with R and white (W) diodes [R + W (R:FR = 53.35)], and LED lamps with R, W, and FR diodes [R + W + FR (R:FR = 0.67)]. The experiment was performed twice, both at a constant 20 °C, but the photosynthetic daily light integral (DLI) during the second replicate (Rep. II) was twice that in the first (Rep. I). In all crops and in both experimental replicates, time to flower, flower or inflorescence and node number, and plant height were similar under the R + W + FR LEDs and the INC lamps. However, in Rep. I, both petunia cultivars developed more nodes and flowering was delayed under the R + W LEDs compared with the INC or R + W + FR LEDs. In Rep. II, petunia flowering time and node number were similar under the three NI treatments. Plant height of both dianthus cultivars was generally shorter under the NI treatment without FR light (R + W LEDs). These results indicate that when the DLI is low (e.g., ≤6 mol·m−2·d−1), FR light is required in NI lighting for the most rapid flowering of some but not all LDP; under a higher DLI, the flowering response to FR light in NI lighting is apparently diminished.

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Promotion of Flowering from Far-red Radiation Depends on the Photosynthetic Daily Light Integral

HortScience ◽

10.21273/hortsci12544-17 ◽

2018 ◽

Vol 53 (4) ◽

pp. 465-471 ◽

Cited By ~ 3

Author(s):

W. Garrett Owen ◽

Qingwu Meng ◽

Roberto G. Lopez

Keyword(s):

Plant Height ◽

Open Flower ◽

Led Lighting ◽

Daily Light Integral ◽

Low Intensity ◽

Short Day ◽

Long Day ◽

Long Day Plants ◽

African Marigold ◽

Light Integral

Under natural short days, growers can use photoperiodic lighting to promote flowering of long-day plants and inhibit flowering of short-day plants. Unlike traditional lamps used for photoperiodic lighting, low-intensity light-emitting diode (LED) lamps allow for a wide array of adjustable spectral distributions relevant to regulation of flowering, including red (R) and white (W) radiation with or without far-red (FR) radiation. Our objective was to quantify how day-extension (DE) photoperiodic lighting from two commercially available low-intensity LED lamps emitting R + W or R + W + FR radiation interacted with daily light integral (DLI) to influence stem elongation and flowering of several ornamental species. Long-day plants [petunia (Petunia ×hybrida Vilm.-Andr. ‘Dreams Midnight’) and snapdragon (Antirrhinum majus L. ‘Oh Snap Pink’)], short-day plants [african marigold (Tagetes erecta L. ‘Moonsong Deep Orange’) and potted sunflower (Helianthus annuus L. ‘Pacino Gold’)], and day-neutral plants [pansy (Viola ×wittrockiana Gams. ‘Matrix Yellow’) and zinnia (Zinnia elegans Jacq. ‘Magellan Cherry’)] were grown at 20/18 °C day/night air temperatures and under low (6–9 mol·m−2·d−1) or high (16–19 mol·m−2·d−1) seasonal photosynthetic DLIs from ambient solar radiation combined with supplemental high-pressure sodium lighting and DE LED lighting. Photoperiods consisted of a truncated 9-hour day (0800–1700 hr) with additional 1-hour (1700–1800 hr, 10 hours total), 4-hour (1700–2100 hr, 13 hours total), or 7-hour (1700–2400 hr, 16 hours total) R + W or R + W + FR LED lighting at 2 μmol·m−2·s−1. Days to visible bud, plant height at first open flower, and time to first open flower (TTF) of each species were influenced by DLI, lamp type, and photoperiod though to different magnitudes. For example, plant height of african marigold and potted sunflower at first open flower was greatest under R + W + FR lamps, high DLIs, and 16-hour photoperiods. Petunia grown under R + W lamps, high DLI, and 10- and 13-hour photoperiods were the most compact. For all species, TTF was generally reduced under high DLIs. For example, regardless of the lamp type, flowering of african marigold occurred fastest under a high DLI and 10-hour photoperiod. Flowering of petunia and snapdragon occurred fastest under a high DLI, R + W + FR lamps, and a 16-hour photoperiod. However, only under high DLIs, R + W or R + W + FR lamps were equally effective at promoting flowering when used to provide DE lighting. Our data suggest that under low DLIs, flowering of long-day plants (petunia and snapdragon) occurs more rapidly under lamps providing R + W + FR, whereas under high DLIs, flowering is promoted similarly under either R + W or R + W + FR lamps.

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Temperature and Photoperiod Influence Flowering and Morphology of Four Petunia spp.

HortScience ◽

10.21273/hortsci.45.3.365 ◽

2010 ◽

Vol 45 (3) ◽

pp. 365-368 ◽

Cited By ~ 10

Author(s):

Ryan M. Warner

Keyword(s):

Base Temperature ◽

Optimal Temperature ◽

Flower Bud ◽

Breeding Programs ◽

Node Number ◽

Daily Light Integral ◽

Long Day ◽

Light Integral ◽

Short Days ◽

Petunia Axillaris

Flowering and morphology of four Petunia Juss. spp. [P. axillaris (Lam.) Britton et al., P. exserta Stehmann, P. integrifolia (Hook.) Schinz & Thell., and P. ×hybrida Vilm.] were evaluated in response to photoperiod and temperature. Photoperiod responses were evaluated under 9-h short days (SD), 9-h photoperiod plus 4-h night-interruption lighting (NI), or a 16-h photoperiod supplemented with high-pressure sodium lamps (16-h HPS). All species flowered earlier under NI than SD and were classified as facultative (quantitative) long-day plants. Increasing the daily light integral within long-day treatments increased flower bud number for P. axillaris only. In a second experiment, crop timing and quality were evaluated in the temperature range of 14 to 26 °C under 16-h HPS. The rate of progress toward flowering for each species increased as temperature increased from 14 to 26 °C, suggesting the optimal temperature for development is at least 26 °C. The calculated base temperature for progress to flowering varied from 0.1 °C for P. exserta to 5.3 °C for P. integrifolia. Flowering of P. axillaris and P. integrifolia was delayed developmentally (i.e., increased node number below the first flower) at 14 °C and 17 °C or less, respectively, compared with higher temperatures. Petunia axillaris and P. integrifolia flower bud numbers decreased as temperature increased, whereas P. ×hybrida flower bud number was similar at all temperatures. The differences in crop timing and quality traits observed for these species suggest that they may be useful sources of variability for petunia breeding programs.

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Growth and Flowering Responses of Seed-propagated Strawberry Seedlings to Different Photoperiods in Controlled Environment Chambers

HortTechnology ◽

10.21273/horttech04061-18 ◽

2018 ◽

Vol 28 (4) ◽

pp. 453-458 ◽

Cited By ~ 2

Author(s):

Johshin Tsuruyama ◽

Toshio Shibuya

Keyword(s):

High Performance ◽

Light Emitting Diode ◽

Photon Flux ◽

Controlled Environment ◽

Light Emitting ◽

Artificial Lighting ◽

Daily Light Integral ◽

Growth Properties ◽

Performance System ◽

Light Integral

The present study investigated growth properties and flowering response of seed-propagated strawberry (Fragaria ×ananassa) seedlings under artificial lighting with different photoperiods to support the development of a high-performance system for the indoor production of strawberry plug transplants. Seedlings of ‘Elan’ and ‘Yotsuboshi’ were grown for 38 days under sunlight in a greenhouse or under light-emitting diode (LED) illumination with photoperiods of 8/16, 12/12, 16/8, or 24/0 hours (light/dark) in growth chambers. The photosynthetic photon flux (PPF) in these photoperiods was maintained at 350, 230, 175, or 115 μmol·m−2·s−1, respectively, to provide the same daily light integral (DLI) of 10 mol·m−2·d−1. The average of DLI of sunlight was 9.9 mol·m−2·d−1. Seedling growth was greater with the 16- and 24-hour photoperiods than with sunlight even though all three treatments provided about the same DLI. Flower buds of the seedlings grown under longer photoperiods started significantly earlier after transplanting in ‘Elan’ but not in ‘Yotsuboshi’. Thus, strawberry transplant production under artificial lighting with an optimized photoperiod can provide high-quality transplants, although the effectiveness is cultivar-specific.

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LED Rail Signals: Full Hardware Realization of Apparatus with Independent Intensity by Temperature Changes

Electronics ◽

10.3390/electronics10111291 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1291

Author(s):

Giuseppe Schirripa Schirripa Spagnolo ◽

Fabio Leccese

Keyword(s):

Temperature Sensor ◽

Energy Efficient ◽

Light Emitting Diode ◽

Junction Temperature ◽

Light Emitting ◽

Temperature Changes ◽

Wide Range ◽

International Regulations ◽

Long Lifetime ◽

Set Up

Nowadays, signal lights are made using light-emitting diode arrays (LEDs). These devices are extremely energy efficient and have a very long lifetime. Unfortunately, especially for yellow/amber LEDs, the intensity of the light is closely related to the junction temperature. This makes it difficult to design signal lights to be used in naval, road, railway, and aeronautical sectors, capable of fully respecting national and international regulations. Furthermore, the limitations prescribed by the standards must be respected in a wide range of temperature variations. In other words, in the signaling apparatuses, a system that varies the light intensity emitted according to the operating temperature is useful/necessary. In this paper, we propose a simple and effective solution. In order to adjust the intensity of the light emitted by the LEDs, we use an LED identical to those used to emit light as a temperature sensor. The proposed system was created and tested in the laboratory. As the same device as the ones to be controlled is used as the temperature sensor, the system is very stable and easy to set up.

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Opportunities and Challenges in Perovskite LEDs Commercialization

Journal of Materials Chemistry C ◽

10.1039/d1tc00232e ◽

2021 ◽

Author(s):

Kai Zhang ◽

Ningning Zhu ◽

Mingming Zhang ◽

Lei Wang ◽

Jun Xing

Keyword(s):

Energy Saving ◽

Energy Efficient ◽

Light Emitting Diode ◽

Environment Friendly ◽

Light Emitting ◽

Lighting Technology

Recently, the light-emitting diode (LED) has been considered as an energy-saving and environment-friendly lighting technology，which is ten times more energy efficient than conventional incandescent lights. As an emerging photoelectric material,...

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Rind Color Development in Satsuma Mandarin Fruits Treated by Low-intensity Red Light-emitting Diode (LED) Irradiation

Food Science and Technology Research ◽

10.3136/fstr.22.59 ◽

2016 ◽

Vol 22 (1) ◽

pp. 59-64 ◽

Cited By ~ 5

Author(s):

Ittetsu Yamaga ◽

Yuki Shirai ◽

Teruko Nakajima ◽

Yasushi Kobayashi

Keyword(s):

Light Emitting Diode ◽

Red Light ◽

Light Emitting ◽

Low Intensity ◽

Satsuma Mandarin ◽

Color Development ◽

Led Irradiation

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Flowering and Morphogenesis of Kalanchoe in Response to Quality and Intensity of Night Interruption Light

Plants ◽

10.3390/plants8040090 ◽

2019 ◽

Vol 8 (4) ◽

pp. 90

Author(s):

Dong Kang ◽

Hai Jeong ◽

Yoo Park ◽

Byoung Jeong

Keyword(s):

Plant Height ◽

White Light ◽

Light Emitting ◽

Short Day ◽

Spad Value ◽

Long Day ◽

Closed Type ◽

Significant Difference ◽

Plant Factory ◽

White Light Emitting Diodes

The effects of the quality and intensity of night interruption light (NIL) on the flowering and morphogenesis of kalanchoe (Kalanchoe blossfeldiana) ‘Lipstick’ and ‘Spain’ were investigated. Plants were raised in a closed-type plant factory under 250 μmol·m−2·s−1 PPFD white light emitting diodes (LEDs) with additional light treatments. These treatments were designated long day (LD, 16 h light, 8 h dark), short day (SD, 8 h light, 16 h dark), and SD with a 4 h night interruption (NI). The NIL was constructed from 10 μmol·m−2·s−1 or 20 μmol·m−2·s−1 PPFD blue (NI-B), red (NI-R), white (NI-W), or blue and white (NI-BW) LEDs. In ‘Spain’, the SPAD value, area and thickness of leaves and plant height increased in the NI treatment as compared to the SD treatment. In ‘Lipstick’, most morphogenetic characteristics in the NI treatment showed no significant difference to those in the SD treatment. For both cultivars, plants in SD were significantly shorter than those in other treatments. The flowering of Kalanchoe ‘Lipstick’ was not affected by the NIL quality, while Kalanchoe ‘Spain’ flowered when grown in SD and 10 μmol·m−2·s−1 PPFD NI-B. These results suggest that the NIL quality and intensity affect the morphogenesis and flowering of kalanchoe, and that different cultivars are affected differently. There is a need to further assess the effects of the NIL quality and intensity on the morphogenesis and flowering of short-day plants for practical NIL applications.

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Variability in photoperiod and the inhibition of flowering in a high latitude population of Saxifraga rivularis

Canadian Journal of Botany ◽

10.1139/b81-052 ◽

1981 ◽

Vol 59 (3) ◽

pp. 388-391 ◽

Cited By ~ 1

Author(s):

J. A. Teeri ◽

S. J. Tonsor

Keyword(s):

High Latitude ◽

High Intensity ◽

Dark Period ◽

Controlled Environment ◽

Photoperiodic Control ◽

Incandescent Light ◽

Devon Island ◽

Low Intensity ◽

Long Day ◽

Long Day Plants

A population of Saxifraga rivularis L. collected at Truelove Lowland, Devon Island, N.W.T., Canada (75°41′ N) exhibits a photoperiodic control of flowering in controlled environment chambers. The plants respond in a manner typical of long-day plants with flowering inhibited by either a 6-h daily dark period, or by a 6-h daily low intensity irradiance regime of incandescent light. The inhibition of flowering by 6 h day−1 of incandescent light does not occur if the incandescent light is given in twelve 0.5-h doses, each followed by 1 h of red-rich high intensity irradiance.

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