Evaluation of the Light Environment of a Plant Factory with Artificial Light by Using an Optical Simulation

Good lighting designs can establish suitable light environments in plant factories with artificial light (PFALs). This study used optical simulations to investigate the effects of lighting designs in PFALs on the coefficient of variation of light absorption (Φp; CV) of individual plants and the coefficient of utilization for the lighting system (U). Three-dimensional models of canola plants were constructed using a scanner, and a 3D model of the cultivation shelf was also created. The photosynthetic photon flux density (PPFD) distribution in the cultivation spaces, with or without the canola plants, was estimated first. The PPFD on the canola leaves was then estimated when the lighting design parameters, such as number, distance, height, radiant flux, and light distribution of the light-emitting diode lamps, were modified. The optical simulation showed good accuracy when estimating the PPFD distributions on the cultivation shelf and the leaves of the canola plants. The results showed that while the PPFD distribution across the growing area was uniform, it was not on a plant canopy. By appropriately controlling the layout of the lamps and their directionality, lighting designs that reduce Φp; CV and improve U in PFAL could be possible, and optical simulations could help to develop them.

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Light-emitting Diodes Can Replace High-pressure Sodium Lighting for Cut Gerbera Production

HortScience ◽

10.21273/hortsci13270-18 ◽

2019 ◽

Vol 54 (1) ◽

pp. 95-99 ◽

Cited By ~ 2

Author(s):

Dave Llewellyn ◽

Katherine Schiestel ◽

Youbin Zheng

Keyword(s):

High Pressure ◽

Treatment Effects ◽

Light Emitting Diode ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Vase Life ◽

Light Emitting ◽

Greenhouse Study ◽

Flower Diameter

A greenhouse study was undertaken to investigate whether light-emitting diode (LED) technology can be used to replace high-pressure sodium (HPS) lighting for cut gerbera production during Canada’s traditional supplemental lighting (SL) season (November to March). The study was carried out at the University of Guelph’s research greenhouse, using concurrent replications of SL treatments within the same growing environment. LED (85% red, 15% blue) and HPS treatment plots were set up to provide equal amounts of supplemental photosynthetically active radiation (PAR) at bench level. This setup was used to assess the production of three cultivars of cut gerbera (Gerbera jamesonii H. Bolus ex Hook.f): Acapulco, Heatwave, and Terra Saffier. There were no treatment differences in SL intensity, with average SL photosynthetic photon flux density (PPFD) and daily light integral (DLI) of 55.9 µmol·m−2·s−1 and 2.3 mol·m−2·d−1, respectively. Flowers harvested from the LED treatment had a 1.9% larger flower diameter in ‘Acapulco’; 4.2% shorter and 3.8% longer stems in ‘Heatwave’ and ‘Terra Saffier’, respectively; and 7.7% and 8.6% higher fresh weights for ‘Acapulco’ and ‘Terra Saffier’, respectively, compared with flowers harvested from the HPS treatment. There were no differences in accumulated total or marketable flower harvests for any of the cultivars. The vase life of ‘Acapulco’ flowers grown under the LED treatment was 2.7 d longer than those grown under the HPS treatment, but there were no SL treatment effects on water uptake for any of the cultivars during the vase life trials. There were no SL treatment effects on specific leaf area for any of the cultivars. There were only minimal treatment differences in leaf, soil, and air temperatures. Cut gerbera crops grown with under LED SL had equivalent or better production and crop quality metrics compared with crops grown under HPS SL.

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LightCue: An Innovative Far-Red Light Emitter for Locally Modifying the Spectral Cue in Outdoor Conditions with Global Consequences on Plant Architecture

Plants ◽

10.3390/plants10112483 ◽

2021 ◽

Vol 10 (11) ◽

pp. 2483

Author(s):

Alain Fortineau ◽

Didier Combes ◽

Céline Richard-Molard ◽

Ela Frak ◽

Alexandra Jullien

Keyword(s):

Plant Architecture ◽

Light Emitting Diode ◽

Red Light ◽

Inhibitory Effect ◽

Photosynthetic Photon Flux Density ◽

High Irradiance ◽

Light Signal ◽

Photon Flux ◽

Photon Flux Density ◽

Light Emitting

Plasticity of plant architecture is a promising lever to increase crop resilience to biotic and abiotic damage. Among the main drivers of its regulation are the spectral signals which occur via photomorphogenesis processes. In particular, branching, one of the yield components, is responsive to photosynthetic photon flux density (PPFD) and to red to far-red ratio (R:FR), both signals whose effects are tricky to decorrelate in the field. Here, we developed a device consisting of far-red light emitting diode (LED) rings. It can reduce the R:FR ratio to 0.14 in the vicinity of an organ without changing the PPFD in outdoor high irradiance fluctuating conditions, which is a breakthrough as LEDs have been mostly used in non-fluctuant controlled conditions at low irradiance over short periods of time. Applied at the base of rapeseed stems during the whole bolting-reproductive phase, LightCue induced an expected significant inhibitory effect on two basal targeted axillary buds and a strong unexpected stimulatory effect on the overall plant aerial architecture. It increased shoot/root ratio while not modifying the carbon balance. LightCue therefore represents a promising device for progress in the understanding of light signal regulation in the field.

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Different LED Light Wavelengths and Photosynthetic Photon Flux Density Effect on Colletotrichum acutatum Growth

Plants ◽

10.3390/plants11010143 ◽

2022 ◽

Vol 11 (1) ◽

pp. 143

Author(s):

Neringa Rasiukevičiūtė ◽

Aušra Brazaitytė ◽

Viktorija Vaštakaitė-Kairienė ◽

Alma Valiuškaitė

Keyword(s):

Flux Density ◽

Photosynthetic Photon Flux Density ◽

Growth Characteristics ◽

Colletotrichum Acutatum ◽

Photon Flux ◽

Photon Flux Density ◽

Photosynthetic Photon Flux ◽

Light Emitting ◽

Led Light ◽

Fungus Growth

The study aimed to evaluate the effect of different photon flux density (PFD) and light-emitting diodes (LED) wavelengths on strawberry Colletotrichum acutatum growth characteristics. The C. acutatum growth characteristics under the blue 450 nm (B), green 530 nm (G), red 660 nm (R), far-red 735 nm (FR), and white 5700 K (W) LEDs at PFD 50, 100 and 200 μmol m−2 s−1 were evaluated. The effect on C. acutatum mycelial growth evaluated by daily measuring until five days after inoculation (DAI). The presence of conidia and size (width and length) evaluated after 5 DAI. The results showed that the highest inhibition of fungus growth was achieved after 1 DAI under B and G at 50 μmol m−2 s−1 PFD. Additionally, after 1–4 DAI under B at 200 μmol m−2 s−1 PFD. The lowest conidia width was under FR at 50 μmol m−2 s−1 PFD and length under FR at 100 μmol m−2 s−1 PFD. Various LED light wavelengths influenced differences in C. acutatum colonies color. In conclusion, different photosynthetic photon flux densities and wavelengths influence C. acutatum growth characteristics. The changes in C. acutatum morphological and phenotypical characteristics could be related to its ability to spread and infect plant tissues. This study’s findings could potentially help to manage C. acutatum by LEDs in controlled environment conditions.

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Morphological Response of Soybean (Glycine max (L.) Merr.) Cultivars to Light Intensity and Red to Far-Red Ratio

Agronomy ◽

10.3390/agronomy9080428 ◽

2019 ◽

Vol 9 (8) ◽

pp. 428 ◽

Cited By ~ 3

Author(s):

Tina Hitz ◽

Jens Hartung ◽

Simone Graeff-Hönninger ◽

Sebastian Munz

Keyword(s):

Cropping Systems ◽

Light Emitting Diode ◽

Red Light ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Shade Avoidance ◽

Internode Elongation ◽

Morphological Response ◽

Petiole Elongation

In soybean production, the shade avoidance response can affect yield negatively in both mono- and inter-cropping systems due to increased heterogeneity of the crop and lodging. This is mainly regulated by photoreceptors responding to the ratio between red and far-red light (R:FR) and photosynthetic photon flux density (PPFD). In this study, three soybean cultivars were grown under different R:FR and PPFD in a light emitting diode (LED) climate chamber to disentangle the effect of each on morphology and dry matter. Results showed that plant organs were influenced differently and indicated an interaction with the increase in assimilates at high PPFD. Internode elongation was mainly influenced by low PPFD with an additive effect from low R:FR, whereas petiole elongation responded strongly under low R:FR. Hence, petiole elongation can be seen as the main response to the threat of shade (high PPFD and low R:FR) and both petiole and internode elongation as a response to true shade (low PPFD and low R:FR). Interactions between cultivar and light treatment were found for internode length and diameter and leaf mass ratio, which may be unique properties for specific cropping systems.

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Optimal LED Wavelength Composition for the Production of High-Quality Watermelon and Interspecific Squash Seedlings Used for Grafting

Agronomy ◽

10.3390/agronomy9120870 ◽

2019 ◽

Vol 9 (12) ◽

pp. 870 ◽

Cited By ~ 1

Author(s):

Filippos Bantis ◽

Athanasios Koukounaras ◽

Anastasios S. Siomos ◽

Kalliopi Radoglou ◽

Christodoulos Dangitsis

Keyword(s):

Blue Emission ◽

Dry Weight ◽

Photosynthetic Photon Flux Density ◽

Stem Diameter ◽

Photon Flux ◽

Photon Flux Density ◽

Light Sources ◽

High Quality ◽

Light Emitting ◽

Shoot Dry Weight

Watermelon is cultivated worldwide and is mainly grafted onto interspecific squash rootstocks. Light-emitting diodes (LEDs) can be implemented as light sources during indoor production of both species and their spectral quality is of great importance. The objective of the present study was to determine the optimal emission of LEDs with wide wavelength for the production of watermelon and interspecific squash seedlings in a growth chamber. Conditions were set at 22/20 °C temperature (day/night), 16 h photoperiod, and 85 ± 5 μmol m−2 s−1 photosynthetic photon flux density. Illumination was provided by fluorescent (FL, T0) lamps or four LEDs (T1, T2, T3, and T4) emitting varying wide spectra. Watermelon seedlings had greater shoot length, stem diameter, cotyledon area, shoot dry weight-to-length (DW/L) ratio, and Dickson’s quality index (DQI) under T1 and T3, while leaf area and shoot dry weight (DW) had higher values under T1. Interspecific squash seedlings had greater stem diameter, and shoot and root DW under T1 and T3, while leaf and cotyledon areas were favored under T1. In both species, T0 showed inferior development. It could be concluded that a light source with high red emission, relatively low blue emission, and a red:far-red ratio of about 3 units seems ideal for the production of high-quality watermelon (scion) and interspecific squash (rootstock) seedlings.

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Regulation of Chloroplast Ultrastructure, Cross-section Anatomy of Leaves, and Morphology of Stomata of Cherry Tomato by Different Light Irradiations of Light-emitting Diodes

HortScience ◽

10.21273/hortsci.46.2.217 ◽

2011 ◽

Vol 46 (2) ◽

pp. 217-221 ◽

Cited By ~ 41

Author(s):

Liu XiaoYing ◽

Guo ShiRong ◽

Xu ZhiGang ◽

Jiao XueLei ◽

Takafumi Tezuka

Keyword(s):

Light Emitting Diode ◽

Photosynthetic Apparatus ◽

Chloroplast Ultrastructure ◽

Photon Flux ◽

Photon Flux Density ◽

Starch Granules ◽

Cherry Tomato ◽

Spongy Tissue ◽

Light Emitting ◽

Tissue Cells

The chloroplast structural alteration and the photosynthetic apparatus activity of cherry tomato seedlings were investigated under dysprosium lamp [white light control (C)] and six light-emitting diode (LED) light treatments designated as red (R), blue (B), orange (O), green (G), red and blue (RB), and red, blue, and green (RBG) with the same photosynthetic photon flux density (PPFD) (≈320 μmol·m−2·s−1) for 30 days. Compared with C treatment, net photosynthesis of cherry tomato leaves was increased significantly under the light treatments of B, RB, and RBG and reduced under R, O, and G. Chloroplasts of the leaves under the RB treatment were rich in grana and starch granules. Moreover, chloroplasts in leaves under RB seemed to be a distinct boundary between granathylakoid and stromathylakoid. Granathylakoid under treatment B developed normally, but the chloroplasts had few starch granules. Chloroplasts under RBG were similar to those under C. Chloroplasts under R and G were relatively rich in starch granules. However, the distinction between granathylakoid and stromathylakoid under R and G was obscure. Chloroplasts under O were dysplastic. Palisade tissue cells in leaves under RB were especially well-developed and spongy tissue cells under the same treatment were localized in an orderly fashion. However, palisade and spongy tissue cells in leaves under R, O, and G were dysplastic. Stomatal numbers per mm2 were significantly increased under B, RB, and RBG. The current results suggested blue light seemed to be an essential factor for the growth of cherry tomato plants.

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Flowering, Stem Extension Growth, and Cutting Yield of Foliage Annuals in Response to Photoperiod

HortScience ◽

10.21273/hortsci13789-18 ◽

2019 ◽

Vol 54 (4) ◽

pp. 661-666

Author(s):

Kellie J. Walters ◽

Allison A. Hurt ◽

Roberto G. Lopez

Keyword(s):

Growth And Development ◽

Light Emitting Diode ◽

Stem Elongation ◽

Growth Index ◽

Photon Flux ◽

Photon Flux Density ◽

Stock Plant ◽

Light Emitting ◽

Flowering Stem ◽

The Aesthetic

Foliage annuals are primarily grown for the aesthetic appeal of their brightly colored, variegated, or patterned leaves rather than for their flowers. Once foliage annuals become reproductive, vegetative growth of many species diminishes or completely ceases and plants can become unappealing. Therefore, the objectives of this study were to quantify how growth and development during production and stock plant cutting yield of bloodleaf (Iresine herbstii), Joseph’s coat (Alternanthera sp.) ‘Brazilian Red Hots’ and ‘Red Threads’, Persian shield (Strobilanthes dyerianus), and variegated potato vine (Solanum jasminoides) are influenced by photoperiod and night interruption (NI) lighting with or without far-red (FR) radiation. Photoperiods consisted of a 9-hour short day (SD) or a 9-hour SD extended to 10, 12, 13, 14, or 16 hours with red (R):white (W):FR light-emitting diode (LED) lamps (R:FR = 0.8) providing a total photon flux density (TPFD) of ≈2 µmol·m−2·s–1 of radiation. In addition, two treatments consisted of a 9-hour SD with a 4-hour NI from lamps containing the same R:W:FR or R:W LEDs (R:FR = 37.4). Bloodleaf plant and Joseph’s coat ‘Brazilian Red Hots’ and ‘Red Threads’ developed inflorescences or flowers under photoperiods ≤12 to 13 hours and were classified as obligate SD plants. Under LEDs providing R:W:FR radiation, stem elongation of reproductive bloodleaf and Joseph’s coat ‘Brazilian Red Hots’ and ‘Red Threads’ increased as photoperiod increased from 9 to 12 hours. In addition, stem elongation of bloodleaf, Joseph’s coat ‘Brazilian Red Hots’ and ‘Red Threads’, and Persian shield and growth index (GI = {plant height + [(diameter 1 + diameter 2)/2]}/2) of bloodleaf and Persian shield was significantly greater under NI with FR radiation than without FR radiation. Fewer or no cuttings were harvested from Joseph’s coat ‘Brazilian Red Hots’ and ‘Red Threads’ under photoperiods ≤12 or ≤13 hours, respectively. To prevent unwanted flowering of bloodleaf plant and Joseph’s coat, a photoperiod ≥14 hours or 4-hour NI must be maintained with LEDs providing either R:W or R:W:FR radiation, however; stem elongation is significantly reduced under R:W LEDs.

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Blue Light Monochromatic Irradiation for 12 Hours in Lighting Pattern with Combinations of Blue and Red Light Elongates Young Cos Lettuce Leaves and Promotes Growth under High Daily Light Integral

HortScience ◽

10.21273/hortsci15959-21 ◽

2021 ◽

pp. 1-6

Author(s):

Tomohiro Jishi ◽

Ryo Matsuda ◽

Kazuhiro Fujiwara

Keyword(s):

Flux Density ◽

Blue Light ◽

Light Emitting Diode ◽

Red Light ◽

Dry Weight ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Photosynthetic Photon Flux ◽

Leaf Elongation

Cos lettuce was grown under different spectral photon flux density distribution (SPFD) change patterns with blue- and/or red light-emitting diode (LED) irradiation with a 24-hour cycle. Twelve treatments were designed with a combination of four relative SPFD (RSPFD) change patterns and three photosynthetic photon flux density (PPFD) levels. The RSPFD change patterns were as follows: BR/BR, simultaneous blue- and red-light irradiation (BR) for 24 h; R/BR, red-light monochromatic irradiation (R) for 12 h followed by 12 hours of BR; B/BR, blue-light monochromatic irradiation (B) for 12 hours followed by 12 hours of BR; and B/R, 12 hours of B followed by 12 hours of R. Each RSPFD change pattern was conducted at three daily average photosynthetic photon flux densities (PPFDave) of 50, 100, and 200 µmol·m−2·s−1. The RSPFD change patterns that included B (B/BR and B/R) resulted in elongated leaves. A low ratio of active phytochrome to total phytochrome under B was considered the reason for leaf elongation. Shoot dry weight was significantly greater under the RSPFD change patterns that included B when the PPFDave was 200 µmol·m−2·s−1. The leaf elongation caused by B would have increased the amount of light received and thereby promoted growth. However, excessive leaf elongation caused the plants to fall, and growth was not promoted under the RSPFD change patterns that included B when the PPFDave was 50 µmol·m−2·s−1. Thus, 12-hour B promoted growth under conditions in which leaf elongation leads to increases in the amount of light received.

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THE EFFECT OF PHOTOSYNTHETIC PHOTON FLUX DENSITY ON CUCUMBER AND TOMATO TRANSPLANTS ASSIMILATIVE INDICES

Proceedings of the 7th International Scientific Conference Rural Development 2015 ◽

10.15544/rd.2015.030 ◽

2015 ◽

Author(s):

Aistė Bagdonavičienė ◽

Aušra Brazaitytė ◽

Julė Jankauskienė ◽

Pavelas Duchovskis

Keyword(s):

Solid State ◽

Leaf Area ◽

Weight Ratio ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Photosynthetic Photon Flux ◽

Light Emitting ◽

Net Assimilation ◽

Positive Effect

The objective of our studies was to evaluate the assimilative indices of cucumber (‘Pasalimo F1’) and tomato (‘Marissa F1’) transplants, cultivated under various photosynthetic photon flux densities (PPFD) were provided by light-emitting diodes (LEDs). Experiment was performed in phytotron complex of Institute of Horticulture, LRCAF. A system of high-power, solid-state lighting modules with 92 % 638 nm (red) + 665 nm (red) + 731 nm (far red) and 8 % 447 nm (blue) was used in the experiments. The generated PPFD of each type of five solid-state modules was ~200 and ~400 μmol m-2 s-1. Our experiment revealed that increased net assimilation rate (NAR) depended on increased PPFD of cucumber and tomato hybrid. 400 μmol m-2 s-1 LED illumination had positive effect on relative growth rate (RGR). Cucumbers which were grown under 200 μmol m-2 s-1 had bigger leaf area ratio (LAR) and specific leaf area (SLA), their development has been bigger as compared to higher 400 μmol m-2 s-1 PPFD. High PPFD LED illumination had positive effect on leaf weight ratio (LWR), shoot root ratio (SRR) and tomato transplants development. These studies with various photosynthetic photon flux densities (PPFD) and LEDs light should be continued throughout plant vegetation.

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Differential Effects of Low Light Intensity on Broccoli Microgreens Growth and Phytochemicals

Agronomy ◽

10.3390/agronomy11030537 ◽

2021 ◽

Vol 11 (3) ◽

pp. 537

Author(s):

Meifang Gao ◽

Rui He ◽

Rui Shi ◽

Yiting Zhang ◽

Shiwei Song ◽

...

Keyword(s):

Light Intensity ◽

Soluble Sugar ◽

Dry Weight ◽

Photosynthetic Photon Flux Density ◽

Carotenoid Content ◽

Photon Flux ◽

Photon Flux Density ◽

Artificial Light ◽

Plant Factory ◽

Phytochemical Contents

To produce high-quality broccoli microgreens, suitable light intensity for growth and phytochemical contents of broccoli microgreens in an artificial light plant factory were studied. Broccoli microgreens were irradiated under different photosynthetic photon flux density (PPFD): 30, 50, 70 and 90 μmol·m−2·s−1 with red: green: blue = 1:1:1 light-emitting diodes (LEDs). The broccoli microgreens grown under 50 μmol·m−2·s−1 had the highest fresh weight, dry weight, and moisture content, while the phytochemical contents were the lowest. With increasing light intensity, the chlorophyll content increased, whereas the carotenoid content decreased. The contents of soluble protein, soluble sugar, free amino acid, flavonoid, vitamin C, and glucosinolates except for progoitrin in broccoli microgreens were higher under 70 μmol·m−2·s−1. Overall, 50 μmol·m−2·s−1 was the optimal light intensity for enhancement of growth of broccoli microgreens, while 70 μmol·m−2·s−1 was more feasible for improving the phytochemicals of broccoli microgreens in an artificial light plant factory.

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