scholarly journals An Adaptive Control Approach for Light-emitting Diode Lights Can Reduce the Energy Costs of Supplemental Lighting in Greenhouses

HortScience ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 72-77 ◽  
Author(s):  
Marc W. van Iersel ◽  
David Gianino
Keyword(s):  
Duty Cycle ◽  
Light Emitting Diode ◽  
Production Costs ◽  
Photon Flux ◽  
Substantial Part ◽  
Response Curves ◽  
Light Emitting ◽  
Full Power ◽  
Supplemental Lighting ◽  
Led Lights

Supplemental lighting in greenhouses is often needed for year-round production of high-quality crops. However, the electricity needed for supplemental lighting can account for a substantial part of overall production costs. Our objective was to develop more efficient control methods for supplemental lighting, taking advantage of the dimmability of light-emitting diode (LED) grow lights. We compared 14 hours per day of full power supplemental LED lighting to two other treatments: 1) turning the LEDs on, at full power, only when the ambient photosynthetic photon flux (PPF) dropped below a specific threshold, and 2) adjusting the duty cycle of the LEDs so that the LED lights provided only enough supplemental PPF to reach a preset threshold PPF. This threshold PPF was adjusted daily from 50 to 250 μmol·m−2·s−1. Turning the LED lights on at full power and off based on a PPF threshold was not practical since this at times resulted in the lights going on and off frequently. Adjusting the duty cycle of the LED lights based on PPF measurements underneath the light bar provided excellent control of PPF, with 5-minute averages typically being within 0.2 μmol·m−2·s−1 of the threshold PPF. Continuously adjusting the duty cycle of the LED lights reduced electricity use by 20% to 92%, depending on the PPF threshold and daily light integral (DLI) from sunlight. Simulations based on net photosynthesis (An) − PPF response curves indicated that there are large differences among species in how efficiently supplemental PPF stimulates An. When there is little or no sunlight, An of Heuchera americana is expected to increase more than that of Campanula portenschlagiana when a low level of supplemental light is provided. Conversely, when ambient PPF >200 μmol·m−2·s−1, supplemental lighting will have little impact on An of H. americana, but can still results in significant increases in An of C. portenschlagiana (1.7 to 6.1 μmol·m−2·s−1 as supplemental PPF increases from 50 to 250 μmol·m−2·s−1). Adjusting the duty cycle of the LEDs based on PPF levels assures that supplemental light is provided when plants can use that supplemental light most efficiently. Implementing automated duty cycle control of LED grow lights is simple and low cost. This approach can increase the cost effectiveness of supplemental lighting, because of the associated energy savings.

scholarly journals Increasing Levels of Supplemental LED Light Enhances the Rate Flower Development of Greenhouse-grown Cut Gerbera but does not Affect Flower Size and Quality

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1332
Author(s):  
David Llewellyn ◽  
Katherine Schiestel ◽  
Youbin Zheng
Keyword(s):  
Flower Development ◽  
Vegetative Growth ◽  
Light Emitting Diode ◽  
Photon Flux ◽  
Light Emitting ◽  
Led Light ◽  
Linear Relationships ◽  
Content Index ◽  
Supplemental Lighting ◽  
Flower Quality

To investigate the influence of supplemental lighting intensity on the production (i.e., rate of flower development, flower quality, and yield) of cut gerbera during Canada’s supplemental lighting season (November to March), trials were carried out at a research greenhouse. Five supplemental light emitting diode (LED) light intensity (LI) treatments provided canopy-level photosynthetic photon flux densities (PPFD) ranging from 41 to 180 µmol m−2 s−1. With a 12-h photoperiod, the treatments provided 1.76 to 7.72 mol m−2 d−1 of supplemental light. Two cultivars of cut gerbera (Gerbera jamesonii H. Bolus ex Hook.f) were used to evaluate vegetative growth and flower production. Plugs of ‘Ultima’ were assessed for vegetative growth and rate of flower development. There were minor LI treatment effects on number of leaves and chlorophyll content index and flowers from plants under the highest versus the lowest LI matured 10% faster. Reproductively mature ‘Panama’ plants were assessed for flower yield and quality. ‘Panama’ flowers from the highest LI treatment had shorter stems than the three lowest LI treatments, and flowers from the middle LI treatment had larger diameter than the other treatments. Flowers from the lowest LI treatment had lower fresh mass than the three highest LI treatments. There were linear relationships between LI and numbers of flowers harvested, with the highest LI treatment producing 10.3 and 7.0 more total and marketable flowers per plant than the lowest LI treatment. In general, increasing levels of supplemental light had only minor effects on vegetative growth (young plants) and size and quality of harvested flowers (mature plants), but flowers from plants grown under higher LIs were more numerous and matured faster.

scholarly journals Light Emitting Diodes (LEDs) as Agricultural Lighting: Impact and Its Potential on Improving Physiology, Flowering, and Secondary Metabolites of Crops

2021 ◽  
Vol 13 (4) ◽  
pp. 1985
Author(s):  
Musa Al Murad ◽  
Kaukab Razi ◽  
Byoung Ryong Jeong ◽  
Prakash Muthu Arjuna Samy ◽  
Sowbiya Muneer
Keyword(s):  
Crop Production ◽  
Morphological Changes ◽  
Light Emitting Diode ◽  
Crop Productivity ◽  
Photon Flux ◽  
Flower Initiation ◽  
Nutrient Metabolism ◽  
Light Emitting ◽  
Cultivation Systems ◽  
Lighting Systems

A reduction in crop productivity in cultivable land and challenging environmental factors have directed advancement in indoor cultivation systems, such that the yield parameters are higher in outdoor cultivation systems. In wake of this situation, light emitting diode (LED) lighting has proved to be promising in the field of agricultural lighting. Properties such as energy efficiency, long lifetime, photon flux efficacy and flexibility in application make LEDs better suited for future agricultural lighting systems over traditional lighting systems. Different LED spectrums have varied effects on the morphogenesis and photosynthetic responses in plants. LEDs have a profound effect on plant growth and development and also control key physiological processes such as phototropism, the immigration of chloroplasts, day/night period control and the opening/closing of stomata. Moreover, the synthesis of bioactive compounds and antioxidants on exposure to LED spectrum also provides information on the possible regulation of antioxidative defense genes to protect the cells from oxidative damage. Similarly, LEDs are also seen to escalate the nutrient metabolism in plants and flower initiation, thus improving the quality of the crops as well. However, the complete management of the irradiance and wavelength is the key to maximize the economic efficacy of crop production, quality, and the nutrition potential of plants grown in controlled environments. This review aims to summarize the various advancements made in the area of LED technology in agriculture, focusing on key processes such as morphological changes, photosynthetic activity, nutrient metabolism, antioxidant capacity and flowering in plants. Emphasis is also made on the variation in activities of different LED spectra between different plant species. In addition, research gaps and future perspectives are also discussed of this emerging multidisciplinary field of research and its development.

Changes in light spectra modify secondary compound concentrations and BVOC emissions of Norway spruce seedlings

2020 ◽  
Author(s):  
Minna Kivimäenpää ◽  
Virpi Virjamo ◽  
Rajendra Prasad Ghimire ◽  
Jarmo Holopainen ◽  
Riitta Julkunen-Tiitto ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Blue Light ◽  
White Light ◽  
Carbon Allocation ◽  
Light Emitting Diode ◽  
Abiotic Stress Tolerance ◽  
Photon Flux ◽  
Emission Rates ◽  
Light Emitting ◽  
Light Spectra

Our objective was to study how changes in the light spectra affects growth, carbohydrate, chlorophyll, carotenoid, terpene, alkaloid and phenolic concentrations, and BVOC (biogenic volatile organic compound) emissions of Norway spruce (Picea abies) seedlings. This study was conducted during the growth of the third needle generation in plant growth chambers. Two light spectra with the main difference in proportion of blue light (400-500 nm) and equal photon flux densities were provided by LED (light-emitting diode) lamps: 1) control (white light + 12 % blue light) and 2) increased blue light (+B) (white light + 45% blue light). The +B treatment increased needle concentrations of total flavonoids and acetophenones. The major changes in the phenolic profile were an accumulation of astragalin derivatives and the aglycone of picein. +B decreased concentrations of the main alkaloid compound, epidihydropinidine, and it’s precursor, 2-methyl-6-propyl-1,6-piperideine, emission rates of limonene, myrcene and total monoterpenes, and concentrations of a few terpenoid compounds, mainly in stems. Growth, needle carbohydrates and pigments were not affected. The results suggest that supplemental blue light shifts carbon allocation between secondary metabolism routes, from alkaloid and terpenoid synthesis to flavonoid and acetophenone synthesis. The changes may affect herbivory and abiotic stress tolerance of Norway spruce.

scholarly journals LED Lights Affecting Morphogenesis and Isosteroidal Alkaloid Contents in Fritillaria cirrhosa D. Don—An Important Chinese Medicinal Herb

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1351
Author(s):  
Chia-Chen Chen ◽  
Maw-Rong Lee ◽  
Chi-Rei Wu ◽  
Hsin-Ju Ke ◽  
Hui-Min Xie ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Light Emitting Diode ◽  
Basal Medium ◽  
Gelling Agent ◽  
Embryogenic Calli ◽  
Chinese Medicinal Herb ◽  
Light Emitting ◽  
Light Spectra ◽  
Led Lights ◽  
Fritillaria Cirrhosa

Investigations were carried out to study the effects of light-emitting diode (LED) lights on growth and development of isosteroidal alkaloids in embryogenic calli of Fritillaria cirrhosa D. Don, an important traditional Chinese medicine herb. Calli were cultured in glass bottles, each containing 100 mL of Murashige and Skoog’s basal medium supplemented with 2% sucrose and 0.4% gellan gum powder, a gelling agent. These bottles were incubated in a specially designed plant growth chamber equipped with eight different LED lights consisting of single or combinations of four different light spectra emitting blue (450 nm), green (525 nm), red (660 nm), and far-red (730 nm) light. After three months of incubation, morphological changes in embryogenic calli were recorded, and LC-MS/MS analysis of cultures was carried out for peimisine, sipeimine, peiminine, and peimine. The highest number of somatic embryos and the maximum fresh weight was recorded in calli incubated under red (9R), infrared (9IR), and a combination of red+blue+infrared (3R3B3IR), respectively, in decreasing order. The highest contents of peimisine, peiminine, and peimine were recorded under red (9R) and infrared (9IR) lights, respectively. Eight LED lights had significant effects on the morphogenesis of embryogenic calli of F. cirrhosa D. Don and contents of isosteroidal alkaloids.

scholarly journals Impedance Measures and a Mounting Technique for Drosophila: Larval Movements, Heart Rate, Imaging, and Electrophysiology

2020 ◽  
Vol 3 (1) ◽  
pp. 12
Author(s):  
Noah de Castro ◽  
Robin Lewis Cooper
Keyword(s):  
Neuromuscular Junctions ◽  
Light Emitting Diode ◽  
Bright Light ◽  
Infrared Camera ◽  
Synaptic Function ◽  
Light Emitting ◽  
The Media ◽  
Led Lights ◽  
Suitable Technique ◽  
Larval Movement

Monitoring movements of larval Drosophila with electrical detection allows one to record the behaviors without the use of lights and cameras. This is a suitable technique when studying the use of light-sensitive proteins in optogenetic studies. Electrical measures are feasible to use in determining when a larva starts to move or continues to move after a light induced activation of channelrhodopsin. We have developed a technique using an electrical measure of the media as an index of larval movement. As a proof of concept, recordings with an infrared camera of the larval movement were simultaneous made with electrical measures. The two techniques parallel each other in their ability to index larval movements. Bright light-emitting diode (LED) lights used in optogenetic experiments tend to saturate the detectors of the camera unless filters are used and different filters maybe necessary depending on the LED spectrum and sensitivity of the camera. Impedance measures are independent of the type of LED or brightness. We also assessed the use of a non-solvent based glue (3M Vetbond) to hold larvae in place while measuring synaptic function of neuromuscular junctions, cardiac function and influence of modulators, or activation of light-sensitive channels.

Discomfort glare caused by white LEDs having different spectral power distributions

2017 ◽  
Vol 50 (6) ◽  
pp. 921-936 ◽  
Author(s):  
WJ Huang ◽  
Y Yang ◽  
M Ronnier Luo
Keyword(s):  
White Light ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
White Leds ◽  
Significant Difference ◽  
Discomfort Glare ◽  
Led Lights ◽  
Green Leds

This paper describes an experiment to investigate discomfort glare caused by white light-emitting diode (LED) lights having different spectral power distributions. It included two groups: a ‘Metamerism’ group and a ‘correlated colour temperatures (CCT)’ group. In the former group, it was found that white lights at 7000 K constructed from different blue LEDs and the same red and green LEDs gave about the same glare perception. In the latter group, there was a significant difference in glare perception between white lights having different CCTs. Finally, glare models, including unified glare rating (UGR) and the newly derived QUGRspd, and mUGRspd models, were tested using the data from the experiment. All of them gave quite accurate predictions of the data.

scholarly journals Photochemical Acclimation of Three Contrasting Species to Different Light Levels: Implications for Optimizing Supplemental Lighting

2017 ◽  
Vol 142 (5) ◽  
pp. 346-354 ◽  
Author(s):  
Shuyang Zhen ◽  
Marc W. van Iersel
Keyword(s):  
Electron Transport ◽  
Light Intensity ◽  
Photochemical Efficiency ◽  
Light Response ◽  
High Light ◽  
Photon Flux ◽  
Ambient Light ◽  
Response Curves ◽  
Low Light ◽  
Supplemental Lighting

Photosynthetic responses to light are dependent on light intensity, vary among species, and can be affected by acclimation to different light environments (e.g., light intensity, spectrum, and photoperiod). Understanding how these factors affect photochemistry is important for improving supplemental lighting efficiency in controlled-environment agriculture. We used chlorophyll fluorescence to determine photochemical light response curves of three horticultural crops with contrasting light requirements [sweetpotato (Ipomea batatas), lettuce (Lactuca sativa), and pothos (Epipremnum aureum)]. We also quantified how these responses were affected by acclimation to three shading treatments-full sun, 44% shade, and 75% shade. The quantum yield of photosystem II (ΦPSII), a measure of photochemical efficiency, decreased exponentially with increasing photosynthetic photon flux (PPF) in all three species. By contrast, linear electron transport rate (ETR) increased asymptotically with increasing PPF. Within each shading level, the high-light-adapted species sweetpotato used high light more efficiently for electron transport than light-intermediate lettuce and shade-tolerant pothos. Within a species, plants acclimated to high light (full sun) tended to have higher ΦPSII and ETR than those acclimated to low light (44% or 75% shade). Nonphotochemical quenching (NPQ) (an indicator of the amount of absorbed light energy that is dissipated as heat) was upregulated with increasing PPF; faster upregulation was observed in pothos as well as in plants grown under 75% shade. Our results have implications for supplemental lighting: supplemental light is used more efficiently and results in a greater increase in ETR when provided at low ambient PPF. In addition, high-light-adapted crops and crops grown under relatively high ambient light can use supplemental light more efficiently than low-light-adapted crops or those grown under low ambient light.

scholarly journals Data Communication Security Issues of Wi-Fi over Li-Fi

2019 ◽  
Vol 8 (3) ◽  
pp. 1977-1981
Keyword(s):  
Light Emitting Diode ◽  
Denial Of Service ◽  
Data Communication ◽  
Electrical Signal ◽  
Visible Light Communications ◽  
Light Emitting ◽  
Security Issues ◽  
The One ◽  
Audio Video ◽  
Led Lights

Visible Light Communications (VLC) system is called Light Fidelity One such example, analog data is passed to a LED (Light-Emitting Diode) bulb (using signal processing technology), after that it transmits data (which is implanted in its beam) to the detector or photodiode. The small commutes in the brisk feeble of LED bulbs is modulated by the receiver circuit into electrical signal. The signal is then reversed into a duplex data runnel that could be recognized in the same way that of audio, video and web programs that run on devices that has internet enabled. Wi-Fi is vulnerable to breaches involving various security issues such as Rouge Access Points, Denial of Service, Wireless Trespasser, Data Interruption, End point attacks etc. To overcome such restrictions, this paper proposes application level substructure for data communication using Li-Fi (Light Fidelity) Technology. By using LED lights as a transmission medium, the indoor wireless communication is achieved in much faster rate than the one WiFi (Wireless Fidelity) can provide.

scholarly journals Phototactic Response of the Oriental Armyworm, Mythimna separata (Lepidoptera: Noctuidae), to Light-Emitting Diode Lights of Different Wavelengths

2019 ◽  
Author(s):  
Kil-Nam Kim ◽  
Hye-Sung Song ◽  
Ryong-Jin Choe ◽  
Zhi-Juan Huang ◽  
Qiu-Ying Huang ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Insect Pest ◽  
Light Trap ◽  
Mythimna Separata ◽  
Light Emitting ◽  
Led Light ◽  
Phototactic Response ◽  
Green Led ◽  
Oriental Armyworm ◽  
Led Lights

Recently, light traps using light-emitting diode (LED) lights have been applied to monitor or control insect pests. The oriental armyworm, Mythimna separata Walker, is an important insect pest that has caused damage to several cereal crops, including corn, wheat and rice. The present study aims to seek out a sensitive wavelength causing high phototactic response in M. separata. The study evaluated the phototactic responses of M. separata moths to several LED lights of different wavelengths and luminance intensities under laboratory condition. Results showed that green (520 nm) LED light resulted in significant phototactic response of M. separata moths compared to LED lights of other wavelengths. Additionally, the highest attraction rate of the moths to green LED light appeared in luminance intensity group of 200 lux compared to the other intensities groups. Experiments under optimum conditions based on the above experiments revealed that the green LED light exhibited the strongest attraction rate (64.44%) among all experimental groups. An experiment performed in a net cage also showed that green LED light resulted in the highest phototactic response of M. separata moths, 1.7 times more than a commercial black light used as control. These findings clearly demonstrate that M. separata moths have a high sensitivity to the green LED light. Therefore, a light trap equipped with green LED light could be useful for monitoring and controlling M. separata moths.

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