Article

The Research on LED Supplementary Lighting System for Plants

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Abstract

As an artificial light source, light-emitting diodes (LEDs) can be used to make the vegetables grow more quickly in closed-type plant production systems, especially in the environment of the light intensity is insufficient. In order to study the improvement of the cherry tomato growth rate using the LED light source, we have a design with a certain ratio of red and blue (relative spectral distribution) LED lighting system and carry out the manufacture of the LED supplementary lighting system. We carried on a track on the growth situation for a group of cherry tomatoes under the LED system and the other group of cherry tomatoes without the LED supplementary lighting system. We observed and compared with the growth of the two group of tomatoes in different growing period. In our experiment, we use supplementary lighting system with the red and blue LEDs which peak wavelenth are respectively 650 nm and 460nm, and the relative spectral distribution ratio is 4:1. The experimental results showed that the LED supplementary lighting system significantly improved the growth speed of tomatoes. Because of the difference preference for the wavelength between the stem and leaf growth stage and the blooming and bearing fruit growth stage, this paper presents the red and blue light proportion choice switch which can be applied to the LED supplementary lighting system.

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... Significant advancement in technology has led to the development of a new generation of luminaires. Additionally, a luminaire could have (i) sensor unit [6,9], (ii) driver unit [10], (iii) dimmer unit [11], and (iv) communication module [3]. Sensor unit might comprise of sensors such as occupancy sensor [6,11,12], temperature sensor, luminosity sensor [10] as per the requirement of the application. ...
... Additionally, a luminaire could have (i) sensor unit [6,9], (ii) driver unit [10], (iii) dimmer unit [11], and (iv) communication module [3]. Sensor unit might comprise of sensors such as occupancy sensor [6,11,12], temperature sensor, luminosity sensor [10] as per the requirement of the application. Driver unit facilitates to turn on and off, individual lighting bulbs in a luminaire. ...
... Illumination could be primarily classified as indoor and outdoor illumination. Smart home lighting [6,14], museum lighting [15], supplemental lighting for growing plants [10] are few examples of indoor illumination. Indoor illumination requires luminaires with less luminous intensity. ...
... Comparing the results, LED switch could yield better results for 9:1 and 4:1 to improve the efficiency and blue LED has a higher power requirement compared to red. [1] Blue light has a beneficial impact when absorbed by chlorophyll and is not affected by chloroplast movements and which is not distributed uniformly through the leaves compared to white, green or red light. [14] Table 5 Plants input requirements Table 5 shows the optimized requirements. ...
... This could change in the future where polar shift could vastly impact the predictability. Greenhouses provide extended possibilities to control the crops' growth environment and is a vital process via tailoring individual elements to optimize its efficiency, which leads to higher influence in sustainability for future crop harvest.Different species of plants vary in their preference for specific wavelengths of light at different stages.[1] Microgreens are now widely grown in every region of the world due to their growth rate and efficiency of nutrients intake. ...
Thesis
In this study, the effects of light frequency, spectrum, duration and water intervals at different working modes on Basil and Pak Choy is examined. The specimens were grown under two conditions, conventional indoors environment and a fully autonomous greenhouse environment. The plants were subjected to red and blue LED of 5:1 and 4:1 ratios in the autonomous system with a 16 hours exposure and was compared to the conventional indoors environment specimen with 4 hours exposure to sunlight. The water intervals for the autonomous system were set at 30 seconds in a 5 minutes interval from seed, until the plant reaches a height of 7 cm which represents its growth stage and changes to 60 seconds in a 4 hours interval. On the other hand, the conventional plants were watered twice daily at 0700hrs and 2300hrs and exposed to direct sunlight for 4 hours. The result shown a growth increase of 5.5 times for Basil and 1.4 times for Pak Choy compared to commercial method. The frequency of the water aids the formation of roots that were capable of developing trichome to increase the roots’ surface area. The changes on leaf density exposed to different light intensity have been determined as more sensitive parameters to detect its changes. The automation process of crops has significantly decrease required attention span on the process and increase uptake of plant yield. This thesis covers multiple study types such as In Vitro, In Vivo and In Silico insight to compare its validity and saturating multiple theories and knowledge to formulate a fully autonomous system capable creating sustainable food source.
... Lighting applications can be broadly classified as indoor and outdoor lighting applications. Indoor lighting applications include home lighting [6], office lighting [2], supplementary lighting system for plants [11], etc. Outdoor lighting applications include street lighting [4] and traffic control [3]. ...
... Light Emitting Diode (LED) luminaires revolutionized the lighting systems as it consumes less power, generates less heat and robust compared to its legacy counter parts. Various lighting systems have been widely discussed in the literature especially after the adaptation of LED luminaires in the lighting applications [4], [11], [12]. Contemporary smart luminaires could perform well with a fewer resources. ...
... Greenhouse horticulture has used supplementary lighting for many years. For this purpose various light sources have been used, but currently researchers are focused on application of light emitting diodes and their potential in cultivation of various species of plants 1,2,3,4,5 , also under water 6,7 . This is caused by several reasons including improving the quality of food 8,9 , avoiding hunger 10 , ecological production of energy 11 , decrease of energy consumption for horticulture 12 . ...
Conference Paper
Agriculture is one of the most important areas of the world economy. However, due to dependency on weather conditions, it is strongly industrialized, for example by introducing additional lighting improving the efficiency of plants growth. Construction and operation of light-emitting diodes provides new possibilities in research and application of new concepts in agricultural lighting. The aim of the work was to investigate the effect of various spectra of light on the efficiency of photosynthesis and the growth of selected species of plants. For this purpose two grow-boxes with dedicated LED-based lighting systems were constructed and placed in the darkroom with controlled temperature. In each box lighting system provided different spectral composition of light and it was possible to adjust the ratio of blue and red as well as the irradiance level. In the paper we present the construction of the grow-boxes and the results of 3 cycles of experiments conducted with this system. During the first cycle two groups of tested plants were cultivated in the LED grow-boxes with constant irradiance level and the third group in natural light conditions. During the second cycle the irradiance in both boxes was gradually increased from 8W/m2 to 38W/m2. During the third cycle the irradiance was set to 38 W/m2 during the whole period (max power MRED module) to get the maximum possible intensity of photosynthesis.
... Because of the foggy days, especially when the plants are growing at germination stage, they need adequate light illumination to finish their growth [1,2]. Therefore, in order to increase their production, supplementary lighting illumination is essential for greenhouse plants [3][4][5]. ...
... Study conducted by Potter and Duncombe (2012), has shown that, when light intensity is increased, the -tetrahydrocannabinol (THC) content of the cannabis is boosted because plants in brighter conditions produce proportionally more female flowers, which contain a greater concentration of THC. As an artificial light source, light-emitting diodes (LEDs) can be used to make the plants grow more quickly in closed-type plant production systems, especially in the environment of the light intensity is insufficient (Xu et al. 2016). LED lights do not consume much power, do not require ballasts and produce a fraction of the heat of High intensity discharge (HID) lamps (Thomas 2012). ...
Conference Paper
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The aim of this study was to investigate the effect of red (600-700 nm, peak 660), blue (400-500 nm, peak 450) and white light on the morphological and photosynthetic qualities of Cannabis sativa L. The two treatments were the white light (WL), and a combination of blue red lights (BR). Plants grown under WL were 23% taller than those grown under the BR light emitting diodes. The leaf area was also greater under WL than BR by 20%. The number of lateral branches and length of dominant lateral branch weren´t significantly different. It was concluded WL that emit a full spectrum of light affects plant growth and development better than BR light. The quantum efficiency ranged from 0.81 to 0.845 indicating the plants were not in stress.
... However, because of the use of artificial light, indoor plant production is one of the most energy-intensive forms of agriculture (Shamshiri et al., 2018). The successful development of new types of energy-saving, highly efficient luminous material technology can decrease the costs of LED light (Xu et al., 2016). ...
Article
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To increase the nutritional value and levels of essential minerals in vegetable food, microgreens are promising targets. The metabolic processes of microgreens can be managed with different cultivation techniques, which include manipulating the properties of light derived by light-emitting diodes (LEDs). In this study Brassicaceae microgreens (kohlrabi Brassica oleracea var. gongylodes, broccoli Brassica oleracea, and mizuna Brassica rapa var. Japonica) were cultivated under different light spectral quality, and the metabolic changes insoluble sugars (hexoses and sucrose), ascorbic acid, β-carotene, and contents of non-heme iron (Fe) and its connection with magnesium (Mg) or calcium (Ca) levels were monitored. Plants grew under the primary LED light spectrum (the combination of blue light at 447 nm, red at 638 and 665 nm, and far-red at 731 nm) or supplemented with LED green light at 520 nm, yellow at 595 nm, or orange at 622 nm. The photoperiod was 16 h, and a total PPFD of 300 µmol m-2 s-1 was maintained. Under supplemental yellow light at 595 nm, the content of soluble carbohydrates increased significantly in mizuna and broccoli. Under all supplemental light components, β-carotene accumulated in mizuna, and ascorbic acid accumulated significantly in kohlrabi. Under supplemental orange light at 622 nm, Fe, Mg, and Ca contents increased significantly in all microgreens. The accumulation of Fe was highly dependent on promoters and inhibitors of Fe absorption, as demonstrated by the very strong positive correlations between Fe and Ca and between Fe and Mg in kohlrabi and broccoli, and the strong negative correlations between Fe and β-carotene and between Fe and soluble carbohydrates in kohlrabi. Thus, the metabolic changes that occurred in treated microgreens led to increases in the contents of essential nutrients. Therefore, selected supplemental LED wavelengths can be used in the cultivation of Brassicaceae microgreens to preserve and increase the contents of specific nutritionally valuable metabolites.
... Sealed flasks present an increase in internal moisture and the content of gases (such as ethylene), which may decrease the number of leaves produced (Park et al. 2018) . Additionally, the photosynthetic rate can be compromised by the use of fluorescent lamps, which have light spectra and intensities that are not efficient for photosynthesis in several species (Xu et al. 2016). Mixotrophic systems, on the other hand, allow for gas exchange between flasks and the external environment while preventing the entrance of microorganisms, thereby improving plantlet morphology, transpiration rate and, consequently, plantlet survival rate in terms of acclimatization (Ševčíková et al. 2018). ...
Article
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Photomixotrophic micropropagation systems have been associated with improved development of several plant species. In this work, we established an efficient protocol for the in vitro micropropagation of Bambusa oldhamii Munro by studying the influence of the rainy and dry seasons on plant tissue contamination, the effects of the gaseous atmosphere inside the culture flasks, and the effects of radiation conditions on plant morphogenetic events. Explants were collected from March to December 2016. The conditions consisted of 100% blue (455 nm), 100% red (630 nm), 30% blue + 70% red, and 30% red + 70% blue LED light or fluorescent light only (as a control). For induction of axillary sprouting, the explants were inoculated in MS media + 2.27 µM thidiazuron or 3.40 µM paclobutrazol. The best growth responses were observed for material collected from June to July. There was an increase of 81.79% in the number of leaves under the 30% blue + 70% red LED treatment in comparison to the control. The facilitation of gas exchange resulted in improved shoot production, with an increase of 70.80% under 30% red + 70% blue LED light in comparison to that of treatments without gas exchange. The blue LED light had an important photomorphogenic effect on the development of bamboo explants into shoots, as shoot proliferation increased. The results obtained will aid in the development of protocols for the in vitro culture of other species of bamboo as well as for the establishment of an efficient protocol to address rooting for this and other bamboo species.
... The illuminance intensity formula can be converted into the cartesian coordination where the illuminance at any point P(x,y,z) can be obtained as in (3) where (X, Y, Z) represent the global coordination with respect to the light source. The equation to obtain the total illuminance from the LED matrix at any point in the surface can be represented in (4) [23]. ...
Preprint
Full-text available
The current revolution in communication and information technology is facilitating the Internet of Things (IoT) infrastructure. Wireless Sensor Networks (WSN) are a broad category of IoT applications. However, power management in WSN poses a significant challenge when the WSN is required to operate for a long duration without the presence of a consistent power source. In this paper, we develop a batteryless, ultra-low-power Wireless Sensor Transmission Unit (WSTx) depending on the solar-energy harvester and LoRa technology. We investigate the feasibility of harvesting ambient indoor light using polycrystalline photovoltaic (PV) cells with a maximum power of 1.4mW. The study provides comprehensive power management design details and a description of the anticipated challenges. The power consumption of the developed WSTx was 21.09µW during the sleep mode and 11.1mW during the operation mode. The harvesting system can harvest energy up to 1.2mW per second, where the harvested energy can power the WSTx for six hours with a maximum power efficiency of 85.714%.
... At the same time, plants with a short lifespan and a rapid onset of the generative phase of development have been studied. Most of the experiments were carried out on leafy green plants or potatoes, to obtain elite seeds [22][23][24][25]. ...
Article
Full-text available
A system for controlling the lighting up regime is proposed in the article, which gives the opportunity to reduce the cost of consumed electricity. The main element of the proposed control system is a processor, which calculates the necessary power of LED irradiators and the lighting up regimes according to a specially programmed program. For selecting the power and the regime of radiation of a given spectrum, a mathematical model of the geometry of the plant stalk in the process of its growth, obtained from the experimental data, is given. A two-factor experiment was carried out to determine the quantitative effect of the red and blue spectra emitted by LED sources on the geometry of the formed stalk of seed potatoes. The paper presents the results of the experimental studies on a genetically homogeneous material of potatoes grown from meristematic cells, making it possible to obtain reliable responses to different spectral composition of blue and red radiation of LED irradiators. The given system of controlling the lighting up regime allows growing the healthy plants in optimal photosynthesis with the minimal costs of electricity.
... For photosynthesis, plants need light of varying intensity and spectral distribution depending on their growth stages. In recent years, the use of light-emitting diode (LED) grow lights in large-scale indoor farming is increasing exponentially due to their ability to stimulate plant growth by providing controlled amounts of light at various growth stages [1][2][3][4]. LEDs are solid-state devices that emit light, the wavelengths of which lie in narrow bands with high photon flux, which allows the manipulation of the spectral characteristics and intensity of the light. ...
Article
Full-text available
Light-emitting diode (LED) grow lights are increasingly used in large-scale indoor farming to provide controlled light intensity and spectrum to maximize photosynthesis at various growth stages of plants. As well as converting electricity into light, the LED chips generate heat, so the boards must be properly cooled to maintain the high efficiency and reliability of the LED chips. Currently, LED grow lights are cooled by forced convection air cooling, the fans of which are often the points of failure and also consumers of a significant amount of power. Natural convection cooling is promising as it does not require any moving parts, but one major design challenge is to improve its relatively low heat transfer rate. This paper presents a novel heat sink design for natural convection cooling of LED grow lights. The new design consists of a large rectangular fin array with openings in the base transverse to the fins to increase air flow, and hence the heat transfer. Numerical simulations and experimental testing of a prototype LED grow light with the new heat sink showed that openings achieved their intended purpose. It was found that the new heat sink can transfer the necessary heat flux within the safe operating temperature range of LED chips, which is adequate for cooling LED grow lights.
... Currently, a strong demand has been observed in the field of LED sources which are commonly accepted as excellent replacements of classic light bulbs. Simultaneously with the development of LED sources, considerable interest has been noticeable also in the literature where studies of lighting and electrical parameters of LEDs have been presented, and LED-based applications have been considered [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. From the point of view of the average consumer, the fact of strong marketing conducted by the manufacturers of LEDs, which focuses only on the advantages of these types of light sources, is also notable. ...
Article
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This article presents considerations on the assessment of marking LED sources with the power of an equivalent light bulb. This problem was studied both on the basis of calculations and measurements performed. 17 LEDs of different powers and luminous fluxes were tested. Calculations assessing conformity with the declared power showed that an important disadvantage for most of the LED sources results from the method of marking them with the power of an equivalent light bulb from the point of view of the luminous flux emitted. Manufacturers do not do this correctly, misleading the potential user. Meanwhile, measurements performed in different ambient temperatures indicated that for only 4 from among the 13 LED sources studied the given value of the power of an equivalent light bulb may be recognized as in accordance with the actual state of affairs and still with a reservation that specified ambient temperature shall be required. In other cases the values of power quoted are either understated or overstated.
... Effects of wavelengths on plants (fromXu et al., 2016). ...
Article
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The present review draws together wide-ranging studies performed over the last decades that catalogue the effects of artificial-light-at-night (ALAN) upon living species and their environment. We provide an overview of the tremendous variety of light-detection strategies which have evolved in living organisms - unicellular, plants and animals, covering chloroplasts (plants), and the plethora of ocular and extra-ocular organs (animals). We describe the visual pigments which permit photo-detection, paying attention to their spectral characteristics, which extend from the ultraviolet into infrared. We discuss how organisms use light information in a way crucial for their development, growth and survival: phototropism, phototaxis, photoperiodism, and synchronization of circadian clocks. These aspects are treated in depth, as their perturbation underlies much of the disruptive effects of ALAN. The review goes into detail on circadian networks in living organisms, since these fundamental features are of critical importance in regulating the interface between environment and body. Especially, hormonal synthesis and secretion are often under circadian and circannual control, hence perturbation of the clock leads to hormonal imbalance. The review addresses how the ubiquitous introduction of light-emitting diode technology may exacerbate, or in some cases reduce, the generalized ever-increasing light pollution. Numerous examples are given of how widespread exposure to ALAN is perturbing many aspects of plant and animal behaviour and survival: foraging, orientation, migration, seasonal reproduction, colonization and more. We examine the potential problems at the level of individual species and populations and extend the debate to the consequences for ecosystems. We stress, through a few examples, the synergistic harmful effects resulting from the impacts of ALAN combined with other anthropogenic pressures, which often impact the neuroendocrine loops in vertebrates. The article concludes by debating how these anthropogenic changes could be mitigated by more reasonable use of available technology – for example by restricting illumination to more essential areas and hours, directing lighting to avoid wasteful radiation and selecting spectral emissions, to reduce impact on circadian clocks. We end by discussing how society should take into account the potentially major consequences that ALAN has on the natural world and the repercussions for ongoing human health and welfare.
... The type, spectra, intensity, and timing of supplemental lighting can each have a large influence on the effects of light on plants (Choong et al., 2018;Craig and Runkle, 2016;Demotes-Mainard et al., 2016;Gomez and Mitchell, 2015;Huch e-Th elier et al., 2016;Islam et al., 2012). HPS lamps have been a mainstay of horticultural lighting for many years, and for at least the past decade, LED lights have received considerable attention in horticulture because of their low power use and suitability for targeting particular spectra (Bantis et al., 2018;Hawley et al., 2018;Massa et al., 2008;Xu et al., 2016). Disadvantages of using HPS lighting are the production of radiant heat and their electrical inefficiency combined with a relatively short bulb lifespan, which can increase operation costs (Craver and Lopez, 2016). ...
Article
Full-text available
Modern citrus nursery production makes use of potted-tree propagation in greenhouses. Supplemental lighting is one method by which nursery tree growth and profitability may be significantly improved, but limited specific information is available. Five replicated experiments were conducted to determine the utility and effects of increasing daylength during the winter months by supplemental illumination from light-emitting diode (LED) or high-pressure sodium (HPS) lights in citrus nursery propagation. Studies used ‘Valencia’ sweet orange scion, the most common citrus cultivar grown in Florida, and the commercially important rootstocks sour orange, ‘Cleopatra’ mandarin, ‘US-812’, ‘US-897’, ‘US-942’, and ‘US-1516’. Comparisons used the three common types of citrus rootstock propagation: seed, stem cuttings, and micropropagation. Six responses were measured in the lighting experiments, including vegetative growth before budding, scion bud survival, and scion bud growth after budding. Supplemental HPS or LED light to extend daylength to 16 h in the citrus nursery during short-day winter months was observed to be effective in increasing unbudded rootstock liner growth and ‘Valencia’ scion growth on all rootstocks and propagation types. Generally, the positive effect on vegetative growth from an increased daylength was stronger with the HPS light than with LED light, while increasing daylength with LED light, but not HPS light, provided some increased bud growth initiation. Use of HPS or LED supplemental lighting to extend daylength offers significant growth advantage for the citrus nursery industry in winter.
... In the base tank, reaction monitoring and control systems are installed to maintain stable biodegradation, and substrate pumping rate is adjusted according to the quality of nutrition and natural evaporation. LED lights are provided for plants growing in each layer ( Xu et al., 2016). ...
Chapter
Excess nitrate in the nutrient solution of some hydroponic crop species has attracted the attention of regulatory agencies because this form of nitrogen can be often toxic to humans, especially children. Inclusion of ammonium in hydroponic nutrient solutions can promote significant increase in productivity and thus, help meet the growing demand for safer foods. However, several factors may alter the availability of ammonium to plants, which may lead to phytotoxicity. However, silicon can mitigate abiotic stresses such as ammonium phytotoxicity, and can be used to prevent possible damage to plants from this form of nitrogen. Therefore, the objective of this review was to gather research information about the nitrogen forms used in hydroponics, their relationships and peculiarities, as well as information on the use of silicon, its available sources and role in mitigating the toxic effects of ammonium.
... Currently, sodium lamps that contain the necessary radiation spectrum carry out the upper lighting. In this case, the duration and the control of the lighting process are important, since under general favorable microclimate conditions, photosynthesis quickly decays, as can be seen from the diagram (Fig. 2) obtained experimentally [13][14][15]. ...
Article
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Introduction. The article deals with the conditions for growing greenhouse plants. Supplementary lighting supports the process of plant photosynthesis and the microclimate in the greenhouse. The authors suggest the ways to reduce energy consumption in greenhouses by controlling the microclimate and process of supplementary lighting in greenhouses. Materials and Methods. Special lighting and temperature are required for growing greenhouse plants. A method of efficient plant growing is light and temperature control. The development of a control algorithm requires the mathematical models that relate the process of photosynthesis to the microclimate parameters. There are given the mathematical models based on the experimental data. Results. The control system and algorithm to control plant-growing conditions have been developed to maintain the greenhouse microclimate. LED lamps are used to control the lighting process. The authors present the developed block diagram of the control system, which contains four channels responsible for the main energy-intensive microclimate factors. The description of the algorithm of the greenhouse light-temperature control is given. Discussion and Conclusion. In conclusion, the need to maintain the greenhouse microclimate and supplementary lighting with the different radiation spectrum for the efficient cultivation of greenhouse plants is shown. The developed structure and control algorithm for the supplementary plant lighting process and greenhouse illumination through using LED lamps help reduce energy consumption.
... Night light can affect individual organisms differently depending on how the spectral composition and intensity of the light overlaps with the spectral sensitivity of the organism. Indeed, a wealth of research has now demonstrated that spectra of ALAN can cause variable responses within and across species (Ouyang et al. 2015;Brüning et al. 2016;Xu et al. 2016;Donners et al. 2018;Ulgezen et al. 2019;Diamantopoulou and Christoforou 2021). The invention of light-emitting diodes (LEDs) has made it easy to customize the light humans emit into the nightscape, but there is little consensus on which spectra will reduce consequences for all organisms (e.g., Davies et al. 2013;de Jong et al. 2017;Bolliger et al. 2020;Boom et al. 2020;Owens and Lewis 2021). ...
Article
Full-text available
Synopsis Artificial light at night (ALAN) is a pervasive anthropogenic pollutant, emanating from urban and suburban developments and reaching nearly all ecosystems from dense forests to coastlines. One proposed strategy for attenuating the consequences of ALAN is to modify its spectral composition to forms that are less disruptive for photosensory systems. However, ALAN is a complicated pollutant to manage due to the extensive variation in photosensory mechanisms and the diverse ways these mechanisms manifest in biological and ecological contexts. Here, we highlight the diversity in photosensitivity across taxa and the implications of this diversity in predicting biological responses to different forms of night lighting. We curated this paper to be broadly accessible and inform current decisions about the spectrum of electric lights used outdoors. We advocate that efforts to mitigate light pollution should consider the unique ways species perceive ALAN, as well as how diverse responses to ALAN scale up to produce diverse ecological outcomes.
... Another study showed that the supplementation with an appropriate ratio of blue and red light in LED phototherapy can increase the dry weight, number of leaves, and leaf area of tomatoes. It also promotes the growth of tomatoes by improving the efficiency of photosynthetic light utilization and regulating the root vitality under natural sunlight conditions in the greenhouse (Gomez and Mitchell, 2015;Xu et al., 2016;Paponov et al., 2020). In addition, supplementation with LED phototherapy using an appropriate ratio of blue and red light may promote the growth and nutrient absorption of lettuce, and makes some ornamental plants more compact, with increased stem diameters and chlorophyll content (Randall and Lopez, 2014;Pinho et al., 2016;Yan et al., 2020). ...
Article
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Normal development of plants is inhibited by inadequate light in winter in greenhouses in Northwest China. Growth lamps, using light-emitting diodes (LEDs) with red blue light (7R2B), were used to supplement daylight for 1, 2, and 3 h. Seedling growth, photosynthesis, and photosynthetic product; the Calvin cycle key and sugar metabolism-related enzymes and their encoding genes; and the light signal sensing regulation of key gene expression were studied in greenhouse cucumbers under three treatments to determine the best supplemental light durations to enhance cucumber cultivation in greenhouses in winter. Treatment with LED red and blue light for 3 h significantly promoted the growth and development of cucumbers, root growth, and dry matter accumulation. It improved the photosynthetic rate, photosynthetic pigment content, and light energy utilization efficiency in cucumbers. Supplementation with red and blue LED light for 3 h upregulated the expression levels of key genes encoding the Calvin cycle and enzymes related to sugar metabolism in cucumber leaves, which promoted the synthesis and accumulation of photosynthates. The expression levels of phytochrome B, cryptochrome 1, and hypocotyl 5 in the cucumber leaves were also significantly upregulated after 3 h of light supplementation. Combined LED red and blue light for 3 h should be used to supplement natural light to enhance the cucumber cultivation in greenhouses in winter.
... As a p-n junction diode, LED emits light in the form of photons when a proper voltage is applied. As a kind of efficient energy-saving lamp, LED is suitable for indoor lighting, street lighting, plant lighting and other lighting [49][50][51]. Further, it can be used in electronic and electrical products as backlight [52]. In fact, the luminescence of one 3 W LED is equivalent to that of one 15 W CFL or one 60 W incandescent light bulb (ILB). ...
Article
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The development path of the lighting industry in mainland China was studied in this work. Lighting electricity accounts for about 12% of social electricity consumption in mainland China, while only approximately 15% of electricity is conversed into light when incandescent light bulbs are used. To reduce electrical energy consumption and mercury emission from coal burning in the lighting industry, China worked out a roadmap to replace incandescent light bulbs with energy-saving fluorescent lamps (FLs). However, FL products utilize mercury to give out light and release mercury in their production, consumption and disposal processes. Therefore, the challenges of the lighting industry that mainland China are facing are controlling mercury pollution through the environmentally-friendly producing of fluorescent lamps, effective collecting and treating of spent fluorescent lamps. It was proposed that to effectively reduce energy consumption and mercury pollution, a good way to do this is developing energy-saving and mercury-free light emitting diode lighting industry. The mainland China Government’s strategies to develop lighting industry are worthy of consideration and emulation by other countries.
Article
Light is considered the most important environmental factor for greenhouse crops, and lack of lighting limits the productivity of greenhouses. Many studies have focused on improving the energy efficiency of lighting in agriculture. In this study, LED lights were mounted in the top, middle and bottom of the plant canopy to provide additional photosynthetically active radiation. Assuming that 100% of the predicted outdoor radiation is available, the canopy light distribution model was used to determine the relationship between the light energy consumption and the optimal yield. Decision-making on lighting scheduling may be considered as a constrained optimisation, and the status of the LEDs in a period acts as the decision variable. Besides, there are two objective functions: one is the energy consumed by the LED device; the other is the expected yield calculated by the crop model of tomatoes. The optimal solution of the multi-objective optimisation is not unique but corresponds to an infinite number of yield/energy combinations. Farmers can select these combinations according to additional restrictions such as energy efficiency ratio or photoperiod. The yield of our strategy was increased by 12.3% under the constraint of equal energy consumption compared to the greenhouse threshold control strategy. Given the same output as the constraint, the energy consumption was reduced by 30.1%. © The Chartered Institution of Building Services Engineers 2019.
Article
This paper presents a neural network-based control method for daylight harvesting in a proof-of-concept greenhouse consisting of emulated sunlight and dimmable LED light fixtures. The objective of this multi-input multi-output (MIMO) lighting system is to deliver desired levels of light, within a specific spectrum range, to locations of interest in a grow tent. To this end, a learning neural network controller with online adaptive weights is presented which can achieve stability with small errors in the presence of disturbances and modeling uncertainties. A stability analysis of the closed-loop system is presented along with a selection method for obtaining the control parameters. The neural controller is enhanced with an anti wind-up mechanism to account for the nonlinear effect of actuator saturation. Experimental results are presented to verify the proposed daylighting control strategy which confirm analytic and simulation studies.
Chapter
In this fast-growing digital world, social media analytics is gaining attention in the field of big data. Big data is the collection of huge amounts of raw digital data that is difficult to analyze with conventional analysis methods. Due to the popularity of social media sites such as Twitter and Facebook, a vast amount of public unstructured data is generated by millions of users every day. This raw bulk data cannot be directly used in decision making and prediction tasks. Therefore many researchers have been working on converting this huge unstructured information into meaningful information through big data analytics. Developing an efficient data analytics tool is essential to understand the multimodal social media data that improves the performance of decision-making and prediction systems. This chapter overviews the strengths of the current state-of-the-art feature engineering approaches that have been developed to represent the characteristics of social media data. In addition, this chapter outlines the proposed framework for analyzing the social media data including the shared images, tags, associated comments, and its social relationship.
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Plant factories have attracted increasing attention because they can produce fresh fruits and vegetables free from pesticides in all weather. However, the emission spectra from current light sources significantly mismatch the spectra absorbed by plants. We demonstrate a concept of using multiple broad-band as well as narrow-band solid-state lighting technologies to design plant-growth light sources. Take an organic light-emitting diode (OLED), for example; the resulting light source shows an 84% resemblance with the photosynthetic action spectrum as a twin-peak blue dye and a diffused mono-peak red dye are employed. This OLED can also show a greater than 90% resemblance as an additional deeper red emitter is added. For a typical LED, the resemblance can be improved to 91% if two additional blue and red LEDs are incorporated. The approach may facilitate either an ideal use of the energy applied for plant growth and/or the design of better light sources for growing different plants.
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The experiment was carried out in the winter and autumn of 2011 using lamb's lettuce (Valerianella locusta Laterr. Em Betce) as a test plant under greenhouse growing conditions. The aim of the study was to evaluate the effect of a prolonged day with modern SSL LED (Solid State Lighting Light Emitting Diodes) technology on photosynthetic parameters and plant yield. Two kinds of LED lamps with different spectral properties were used. The first emitted a white light and the second a mixture of red and blue light. Measurements of chlorophyll fluorescence and gas exchange were taken in natural and artificial light. Control plants were not treated with additional lighting. During the day with natural light in March (winter growing), photosynthesis intensity, stomatal conductance and transpiration of lamb's lettuce leaves were higher than in November (autumn growing). In the evening hours of March and November, during artificial plant lighting, similar photosynthesis intensity was observed. This intensity was significantly higher than in the afternoon hours (by natural light) in the autumn. The highest content of chlorophyll a, b and carotenoids was found in the treatment with red+blue LEDs in winter growing. Supplemental lighting with red+blue LED light stimulated the high efficiency of the photosynthetic apparatus, which was manifested by the highest Performance Index (PI). The highest weight of the rosettes was noted in the autumn growing period in plants that were under the influence of the red+blue supplemental lighting followed by the white LED. This could be the result of a significant stimulation of photosynthesis during supplemental lighting with the LED lamps during this period.
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