Search Results (211)

The inclusion of the Internet of Things (IoT) in indoor agricultural systems has become a fundamental tool for improving cultivation systems by providing key information for decision-making in pursuit of better performance. This article presents the design and implementation of an IoT-based agricultural system installed in a plant growth chamber for hydroponic cultivation under controlled conditions. The growth chamber is equipped with sensors for air temperature, relative humidity (RH), carbon dioxide (CO₂) and photosynthetically active photon flux, as well as control mechanisms such as humidifiers, full-spectrum Light Emitting Diode (LED) lamps, mini split air conditioner, pumps, a Wi-Fi surveillance camera, remote monitoring via a web application and three Nutrient Film Technique (NFT) hydroponic systems with a capacity of ten plants each. An ATmega2560 microcontroller manages the smart system using the MODBUS RS-485 communication protocol. To validate the proper functionality of the proposed system, a case study was conducted using lettuce crops, in which the impact of different nutrient solution concentrations (50%, 75% and 100%) on the phenotypic development and nutritional content of the plants was evaluated. The results obtained from the cultivation experiment, analyzed through analysis of variance (ANOVA), show that the treatment with 75% nutrient concentration provides an appropriate balance between resource use and nutritional quality, without affecting the chlorophyll content. This system represents a scalable and replicable alternative for protected agriculture. Full article

Modern life, characterized by constant exposure to artificial light from electronic devices, such as light-emitting diodes (LEDs), disrupts the natural circadian rhythm and induces important metabolic changes. The impact of blue light exposure on male and female rat’s onset of puberty, hormonal and biochemical parameters was assessed by comparison between the four study groups: the control group (CTRL) maintained under normal light conditions, the group exposed to blue light from a mobile phone (MP), the group subjected to blue light from a computer screen (PC), and the group exposed to blue light from an LED lamp (LED). Both female and male rats exposed to PC and LED failed to thrive, with a significantly lower body weight intake than the CTRL group. All three distinct sources of blue light interfered with the cyclicity of the estrous cycle in female rats. A marked decrease in the number of complete estrous cycles and the highest incidence of incomplete cycles were noticed in the LED group. Elevated ALT, AST, glucose, and insulin levels were influenced in a gender-specific manner, and depending on the source of emitted light. Prolonged blue light exposure induces significant metabolic disruptions and possesses important future research potential in identifying explicit pathways regarding this environmental stressor. Full article

Constant luminous flux lamps are required for ensuring reliable and consistent illumination in various applications, including emergency lighting, outdoor activities, and general use. However, some activities may require maintaining a constant luminous flux, where the design must control the current during the use. This paper presents the design of a portable light-emitting diode (LED) lighting system powered by batteries that maintains constant luminous flux using the zero-average dynamic control (ZAD) and a proportional-integral-derivative (PID) controllers. This system can adapt the current to maintain the luminous flux required for reliable portable lighting applications used in outdoor activities. The results show that the system can provide constant illumination with 12-volt, 18-volt, and 24-volt batteries, and a 12-volt battery with a state of charge of 10%, enhancing usability for outdoor activities, emergency situations, and professional applications. Full article

The effect of lighting basil with LED DR/B LB (Light Emitting Diode deep red/blue low blue) lamps throughout the cultivation cycle or for only 7 days before harvest, after the period of using HPS (High Pressure Sodium) lamps, was studied in comparison with the use of HPS lamps only, at the same light intensity. Plants of two Genovese type basil cultivars, recommended for pot and hydroponic cultivation, were used for the experiment. Plant growth observations were made and herb and leaf yields, dry matter, nitrates, potassium, phosphorus, calcium, total sugars, total soluble solids, ascorbic acid, chlorophylls, and carotenoids were determined. Plants of both tested basil cultivars grown under LED lighting were characterized by a higher content of ascorbic acid, carotenoids, and sugars and a lower content of nitrates than those grown under HPS lights. In plants grown under LED lighting only, nitrate content was on average 31% lower than under HPS lamps. The use of LEDs for the last 7 days of cultivation resulted in a significant reduction in nitrate content in only one of the studied cultivars. Further research on the effect of lighting type on sweet basil yield and quality, depending on other factors, both genetic and environmental, is recommended. Full article

The presence of fungal spores in water poses a significant risk to public health, requiring effective inactivation strategies. Ultraviolet (UV) radiation is a widely used approach, traditionally employing mercury vapor lamps. However, these lamps have efficiency limitations and contain hazardous materials. As an alternative, ultraviolet light-emitting diodes (UV-LEDs) have emerged as a safer and more sustainable option. Despite their advantages, research on their efficacy against fungal spores remains limited. This study investigates the inactivation and post-exposure response of Aspergillus niger and Penicillium sp. spores using a collimated UV-LED system. The impact of two different wavelengths (265 nm and 280 nm) and post-treatment conditions (light and darkness for 24 h) on fungal viability was analyzed. Kinetic modeling was applied to assess the resistance of the spores and their capacity for photoreactivation. The results demonstrate that both the UV wavelength and the environmental conditions after exposure significantly influence disinfection outcomes. Penicillium sp. exhibited greater susceptibility to UV radiation but also higher photoreactivation potential, while A. niger showed stronger resistance and lower recovery capacity. The UV dose required for 99% inactivation, considering photoreactivation effects, was 323.7 ± 90.0 mJ cm⁻² and 321.9 ± 43.8 mJ cm⁻² for A. niger, whereas for Penicillium sp., it was 167.7 ± 13.0 mJ cm⁻² and 146.5 ± 29.2 mJ cm⁻² at 265 nm and 280 nm, respectively. These findings emphasize the necessity of tailoring UV-LED disinfection strategies based on the specific characteristics of the target organisms and post-treatment environmental factors. Full article

In this study, for first time, the efficiency of the yield and fruit quality of the pink tomato cultivar ‘Tomimaru Muchoo’ was studied in hydroponic cultivation with top and interlighting with LEDs (light-emitting diodes) and diffusion glass (DGlass) to cover the glasshouse roof (LED+LED+DGlass). DGlass was also tested in tomato cultivation with only top lighting by sodium lamps (HPS+DGlass). The control, which had no DGlass (HPS, high-pressure sodium), was a crop with sodium lamps from above, where the roof was covered with conventional glasshouse glass. Selected parameters of tomato plant growth and development, photosynthetic activity, and chemical composition were analysed. Tomato fruits were evaluated for their physical and chemical characteristics as well as sensory quality. LED+LED+DGlass-supplemented tomato plants had the shortest fruiting stems, a higher dry matter of leaves, higher Mg²⁺ ion concentration, and photosynthetic apparatus activity (PI, PSII performance index) compared with the control (HPS). More light under DGlass conditions with and without LEDs (HPS+DGlass and LED+LED+DGlass) increased the tomato leaf thickness and number of mesophyll layers. The highest tomato fruit yield was obtained in the LED+LED+DGlass combination compared with the conventional growing technology (HPS). Fruits from this combination were characterised by the highest total soluble solids (TSS), carotenoids, and ascorbic acid content and the most favourable sugar/acid ratio. In the sensory evaluation, these fruits were sweeter and less acidic than fruits from the other crop combinations. The results obtained confirm the significant influence of light quality on plant growth, development, and yield. Full article

This study presents a pioneering investigation into the use of Light Emitting Diodes (LEDs) for in vitro rooting of ‘Marubakaido’ apple tree rootstocks, marking the first report of this approach in the literature. The research evaluates the effects of four distinct light sources: blue LED (450 nm), red LED (660 nm), a combination of red and blue LEDs, and traditional fluorescent lamps as a control. Mini-cuttings were inoculated in Murashige and Skoog (MS) medium with reduced nutrient concentrations, supplemented with indoleacetic acid (IAA) and sucrose. The explants were incubated under controlled conditions for 30 days, enabling a comprehensive assessment of the impact of different light sources on various growth metrics. The results revealed that blue LEDs significantly enhanced dry mass accumulation in seedlings compared to both red LEDs and fluorescent lamps, demonstrating their superior effectiveness in promoting plant growth. The use of LEDs not only improves seedling development but also offers economic advantages over fluorescent lamps. LEDs are characterized by high luminous efficiency, low energy consumption, and a long operational lifespan, which collectively reduce costs in plant production systems. This research advances the understanding of light-mediated effects on plant tissue culture and highlights the potential of combining blue and red LEDs as a viable alternative to fluorescent lighting. These findings could revolutionize practices in horticulture and plant propagation, providing a more efficient and sustainable approach to in vitro cultivation. Full article

Lighting is a fundamental driver of plant productivity in controlled-environment agriculture (CEA), directly affecting physiological processes, resource efficiency, and sustainability. This study evaluates the effects of distinct lighting systems, industrial Light-Emitting Diodes (iLEDs), horticultural LEDs (hLEDs), high-pressure sodium (HPS) lamps, and controls (no supplemental light), each providing unique light spectra, on cucumber (Cucumis sativus L.) growth, physiology, and environmental impact under a controlled light intensity of 250 µmol m⁻² s⁻¹ in a commercial CEA setup. The results indicated that iLEDs enhance intrinsic water use efficiency (35.65 µmol CO₂/mol H₂O) and reduce transpiration, reflecting superior physiological resource use. Electrophysiological measurements indicated significantly more stable stress responses in plants subjected to iLEDs and hLEDs as compared to HPS and control treatments, indicating the effectiveness of LED light spectra in mitigating stress-related physiological impacts. Furthermore, compact growth and shorter stem internodes were observed under iLEDs as well as hLEDs, highlighting the spectral effects on photomorphogenesis, likely caused by a balanced light spectrum. HPS lighting achieved the highest yield (42.86 kg m⁻²) but at a significant environmental cost, with 342.65 kg CO₂e m⁻² emissions compared to 204.29 kg CO₂e m⁻² for iLEDs, with competitive yield of 38.84 kg m⁻². Economic analysis revealed that iLEDs also offered the most cost-effective solution due to lower energy consumption and extended lifespan. This study focused on the interaction between light spectra, photosynthetic performance, stress resilience, and resource efficiency, advancing sustainable strategies for energy-efficient food production in CEA systems. Full article

Artificial light at night (ALAN) is an expanding environmental issue, particularly in urban areas. This review aimed to present the state of the art regarding the impact of ALAN on specific and interrelated aspects related to physiological processes and life cycle events in tree species. The reviewed studies highlighted the multifaceted effects of artificial light on plants, offering insights and perspectives to guide future research in this evolving and stimulating field. ALAN disrupts circadian rhythms, alters photoperiodic responses, and affects photosynthesis and carbohydrate metabolism. Changes in phenology such as delayed senescence and altered budburst timing demonstrated species-specific responses, often compounded by other urban stressors like heat and drought. Despite an increased interest, knowledge gaps remain concerning the species-specific responses and the effects of light spectra as well as the long-term consequences on tree physiology. These gaps highlight the need for integrated research approaches and urban planning strategies to mitigate ALAN effects, ensuring the resilience of urban trees and preserving ecosystem services in the context of growing urbanization and climate change. Full article

Energy consumption in buildings is linked to lighting technology. Light-emitting diode (LED) technology includes lamps and luminaires for general lighting applications. Due to their structure, LED lamps are expected to generate specific waste electrical and electronic equipment (WEEE) streams. LEDs are the main source of luminous flux, and their elemental composition is of particular interest to the recycling sector. In this study, surface-mount device (SMD) LEDs from six types of LED lamps (E27, E14, G9, R7S, GU10, and MR16) were removed, collected, separated by correlated colour temperature (CCT) (2700 K, 3000 K, 4000 K, and 6500 K), and characterised for the presence of rare earth elements and precious metals. They were digested with HNO₃, aqua regia, and HF in a hot plate and characterised by inductively coupled plasma mass spectrometry (ICP-MS). The concentration of each element as a function of CCT ranged as follows: lanthanum, 242–1840 mg/kg; cerium, 132–284 mg/kg; europium, 15–69 mg/kg; gadolinium, 1.9–3.8 mg/kg; terbium, 0.1–0.4 mg/kg; lutetium, 29–6381 mg/kg; yttrium, 4804–11,551 mg/kg; silver, 2712–5262 mg/kg; gold, 502–956 mg/kg; and palladium, 32–110 mg/kg. These results indicate the need for selective removal and separate recycling processes of SMD LEDs from LED lamps. Full article

The aim of this study was to evaluate the growth and flowering characteristics of three Oncidesa cultivars under four distinct canopy treatments in a greenhouse environment. The control canopy treatment (canopy D) involved covering the greenhouse with black shade nets to reduce natural light penetration. Canopy B included black shade nets in combination with a transparent plastic screen on the sides to further modify the light conditions. Additionally, two other treatments were applied: black shade nets with (canopy A) or without (canopy C) plastic sheeting, supplemented with daily lighting from high-pressure sodium lamps. Ten horticultural traits were measured to assess the impact of these canopy treatments on different cultivars at various growth stages. The results show that canopy treatments significantly affected all the measured traits of the Oncidesa cultivars, except for leaf width. Apollo plants treated under canopy A exhibited longer and thicker pseudobulbs, wider leaves, higher chlorophyll content, and a greater number of branches and florets compared to Honey Angel and Golden Star. Plants under canopy C showed superior growth traits across all cultivars, while those under canopies A and D exhibited better flowering quality. These findings suggest that different canopy treatments had varying effects on the growth and flowering traits of Oncidesa cultivars, with each cultivar showing distinct adaptability to specific canopy conditions. Full article

The sweet basil Ocimum basilicum L. is the subject of numerous studies and is cultivated as a food and ornamental plant. Moreover, O. basilicum could be useful in the prevention of stroke ischemia, and its anticancer properties were recently shown. Caffeic acid derivatives, such as rosmarinic acid (RA), chicoric acid, salvianolic acids, and anthocyanins, provide the medicinal properties of basil. Therefore, investigations of the optimal growth conditions that can provide cost-effective cultivation of highly productive basil plants are relevant and important. The aim of the present work was to study the effects of a combination of soil composition and light conditions on the morphological and biochemical characteristics of O. basilicum. In totally artificial (indoor) environments, light-emitting diodes (LEDs) may provide a broad range of narrowband wavelengths with different intensities. This technology can lower operating costs. In addition to the spectral composition, light intensity (PPFD, µmol m⁻²s⁻¹) is an important parameter for the optimal growth of plants. In the experiment, we used different spectra of LED lamps with intensities of 300 µmol m⁻²s⁻¹: warm white, monochromatic (green and red), and a combination of blue and red. Plants were grown under various lighting conditions in soil supplemented with fertilizer, Z-ion, and Crystallon. The results showed that supplementation of soil with Crystallon had a greater effect on the growth of both above- and below-ground parts of O. basilicum plants. Interestingly, growing O. basilicum plants under R and RB light led to a 2-fold increase in the biosynthesis of both the key caffeic acid derivative RA and anthocyanin. However, given that under RB light, there is no positive effect of Crystallon on growth, the productivity of RA and anthocyanin reached a maximum when O. basilicum plants were grown under R light and Crystallon. Under these conditions, the productivity of anthocyanins and caffeic acid derivatives in O. basilicum was more than eight times greater than that in untreated O. basilicum plants. Full article

Disruptions in power quality have a negative impact on many energy consumers. These include lighting, where interference manifests itself, among others, in the form of light flickering. The article presents phenomena accompanying the operation of modern light sources against the background of exemplary results of studies on the flicker of conventional light sources, such as incandescent or fluorescent lamps. The flickering effect of light generated in modern lamps can occur under stable voltage conditions in the supply network. The main subjects of the conducted research were solid-state light sources—light-emitting diode (LED) lamps, currently available on the lighting market. To assess the effects of these phenomena, it is necessary to use measures other than those traditionally used. The method used allows for the measurement of flicker resulting from both power supply disturbances and the properties of modern light sources. Using the developed measurement system, it is possible to record temporal changes in flicker coefficients resulting from, for example, changing supply voltage conditions. Due to the possibility of flickering light from sources offered by different manufacturers, as shown by research, it is advisable to carry out measurements at the place of use of the lighting. Full article

Simultaneous illumination and communication using solid-state lighting devices like white light-emitting diode (LED) light sources is gaining popularity. The white light LED comprises a single-colored yellow phosphor excited by the blue LED chip. Therefore, color-quality determining parameters like color-rendering index (CRI), correlated color temperature (CCT), and CIE 1931 chromaticity coordinates of generic white LED sources are poor. This article presents the development of multi-color phosphors excited by a blue LED to improve light quality and bandwidth. A multi-layer stacking of phosphor layers excited by a blue LED led to the quenching of photoluminescence (PL) and showed limited bandwidth. To solve this problem, a lens-free, electrically powered, broadband white light source is designed by mounting multi-color phosphor LEDs in a co-planar ring-topology. The CRI, CCT, and CIE 1931 chromaticity coordinates of the designed lamp (DL) were found to be 90, 5114 K, and (0.33, 0.33), respectively, which is a good quality lamp for indoor lighting. CRI of DL was found to be 16% better than that of white LED (WL). Assessment of visible light communications (VLC) feasibility using the DL includes time interval error (TIE) of data pattern or jitter analysis, eye diagram, signal-to-noise ratio (SNR), fast Fourier transform (FFT), and power spectral density (PSD). DL transmits binary data stream faster than WL due to a reduction in rise time and total jitter by 31% and 39%, respectively. The autocorrelation function displayed a narrow temporal pulse for DL. The DL is beneficial for providing high-quality illumination indoors while minimizing PL quenching. Additionally, it is suitable for indoor VLC applications. Full article

This work aims to provide the hardware (HW) design of the optoelectronics interfaces for a visible-light communication (VLC) system that can be employed for several use cases. Potential applications include the transmission of ultra-high-definition (UHD) streaming video through existing reading lamps installed in passenger vans. In this use case, visible light is employed for the downlink, while infrared light is used for the uplink channel, acting as a remote controller. Two primary components -a Light Fidelity (LiFi) router and a USB dongle—were designed and implemented. The ‘LiFi Router’, handling the downlink channel, comprises components such as a visible Light-Emitting Diode (LED) and an infrared receiver. Operating at a supply voltage of 12 V and consuming current at 920 mA, it is compatible with standard voltage buses found in transport vehicles. The ‘USB dongle’, responsible for the uplink, incorporates an infrared LED and a receiver optimized for visible light. The USB dongle works at a supply voltage of 5 V and shows a current consumption of 1.12 A, making it well suited for direct connection to a universal serial bus (USB) port. The bandwidth achieved for the downlink is 11.66 MHz, while the uplink’s bandwidth is 12.27 MHz. A system competent at streaming UHD video with the feature of being single-input multiple-output (SIMO) was successfully implemented via the custom hardware design of the optical transceivers and optoelectronics interfaces. To ensure the system’s correct performance at a distance of 110 cm, the minimum signal-to-noise ratio (SNR_min) for both optical links was maintained at 10.74 dB. We conducted a proof-of-concept test of the VLC system in a passenger van and verified its optimal operation, effectively illustrating its performance in a real operating environment. Exemplifying potential implementations possible with the hardware system designed in this work, a bit rate of 15.2 Mbps was reached with On–Off Keying (OOK), and 11.25 Mbps was obtained with Quadrature Phase Shift Keying (QPSK) using Orthogonal Frequency-Division Multiplexing (OFDM) obtaining a bit-error rate (BER) of 3.3259 × 10⁻⁵ in a passenger van at a distance of 72.5 cm between the LiFi router and the USB dongle. As a final addition, a solar panel was installed on the passenger van’s roof to power the user’s laptop and the USB dongle via a power bank battery. It took 13.4 h to charge the battery, yielding a battery life of 22.3 h. This characteristic renders the user’s side of the system entirely self-powered. Full article