High-pressure Sodium Lamps Research Articles

The effect of three types of street lighting on the morphology and physiology of the common hackberry (Celtis occidentalis L.) leaves

ABSTRACT Our studies covered the responses of the common hackberry (Celtis occidentalis L.) to artificial lighting at night. We analyzed the effect of three types of lamps used in public lighting: high-pressure sodium lamp (HPS) and two types of LED lamps. Physiological, macro- and micromorphological measurements were carried out during the research. Common hackberry tree was affected by the night light of street lamps, although the tested individuals received natural lighting during the day. Moreover, there were differences observed between the effects of the investigated lamp types. The high-pressure sodium lamp (HPS) resulted in histologically thicker leaves with higher photosynthetic yields, together with more efficient stomatal movements. The LED lamp with a color temperature of 3000 K enhanced the establishment of the photosynthetic apparatus and the growth of the palisade parenchyma. The physiology and histological development of leaves illuminated at night with a narrow-spectrum LED with a color temperature of 1900–2400 K remained inferior compared to those on shoots kept in the dark at night. Our results confirm that the type of the light source is a relevant factor in considering the effects or prevention of light pollution on plant anatomy.

Ultraviolet radiation exposure in cannabis-growing facilities

Cannabis cultivation and processing is becoming an important industry in the United States and Canada. The industry employs over 400,000 workers in the United States and is growing rapidly. Both natural sunlight and artificial lamp-generated radiation are commonly used to grow cannabis plants. These optical sources can contain both visible and ultraviolet radiation (UVR) wavelengths, and overexposure to UVR is associated with negative health effects. The severity of these adverse health effects is governed by the specific wavelengths and exposed dose of UVR, yet worker exposure to UVR within cannabis-growing facilities has not been studied. In this study, worker exposure to UVR was assessed at five cannabis production facilities in Washington State, including indoor, outdoor, and shade house facilities. Lamp emission testing was performed at each facility and worker UVR exposures were measured for 87 work shifts. Observations of worker activities and use of personal protective equipment in association with UVR exposure measurements were recorded. For lamp emission measurements, at 3 feet from the center of the lamp, the average irradiances were 4.09 × 10−4, 6.95 × 10−8, 6.76 × 10−9, 3.96 × 10−9, and 1.98 × 10−9 effective W/cm2 for germicidal lamps, metal halide lamps, high-pressure sodium lamps, fluorescent lamps, and light emitting diodes, respectively. The average measured UVR exposure was 2.91 × 10−3 effective J/cm2 (range: 1.54 × 10−6, 1.57 × 10−2 effective J/cm2). Thirty percent of the work shifts monitored exceeded the American Conference for Governmental Industrial Hygienists (ACGIH®) threshold limit value (TLV®) of 0.003 effective J/cm2. Exposures were highest for workers who spent all or part of the work shift outdoors, and solar radiation was the primary source of worker UVR exposure for most of the work shifts that exceeded the TLVs. Outdoor workers can reduce UVR exposure by applying sunscreen and wearing appropriate personal protective equipment. Although the artificial lighting used in the cannabis production facilities included in this study did not contribute substantially to the measured UV exposures, in many cases the lamp emissions would generate theoretical exposures at 3 feet from the center of the lamp that would exceed the TLV. Therefore, employers should choose low UVR emitting lamps for indoor grow operations and should use engineering controls (e.g., door-interlocks to de-energize lamps) to prevent worker exposure to UVR from germicidal lamps.

A Comparative Life Cycle Assessment and Costing of Lighting Systems for Environmental Design and Construction of Sustainable Roads

The management of the life cycle of the transport network is one of the main challenges of sustainable mobility. Roads and highways cause significant damage to the ecosystem. Specifically, lighting systems contribute to climate change, energy consumption, and human health effects. In this context, this work proposes the combination of life cycle assessment (LCA) with life cycle costing (LCC) to analyze the eco-efficiency of the life cycle of a road, including evaluation of the relative contribution of the lighting system to the total impact. Four scenarios were included in the model: (S1) high-pressure sodium lamps with ballast powered from the grid; (S2) halogen lamps powered from the grid; (S3) light-emitting diode lamps powered from the grid; and (S4) light-emitting diode lamps powered from a standalone photovoltaic system. The life cycle stages of raw material extraction, construction, use, maintenance, and end of road life were included in the analysis. The results show that scenarios S3 and S1 are the most eco-efficient relative to the less favorable S2 scenario (80% and 74% lower, respectively). Scenarios with the least environmental impact are the most economically viable.

Different LED light intensity and quality change perennial ryegrass (Lolium perenne L.) physiological and growth responses and water and energy consumption.

Light intensity and spectral composition highly affect plant physiology, growth, and development. According to growing conditions, each species and/or cultivar has an optimum light intensity to drive photosynthesis, and different light spectra trigger photosynthetic responses and regulate plant development differently. For the maintenance of natural sports pitches, namely professional football competitions, turf quality is a key condition. Due to the architecture of most football stadiums, the lawns receive low intensities of natural light, so supplementary artificial lighting above the turf is required. The use of light-emitting diodes (LEDs) can have a higher cost-benefit ratio than traditional high-pressure sodium lamps. The continuous emission spectrum, combined with high spectral selectivity and adjustable optical power, can be used to optimize plant growth and development. Thus, perennial ryegrass (Lolium perenne L.) plants, commonly used for lawns, were primarily grown at three different intensities (200, 300, and 400 μmol m-2 s-1) of cool white light. Despite the higher water and energy consumption, 400 μmol m-2 s-1 maximizes the plant's efficiency, with higher photosynthetic rates and foliar pigment concentration, and more foliar soluble sugars and aboveground biomass accumulation. Then, it was evaluated the perennial ryegrass (Double and Capri cultivars) response to different spectral compositions [100% cool white (W), 80% Red:20% Blue (R80:B20), 90% Red:10% Blue (R90:B10), and 65% Red:15% Green:20% Blue (R65:G15:B20)] at 400 μmol m-2 s-1. Both cultivars exhibited similar responses to light treatments. In general, W contributed to the better photosynthetic performance and R90:B10 to the worst one. Water consumption and aboveground biomass were equal in all light treatments. R80:B20 allows energy savings of 24.3% in relation to the W treatment, showing a good compromise between physiological performance and energy consumption.

Erratum to: Effect of Stem Number on Growth, Fruit Quality, and Yield of Sweet Peppers Grown in Greenhouses under Supplemental Lighting with High Pressure Sodium Lamps in Winter

Erratum to: Effect of Stem Number on Growth, Fruit Quality, and Yield of Sweet Peppers Grown in Greenhouses under Supplemental Lighting with High Pressure Sodium Lamps in Winter

Thermal Behavior and Leaf Temperature in a High Pressure Sodium Lamp Supplemented Greenhouse

고압나트륨등(high-pressure sodium, HPS 램프)은 작물 생육 발달에 필요한 충분한 양의 광합성유효방사를 제공하는 동시에 복사열을 통해 온실 난방 부하를 절감할 수 있어 겨울철 시설원예 보광 조명으로 널리 이용되고 있다. 그러나 겨울철에 생육 중기를 맞이하는 시설 과채류의 경우, 작물의 정단부가 복사열에 영향을 많이 받고, 캐노피 위치에 따라 엽온 차이가 증가될 수 있다. 또한 온실 기온 역시 보광등에서 발생한 열이 상부로 상승 및 정체되면서 불필요한 에너지 낭비 및 온도 불균일성 역시 심화될 수 있다. 따라서 본 연구의 목표는 CFD 열전달 해석을 통해 HPS 램프에 의한 열적 특성 및 생육 단계별 수평적 엽온 변화를 분석하고, 온실 내 수직적 기온 및 작물의 캐노피별 엽온을 측정하여, 온실 내 환경 균일성 제고 및 효과적 에너지 활용 방안을 모색하는 것이었다. 생육 초기, 중기, 및 후기를 대변하는 초장(1.0, 1.6, 2.2m)에서의 정단부 수평적 엽온을 CFD 시뮬레이션을 통해 분석하였다. 또한 HPS 램프 작동 이후 수직적 기온과 캐노피 높이별 엽온을 측정하였다. 실험 결과, 보광 시 엽온과 기온 간의 차이가 커지고, 수직적 기온 역시 불균일해짐을 알 수 있었다. 생육 단계가 진전될수록, 고온의 복사열이 중심부에 집중되며, 상단부 수평적 엽온 편차가 커지고, 균일성 역시 떨어지는 것을 알 수 있었다. 열 획득 모델을 통한 수치해석 결과, 보광등이 2022년 12월 기간난방부하에 약 50.1% 기여하는 것을 알 수 있었다. 평균절대오차 및 평균제곱근 오차는 생육 초기 및 생육 중기 모두 0.5 이하로, 실측값과 예측값에 높은 일치도를 보였다. 수직적 기온 및 엽온 분포와 생육 단계별 수평적 엽온 분포에 관한 본 연구의 결과는 효율적 에너지 관리 및 작물 생육 발달에 관한 의사결정에 도움이 될 수 있을 것으로 생각된다.

Light spectra of biophilic LED-sourced system modify essential oils composition and plant morphology of Mentha piperita L. and Ocimum basilicum L.

Investigating morphological and molecular mechanisms that plants adopt in response to artificial biophilic lighting is crucial for implementing biophilic approaches in indoor environments. Also, studying the essential oils (EOs) composition in aromatic plants can help unveil the light influence on plant metabolism and open new investigative routes devoted to producing valuable molecules for human health and commercial applications. We assessed the growth performance and the EOs composition of Mentha x piperita and Ocimum basilicum grown under an innovative artificial biophilic lighting system (CoeLux®), that enables the simulation of natural sunlight with a realistic sun perception, and compared it to high-pressure sodium lamps (control) We found that plants grown under the CoeLux® light type experienced a general suppression of both above and belowground biomass, a high leaf area, and a lower leaf thickness, which might be related to the shade avoidance syndrome. The secondary metabolites composition in the plants' essential oils was scarcely affected by both light intensity and spectral composition of the CoeLux® light type, as similarities above 80% were observed with respect to the control light treatments and within both plant species. The major differences were detected with respect to the EOs extracted from plants grown under natural sunlight (52% similarity in M. piperita and 75% in O. basilicum). Overall, it can be speculated that the growth of these two aromatic plants under the CoeLux® lighting systems is a feasible strategy to improve biophilic approaches in closed environments that include both plants and artificial sunlight. Among the two plant species analyzed, O. basilicum showed an overall better performance in terms of both morphological traits and essential oil composition. To increase biomass production and enhance the EOs quality (e.g., higher menthol concentrations), further studies should focus on technical solutions to raise the light intensity irradiating plants during their growth under the CoeLux® lighting systems.

From sodium-vapour to LEDs: how an outdoor lighting retrofit affects insects in Singapore

Abstract In the Anthropocene, the planet is warming and global biodiversity, including of insects, is being lost at an unprecedented rate. One largely urban sustainability solution, shifting to energy-efficient, light-emitting diode (LED) bulbs on outdoor lighting, has impacts on insects that are inadequately understood, especially in the tropics and brightly lit cities. Working in Singapore—a highly urbanised and light-polluted tropical city-state—we performed a field experiment to test the hypothesis that newly retrofitted LED lights are more attractive (i.e., detrimental) to insects compared to the high-pressure sodium (HPS) lamps they replace. Instead, our sticky traps, which we mounted on both light types, caught statistically equal numbers of arthropods (individuals and families). Traps on LED lamps also attracted proportionally fewer dipterans and more hemipterans and hymenopterans, but these effects were site-specific. Overall, we found no support for our hypothesis—our findings may reflect differential emissions of ultraviolet wavelengths by both light types and/or the possibility that urban insect assemblages with historic exposure to light pollution may not respond as expected to the retrofit. We caution against extrapolating findings from impact studies to untested contexts and highlight the need for (1) more studies in the rapidly urbanising tropics and (2) field tests of the effectiveness of measures to limit any negative ecological impacts of LED lighting, including other lethal and sublethal effects that we did not assess. We also discuss possible implications for ecosystem services and insect conservation.

Supplemental Lighting Quality Influences Time to Flower and Finished Quality of Three Long-Day Specialty Cut Flowers

Year-round demand for locally sourced specialty cut flowers continues to increase. However, due to low radiation intensities and temperatures, growers in northern latitudes must utilize greenhouses, but limited production information detailing manipulation of the radiation environment exists. Therefore, our objective is to quantify the influence of supplemental lighting (SL) quality on time to flower and harvest and stem quality of three long-day specialty cut flowers. Godetia ‘Grace Rose Pink’ (Clarkia amoena), snapdragon ‘Potomac Royal’ (Antirrhinum majus), and stock ‘Iron Rose’ (Matthiola incana) plugs are transplanted into bulb crates and placed in one of six greenhouse compartments with SL providing a total photon flux density of 120 µmol·m−2·s−1 from 0700 to 1900 HR. After four weeks, SL is extended to provide a 16 h photoperiod to induce flowering. SL treatments are provided by either high-pressure sodium (HPS) fixtures or various light-emitting diode (LED) fixtures. Treatments are defined by their 100 nm wavebands of blue (B; 400–500 nm), green (G; 500–600 nm), red (R; 600–700 nm), and far-red (FR; 700–800 nm) radiation (photon flux density in μmol·m−2·s−1) as B7G60R44FR9 (HPS120), B20G50R45FR5, B20R85FR15, B30G25R65, B120, or R120. Time to harvest (TTH) is up to 14, 15, and 10 d slower under R120 SL for godetia, snapdragon, and stock, respectively, compared to the quickest treatments (HPS120, B120, and B20R85FR15 SL). However, R120 SL produces cut flowers up to 18% longer than those grown under the quickest treatments. Both broad-spectrum LED fixtures slightly delay TTH compared to the quickest treatments. Stem caliper is not commercially different between treatments for godetia or snapdragon, although stems are up to 14% thinner for stock grown under B120 SL compared to the other treatments. Flower petal color is not commercially different between SL treatments. We recommend utilizing a SL fixture providing a spectrum similar to B20R85FR15 SL or B20G50R45FR5, as they elicit desirable crop responses with minimal developmental, quality, and visibility tradeoffs. While HPS lamps perform similarly to the recommended fixtures, we recommend utilizing LEDs for their higher photon efficacy and potential energy savings.

Investigation of different lighting (LED, HPS and FLO) in aquaponics systems for joint production of different plants (Lettuce, Parsley and Cress) and koi carp

We investigated the effects of growth performance of three plant species parsley (Petroselinum crispum), lettuce (Lactuca sativa) and cress (Lepidium sativum) under the three different lighting sources, Light-Emitting Diode lamp (LED; 200w), High-Pressure Sodium lamp (HPS; 200w) and Fluorescent lamp (FLO; 200w) in an aquaponic system. A total number of 43 koi fish (Cyprinus carpio var. koi) with 3628 g total biomass (84.4 g per individual) were used. The fish used in the experiment recorded 36% growth and reached an average individual weight of 132.7 g at the end of the experiment. The parsley plant was measured as 8.76 ±7.32 g; 7.45 ±4.13 g; 2.04 ±1.96 g weight after 45 days, the lettuce plant was 54.09 ± 25.60 g; 60.83 ±19.39 g; 17.81 ±6.40 g weight after 54 days, cress plant was 1.03 ±0.58 g; 1.15 ±0.46 g; 1.31 ±0.58 g weight after 42 days, under the HPS, LED, and FLO light sources, respectively. HPS and LED light sources in lettuce and parsley showed better plant development than the FLO, while no significant difference occurred in cress plants under three light conditions. We conclude that using HPS or LED lights in indoor aquaponics has the potential to produce good quality and adequate amounts of plants.

Optimization of the spectral composition emission of the combined spectrum led phytoirradiators

The results of the full-fledged vegetation of cucumber plants of the Svyatogor F1 variety under light culture conditions are presented. The studies were carried out on an experimental research hydroponic setup at photosynthetic photon irradiance EPPFD = 250 ± 10 μmol/(s·m2). In the experiment phytoirradiators with high-pressure sodium lamps of the DNaZ type (control variant), as well as LED combined spectrum phytoirradiators are used. Keywords phytoirradiator, LED light source, photoculture, photobiological research, radiation spectrum, photosynthetically active radiation, photosynthetic photon irradiance, cucumber plant

Shedding light on the effects of LED streetlamps on trees in urban areas: Friends or foes?

Streetlamp illumination disturbs the natural physiological processes and circadian rhythms of living organisms, including photosynthesizing “citizens”. The light-emitting diode (LED) technology has replaced high-pressure sodium lamps. Therefore, the effects of LED streetlamps on urban trees need to be elucidated as these new lamps have a different light spectrum (with a peak in the blue and red regions of the spectrum, i.e., highly efficient wavebands for photosynthesis) compared to older technologies. To address the above-mentioned issue, two widely utilised tree species in the urban environment, including Platanus × acerifolia (P) and Tilia platyphyllos (T), were grown with or without the effect of LED streetlamps using two realistic illumination intensities (300 and 700 μmol m−2 s−1). Gas exchanges and biochemical features (starch, soluble sugar, and chlorophyll content) of illuminated vs non-illuminated trees were compared during the whole vegetative season. Our results showed that both tree species were strongly influenced by LED streetlamps at physiological and biochemical levels. Specifically, the mature leaves of P and T streetlamp-illuminated trees had a lower CO2 assimilation rate at dawn and had higher chlorophyll content, with lower starch content than controls. Our results showed that the differences between the effects of the two selected light intensities on the physiochemical attributes of P and T trees were not statistically significant, suggesting the absence of a dose-dependent effect. The most significant difference between T and P trees concerning the LED-triggered species-specific effect was that the delay in winter dormancy occurred only in P individuals. This study provided insights into the extent of LED streetlamp disturbance on trees. Our findings might raise awareness of the necessity to provide less impacting solutions to improve the wellness of trees in the urban environment.

Bioactive extracts and association with C and N in Eleutherococcus senticosus subjected to chitosan nanoparticles in contrasting light spectra.

Bioactive compounds are major reasons for the value of Eleutherococcus senticosus, which can be modified by different lighting spectra. Light-emitting diode (LED) provides lights with specific spectra which can interact with other treatments to impact plant bioactive production. Chitosan nanoparticle (CN) is a biopolymer derived from marine creatures. It's usage may be a practical approach to cope with uncertainties in secondary metabolites induced by illumination. Carbon (C) and nitrogen (N) cyclings link plant eco-physiological performance and bioactive substance; hence their associations may reveal the mechanism of joint light-CN interaction. In this study, E. senticosus seedlings were raised under artificial lighting spectra from high-pressure sodium (HPS) lamps (44% red, 55% green, 1% blue) and white (44% red, 47% green, 8% blue) and red colored (73% red, 13% green, 14% blue) LED panels. Half of the seedlings received CN and the other half received distilled water as the control. Compared to the HPS spectrum, the red-light induced stronger shoot growth with greater biomass accumulation and higher water uptake but resulted in lower N concentration and biomass ratio in the root. The white light caused more biomass allocated to the root and strengthened stem C concentration. Stem eleutheroside B increased with shoot growth, while root eleutheroside B had a positive association with leaf C and stem protocatechuic acid had a negative association with leaf N. Having the CN treatment in white and red LED lights is recommended for increasing accumulation of bioactive compounds in the shoots and roots of E. senticosus seedlings, respectively.

Lighting of pedestrian and pedestrian-driving routes in a housing estate as a source of light pollution

This paper is devoted to the extremely important issue of lighting pedestrian and pedestrian-driving routes within a housing estate. Both aspects are discussed with regard to the safety of route users and the potential impact on the natural environment through the phenomenon of light pollution. It was found that most of the outdated high-pressure sodium lamps present in the analysed Podwawelskie housing estate in Kraków do not fulfil their basic purpose, which is to sufficiently illuminate the ground below. Nevertheless, the light of these lamps does not make a noticeable contribution to the basic form of light pollution, which is the city's sky glow. It has been suggested that it would be best to replace these types of lamps with LED lighting, which has already been partly done. The LED lamps provide lighting that is sufficient to ensure the safety of residents. However, their improper installation may cause glare for pedestrians or residents of neighbouring houses. Additionally, their light reflected from an excessively bright pavement makes a significant contribution to the artificial sky glow. Solutions are proposed that minimise the negative impact of this lighting on the environment while ensuring comfort for the residents of the estate, which is in line with the principles of sustainable development.

Recycling and Material Flow Analysis of End-of-Life Fluorescent Lamps in South Korea

Proper management and treatment of end-of-life fluorescent lamps with a toxic metal of mercury has attracted critical concern in the solid waste community. In this study, material flow analysis (MFA) and substance flow of mercury were performed on the lamps by life cycle in South Korea. It was found that, in 2020, approximately 2957 tons (or 27.9 million units) of end-of-life fluorescent lamps from households were collected and recycled by the recycling facilities in South Korea. Approximately 278 kg of mercury was recovered from the lamps and treated at the hazardous incineration facilities. Based on the results of dynamic flow analysis, the amount of fluorescent lamps to be retried is expected to continually decrease to be about 14.2 million units, which is estimated to be 23 kg of mercury. However, continued collection efforts on end-of-life fluorescent lamps owing to increasing demands for light-emitting diode lamps should be made from the perspectives of proper treatment of mercury as well as resource recovery. More detailed studies on other mercury-containing lamps (e.g., metal halogen lamps, high-pressure mercury lamps, and high-pressure sodium lamps) are warranted to determine mercury flows in waste streams for proper collection and treatment upon disposal.

Modifying spectral distributions during the seedling stage influences the flowering and branching of Petunia × hybrida

The present study investigated the growth attributes of Petunia × hybrida ‘Shock Wave’ to ascertain the effect of different spectrum distributions. Upon germination, seedlings were placed under eighteen lighting treatments that included modifying and constant combinations of red625nm (R) and blue476nm (B) LEDs, as well as broad-spectrum lamps such as fluorescent, high-pressure sodium, and white LED. After 28 days, randomly selected seedlings were transferred to a common environment, where they stayed for 62 days to examine the effect of light treatments during seedling stage on the flowering and branching attributes. Results indicated that the growth of the seedlings improved under modifying R: B ratios compared to constant ones, and broad-spectrum lamps. A gradual increase in blue light percentage enhanced shoot dry weight, shoot length, and leaf area. A different pattern was observed for leaf number, root dry weight, and root length, as a gradual decrease in blue light percentage was in their favor. In addition, modifying spectral distributions enhanced electricity use efficiency as they converted more electricity to plant biomass compared to constant ratios. The results showed that seedlings under a lighting treatment with a gradual increase in blue light had the earliest time to flower, while the seedlings grown under high-pressure sodium lamp showed the highest number of flowers. Also, the apical dominance affected by spectral distribution resulted in a significant difference in the number and length of lateral branches. Overall, our study demonstrated that modifying percentages of red and blue light during seedling cultivation is an efficacious alternative to the standard lighting systems, and it can be further investigated in controlled environments.

The Physiology, Growth and Essential Oil Content of Lemon Balm (Melissa officinalis L.) in Response to Different LED Treatments

Background: Light-emitting diodes (LEDs) are a promising technology that has enormous potential to improve irradiance efficiency and to replace traditionally used horticultural lighting. Compared with traditional light sources (e.g., high-pressure sodium lamps and metal halide lamps) used in crop production, LEDs tends to have long life, generate less heat waste and providing the perfect spectrum for plant growth. Methods: This work sought to investigate the effect of using blue LED lights on growth and development in Lemon balm (Melissa officinalis L.) under sole-source LED lighting spectra. Lighting spectra were provided by differing combinations of LEDs of 4 different peak wavelengths, (Blue 435, Blue 450, Red 663 nm and Green 540 nm) with ratios of (1.95:2.3:1 R: G: B 450 nm (white), 5: 1R: B 450 nm, 2.5:1 R: B 450 nm and 2.5:1 R: B 435 nm) at a PPFD of 95 ìmol m-2 s-1 (PAR). Result: showed that the blue light with a wavelength peak at 435 nm in combination with red light at 663 nm at the ratio of (2.5:1 R: B) and white LEDs enhanced the physiology of lemon balm (i.e., significantly increased assimilation rate, stomatal conductance and transpiration rate), consequently fresh and dry shoot weight increased and the shoot essential oil content.

Performance Analysis of LED Driver Circuit using DC-DC Converter Topology

High Pressure Sodium (HPS) lamp has been extensively employed in outdoor lighting. But the need of time is to save electricity since HPS has high consumption of electricity. Light Emitting Diodes (LEDs) are better choice to replace HPS. Since they are compact and with very low power ratings, they have very high illumination. The basic difference between LED and HPS is that, HPS works on normal AC voltage supply whereas LED requires low DC voltage to operate. Hence a converter circuit with low voltage rating is required for proper functioning of LED. In this paper, simulation and hardware implementation of an LED driver base on a permutation of the buck converter as the DC-DC power conversion (PC) stage and buck-boost converter as the power factor rectification (PFR) stage is presented. This paper presents the hardware implementation of LED driver circuit for 12 V LED lighting strip.

The short-term effects of planktivorous fish foraging in the presence of artificial light at night on lake zooplankton.

Numerous studies have revealed that artificial light at night alters the natural patterns of light in space and time and may have various ecological impacts at different ecological levels. However, only a few studies have assessed its effect on interactions between organisms in aquatic environments, including predator-prey interactions in lakes. To fill this gap, we performed a preliminary enclosure experiment in which we compared the foraging effect of juvenile perch (Perca fluviatilis) on a natural lake zooplankton community in the absence and presence of light of high-pressure sodium (HPS) lamps mimicking artificial light emitted by a boat. The results revealed that even short-lasting exposure to HPS lamps may result in increasing fish predation, which in turn decreased the mean body size in zooplankton populations (e.g. Bosmina thersites) and affected the relative proportion between different taxa in zooplankton communities.

The Effect of LED and HPS Assimilation Lighting on Leaf Anatomy, Chlorophyll and Carotenoid Autofluorescence Signals, and Some Physiological and Chemical Leaf Traits Related to the Productivity of Cucumber (Cucumis sativus L.) in High-Wire Cultivation

Supplemental lighting with light-emitting diode (LED) lamps and/or high-pressure sodium (HPS) lamps was applied to increase the activity of the photosynthetic apparatus and thus productivity of greenhouse cucumber (Cucumis sativus L.) in a high-wire growing system. The colocalisation of the chlorophyll of PSII (located mainly in grana) and carotenoid fluorescence signals in chloroplasts of cucumber leaves was studied under confocal microscopy. Leaf anatomy and some chemical quality traits (dry matter, chlorophyll, carotenoids, total soluble solids, total sugars and nitrate reductase activity) as well as selected chlorophyll fluorescence parameters were also investigated and subjected to the multidimensional principal component analysis together with the data on fruit yield. Under LED lighting, a lower correlation between the occurrence of chlorophyll and carotenoid fluorescence signals was observed, especially in older (lower-located) leaves, which may have resulted from changes in the distribution of carotenoids within chloroplasts and/or relative concentrations of chlorophyll and carotenoids. Compared to toplighting with HPS lamps, most commonly used in commercial greenhouse cucumber production, the application of LED interlighting, especially in combination with LED toplighting, led to the increase in chlorophyll and carotenoid content and photosynthetic performance index in older leaves, which was related to the increased cucumber productivity.