Light-emitting Diode Light Research Articles

Biofeedback control of photosynthetic lighting using real-time monitoring of leaf chlorophyll fluorescence.

Optimizing photosynthetic lighting is essential for maximizing crop production and minimizing electricity costs in controlled environment agriculture (CEA). Traditional lighting methods often neglect the impact of environmental factors, crop type, and light acclimation on photosynthetic efficiency. To address this, a chlorophyll fluorescence-based biofeedback system was developed to adjust light-emitting diode (LED) intensity based on real-time plant responses, rather than using a fixed photosynthetic photon flux density (PPFD). This study used the biofeedback system to maintain a range of target quantum yield of photosystem II (ΦPSII) and electron transport rate (ETR) values and to examine if the adjustment logic (ΦPSII or ETR-based) and crop type influence LED light intensity. The system was tested in a growth chamber with lettuce (Lactuca sativa) 'Green Towers' and cucumber (Cucumis sativus) 'Diva' to maintain six ETR levels (30, 50, 70, 90, 110, 130 μmol·m-2·s-1) and five ΦPSII levels (0.65, 0.675, 0.7, 0.725, 0.75) during a 16-hour photoperiod. The ETR-based biofeedback quickly stabilized the target ETR within 30-45 minutes, whereas the ΦPSII-based system needed more time. The system adjusted light intensities according to target values, acclimation status, and crop-specific responses. For example, to maintain a target ETR of 130 μmol·m-2·s-1, the gradual increase in ΦPSII over time due to light acclimation allowed the required PPFD to decrease by 35 μmol·m-2·s-1. Lettuce showed higher photosynthetic efficiency and lower heat dissipation than cucumber, leading to higher PPFD adjustments for lettuce. This biofeedback system effectively controls LED light, optimizing photosynthetic efficiency and potentially reducing lighting costs.

Enhancement of Light Extraction Efficiency Using Wavy-Patterned PDMS Substrates

This study introduces an organic light-emitting diode (OLED) light extraction method using a wavy-patterned polydimethylsiloxane (PDMS) substrate created via oxygen (O2) plasma treatment. A rapid fabrication process adjusted the flow, pressure, duration, and power of the O2 plasma treatment to replicate the desired wavy structure. This method allowed the treated samples to maintain over 90% total transmittance and enabled controlled haze adjustments from 10% to 70%. Finite-difference time-domain (FDTD) simulations were employed to determine optimal amplitudes and periods for the wavy structure to maximize optical performance. Further experiments demonstrated that bottom-emitting green fluorescent OLEDs constructed on these substrates achieved an external quantum efficiency (EQE) of 3.5%, representing a 97% improvement compared to planar PDMS OLEDs. Additionally, color purity variation was minimized to 0.044, and the peak wavelength shift was limited to 10 nm, ensuring consistent color purity and intensity even at wide viewing angles. This study demonstrates the potential of this cost-effective and efficient method in advancing high-quality display.

A safe and robust in-situ polymerized cementitious electrolyte coupled with NiCo2S4@CuCo2S4 electrode for superior load-bearing integrated electrochemical capacitor.

Load bearing/energy storage integrated devices (LEIDs) featuring cementitious electrolytes have become ideal for large-scale energy storage. Nevertheless, the progression of LEIDs is still in its nascent phase and considerable endeavors concerning cementitious electrolytes and electrode materials are necessary to further boost the charge storage ability. Here, we propose a facile synchronous reaction method for preparing sodium acrylate (SA)-based in-situ polymerized cementitious electrolyte. The soft polymer network and hard cement matrix are interwoven together. The resulting cementitious electrolyte not only exhibits improved mechanical properties (flexural strength of 14.7MPa and compressive strength of 44.7MPa), but also possesses enhanced ionic conductivity (26.7mScm-1). Moreover, a core-shell NiCo2S4@CuCo2S4/NF heterostructure is synthesized on nickel foam (NF) substrate by hydrothermal assisted electrodeposition techniques, which showcases a remarkable capacitance of 5626.6mFcm-2 at 1mAcm-2. As a proof, with integrated merits of the optimal cementitious electrolyte and NiCo2S4@CuCo2S4/NF electrode, the as-built LEID demonstrates a high energy density of 138.5μWhcm-2 at 0.75mWcm-2 and a cycling durability of 90.7% after 8000 cycles, showing good practicability in lighting light-emitting diodes (LEDs) or driving a thermal hygrometer. Notably, the LEID can endure external forces without distinctly sacrificing electrochemical properties. This work provides insight into developing novel cementitious electrolytes and electrode materials toward superior LEIDs.

Effects of Intra-Canal Medicaments on Infrared Light Energy Transmission Through Enamel and Dentin During Photobiomodulation - An In Vitro Study.

This in vitro study assessed how shade changes induced by endodontic medicaments affect the transmission of single and multiples wavelengths of infrared light through enamel and dentin. Eighteen extracted single-rooted permanent teeth were prepared, removing all extrinsic staining, and cementum. Tooth slices were treated for 4 weeks with UltraCal™ XS, Ledermix™, or were untreated controls. Light transmission through enamel-dentin (ED) and dentin (D) regions was assessed using diode lasers (660, 808, 904 nm) and a multi-wavelength light emitting diode (LED) light source (700-1100 nm). Absorption studies were performed to evaluate light absorption by components of medicaments. Samples treated with Ledermix™ showed the greatest shade change, with a corresponding reduction in visible and near infrared light transmission (p < 0.001) in dentin, while UltraCal™ XS had a milder effect (p < 0.01). Across different substrates, the greatest light transmission was seen for the multi-wavelength LED light source, followed by 904 nm, 808 nm, and finally 660 nm. Spectrophotometric studies revealed light absorption by turbid and saturated calcium hydroxide solutions. This study shows that medicaments may influence transmission of visible red and near infrared light. Photobiomodulation protocols used in regenerative endodontics should take this effect into account, by incorporating longer near-infrared wavelengths (up to 1100 nm) and using multi-wavelength light sources to account for this absorption.

Merged Red and NIR Light Sources for Photobiomodulation Therapy in Diabetic Wound Healing.

Photobiomodulation (PBM) is considered an effective and safe therapeutic modality in supporting the treatment of complications from a global pandemic-diabetes. In this study, PBM therapy is investigated to accelerate wound healing in diabetic mice (DM), under the combined biological effects of red light from a red organic light-emitting diode (ROLED) and near-infrared (NIR) light from an NIR conversion film (NCF) with dispersed CuInS2/ZnS quantum dots (QDs). The QD concentration and the NCF structure were optimized to maximize the optical properties and mechanical stability. A merged red/NIR device (MRND) was produced by integrating the optimized NCF and ROLED for PBM therapy. As a result of irradiating DM with MRND at a dose of 2 J/cm2, after 10 days, the wounds recovered three times faster than DM without MRND. Additionally, MRND light not only restored the epidermal thickness to normal but also significantly reduced the levels of pro-inflammatory cytokines. The experimental results show that the proposed PBM therapy has the potential to improve the quality of life of diabetic patients by helping them with rapid wound healing.

Design and Implementation of Elevator Push-Buttons with Integrated Ultraviolet-C Light-Emitting Diode Light Sources for Disinfection

Background: More effective and automated techniques for disinfecting elevator push-buttons currently need to be developed, especially given that they are frequently touched by hundreds of individuals. Methods: An automatic elevator push-button disinfection device equipped with four 265 nm ultraviolet-C (UVC) light-emitting diode (LED) packages has been developed for disinfection after each touch to reduce the risk of infection. In this paper, the UVC leakage test, UVC LED package reliability test, and bacteria disinfection efficiency test were performed. Results: The disinfection efficiency for Staphylococcus aureus and Escherichia coli can reach over 90% in 10 s, and end users can set multiple disinfection periods in light of their circumstances. The disinfection device is safe for the human body if the distance exceeds 120 mm. The accelerated aging test result demonstrates that the disinfection device is reliable under normal operation and end-users can increase the disinfection time by compensating for the irradiance drop. Conclusions: The automatic elevator push-button disinfection device provides a safe, highly efficient, and stable disinfection solution for elevator push-buttons.

Exploring Illumination and Communication: A Comprehensive Analysis of LED Lighting in Modern Interior Architectural Designs, Enhanced by Weighted Sum Model and Cluster Analysis for Informed Lighting Selection

ABSTRACTThe study of light is crucial in modern interiors, as it dispels darkness and enhances both functionality and aesthetics. From the primal flicker of flames in ancient caves to the advanced light emitting diode (LED) systems of today, lighting has been pivotal in shaping our surroundings and experiences. In contemporary interior architectural designs, lighting fulfills not only functional roles but also greatly influences the aesthetics and atmosphere of a space. Light has been an integral element in sleek interior architecture. With the advancements in LED technology, the approach to illuminating spaces has been transformed providing energy‐efficient solutions. This paper explores the role of LED lighting in modern interior architectural designs focusing on its impact on illumination and communication. Using a weighted sum model and cluster analysis, the various LED lighting configurations are evaluated for their suitability in different spaces. Performance metrics such as illuminance levels, uniformity, adherence to standards, signal‐to‐noise ratio (SNR) and bit error rate (BER) are analyzed. By varying the configurations of LED array per position from 10 × 10 to 100 × 100 the performance across different scales is assessed. The results offer insights for selecting LED lighting options that optimize functionality, aesthetics and energy efficiency in modern interior spaces.

Strawberry plant growth enhancement: Effects of artificial light and methyl jasmonate-salicylic acid treatments on physiology and metabolism.

Strawberries, known for their antioxidant properties, exhibit changes in physiology and metabolite profiles based on cultivation techniques. In Indonesia, strawberries are typically grown in highland regions, but climate change has necessitated adjustments in cultivation practices to enhance production and quality. This study investigates the adaptation of strawberry plants in lowland environments using light-emitting diodes (LEDs) and the exogenous application of methyl jasmonate (MeJA) and methyl salicylic acid (MeSA). A randomized block design was used with two factors: LED light types and MeJA-MeSA treatments. While the treatments did not significantly affect shoot growth (initially 1.5-2cm, increasing 3-5 times by day 3), chlorophyll content, or fruit sugar levels, notable effects were observed in leaf glucose accumulation. The control group showed a fivefold increase (0.55μgml-1), while LED-hormone treatments resulted in a 27-64% lower increase (0.20-0.40μgml-1). Fructose levels followed a similar pattern, and malic acid content was highest in the MeJA treatment (5.76mgml-1), with MeSA treatments also enhancing malic acid (5.91mgml-1). The secondary metabolite analysis, conducted using GC-MS and LC-MS, identified key defense-related compounds, including terpenoids, saturated fats, alkaloids, and amino acid derivatives, which play a role in the plant's defense mechanisms. These findings highlight the potential of LED lighting and hormone applications to modulate strawberry physiology and suggest further research into their role in plant stress responses.

Violet LED light-activated MdHY5 positively regulates phenolic accumulation to inhibit fresh-cut apple fruit browning.

Fresh-cut fruit browning severely affects the appearance of fruit. Light treatment can effectively inhibit fresh-cut apple fruit browning, but the regulatory mechanism remains unknown. Here, we discovered that violet LED (Light-Emitting-Diode) light treatment significantly reduced fresh-cut apple fruit browning. Metabolomic analysis revealed that violet LED light treatment enhanced the phenolic accumulation of fresh-cut apple fruit. Transcriptomic analysis showed that the expression of phenolic degradation genes POLYPHENOL OXIDASE (MdPPO) and PEROXIDASE (MdPOD) was reduced, and the expression of phenolic synthesis gene PHENYLALANINE AMMONIA LYASE (MdPAL) was activated by violet LED light treatment. Moreover, two ELONGATED HYPOCOTYL 5 (MdHY5 and MdHYH) transcription factors involved in light signaling were identified. The expression of MdHY5 and MdHYH was activated by violet LED light treatment. Violet LED light treatment no longer inhibited fresh-cut apple fruit browning in MdHY5- or MdHYH- silenced fruit. Further experiments revealed that MdHY5 and MdHYH suppressed MdPPO and MdPOD expression and promoted MdPAL expression by binding to their promoters. In addition, MdHY5 and MdHYH bound to each other's promoters and enhanced their expression. Overall, our findings revealed that violet LED light-activated MdHY5 and MdHYH formed a positive transcriptional loop to regulate the transcription of MdPPO, MdPOD, and MdPAL, which in turn inhibited the degradation of phenolics and promoted the synthesis of phenolics, thus inhibiting fresh-cut apple fruit browning. These results provide a theoretical basis for improving the appearance and quality of fresh-cut apple fruit.

Speed breeding advancements in safflower (Carthamus tinctorius L.): a simplified and efficient approach for accelerating breeding programs.

This study investigated the potential of extended irradiation combined with immature embryo culture techniques to accelerate generation advancements in safflower (Carthamus tinctorius L.) breeding programs. We developed an efficient speed breeding method by applying light-emitting diodes (LEDs) that emit specific wavelengths, alongside the in vitro germination of immature embryos under controlled environmental conditions. The experimental design for light treatments followed a 2 × 4 completely randomized factorial design with four replications, incorporating two safflower varieties, Remzibey-05 and Dinçer, and four LED treatments (white, full-spectrum, red + blue + white, and control). A lighting regimen of 22 h of light and 2 h of darkness was applied for all the LED treatments, whereas the control received 18 h of light and 6 h of darkness. Additionally, the immature embryo culture experiment used a 2 × 2 × 4 factorial arrangement, assessing two safflower cultivars, two media types, and four embryo developmental stages, with three replications. The parameters evaluated included plant height, branch number, seed number per plant, seed number per head, time to flower initiation, time to 50% flowering, time to harvest, and germination percentage of in vitro cultured immature embryos at various developmental stages. The harvest time among the light treatments ranged from 50.62 to 73.12days, with the shortest time achieved under the red + blue + white LED combination and the longest under the control treatment. The plant height, number of seeds per plant, and number of seeds per head were highest under the full-spectrum LED, control and red + blue + white LED combinations, respectively. Immature embryos rescued at 10dayspost-pollination presented a 57% germination rate, with an increasing trend in germination as the number of dayspost-pollination increased. The germination rates did not significantly differ across varieties or hormone treatments. This study demonstrated the potential to achieve six generations per year by combining prolonged illumination with targeted LED lighting and immature embryo culture techniques. These findings provide valuable insights for optimizing safflower growth and development and advancing speed breeding in controlled environments.

Experimental Protocol for Color Difference Evaluation Under Stabilized LED Light.

There are two key factors to consider before implementing a color discrimination experiment. First, a set of color patches should be selected or designed for the specific purpose of the experiment to be carried out. Second, the lighting conditions should be controlled to eliminate the impact of lighting instability on the experiment. This paper addresses both of these challenges. It proposes a method to print pairs of color patches with non-noticeable color differences. It also proposes a method to stabilize the Spectral Power Distributions (SPDs) of a Light-Emitting Diode (LED) lighting system. Finally, it introduces an experimental protocol for a color discrimination study that will be performed thanks to the contributions presented in this paper.

LED light improves shoot multiplication, steviol glycosides and phenolic compounds biosynthesis in Stevia rebaudiana Bertoni in vitro culture

Light-emitting diode (LED) lamps are efficient elicitors of secondary metabolites. To investigate the influence of LED light on steviol glycosides (SGs) and phenolic compounds biosynthesis, stevia shoots were cultured under the following LED lights: white–WL, blue–B, red–R, 70% red and 30% blue–RB, 50% UV, 35% red and 15% blue–RBUV, 50% green, 35% red and 15% blue–RBG, 50% yellow, 35% red and 15% blue–RBY, 50% far-red, 35% red and 15% blue–RBFR and white fluorescent light (WFl, control). RBG light stimulated shoots’ biomass production. RBFR had a beneficial impact on stevioside biosynthesis (1.62 mg/g dry weight, DW), while RBUV favoured the production of rebaudioside A (3.15 mg/g DW). Neochlorogenic, chlorogenic, caffeic, 4-feruloylquinic, isochlorogenic A, rosmarinic acids and the flavonoid quercitrin were identified in the obtained material. A stimulatory effect of RBFR and RBUV on the biosynthesis of phenolic compounds was noted. LED light also influenced stomata appearance, stomata density, photosynthetic pigments, soluble sugar content and antioxidant enzyme activities in stevia shoots. This is the first report to provide evidence of the stimulating effect of LED light on biomass yield, SGs production and phenolic compounds in stevia shoot cultures.

Pupilmate: A do-it-yourself frugal pupilometer.

The pupillary direct and consensual reflex is an important non-invasive quick assessment of the neurological state of the eye. Currently, there is no cheap and affordable recording tool for screening and documentation of a relative afferent pupillary defect. We describe how to construct a frugal, do-it-yourself handheld scotopic binocular pupillometer device called Pupilmate. Two simple Wi-Fi-enabled board cameras fitted on both sides of the back of a rectangular cardboard box separated by a central paper divider, one side of the rectangular box was left open. An infrared red (IR) light source in the form of light-emitting diodes (LEDs) was fitted around each of the cameras. Two white light LEDs were fitted on either side of the box controlled by a two-way switch. A simultaneous video stream of both pupils could then be tuned in on any chosen device using the internet. Each pupil is manually illuminated for a desired time allowing recording of direct as well as consensual reflexes, which are objectively observed. Pupil reaction was easily recorded and repeatable using Pupilmate. It served as a good medium for initial screening in an outpatient department (OPD) setting, outreach programs, clinics, etc.

Effects of supplementary light treatment on saffron: integrated physiological, metabolomic, and transcriptome analyses.

Saffron (Crocus sativus L.) is a perennial, bulbous flower whose stigma is one of the most valuable spices, herbal medicines, and dyes. Light is an essential environmental regulator of plant growth, development, and metabolism. With the popularization of customized light-emitting diode (LED) light sources in facility agriculture, accurate light control has become essential for regulating crop yield and quality. In this study, white, red, and blue LED lights were applied to extend the photoperiod at the start and end of the day during the indoor stage of saffron cultivation. We investigated saffron growth and flowering using non-target metabolomic and transcriptome analyses to determine the flux and accumulation of metabolites from the stigma under different light treatments. The results revealed that supplemental red and white lights both promoted dry mass accumulation in the stigma, with the optimal appearance achieved using white light. Supplemental white light promoted saffron flowering, whereas supplemental blue light delayed it. Supplemental blue light promoted crocin-1 and crocin-3 accumulation, whereas supplemental red light promoted crocin-2 accumulation. Expression analysis of key genes and their correlations with crocin-related metabolites may provide useful information for screening functional genes involved in crocin synthesis. This study provides useful information for future application of LED light to improve the planting technology, quality, and yield of saffron, and reveals underlying molecular information for the further research.

Comparison spectral analysis and photometric parameters for different indoor and outdoor LEDs lighting

Light emitting diode (LED) lighting have gained in popularity owing to the advantages offered by them over incandescent lamps with respect to energy efficiency, strong robustness, operation life, and steadiness with time, making them suitable for a wide range of applications like residential and commercial lighting. In this work, the luminous flux and thermal stabilization time, color parameters, and spectral mismatch factors and their uncertainties have been measured and estimated for some indoor and outdoor commercial LED lamps of three different brands with nominal powers of 3, 9, and 36 watts. These lamps were classified into indoor-1, indoor-2, indoor-3, and outdoor LED lamps in order to enable the present analysis. The measurement methodology included a sophisticated luminous flux system using a 2.5-meter integrating sphere at the National Institute of Standards, NIS, equipped with the NIS photometer LMT U1000 and a series of NIS luminous flux secondary standard lamps calibrated at the National Physical Laboratory, NPL, in England. This is important for making proper, accurate measurements of the total luminous flux emitted by different LED lamps. In addition, an NIS Spectroradiometer (Ocean Optics HR 2000) and a photometric bench were used in order to measure the spectral power distribution of the lamps, by means of which we had the possibility to calculate the spectral mismatch correction factor quantify the color parameters and estimate the associated measurement uncertainties. The comprehensive approach in our study involves assessing luminous flux, thermal stabilization time, spectral mismatch correction factors, and chromaticity color coordinates, all in comparison to established standards provided by NIS Secondary Standard Lamps. This paper demonstrates that the obtained spectral mismatch correction factors and chromaticity color coordinates with their uncertainties can be used as basic corrections to luminous flux and color measurements. By doing this, the accuracy and dependability of these kinds of measurements are significantly improved, increasing the knowledge about the performance of LED lamps.

Nitrate accumulation and mineral nutrition of lettuce under varied light emitting diode lighting

This study aims to investigate strategies to minimize nitrate accumulation in lettuce to mitigate its potential harmful effects on human health. Lettuce cultivation under light-emitting diode lighting (LED) is becoming increasingly popular, and determining the effects of different LED sources on lettuce nutrition and nitrate accumulation is an important topic. The effects of different nitrate levels in the nutrient solution and different LED sources on lettuce nutrition and nitrate accumulation have been investigated under controlled conditions. Lettuce plants were grown for 48 days under White (W), Blue (B), Blue + Far Red (B + FR), Red (R), Red + Blue (R + B), Red + Far Red (R + FR), Red + Blue + Far Red (R + B + FR) LED lights using nutrient solutions containing 20, 24, and 28 mM nitrate. The highest marketable yield was obtained under B lighting, followed by R, R + B, R + FR, and R + B + FR. To reduce nitrate accumulation, lighting setups using W, R + B + FR, R + B, and R have proven to be advantageous. In these treatments, nitrate levels were determined to be 1039, 1118, 1167, and 1170 mg kg−1, which were lower compared to the other treatments. The concentrations of measured nutrients in plants were highest under B + FR, R + FR, and R + B lighting. The total chlorophyll concentration increased with the N dose, with the highest levels observed in the B, B + RF, and R + B + FR treatments. In conclusion, LED lighting influences lettuce nutrition and nitrate accumulation, with W, R + B + FR, R + B, and R treatments most effective in reducing nitrate levels. These findings should be validated in commercial greenhouse conditions to assess their practical applicability for large-scale production.

Linked Color Imaging with Light-Emitting Diode Light Enhances the Visibility of Gastric Neoplasm: A Prospective, Multicenter, Comparative Trial.

Early detection of gastric cancer can play a key role in improving prognosis. Recently, light-emitting diodes (LED) have been developed as novel endoscopic systems. However, the differences in the visibility of gastric neoplastic lesions between LED and laser endoscopy remains unclear. We conducted a prospective multicenter trial to evaluate the non-inferiority of LED endoscopy in the visibility of gastric neoplastic lesions undergoing endoscopic submucosal dissection (ESD) in comparison to laser endoscopy. A multicenter, prospective, cross-sectional study was conducted in patients undergoing ESD for gastric neoplastic lesions at five hospitals throughout Japan. Seventy patients with 74 lesions were included in this study. The primary endpoint was the non-inferiority of the difference in the individual scores of linked color imaging (LCI) and white-light imaging (WLI) for LED and laser endoscopy for gastric neoplastic lesions. The mean individual score was 2.66 ± 1.02, 3.17 ± 0.83, 2.75 ± 1.05, and 3.21 ± 0.84 in LED-WLI, LED-LCI, laser-WLI, and laser-LCI, respectively. The difference in individual scores of LCI and WLI was 0.51 ± 0.77 and 0.46 ± 0.80 in LED and laser endoscopy, respectively. The mean difference between LED and laser endoscopy was 0.04 (95% confidence interval [CI]: - 0.05 to 0.13, P < 0.001). This study revealed the non-inferiority of the differences in individual scores between LCI and WLI in the comparison of LED and laser endoscopy for gastric neoplastic lesions.

Effect of Artificial LED and Natural Light on the Growth of Cucumber Plant (Cucumis sativus) in Hydroponic System

Hydroponics is the latest innovation in farming where plants are grown in the absence of soil. In India adoption rate of hydroponics is estimated 13 – 15 % annually. In this context present study was conducted to analyze the morphological characteristics of cucumber plant in Dutch Bucket Hydroponic system. Moreover, comparative evaluation of morphological characteristics of cucumber plants were carried out under natural light as well as artificial light emitting diode (LED). The experiment was carried out in the Naturally Ventilated Polyhouse (NVPH) and in the laboratory (as an indoor practice) in the campus of Dadasaheb Mokashi Collage of Agricultural Engineering and Technology Rajmachi, Karad, Maharashtra, India. Cucumber (Cucumis sativus) HY shiny variety was grown in both the environments to evaluate different morphological characteristics such as average leaf count, leaf area, stem diameter, plant height and root length. Dutch bucket system of 10 buckets (each having capacity of 11 liters) was installed each in natural and artificial light source. Cucumber plants were grown in both environment for months June- July 2024. From the present experiment it was observed that, most of the selected parameters were found more satisfactory in artificial light as compared to natural light. Before the flowering stage, average leaf count, average leaf area, average plant height, and average root length was observed approximately 26, 123.15 cm2, 154 cm, 30.1 cm for artificial light and 22, 56.07 cm2, 110 cm, 25.3 cm for natural light, respectively. The average stem diameter was observed almost similar in both the systems and it was about 1.1 cm. Therefore, from this study it was envisaged that overall average leaf count, average leaf area, average plant height and average root length was improved in artificial light by 18%, 54%, 28%, and 25%, respectively over natural light.

Impact of Light-Emitting Diode (LED) Lighting and Microbial Inoculum on Rice Seedling Phenotype, Physiology, and Microbial Communities

Raising rice (Oryza sativa L.) seedlings under LED lighting reduces nursing space and labor while ensuring health and quality. This study compared rice seedlings grown under natural light (NL) and LED lighting (AL), with and without inoculation of the beneficial fungus Falciphora oryzae. The results showed that NL-grown seedlings had greater stem diameters and shoot and root weights. The AL treatment induced higher plant height in some cultivars and longer root lengths in others. Microbial inoculation minimally affected phenotypes but increased root length in one cultivar. Chlorophyll content was unchanged across the treatments, while malondialdehyde (MDA) levels rose under AL in one cultivar, and catalase (CAT) levels were elevated in two cultivars under AL. Microbial inoculation reduced CAT levels under AL. The AL + M treatment increased rhizosphere prokaryotic community evenness and altered prokaryotic compositions in the rhizosphere and root endosphere, with Burkholderia and Paraburkholderia taxa showing differential responses to the treatments. These findings underscore the role of microbial inoculation in enhancing rice seedling health and resilience under artificial lighting, contributing to sustainable agriculture and food security.

Measuring the External Quantum Efficiency of Tandem Photovoltaic Modules Using an LED‐Based Solar Simulator

An external quantum efficiency (EQE) measurement procedure for full‐size tandem modules using a light‐emitting diode (LED)‐based solar simulator is introduced. This elegant procedure uses the LED light source for both, setting a close to one‐sun bias spectrum and performing the actual EQE measurement by modulating individual LED channels. Measurement comparisons using filtered silicon solar cells and a perovskite on silicon (PSC/Si) single‐cell module demonstrate good agreement between the EQEs obtained with the presented procedure and reference EQEs, determined at Fraunhofer ISE CalLab PV Cells and the National Metrology Institute of Germany. Applying the procedure to a full‐size PSC/Si tandem module results in a close match of the full module EQE and the EQE of an optically similar single‐cell module measured at CalLab PV Cells. Performing a spectral adjustment of the LED solar simulator based on the full‐module and single‐cell module EQE, only minor spectral variations, reflected in minimal deviations of the resulting spectral mismatch factors of less than 0.4%, are determined. The presented results confirm the applicability of the procedure as an efficient and accurate approach for EQE measurements and underline its overall relevance for the calibration of full‐size tandem modules.