Spectral Composition Of Light Research Articles

Effects of Supplemental Lighting on Flavonoid and Anthocyanin Biosynthesis in Strawberry Flesh Revealed via Metabolome and Transcriptome Co-Analysis.

The spectral composition of light influences the biosynthesis of flavonoids in many plants. However, the detailed composition of flavonoids and anthocyanins and the molecular basis for their biosynthesis in strawberry fruits under two light-quality treatments, red light supplemented with blue light (RB) and ultraviolet B (UVB) irradiation, remain unclear. In this study, the content of flavonoids and anthocyanins was significantly increased in strawberry fruits under RB light and UVB, respectively. The content of flavonoids and anthocyanins in strawberry fruits under UVB light was dramatically higher than that in strawberry fruits irradiated with RB light, and a total of 518 metabolites were detected by means of LC-MS/MS analysis. Among them, 18 phenolic acids, 23 flavonoids, and 8 anthocyanins were differentially accumulated in the strawberry fruits irradiated with red/blue (RB) light compared to 30 phenolic acids, 46 flavonoids, and 9 anthocyanins in fruits irradiated with UVB. The major genes associated with the biosynthesis of flavonoids and anthocyanins, including structural genes and transcription factors (TFs), were differentially expressed in the strawberry fruits under RB and UVB irradiation, as determined through RNA-seq data analysis. A correlation test of transcriptome and metabolite profiling showed that the expression patterns of most genes in the biosynthesis pathway of flavonoids and anthocyanins were closely correlated with the differential accumulation of flavonoids and anthocyanins. Two TFs, bZIP (FvH4_2g36400) and AP2 (FvH4_1g21210), induced by RB and UVB irradiation, respectively, exhibited similar expression patterns to most structural genes, which were closely correlated with six and eight flavonoids, respectively. These results indicated that these two TFs regulated the biosynthesis of flavonoids and anthocyanins in strawberry fruit under RB light and UVB, respectively. These results provide a systematic and comprehensive understanding of the accumulation of flavonoids and anthocyanins and the molecular basis for their biosynthesis in strawberry fruits under RB light and UVB.

Comparative Transcriptome Analysis Reveals the Light Spectra Affect the Growth and Molting of Scylla paramamosain by Changing the Chitin Metabolism.

Light is an essential ecological factor that has been demonstrated to affect aquatic animals' behavior, growth performance, and energy metabolism. Our previous study found that the full-spectrum light and cyan light could promote growth performance and molting frequency of Scylla paramamosain while it was suppressed by violet light. Hence, the purpose of this study is to investigate the underlying molecular mechanism that influences light spectral composition on the growth performance and molting of S. paramamosain. RNA-seq analysis and qPCR were employed to assess the differentially expressed genes (DEGs) of eyestalks from S. paramamosain reared under full-spectrum light (FL), violet light (VL), and cyan light (CL) conditions after 8weeks trial. The results showed that there are 5024 DEGs in FL vs. VL, 3398 DEGs in FL vs. CL, and 3559 DEGs in VL vs. CL observed. GO analysis showed that the DEGs enriched in the molecular function category involved in chitin binding, structural molecular activity, and structural constituent of cuticle. In addition, the DEGs in FL vs. VL were mainly enriched in the ribosome, amino sugar and nucleotide sugar metabolism, lysosome, apoptosis, and antigen processing and presentation pathways by KEGG pathway analysis. Similarly, ribosome, lysosome, and antigen processing and presentation pathways were major terms that enriched in FL vs. CL group. However, only the ribosome pathway was significantly enriched in up-regulated DEGs in VL vs. CL group. Furthermore, five genes were randomly selected from DEGs for qPCR analysis to validate the RNA-seq data, and the result showed that there was high consistency between the RNA-seq and qPCR. Taken together, violet light exposure may affect the growth performance of S. paramamosain by reducing the ability of immunity and protein biosynthesis, and chitin metabolism.

Open-Source Python Module for the Analysis of Personalized Light Exposure Data from Wearable Light Loggers and Dosimeters

ABSTRACT Light exposure fundamentally influences human physiology and behavior, with light being the most important zeitgeber of the circadian system. Throughout the day, people are exposed to various scenes differing in light level, spectral composition and spatio-temporal properties. Personalized light exposure can be measured through wearable light loggers and dosimeters, including wrist-worn actimeters containing light sensors, yielding time series of an individual’s light exposure. There is growing interest in relating light exposure patterns to health outcomes, requiring analytic techniques to summarize light exposure properties. Building on the previously published Python-based pyActigraphy module, here we introduce the module pyLight. This module allows users to extract light exposure data recordings from a wide range of devices. It also includes software tools to clean and filter the data, and to compute common metrics for quantifying and visualizing light exposure data. For this tutorial, we demonstrate the use of pyLight in one example dataset with the following processing steps: (1) loading, accessing and visual inspection of a publicly available dataset, (2) truncation, masking, filtering and binarization of the dataset, (3) calculation of summary metrics, including time above threshold (TAT) and mean light timing above threshold (MLiT). The pyLight module paves the way for open-source, large-scale automated analyses of light-exposure data.

Effect of cryptochrome 1 deficiency and spectral composition of light on photosynthetic processes in A. thaliana under high-intensity light exposure

Effect of cryptochrome 1 deficiency and spectral composition of light on photosynthetic processes in A. thaliana under high-intensity light exposure

Photochemical activity in developing pea (Pisum sativum L.) cotyledons depends on the light transmittance of covering tissues and the spectral composition of light.

Many crops require not only leaf photosynthesis for their seed development but also the photochemical reactions that occur in the seeds. The purpose of this work was a comparative analysis of light transmittance and photochemical activity in the leaves of Pisum sativum L. and its pericarp, seed coat, and cotyledons at the early, middle, and late maturation stages. The spectral composition of light was measured using a spectroradiometer in the range of 390-760 nm. We assessed the light transmittance of plant tissues by placing the plant tissue between the light source and the spectroradiometer's sensor. PAM fluorometry was used to quantify the photochemical activity in plant tissues: this technique is handy for evaluating the efficiency of converting light energy into chemical energy through the analysis of the kinetics of chlorophyll fluorescence excitation and quenching. On average, a photochemically active green leaf of pea transmitted 15 % of solar radiation in the 390-760 nm, blue light was delayed entirely, and the transmitted red light never exceeded 5 %. Photochemically active radiation passing through the pericarp and coat and reaching the cotyledons at the early and middle seed maturation stages manifested a high proportion of green and far-red light; there was no blue light, and the percentage of red light was about 2 %. However, the cotyledons were photochemically active regardless of low irradiance and spectral ranges untypical of leaf photosynthesis. At the early and middle maturation stages, the maximum quantum yield of photosystem II (Fv/Fm) averaged 0.5 at the periphery of cotyledons and 0.3 at their center. Since the intensity of embryonic photochemical reactions significantly affects the efficiency of reserve nutrient accumulation, this parameter is a promising marker in pea breeding for seeds with improved nutritional qualities.

ШЛЯХИ ПОБУДОВИ ЕНЕРГОЕФЕКТИВНИХ СВІТЛОДІОДНИХ СИСТЕМ ФІТООСВІТЛЕННЯ

Lighting of plant crops (phytolighting) realized on the basis of LEDs has revolutionized the field of indoor agriculture and cultivation of crops in closed controlled environments due to the possibility of optimizing the spectral composition and high energy efficiency. The use of specialised quasi-monochromatic radiation allows the activation of specific photomorphogenic, biochemical or physiological responses in plants, while LED radiation of a specific spectral composition (e.g. UV radiation) allows the control of plant pests and diseases. The literature review indicates that there is a species- and cultivar-specific response of plants to light radiation of a particular spectral composition and that this response varies with the stage of plant development, the intensity of illumination, the duration of plant development and specific interactions with the environment. Based on the developed recommendations for the spectral composition of radiation intended for plant illumination, the requirements for the spectral composition of light for phytolighting systems were determined. The efficiency of LEDs with different spectral compositions for plant illumination and the most energy efficient LEDs for use in phytolighting systems were determined. Special software was developed to determine the photon radiation efficiency and it was determined for a wide range of LED light sources. The LEDs studied had photon efficiencies ranging from 3.78 μmol/J (quasi-monochromatic blue LEDs) to 5.46 μmol/J (quasi- monochromatic red LEDs). White LEDs, depending on their colour rendering index, had a photon spectral efficiency in the range of 4.62-4.79 μmol/J. Some modern white LEDs with a high colour rendering index have a photon spectral efficiency close to that of phytolighting based on special quasi-monochromatic LEDs, but their efficiency, taking into account the weighting factor of the use of photons of different wavelengths for photosynthesis, is much lower.

Does a flashing artificial light have more or conversely less impacts on animals than a continuous one? A systematic review

Background: Light pollution has been increasingly recognised as a threat to biodiversity, especially with the current expansion of public lighting. Although the impacts of light intensity, spectral composition and temporality are more often studied, another component of light, its flicker frequency, has been largely overlooked. However, flashing light could also have impacts on biodiversity, and especially on animal behaviour and physiology. Objective: This systematic review aimed at identifying the reported physiological and behavioural impacts of flashing light on animals when compared to continuous light. Methods: We followed the standards recommended by the Collaboration for Environmental Evidence (CEE) in order to achieve a comprehensive, transparent and replicable systematic review. Citations were primarily extracted from three literature databases and were then screened for relevance successively on their titles, abstracts and full-texts. Retained studies were finally critically appraised to assess their validity and all relevant data were extracted. Only studies which compared a flashing light to a continuous one were included. Results: At first, we found 19,730 citations. Screening and critical appraisal resulted in 32 accepted articles corresponding to 54 accepted observations—one observation corresponding to one species and one outcome. We collated data on four main taxa: Aves (the most studied one), Actinopterygii, Insecta and Mammalia as well as on plankton. Conclusions: The impacts of flashing light are currently critically understudied and varied between species and many light specificities (e.g. frequency, wavelength, intensity). Therefore, no definitive conclusions could be drawn for now. Thus, research on flashing light should be pressingly carried out in order to better mitigate the impacts of Artificial Light at Night (ALAN) on wildlife. In the meantime, we would recommend precautionary principles to be applied: flashing lighting should be limited when not deemed essential and flicker frequencies managed to prevent animals from experiencing any potential harm from flashing light.

Optimizing the spectral composition of light from LED phytolighting systems to improve energy efficiency

The use of LEDs for plant lighting (phytolighting) provides a more energy- efficient alternative to traditional lighting methods. Combination of LEDs with different spectral composition and the possibility to change the composition of resulting radiation in a single lighting device allows one to improve the efficiency of phytolighting systems and optimize them for different conditions of plant growth and development. In this work, we have investigated quasi-monochromatic LEDs specialized for efficient phytolighting and efficient white LEDs with different CRI. Being based on the research, the most effective LEDs for building phytolighting systems have been identified, and their optimal ratio with red quasi-monochromatic LEDs for building phytolighting systems in rooms with a constant presence of people (greenhouses, winter gardens, etc) has been determined.

Impact of green and blue-green light on the growth, pigment concentration, and fatty acid unsaturation in the microalga Monoraphidium braunii.

The spectral composition of light is an important factor for the metabolism of photosynthetic organisms. Several blue light-regulated metabolic processes have already been identified in the industrially relevant microalga Monoraphidium braunii. However, little is known about the spectral impact on this species' growth, fatty acid (FA), and pigment composition. In this study, M. braunii was cultivated under different light spectra (white light: 400-700 nm, blue light: 400-550 nm, green light: 450-600 nm, and red light: 580-700 nm) at 25°C for 96 h. The growth was monitored daily. Additionally, the FA composition, and pigment concentration was analyzed after 96 h. The highest biomass production was observed upon white light and red light irradiation. However, green light also led to comparably high biomass production, fueling the scientific debate about the contribution of weakly absorbed light wavelengths to microalgal biomass production. All light spectra (white, blue, and green) that comprised blue-green light (450-550 nm) led to a higher degree of FA unsaturation and a greater concentration of all identified pigments than red light. These results further contribute to the growing understanding that blue-green light is an essential trigger for maximized pigment concentration and FA unsaturation in green microalgae.

Creation of a Photobioreactor for the Effective Growth of Chlorella and Study of the Effect of the Spectral Composition of Light on Its Biomass

Chlorella is a green eukaryotic microalga (Chlorella vulgaris). The microscopic cell is spherical, 2–10 μm in diameter. This microalga is one of the most important and promising for biomass production. Chlorella is cultivated in ponds or bioreactors with specified parameters that create favorable conditions for the growth of chlorella biomass. Each set of conditions creates the opportunities for changing the growth rate and output of individual products. Two strains of chlorella were the object of the study: 1 – chlorella with a thin cell wall (Chlorella vulgaris VKPM Al-24); 2 – chlorella with a thick cell wall (Chlorella vulgaris Beijer). The culture of chlorella was cultivated on modified Tamiya nutrient medium, at 24°C and 24-hour illumination. It was cultivated for 5 days in 1000 ml flasks, in opaque grow boxes with different lighting regimes. The control variant was grown in a light room with white fluorescent lamps with an intensity of 150 μmol/m2 s, and the culture was also grown in the dark. Laboratory experiments studying the effect of spectral composition of light on growth of two strains of chlorella culture allowed identifying some regularities: 1 – the largest increase in biomass is observed when using white fluorescent lamps (T = 2700K); 2 – in the case of using FR>R or FR=R, their inhibitory effect on the growth of the studied strains of chlorella was observed. In addition, similar results were obtained when determining the optical density of the cultures, suggesting that the chlorella strains studied are similarly responsive to the action of different spectral compositions of light. Analyzing the absorption spectrum, it should be noted that it has a continuous character. It has been experimentally established that the first maximum is located in the red region (660 to 690 nm) and the second in the blue region (430 to 450 nm). The minimum absorption is observed in the green light region (500 to 610 nm).

Photosynthesis, Yield and Quality in Wild Rocket (Diplotaxis tenuifolia L.) under Photoluminescent Greenhouse Covers

Manipulation of light spectral composition is a useful tool to drive morphological, physiological and metabolic responses in several crops, ultimately improving yield and quality. Novel materials for greenhouse covering are being developed in order to make a better use of the available sunlight: among these are the cover films or panels incorporating fluorescent additives which are able to convert UV solar radiation into visible light. In this research, we compared the physiological traits and the agronomical performance of wild rocket grown in pots in the winter–spring season, under four different greenhouse prototypes covered with poly-methyl-methacrylate (PMMA)-based panels. PMMA panels doped at 3% (Dop3) or 7% (Dop7) w/w with a blend of rare-earth elements (partially converting the solar UV radiation to red and blue wavelengths) were compared with an undoped (UD) and a whitewashed (WW) PMMA greenhouse. The rocket yield was higher in Dop3 (+30%), while it was unaffected in Dop7 and lower in WW (−39%), compared to the control (6.06 kg m−2). The leaf greenness decreased while both the ABTS and the hydrophilic antioxidant activities increased under the doped and the whitewashed greenhouses. The Dop3 treatment provided the best results in terms of yield and quality of greenhouse wild rocket in winter–spring cycle. However, the analysis of OJIP kinetics of chlorophyll fluorescence revealed that the main factor affecting the photosynthetic performance was the light intensity inside each greenhouse rather than the modulation of light spectrum, because of the different shading properties of the doping and whitewashing treatments. Although these results did not allow us to distinguish between the combined effects of shading and light spectrum modulation, the use of photoluminescent covers can be foreseen as a promising innovation in greenhouse horticulture.

Analysis of Cross-Influence of Microclimate, Lighting, and Soil Parameters in the Vertical Farm

Urban vertical farming is an innovative solution to address the increasing demand for food in densely populated cities. With advanced technology and precise monitoring, closed urban vertical farms can optimize growing conditions for plants, resulting in higher yields and improved crop quality. However, to fully optimize closed urban vertical farming systems, research is needed to enhance crop yields and reduce the growing season. The present study is focused on the research of the mutual influence of microclimate parameters, such as temperature, humidity, and carbon dioxide concentration, as well as the spectral composition of light, humidity, and amount of peat in the substrate. The research was conducted within the cultivation of the “Innovator” potato variety at the experimental automated vertical farm of the “Fundamentals of Biotechnology” of the Russian Academy of Sciences. Based on the correlation and Fourier analysis of the dependences of soil moisture and carbon dioxide concentration on time, it is shown that after watering potatoes, there is a 56 h delayed decrease in the concentration of carbon dioxide in the cultivation room, which can be explained by a delayed increase in the intensity of the photosynthesis process. Moreover, a comparison of CO2 dependence on time with the lighting dynamics at the scale of one day indicates the presence of the intrinsic daily biological rhythm of the CO2 absorption rate that does not depend on the external lighting conditions. In addition, by analyzing the dependencies of microclimate parameters and the spectral composition of the lighting over time, it was found that switching on lighting influences the microclimate parameters, which can be explained by the heating of LEDs used for lighting. Moreover, the multiple regression analysis of microclimate parameters and soil moisture showed that an increase in peat content in the substrate leads to a transition from the decisive influence of air humidity on soil moisture to the dominant influence of air temperature. The obtained results reveal the complex mutual influence of the parameters determining the growing conditions within automated closed vertical farms. Consideration of this influence is necessary when optimizing the conditions of vegetation and the development of intelligent plant-growing systems.

Changes in the light environment: Short-term responses of photosynthesis and metabolism in spinach.

Modification in the light environment can induce several changes even within a short time. In this article, light intensity and spectrum-dependent changes in photosynthetic and metabolic processes were investigated in spinach leaves. Short-term exposure of the youngest fully developed leaves provided an elevated CO2 assimilation capacity under red light compared with blue or white light, although the electron transport rate was lower. The stomatal opening was mainly stimulated by blue light. These spectrum-induced changes also depended on light intensity. When white light was used to activate the photosynthesis, the white light showed a similar light response to blue light regarding the electron transport processes and red light in terms of stomatal opening. In contrast, concerning CO2 assimilation characteristics, the white light resembled blue light at low and red light at high light intensities. These results indicate that the photosynthetic processes strongly interact with the light intensity and spectral composition. Furthermore, changes in spectral composition modified the primary metabolic processes as well. Red light induced the sugar accumulation, while more organic acids that belong to the respiration pathway were produced under blue and white lights. These changes occurred even within a short (30 min) time frame. These results also draw attention to the importance of the light environment used during the measurements of the photosynthetic activity of plants and/or sample collections.

Dependence of state transitions on illumination time in arabidopsis and barley plants.

Solar energy absorbed by plants can be redistributed between photosystems in the process termed "state transitions" (ST). ST represents a reversible transition of a part of the PSII light harvesting complex (L-LHCII) between photosystem II (PSII) and photosystem I (PSI) in response to the change in light spectral composition. The present work demonstrates a slower development of the state 1 to state 2 transition, i.e., L-LHCII transition from PSII to PSI, in the leaves of dicotyledonous arabidopsis (Arabidopsis thaliana) than in the leaves of monocotyledonous barley (Hordeum vulgare) plants that was assessed by the measurement of chlorophyll a fluorescence at 77 K and of chlorophyll a fluorescence at room temperature. It is known that the first step of the state 1 to state 2 transition is phosphorylation of Lhcb1 and Lhcb2 proteins; however, we detected no difference in the rate of accumulation of these phosphorylated proteins in the studied plants. Therefore, the parameters, which possibly affect the second step of this transition, i.e., the migration of L-LHCII complexes along the thylakoid membrane, were evaluated. Spin-probe EPR measurements demonstrated that the thylakoid membranes viscosity in arabidopsis was higher compared to that in barley. Moreover, confocal microscopy data evidenced the different size of chloroplasts in the leaves of the studied species being larger in arabidopsis. The obtained results suggest that the observed deference in the development of the state 1 to state 2 transition in arabidopsis and barley is caused by the slower L-LHCII migration rate in arabidopsis than in barley plants rather than by the difference in the Lhcb1 and Lhcb2 phosphorylation.

FEATURES OF GROWTH AND INULIN CONTENT IN CALLUS CULTURES Cichorium intybus L. in vitro

In vitro callus cultures of common chicory (Cichorium intybus L.) were obtained and their growth and biochemical characteristics depending on the hormonal composition of the MS medium and the spectral composition of light were studied. The study of the effect of light culture on callus tissue formation and inulin accumulation in it was carried out in opaque grow tents with radiation aligned with the flux density of pho- tosynthetic photons and different ratios of its levels in the region of 660 nm (R, red) and 730 nm (FR, far red). The control variant was placed under white linear fluorescent lamps. The resulting cultures were character- ized by high proliferative activity and the capability for morphogenesis. It has been established that the inter- action of two factors—the presence of auxins in the nutrient medium (IAA or NAA at a concentration of 7.5 mg/L in combination with BAP 0.5 mg/L) and cultivation under light culture conditions (FR R, FR = R, FR R)—had a significant impact on the biosynthetic potential of cell cultures. In the obtained cultures, a study of the quantitative content of inulin was carried out. It has been shown that the high content of inulin (7.55–7.95%) in callus cultures was on the MS medium in combination with IAA at FR R illumination. This is probably due to the fact that well proliferating and highly morphogenic callus tissue was formed under these conditions. The obtained results confirm the hypothesis about the specificity of cultured cells to in vitro synthesize and accumulate secondary metabolites in dedifferentiated cells and the dependence of this process on factors of chemical and physical nature.

Light spectrum effects on rocket and lamb's lettuce cultivated in a vertical indoor farming system

Rocket and lamb's lettuce are new leafy vegetables whose consumption in salads is increasing, especially as ready-to-eat products. These plants are often cultivated in greenhouses under artificial light, and are very important due to their pleasant taste, texture, and nutritional value to humans. The present study analyzes the effects of light quality provided by light emitting diodes (LEDs) on the yield and quality of different leafy vegetable species. Lamb's lettuce and rocket plants were grown in the same conditions under 4 light spectrums color fractions (NS-12, AP57, AP673L, and G2) for 27 and 37 days, respectively. Then fresh and dry weight, chlorophyll fluorescence, and chromatic characteristics were determined. The leaf quality of lamb's lettuce and rocket was characterized by measurements of the contents of carbohydrates, organic acids, and amino acids in leaves. Vegetative growth was significantly influenced by light quality and was species-dependent, and treatment with the highest proportion of Red:Blue light (G2) produced the highest fresh weight and maximum efficiency of PSII. The results of the chlorophyll fluorescence parameters were more influenced by the species rather than by the spectrum lights, except for the efficiency of PSII, which was higher in treatments with the lowest Red: Far-red ratio (AP67 and G2). G2 light spectrum reduces chlorophyll and carotenoid content compared to other treatments. Among all the primary metabolites analyzed, non-structural carbohydrates were the most dependent on light quality. Generally, the lights with the greatest effect on the parameters analyzed were those with higher Red:Blue ratios and a higher far-red fraction. No effect of light spectra on glutamate concentration was observed. However, a concentration increase was observed in treatments with a higher proportion of far-red light. Regarding organics acids, the different light spectrums did not affect the concentration of the majority of acids (citrate and malate) in rocket and lamb´s lettuce plants. The spectral composition of light has an influence on the quality and quantity of lamb's lettuce and rocket production. Therefore, each species studied responds differently to the light spectrums.

Investigating the Physiological and Molecular Responses of Solanum lycopersicum hp Mutants to Light of Different Quality for Biotechnological Applications.

The effect of the light of different spectral compositions, white fluorescent light (WFL), red light (RL, 660 nm), blue light (BL, 450 nm), green light (GL, 525 nm), and white LED light (WL, 450 + 580 nm), on the physiological parameters of Solanum lycopersicum 3005 hp-2 (defective for a DET1 gene) and 4012 hp-1w; 3538 hp-1; 0279 hp-1.2 (defective for a DDB1a gene) photomorphogenetic mutants was studied. The parameters of the primary photochemical processes of photosynthesis, photosynthetic and transpiration rates, the antioxidant capacity of low-molecular weight antioxidants, the content of the total phenolic compounds, including flavonoids, and the expression of the genes involved in light signaling and biosynthesis of secondary metabolites were determined. Under BL, the 3005 hp-2 mutant showed the highest nonenzymatic antioxidant activity, which occurred to a greater extent due to the increase in flavonoid content. At the same time, under BL, the number of secretory trichomes on the surface of the leaves of all mutants increased equally. This suggests the accumulation of flavonoids inside leaf cells rather than in trichomes on the leaf surface. The data obtained indicate the possibility of using the hp-2 mutant for biotechnology to increase its nutritional value by enhancing the content of flavonoids and other antioxidants by modulating the spectral composition of light.

Development of a multichannel spectral simulation tool and experimental validation with different lighting scenarios

The spectral composition of light has been linked to various non-image-forming responses besides visual photoreception. Accordingly, simulation tools must incorporate the spectral composition of light to account for such responses. A simulation tool was developed which uses N-step algorithm and subdivides the (red, green, and blue) RGB bands into multiple channels. This research intends to validate the tool for different lighting scenarios. A physical model was constructed in which the integral irradiance from 380 nm to 780 nm was measured for three scenarios: diffuse daylight, electric light with variable correlated colour temperature and a combination of both. All three scenarios were simulated with 3, 9, 27 and 81 channels. For scenarios with electric light and combination of daylight and electric light, the nine-channel simulation improved the mean absolute percentage error (MAPE) by 13.9% to 33.9% compared to the three-channel simulation. For continuous daylight, there was only a small improvement of 0.4% when increasing from 3 to 27 channels. In comparison to 9 channels, 27 channels slightly improved MAPE in all the scenarios but substantially increased the simulation time. Increasing the number of channels to 81 is likelier to bring a contribution to more complex scenarios than that presented in this study.

Determination of Correlated Color Temperature in Ex Vivo Porcine Eyes during Intraocular Illumination.

(1) Background: In ophthalmic surgery, white light is mostly applied to illuminate the intraocular space, and ophthalmologists are comfortable working with it. Diaphanoscopic illumination changes the spectral composition of light, resulting in a change in the correlated color temperature (CCT) of the intraocular illumination. This color change makes it difficult for surgeons to recognize the structures in the eye. CCT during intraocular illumination has not yet been measured before, and it is the aim of this study to perform such measurement. (2) Methods: CCT was measured inside ex vivo porcine eyes during diaphanoscopic illumination and endoillumination using a current ophthalmic illumination system with a detection fiber inside the eye. By applying pressure on the eye with a diaphanoscopic fiber, the dependency of CCT on pressure was examined. (3) Results: The intraocular CCT values during endoillumination were 3923 K and 5407 K for the halogen and xenon lamps, respectively. During diaphanoscopic illumination, a strong unwanted red shift was observed, resulting in 2199 K and 2675 K for the xenon and the halogen lamps, respectively. Regarding different applied pressures, the CCT did not differ considerably. (4) Conclusions: This red shift should be compensated for in the development of new illumination systems since surgeons are used to white light illumination, which also simplifies the identification of retinal structures.

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.