Proportion Of Blue Light Research Articles

Effects of different LED light spectra and nutrient solution strength on the growth, photosynthetic parameters, and nutrients uptake in tomato seedlings

Light-emitting diode (LED) lighting is currently the most energy-efficient lighting technology, and its use in agriculture is rapidly increasing. This research aimed to investigate the interaction effect of nutrient solution concentration and light quality on tomato seedlings growth. The tested factors included two nutrient solution concentrations (50% and 33% Hoagland solution) and four ratios of blue (440 nm) to red (660 nm) light in LED lighting at a constant light intensity (B2R1, B1R1, B1R2, and B1R3). Height growth was greatest in the 33% nutrient solution × B1R2 light treatment and smallest in the 33% nutrient solution × B2R1 light treatment. Regardless of the nutrient solution concentration, total chlorophyll and carotenoid concentrations decreased with an increase in the proportion of blue light. Plant absorption of sulfur was highest in the 50% nutrient solution × B1R2 light treatment, significantly higher than all other treatments. Although the 50% nutrient solution × B1R2 light treatment also showed the greatest magnesium absorption, it did not differ significantly from most of the other treatments. In general, for growing tomato seedlings, a high ratio of blue light regime (B2R1) with a dilute nutrient solution, enriched with magnesium and sulfur, can be recommended to prevent elongation disorder and have no negative impact on various growth and physiological indicators.

Effects of Different Combinations of Red and Blue Light on the Edible Organ Morphology and Quality of Buckwheat (Fagopyrum esculentum Moench) Microgreens

Buckwheat microgreens are rich in nutrients and have a unique flavor that is favored by consumers. The light environment is closely related to the growth and development of the plant. In order to study the effects of treatments with different combinations of red and blue light on the edible organ morphology and nutritional quality of buckwheat microgreens, five experimental treatments were designed, with energy ratios of red light to blue light of 5:1 (R5B1), 3:1 (R3B1), 1:1 (R1B1), 1:3 (R1B3) and 1:5 (R1B5), respectively, and a white light treatment used as the control (CK). The results showed that different combination treatments of red and blue light had obvious effects on the growth of buckwheat microgreens. The hypocotyl length and main root length of buckwheat microgreens treated with a high proportion of red light (R5B1) were obviously higher than those of other treatment designs. However, contents of soluble protein, chlorophyll, rutin and total flavonoids in buckwheat microgreens showed an increasing trend with an increase in the proportion of blue light. Considering the fresh weight, dry weight and quality indexes of the edible organ, the combination of red light and blue light with a ratio of 1:1 was most suitable for buckwheat microgreen production. The results could provide a reference for the production of buckwheat microgreens.

Effect of Light Quality on the Growth and Mechanical Property of Tomato Grafted Seedlings

Seedlin g quality is directly related to the success rate of automatic grafting. To select the suitable light quality for cultivating mechanically grafted tomato seedlings, the effects of different LED light qualities on the morphological parameters and mechanical properties of tomato seedlings were measured in an artificial light environment in a plant factory. Combination of red (R) and blue (B) LEDs as follows: R: B=100:0 (RLT), R: B=75:25(RBI), R: B=50:50(RBII), R: B=25:75(RBIII), R: B=0:100(BLT). The results showed that Red light is beneficial for the elongation of the hypocotyl of seedlings, Blue light is beneficial for the accumulation of dry matter in seedlings and monochromatic red light can reduce the seedling index. The effect of light quality on rootstocks and scions is different. Increasing the proportion of blue light is beneficial for increasing the stem diameter of scions, but it is not significant for the stem diameter of rootstocks. On the 25th to 30th day, the growth rate of stem diameter is the fastest. Based on morphological characteristics, the suitable light quality for rootstocks is RBI and RBII, and scions are RBII and RBIII. The mechanical properties of rootstocks and scions under different light-quality treatments were measured, and the results showed that the mechanical properties of scions were generally better than those of rootstocks. The rootstock has a significantly better bending strength than the scion, while the scion has a significantly better radial and axial compression force than the rootstock. Considering the automatic grafting process and mechanical characteristics, BLT and RBII were selected as the suitable light quality for rootstocks and scions. Based on the influence of comprehensive light quality on morphological and mechanical characteristics, the suitable light quality for cultivating mechanically grafted tomato seedlings is RBII.

Characterisation of night-time outdoor lighting in urban centres using cluster analysis of remotely sensed light emissions

Evidence of the negative impact of light pollution on ecosystems is increasing every year. Its monitoring and study requires the identification, characterisation and control of the emitting sources. This is the case of urban centres with outdoor lighting that spills light outside the place it is intended to illuminate. The quantity and nature of the pollutant (artificial light at night) depends on the lamps used and how they are positioned, which is important because a greater proportion of blue light means a greater scattering effect. In this study, we analysed the emissions of 100 urban centres in the north of Granada province (Spain), using images from International Space Station (ISS) in 2012 and 2021, and compared the results with public lighting inventories and with data from the VIIRS instrument. Using inference and cluster analysis techniques, we confirmed an overall increase in emissions and a shift in their colour towards blue, consistent with the results of the lighting inventory analysis. However, there is a discrepancy with the results obtained from VIIRS images, which is explained by the lack of sensitivity of this instrument to blue light. We concluded that the analysis of ISS images is a powerful tool for the study and characterisation of street lighting and its evolution, especially when the changes occur in the blue band.

Effect of red and blue light supplementation on the efficacy of Noccaea caerulescens in decontaminating metals and alleviating leaching risk.

This study was conducted to investigate the impact of supplementing blue and red light on the biomass yield, metal uptake, contaminant purification, and the alleviation of leaching risks by Noccaea caerulescens, a well-known hyperaccumulator of Cd and Zn. As previously reported for the closely related Thlaspi arvense, N. caerulescens retarded the leaching of Cd and Zn but aggravated the leaching of Pb and Cu, because the species mobilized all metals in soil but only extracted Cd and Zn. Monochromic red light reduced the leaching of Pb and Cu by 13.8% and 1.3%, respectively, but simultaneously weakened Cd phytoremediation by reducing shoot biomass. Our results demonstrated that a small proportion of blue light (10%) could eliminate the negative effect of monochromatic red light on plant shoot growth. However, root biomass decreased by 14.3%, 26.2%, 21.4%, and 61.9% as the percentage of blue light increased from 10 to 100%. Noccaea caerulescens generated the most biomass and accumulated the highest metal concentrations, except for Pb, when the ratio of red to blue light was 1:1. In addition, leachate volume was significantly reduced under the 10% and 50% blue light treatments compared to other light treatments. Therefore, light supplementation with a suitable proportion of blue light can enhance metal purification by N. caerulescens and alleviate potential leaching risk during phytoremediation.

Effects of Four Photo-Selective Colored Hail Nets on an Apple in Loess Plateau, China

Hail, known as an agricultural meteorological disaster, can substantially constrain the growth of the apple industry. Presently, apple orchards use a variety of colored (photo-selective) hail nets as a preventative measure. However, it is unclear which color proves most effective for apple orchards. This study provides a systematic investigation of the impact of four photo-selective colored hail nets (white, blue, black, and green; with white being the control) on the microenvironment of apple orchards, fruit tree development, fruit quality, and yield over a two-year period (2020–2021). Different photo-selective nets do not evidently alter the intensity of light, although the nets’ shading effects decrease in the order from black to green to blue. Among them, blue nets increased the proportion of blue light, while green nets enhanced the proportion of green light. On the other hand, black, green, and blue nets diminished the proportion of red and far-red light. Such photo-selective nets effectively lowered soil temperature but did not have an impact on relative humidity and air temperature. Encasing apple trees with blue nets promoted growth, increasing shoot length, thickness, leaf area, and water content, while simultaneously decreasing leaf thickness. Black nets had comparable effects, although the impacts of green nets were inconsistent. Different photo-selective nets did not significantly influence the leaf shape index or overall chlorophyll content. However, black and green nets reduced the chlorophyll a/b ratio, while blue nets slightly boosted this ratio. Additionally, blue nets proved beneficial for apple trees’ photosynthesis. With the employment of a principal component analysis and comprehensive evaluation, this study concludes that blue nets offer the most favorable environmental conditions for apple growth while protecting apple orchards against hail, compared to black, white, and green nets.

Effect of Different Ratios of Red and Blue Light on Maximum Stomatal Conductance and Response Rate of Cucumber Seedling Leaves

Light can regulate leaf stomatal development and movement, but the effects of different red-to-blue light mass ratios on leaf stomatal morphology and openness are not fully understood. In this trial, five different red-to-blue light (R:B) ratio treatments were used to study the changes in morphology, photosynthesis, and stomatal-related indexes of cucumber seedlings under fixed light intensity (200 μmol·m−2·s−1). The results showed that the thickness of spongy tissue and stomatal size (SZ) of cucumber seedling leaves decreased, and the photosynthetic potential, stomatal density (SD), maximum stomatal conductance and stomatal responsiveness increased with decreasing R:B content. The experimental results showed that when R:B = is 1:9, cucumber seedlings had the greatest stomatal density and the fastest response rate, and the stomatal opening rate was accelerated with the increase in the proportion of blue light; when R:B = is 3:7, the stomatal conductance was the greatest and the net photosynthetic rate was the highest. This trial provides some implications for changing plant light quality and thus affecting stomatal development and movement.

Solutions to light pollution based on Principles of spectroscopy and normal distribution

In order to study the main ways of light pollution and factors affecting light pollution, this paper first determines light pollution from the main source, namely lighting pollution, and lighting mainly refers to the light emitted by LED lamps. Therefore we come to study the light intensity of LED lamps to study light pollution. Secondly, we simplified the spectrum of LED lights into three chromatograms of red, yellow and blue, and we gradually reduced the proportion of blue light in our study to observe the intensity changes of the chromatograms. Next, we investigated the relationship between the stars visible to the naked eye and the light intensity of the illumination, and the technical indicators of sky pollution were translated into stars visible to the naked eye to further determine the intensity of light pollution. Finally, we carried out a sensitivity analysis of the model and the results showed that the model is more adaptable and easier to generalise.

Threshold or not: Spectral composition and light-intensity dependence of growth and metabolism in tomato seedlings

Application of LED lighting technology in indoor cultivation systems enables to improve vegetable cultivation, including tomato plantlet production. Most studies investigated the effects of light intensity and spectral composition separately and most of them used low light intensities. The present study examined the effects of light intensity and spectral composition together on the growth, flowering and accumulation of primary and secondary metabolites in tomato leaves. The most important light factors affecting the growth and metabolism in tomato plants were determined together with the roles of photoreceptor phytochromes and cryptochromes. The changes of some morphological, physiological and metabolic parameters, such as plant height, photosynthetic activity, stomatal conductance and sugar accumulation showed a linear correlation with the increased proportion of blue light within 5–30% blue light range. Others, including stem diameter, biomass, leaf area and protein content grew up only to a point. Above this threshold, the blue light had adverse effects. Red or green light fluence stimulated the biomass production, flowering and the accumulation of carbohydrates in which phytochromes (B1 and B2) are involved. The proportion of red light influenced the specific area of leaves and also the chlorophyll biosynthesis. High amount of blue light stimulated the protein, carotenoid, anthocyanin and flavonoid biosynthesis in tomato leaves. It may have happened through CRY2-mediated regulation. The optimal blue proportion was around 15% for the growth of young tomato plants, however, it can also shift to higher blue proportion if the growth light intensity was low indicating that the optimal level of blue light depends also on the light intensity. The results showed that light intensity and spectral composition regulate the growth and metabolism of tomato plants in interaction.

Effect of Red and Blue Light on Cucumber Seedlings Grown in a Plant Factory

Light-emitting diodes (LEDs) have been regarded as the best artificial source of light for a plant factory. However, the effect of light quality on seedling production in such environments requires further study. On the basis of the practical application of light on cucumber seedlings (Ansha Company) in plant factories, the present investigation tracked and recorded the specific effects of red and blue light on the growth of the seedlings by analyzing the photo-biological mechanism involved. The growth parameters, as well as the photosynthetic characteristics of cucumber seedlings, were measured at different variations of light quality. The results showed that when the proportion of red light in the light source was higher than blue light, the height of the seedlings, leaf size, stem diameter, Dixon Quality Index (DQI), relative chlorophyll content, and the net photosynthetic rate were higher than those of the experimental group with a relatively high proportion of blue light. In the case of R7B3 (70% red light and 30% blue light), the stem diameter, DQI, and net photosynthetic rate of seedlings were 14%, 57%, and 22% higher than the minimum value, respectively. The present study analyzed the influence of red and blue light on plant growth characteristics during actual production and provides standardization for it.

Synthesis and structural characteristics analysis of melanin pigments induced by blue light in Morchella sextelata.

Morchella sextelata, a highly sought-after edible mushroom worldwide, is evaluated based on its cap color as an essential commercial property indicator. In the present study, the effects of blue light on cap pigmentation in M. sextelata, as well as the synthesis and structural characteristics of melanin pigments within the cap were examined. The results showed that an increase in the proportion of blue light within the lighting environment promoted melanin synthesis and melanization of the cap. Transmission and scanning electron microscopy revealed the localization of melanin within the mycelium and its ultrastructural characteristics. The UV-visible analysis demonstrated that melanin exhibited a maximum absorption peak at 220 nm and possessed high alkaline solubility as well as acid precipitability. The structural characteristics of melanin were analyzed using FTIR, NMR, HPLC, and elemental analysis, which confirmed the presence of eumelanin, pheomelanin, and allomelanin in both brown and black caps. Furthermore, blue light can stimulate the synthesis of both eumelanin and pheomelanin. The obtained results can serve as the foundation for comprehending the mechanism by which light regulates color formation in mushrooms.

Response of Cyanic and Acyanic Lettuce Cultivars to an Increased Proportion of Blue Light.

Simple SummaryIndoor crop cultivation systems such as vertical farms or plant factories necessitate artificial lighting. The composition of light quality (i.e., spectral composition) within these systems plays a key role in crop growth and development. Conflicting results on the effects of the light spectrum reported for different plant species and cultivars confirm the specificity of light requirements and the dependency on interacting factors. In this paper, we have therefore investigated how a certain light quality (light with a high share of blue) affects photosynthetic and morphological parameters in two contrasting lettuce cultivars (red and green leaves) with a similar leaf shape and phenotype. The results obtained suggest the occurrence of distinctive morpho-physiological adaptive strategies in green and red pigmented lettuce cultivars to adapt to the higher proportion of blue light environment.Indoor crop cultivation systems such as vertical farms or plant factories necessitate artificial lighting. Light spectral quality can affect plant growth and metabolism and, consequently, the amount of biomass produced and the value of the produce. Conflicting results on the effects of the light spectrum in different plant species and cultivars make it critical to implement a singular lighting solution. In this study we investigated the response of cyanic and acyanic lettuce cultivars to an increased proportion of blue light. For that, we selected a green and a red leaf lettuce cultivar (i.e., ‘Aquino’, CVg, and ‘Barlach’, CVr, respectively). The response of both cultivars to long-term blue-enriched light application compared to a white spectrum was analyzed. Plants were grown for 30 days in a growth chamber with optimal environmental conditions (temperature: 20 °C, relative humidity: 60%, ambient CO2, photon flux density (PFD) of 260 µmol m−2 s−1 over an 18 h photoperiod). At 15 days after sowing (DAS), white spectrum LEDs (WW) were compared to blue-enriched light (WB; λPeak = 423 nm) maintaining the same PFD of 260 µmol m−2 s−1. At 30 DAS, both lettuce cultivars adapted to the blue light variant, though the adaptive response was specific to the variety. The rosette weight, light use efficiency, and maximum operating efficiency of PSII photochemistry in the light, Fv/Fm’, were comparable between the two light treatments. A significant light quality effect was detected on stomatal density and conductance (20% and 17% increase under WB, respectively, in CVg) and on the modified anthocyanin reflectance index (mARI) (40% increase under WB, in CVr). Net photosynthesis response was generally stronger in CVg compared to CVr; e.g., net photosynthetic rate, Pn, at 1000 µmol m−2 s−1 PPFD increased from WW to WB by 23% in CVg, compared to 18% in CVr. The results obtained suggest the occurrence of distinct physiological adaptive strategies in green and red pigmented lettuce cultivars to adapt to the higher proportion of blue light environment.

Retinal Protection from LED-Backlit Screen Lights by Short Wavelength Absorption Filters.

(1) Background: Ocular exposure to intense light or long-time exposure to low-intensity short-wavelength lights may cause eye injury. Excessive levels of blue light induce photochemical damage to the retinal pigment and degeneration of photoreceptors of the outer segments. Currently, people spend a lot of time watching LED screens that emit high proportions of blue light. This study aims to assess the effects of light emitted by LED tablet screens on pigmented rat retinas with and without optical filters. (2) Methods: Commercially available tablets were used for exposure experiments on three groups of rats. One was exposed to tablet screens, the other was exposed to the tablet screens with a selective filter and the other was a control group. Structure, gene expression (including life/death, extracellular matrix degradation, growth factors, and oxidative stress related genes), and immunohistochemistry in the retina were compared among groups. (3) Results: There was a reduction of the thickness of the external nuclear layer and changes in the genes involved in cell survival and death, extracellular matrix turnover, growth factors, inflammation, and oxidative stress, leading decrease in cell density and retinal damage in the first group. Modulation of gene changes was observed when the LED light of screens was modified with an optical filter. (4) Conclusions: The use of short-wavelength selective filters on the screens contribute to reduce LED light-induced damage in the rat retina.

28.1: Invited Paper: The Application of Wide Spectrum Low Peak Blue light technology in health TV display

This paper reports a method to reduce the high energy and short wave blue light damage to human eyes, by reducing the proportion of blue light in using two chips in LED as blue light chips with different main wavelengths. At the same time, the filter blue light particle are coated on the membrane to remove high‐energy short wave blue light to achieve eye protection effect. The project can increase the half‐wave width to 25 nm and reduce the blue light peak to 50%, so that the wide spectrum of the display screen is close to the continuous spectrum of natural light. The above scheme will not affect the brightness and gamut. Meanwhile, that project can maintain the original color temperature of the display, provide the best viewing effect and safeguard the human eye health while protecting the health of the users.

THE GROWTH, PHOTOSYNTHETIC PARAMETERS AND NITROGEN STATUS OF BASIL, CORIANDER AND OREGANO GROWN UNDER DIFFERENT LED LIGHT SPECTRA

Growth, morphological parameters, photosynthetic performance and nitrogen status were investigated in leafy herbs grown in light-limited time in a greenhouse under different light spectra emitted by LEDs. Fluorescence-based sensors that detect crop N status and maximum photochemical efficiency of photosystem II were used in this study. Four light treatments with the ratio of Red, Blue and White LEDs including 1) R40 + B50 + W10, 2) R70 + B20 + W10, 3) R70 + B20 + W10 + Far-Red and 4) White LEDs as control were used in this study. Dominant red light and/or white LED lights at 200 µmol m–2 s–1 at plant level and a 12 h photoperiod provided the most favourable conditions for plant growth and development compared to a high proportion of blue light (R40 + B50 + W10). However, plants grown under a high proportion of blue light had a higher chlorophyll index and nitrogen balance index (NBI) than under dominant red light treatments. Our study indicates the significant potential of fluorescence-based sensors in photobiology research as well as in the production of leafy herbs under LED lights.

Photosynthetic apparatus performance of tomato seedlings grown under various combinations of LED illumination.

It is already known that the process of photosynthesis depends on the quality and intensity of light. However, the influence of the new light sources recently used in horticulture, known as Light Emitting Diodes (LEDs), on this process is not yet fully understood. Chlorophyll a fluorescence measurement has been widely used as a rapid, reliable, and noninvasive tool to study the efficiency of the photosystem II (PSII) and to evaluate plant responses to various environmental factors, including light intensity and quality. In this work, we tested the responses of the tomato photosynthetic apparatus to different light spectral qualities. Our results showed that the best performance of the photosynthetic apparatus was observed under a mixture of red and blue light (R7:B3) or a mixture of red, green and blue light (R3:G2:B5). This was demonstrated by the increase in the effective photochemical quantum yield of PSII (Y[II]), photochemical quenching (qP) and electron transport rate (ETR). On the other hand, the mixture of red and blue light with a high proportion of blue light led to an increase in non-photochemical quenching (NPQ). Our results can be used to improve the production of tomato plants under artificial light conditions. However, since we found that the responses of the photosynthetic apparatus of tomato plants to a particular light regime were cultivar-dependent and there was a weak correlation between the growth and photosynthetic parameters tested in this work, special attention should be paid in future research.

Spectral effects of blue and red light on growth, anatomy, and physiology of lettuce.

Characterizing spectral effects of blue and red light ratios on plants could help expand our understanding of factors that regulate growth and development, which is becoming increasingly important as narrowband light-emitting diodes become common for sole-source lighting. Herein we report growth, physiological, and anatomical responses of two lettuce cultivars grown indoors under various blue and red ratios including monochromatic treatments. When used in combination with red, increasing the proportion of blue light generally reduced growth but increased chloroplast abundance and single-leaf photosynthetic efficiency. However, when used as single wavebands, both blue and red light increased leaf area and epidermal cell area, but reduced root dry mass, SPAD index, stomatal density, and leaf thickness compared to dichromatic light. In addition, chloroplast abundance and single-leaf physiological responses were higher in plants grown under monochromatic blue compared to red light, but the opposite trend was measured for shoot biomass. Our results show that spectral effects on morpho-anatomical leaf responses can largely influence plant growth and single-leaf physiological responses. However, a significant blue light reduction in radiation capture ultimately limits growth and productivity of lettuce plants when dichromatic blue and red light is used.

Moths are strongly attracted to ultraviolet and blue radiation

Abstract We carried out three choice experiments with 6116 nocturnal lepidopteran individuals (95 species, 7 families, 32 075 counts), each replicated 105 times during the seasons of 2 years. Moths were released indoors at the centre of a 10 × 10 m area with different lamps placed at each corner. In experiment 1, lamps emitted ultraviolet (UV) (peak at 365 nm), blue (450 nm), green (520 nm) or cool white (450 and 520 nm) radiation. In experiment 2, UV was replaced by red (640 nm). In experiment 3, we used UV and three mixed radiation lamps of different emission intensities (365–520 nm). We applied a linear mixed effect model to test for differences in attraction to the light sources. Among all counts, 12.2% (males) and 9.2% (females) were attracted to a lamp. Among the lamp counts, 84% were made at the UV lamp in experiment 1. In experiment 2, 63% of the counts were made at the blue lamp. In experiment 3, most counts were made at the strongest mixed radiation lamp (31%), and the UV lamp (28%). Patterns were generally similar across Lepidopteran families, and for both sexes. Moths are clearly preferentially attracted to short‐wave radiation. Even small quantities of UV radiation, emitted, for example, by metal halide lamps and certain mercury vapour tubes, will disproportionately contribute to light pollution. Since blue light also attracts moths strongly, lamps with a low proportion of blue light should be given priority in lighting planning.

2.3: Invited Paper: Visual Fatigue and Comfort Evaluation of the Different Proportions of Blue Light on the Same Display by Visual Research Task

Under the same indoor light condition, using visual search tasks, the study tested the effects of liquid crystal display (LCD) with different blue light ratio (the proportion of blue lightwere 20%, 40%, 60%, 80%, 100%) which were adjusted by software on users' visual fatigue and comfort. The test task time of each condition was 40 minutes. The evaluation methods were mainly based on ISO 9241‐304 Ergonomics of human‐system interaction‐User performance test methods for electronic visual displays, etc. The evaluation indexes mainly included the performance of visual search tasks, critical flicker frequency (CFF), visual fatigue subjective perception scale and EEG. The research results showed that the changes of task conditions in different indicators showed a non‐linear trend. 60% of blue light accounted for better performance in the performance of visual search and emotional state, while 40% of blue light accounted for the most serious fatigue. The EEG results showed that compared with 60% and 80%, 100% blue light condition had the best performance, lower attention control and workload, which to some extent verified the previous research results that blue light improved the brain arousal. The results showed that the impact of blue light on users involves many aspects, not a single dimension. The results of this study will provide a reference to adjust the standard of blue light ratio by software.

The Proportion of Blue Light from Light-emitting Diodes Alters Microgreen Phytochemical Profiles in a Species-specific Manner

Microgreens are specialty vegetables that contain human health-promoting phytochemicals. Typically, microgreens are cultivated in controlled environments under red and blue light-emitting diodes (LEDs). However, the impact of varying the proportions of these light qualities on the composition of diverse phytochemicals in indoor-grown microgreens is unclear. To address this problem, the levels of chlorophylls, carotenoids, ascorbates, phenolics, anthocyanins, and nitrate were examined in arugula (Eruca sativa L.), ‘Red Russian’ kale [Brassica napus L. subsp. napus var. pabularia (DC.) Alef.], ‘Mizuna’ mustard (Brassica juncea L.), and red cabbage (Brassica oleracea L. var. capitata f. rubra) microgreens following cultivation under LEDs supplying varying proportions of blue light (5% to 30%) and red light (70% to 95%). Varying the proportion of blue light did not affect the extractable levels of total chlorophyll, total carotenoids, or nitrate in all four microgreen species. Generally, the levels of reduced and total ascorbate were greatest in arugula, kale, and mustard microgreens at 20% blue light, and a minor decrease was apparent at 30% blue light. These metabolite profiles were not impacted by the blue light percentage in red cabbage. Kale and mustard accumulated more total phenolics at 30% blue light than all other blue light regimens; however, this phytochemical attribute was unaffected in arugula and red cabbage. The total anthocyanin concentration increased proportionally with the percentage of supplied blue light up to 30% in all microgreens, with the exception of mustard. Our research showed that 20% blue light supplied from LED arrays is ideal for achieving optimal levels of both reduced and total ascorbate in all microgreens except red cabbage, and that 30% blue light promotes the greatest accumulation of total anthocyanin in indoor-grown Brassicaceae microgreens, with the exception of mustard.