Light Regimes Research Articles

Phytoplankton and Its Role in the Formation of the Underwater Light Regime in Artificial Reservoirs

Phytoplankton and Its Role in the Formation of the Underwater Light Regime in Artificial Reservoirs

Effects of light regimes and benthic fish disturbance on the foraging behavior of Vallisneria natans in heterogeneous sediments.

In shallow eutrophic lakes, submersed macrophytes are significantly influenced by two main factors: light availability and benthic fish disturbance. Plant foraging is one of the most crucial aspects of plant behavior. The present study was carried out to effects of light regimes and fish disturbance on the foraging behavior of Vallisneria natans in heterogeneous sediments. V. natans was cultivated in heterogeneous sediments with four treatments: high-light regime (H), high-light regime with benthic fish (HF), low-light regime (L), and low-light regime with benthic fish (LF). We use plant trait network analysis to evaluate the relationships between traits in heterogeneous sediments. We found the plant foraging intensity was positively correlated with trait network modularity. The biomass of stem, maternal plant biomass ratio, and ramet number were the hub traits of plant growing in heterogeneous habitats. Although the plant relative growth rate (RGR) was positively correlated with foraging intensity, the hub traits had closer links with plant RGR than foraging intensity. Light regime and benthic fish indirectly affected the plant foraging intensity by changing the chlorophyll a content and pH of overlying water. Overall, our analysis provides valuable insights into plant foraging behavior in response to environmental changes.

Novel light regimes in European forests.

Tree canopies are one of the most recognizable features of forests, providing shelter from external influences to a myriad of species that live within and below the tree foliage. Canopy disturbances are now increasing across European forests, and climate-change-induced drought is a key driver, together with pests and pathogens, storms and fire. These disturbances are opening the canopy and exposing below-canopy biodiversity and functioning to novel light regimes-spatial and temporal characteristics of light distribution at forest floors not found previously. The majority of forest biodiversity occurs in the shade within and below tree canopies, and numerous ecosystem processes are regulated at the forest floor. Altered light regimes, in interaction with other global change drivers, can thus strongly impact forest biodiversity and functioning. As recent European droughts are unprecedented in the past two millennia, and this has initiated probably the largest pulse of forest disturbances in almost two centuries, we urgently need to quantify, understand and predict the impacts of novel light regimes on below-canopy forest biodiversity and functions. This will be a crucial element in delivering much-needed information for policymakers and managers to adapt European forests to future no-analogue conditions.

Diurnal cycles drive rhythmic physiology and promote survival in facultative phototrophic bacteria

Bacteria have evolved many strategies to spare energy when nutrients become scarce. One widespread such strategy is facultative phototrophy, which helps heterotrophs supplement their energy supply using light. Our knowledge of the impact that such behaviors have on bacterial fitness and physiology is, however, still limited. Here, we study how a representative of the genus Porphyrobacter, in which aerobic anoxygenic phototrophy is ancestral, responds to different light regimes under nutrient limitation. We show that bacterial survival in stationary phase relies on functional reaction centers and varies depending on the light regime. Under dark-light alternance, our bacterial model presents a diphasic life history dependent on phototrophy: during dark phases, the cells inhibit DNA replication and part of the population lyses and releases nutrients, while subsequent light phases allow for the recovery and renewed growth of the surviving cells. We correlate these cyclic variations with a pervasive pattern of rhythmic transcription which reflects global changes in diurnal metabolic activity. Finally, we demonstrate that, compared to either a phototrophy mutant or a bacteriochlorophyll a overproducer, the wild type strain is better adapted to natural environments, where regular dark-light cycles are interspersed with additional accidental dark episodes. Overall, our results highlight the importance of light-induced biological rhythms in a new model of aerobic anoxygenic phototroph representative of an ecologically important group of environmental bacteria.

Basil and Lettuce Microgreens Production in Low-Cost Hydroponic Installations, under Operational and Semi-Controlled Conditions

Microgreens produced hydroponically at home, represent a solution of the future due to the advantages it has. The purpose of this research is to analyze certain elements relevant for the microgreens crop (basil and lettuce), simultaneously, in identical low-cost hydroponic platforms, in operational (common spaces) and semi-controlled conditions (plant growing tent). The obtained results were analyzed, both from the point of view of the growing conditions and the influence of light regimes, as well as the development of seedlings, production (fresh weight and dry weight) and quality (total phenolic) of the microgreens. In operational environmental conditions there is a higher variation of the environmental parameters, compared to the semi-controlled environment, but the oscillation of natural light seems to have a better influence on the development of microgreens. Internode length in operational environmental conditions varies for basil between 25.2-35.2 mm, for lettuce between 31.9-32.8 mm, and in semi-controlled environmental conditions, it varies for basil between 25.2-32.1 mm and for lettuce between 30.2-31.9 mm. In semi-controlled conditions, the average fresh weight production achieved by the two species (and four varieties) is 734.73 g m-2 for basil, 809.56 g m-2 for lettuce, and represents 823.74 g m-2 for basil, 777.61 g m-2 for lettuce in operational environmental conditions. The variability of the data recorded for total phenols is very high. Lettuce contains 98-107.33 mg kg-1, and basil 107.67-186.33 mg kg-1 total phenols. Feedback from these tests will be used for final validation of the low-cost hydroponic platform components.

Effects of Chloride and Sulfate Salts on Seed Germination and Seedling Growth of Ballota hirsuta Benth. and Myrtus communis L.

Soil salinity is a well-known abiotic factor affecting the germination and seedling growth of various plant species. Therefore, we evaluated the effects of different chloride salts (NaCl, KCl and MgCl2) and sulfate salts (Na2SO4, K2SO4 and MgSO4) on the seed germination and early seedling growth of two important ethnomedicinal shrubs of North Africa and the Mediterranean basin (Ballota hirsuta and Myrtus communis). Seeds of these species were subjected to five salinity levels (0-100 mM) and incubated at 20 °C under a light regime (12 h photoperiod). Both species demonstrated their highest germination percentage under control conditions (i.e., without salinity). However, as salinity levels increased, the germination percentages for both species decreased, regardless of the type of salt used. Cations appeared to be more determinative than the anions in regulating the seed germination of both species. M. communis seeds displayed greater sensitivity to sodium (Na+) salts, especially when accompanied with chloride (Cl-) anions. At the higher salt concentrations (75 and 100 mM), Na+ salts had a more pronounced inhibitory effect on M. communis seedling growth compared to potassium (K+) and magnesium (Mg2+) salts. Conversely, Mg2+ salts were more detrimental to seedling growth in B. hirsuta. Based on our results, it can be concluded that both of these species are able to tolerate a moderate level of salinity. Overall, B. hirsuta may be a promising choice for rehabilitating the soils dominated by chloride salts, while M. communis could be utilized for restoring sulfate-dominated soils.

Plasticity of shallow reef corals across a depth gradient

Global warming harms coral reefs. Mesophotic coral reef ecosystems (MCEs) have been suggested to serve as refugia for shallow reefs. Information on the adaptation potential of shallow corals at MCEs is a prerequisite for understanding the refuge potential of MCEs. In this study, we investigated the photoacclimation potential of four shallow coral species transplanted at different depths over 1 year. The results showed that the corals—Pocillopora damicornis, Porites cylindrica, and Turbinaria reniformis—survived and acclimated to a wide range of light regimes at the depths of 5, 20, and 40 m. However, Acropora tenuis survived only at 5 and 20 m depth and showed significant morphological alteration at 20 m depth. Our results indicate that shallow corals have substantial plasticity with respect to depth changes. Changes in photosynthetic performance and phenotypic plasticity within these coral species may act as a buffer for depth-related changes and as modulators of evolutionary responses.

Modulation of morpho-physiological attributes and in situ analysis of secondary metabolites using Raman spectroscopy in response to red and blue light exposure in Artemisia annua

Differential light conditions, such as variations in photoperiod, light quality, and light intensity, play a crucial role as external factors that can influence plant morphogenesis and secondary metabolism. However, there is still a lack of understanding of how Artemisia annua responds to monochromatic and dichromatic light regimes in terms of the different physiological mechanisms that control plant growth and secondary metabolite production. Therefore, the primary aim of this study was to investigate and assess the various physiological parameters, biochemical analysis, and molecular aspects in detail. Therefore, the plantlets were exposed to LED lighting such as monochromatic red light (R), monochromatic blue light (B), white light (W), and a combination of red and blue light (RB, 1:1) at a PPFD (photosynthetic photon flux density) of 200 mol. m−2. s−1 for 10 days. Our results indicate that exposure to RB light resulted in an immense increase in ROS accumulation, flavonoids, lignin, and artemisinin by 4.7-fold, 44%, and 53.4%, respectively, in contrast to W light. Whereas blue light led to increments of 160.2% in phenolic and 107.9% in anthocyanin content. RB and B light also influence the parameters of chlorophyll fluorescence, as well as leaf area, stomatal density, trichome size, antioxidant enzyme activity, and the production of more secondary metabolites to combat oxidative stress. Real-time PCR analysis of biosynthetic pathway-associated genes HMGR, DXR, DXS, FPS, ADS, CYP71AVI, DBR2, ALDH1, and flavonoid key biosynthesis pathway genes PAL, C4H, 4CL, CHS, and F3′H showed the highest increment under RB, light followed by B and R light exposure. Further, RB LED light has significant potential for enhancing natural bio-active compounds as revealed by Raman spectroscopy, such as camphor, limonene, terpene-4-ol, α pinene, 1,8-cineole, β-caryophyllene, artemisinin, kaempferol, luteolin, rutin, and caffeic acid in A. annua. Taken together, red and blue LEDs can serve as significant elicitors for the production of commercially important metabolites.

Intermittent light program impacts on reproductive performance, health and welfare of breeding hens.

The lighting regime significantly impacts poultry production, reproductive performance, health and welfare. This study aimed to test the effect of the intermittent light (IL) regime on reproductive organs and hormones, semen quality, and behavioral performance. Thus, 270 Rhode Island Red hens aged 20 weeks were distributed among three groups of six replicates and 15 birds each, housed in floor pens. The first group was used as a control (C) and was exposed to constant light for 16 h d, while birds in other groups were exposed to IL for 20 min h (T20) and 40 min h (T40) during the 16 h light period. The outcomes were that follicle number was higher for T20 compared to T40 but not the controls, while T40 is different from T20 but not the controls. The same is true for testosterone. The sperm concentration is lower for T40 compared to the controls, with no difference between T20 and the controls. Body temperature was not different among groups. Conversely, differences were not noticed for leg alterations; plumage conditions; and relative ovary, oviduct, and/or testes weight and hatchability. Thus, the IL T20 program should be further investigated as a lighting regimen for managing Rhode Island Red laying hens for stimulating follicle number and testosterone without negatively impacting the physiological response and health traits. From a practical point of view, the IL schedule of 20 min h during 20-36 weeks of age can be economically viable due to saving 66 % of the light cost.

Fatty Acid Composition of Total Lipids in Atlantic Salmon Salmo salar L. Parr and Smolts Reared in Aquaculture at Various Lighting Regimes

Continuous artificial lighting (24LD) was introduced experimentally in the standard technology to grow salmon juveniles in a southern region (Republic of North Ossetia–Alania) and its effect on fatty acid (FA) composition of total lipids in muscles and the liver was assessed in parr and smolts of the Atlantic salmon Salmo salar L. Changes in the key FA were observed in the FA spectrum of fish, indicating that smoltification was complete and that smolts were ready for new habitat conditions. Thus the content of polyunsaturated FAs (PUFAs) significantly increased as a result of an increase in (n-3) PUFAs, and, in particular, marine-type 22:6(n-3), and high values were observed for (n-3)/(n-6) and 22:6(n-3)/18:3(n-3) PUFA ratios. The most significant changes were detected in muscles. In all experimental groups, a decrease in saturated FAs (SFAs) and an increase in total lipid unsaturation was attributed primarily to PUFAs, while monounsaturated FAs (MUFAs) decreased along with SFAs. The experimental data on the lipid and FA composition in salmon juveniles and a higher proportion of smolts in the test groups indicated that smoltification was the most successful in groups with continuous lighting and 24-h feeding and a natural regime of lighting and feeding.

Mapping subcanopy light regimes in temperate mountain forests from Airborne Laser Scanning, Sentinel-1 and Sentinel-2

Sunlight is the primary source of energy in forest ecosystems and subcanopy light regimes largely determine the establishment, growth and dispersal of plants and thus forest floor plant communities. Subcanopy light regimes are highly variable in both space and time, which makes monitoring them challenging. In this study, we assess the potential of Sentinel-1 and Sentinel-2 time series for predicting subcanopy light regimes in temperate mountain forests. We trained different random forest regression models predicting field-measured total site factor (TSF, proportion of potential direct and diffuse solar radiation reaching the forest floor, here defined as the transition zone between belowground and aboveground biomass) from a set of metrics derived from Sentinel-1 and Sentinel-2 time series. Model performance was benchmarked against a model based on structural metrics derived from Airborne Laser Scanning (ALS) data, serving as an empirical gold-standard in modelling subcanopy light regimes. We found that Sentinel-1 and Sentinel-2 time series performed nearly as good as the model based on high-resolution ALS data (R2/RMSE of 0.80/0.11 for Sentinel-1/2 compared to R2/RMSE of 0.90/0.08 for ALS). We furthermore tested the generalizability of the trained models to two new sites not used for training for which field data was available for validation. Prediction accuracy for the ALS model decreased substantially for the two independent test sites due to variable ALS data quality and acquisition date (ΔR2/ΔRMSE of 0.29/0.05 and 0.11/0.03 for both independent test sites). The prediction accuracy of the Sentinel-1/2 model, however, remained more stable (ΔR2/ΔRMSE of 0.13/0.02 and 0.13/0.04). We therefore conclude that a combination of Sentinel-1 and Sentinel-2 time series has the potential to map subcanopy light conditions spatially and temporally independent of the availability of high-resolution ALS data. This has important implications for the operational monitoring of forest ecosystems across large scales, which is often limited by the challenges related to acquiring airborne datasets.

Investigating how nitrogen nutrition and pruning impacts on CBD and THC concentration and plant biomass of Cannabis sativa

Precise crop fertilization requires an in-depth understanding of plant uptake and utilisation to optimise sustainable production. This study investigated the influence of nitrogen (N) nutrition and pruning on the cannabinoid concentrations and biomass of a commercial cannabis cultivar; the rationale for this study is how N supply and pruning affect cannabinoid yields and concentration in a commercial setting. Clones of a Cannabis sativa L. (CBD-type) were grown in a controlled-environment glasshouse in pots with coarse sand. After five weeks of vegetative growth under 210 mg/L N and an 18 h light regime, rates of 30, 60, 210, and 500 mg/L N were applied to plants for twelve weeks and a light regime set at 12 h. Double stem pruning was applied as an additional treatment to investigate efficacy on biomass increase. Biomass, N concentrations, and cannabinoid concentrations were measured after the final harvest. Pruning treatment did not increase cannabinoid concentrations or affect biomass. It was coincidentally found that plants on the glasshouse edge with higher exposure to sunlight developed more biomass and higher cannabinoid concentrations. Only biomass in leaves was increased significantly via higher nitrogen nutrition. Cannabinoid concentration, as well as cannabinoid yield per plant were decreased with the increase in N supply. High rates of fertilizer are not recommended because of reduced cannabinoid concentration and biomass yield: the ideal N supply is likely to be between 60 and 210 mg/L. This research will benefit growers and advisors in understanding the complexity of effects of nitrogen fertiliser and pruning practices on plant biomass and secondary metabolite production in medicinal cannabis.

Seed longevity and germination of the emerging invasive species wavyleaf basketgrass (Oplismenus undulatifolius) under varied light regimes

AbstractInvasive nonindigenous species pose a serious threat to native biodiversity and ecosystem functioning. Understanding how species’ performance varies under conditions in the current and invaded range can help to predict the dynamics of the invading species in its new environment. Plants with the ability to alter growth in response to variation in light conditions may be favored in landscapes that experience frequent disturbance, as these species may be able to exploit a wide range of niches. Seedbank persistence may also play a critical role in successful plant invasion, as extended seed viability may increase the chance of outlasting unfavorable conditions, maintain population genetic diversity, and allow reinvasions. This study investigated seed longevity and the effect of light intensity on germination of wavyleaf basketgrass [Oplismenus undulatifolius (Ard.) Roem. & Schult.], a newly established invasive species in U.S. mid-Atlantic forest understories. Oplismenus undulatifolius seeds were collected across 5 yr from the original site of introduction in Maryland, USA, and stored in standard lab conditions, then subjected to germination trials under four light conditions in a controlled growth chamber. Seeds remained viable for at least 9 yr, and light intensity did not significantly impact seed germination. Our study demonstrates the importance of evaluating environmental and temporal effects on germination traits, because the scope of surveillance in the field may need to be expanded based on new information about environmental tolerance. Long-term monitoring may also be necessary to effectively control invasive plant populations capable of forming a persistent seedbank.

Physical properties of different polymorphs of sulfur doped ZnO studied in the framework of first-principles approaches

Various physical properties of pure and sulfur-doped zinc oxide in the germanium phosphide (GeP), cesium chloride (CsCl), and nickel arsenide (NiAs) type structures are studied using the first-principles approaches in this research. The structural characteristics of the ZnOS alloys in GeP, CsCl, and NiAs type polymorphs show a slight deviation from Vegard's law, which is consistent with the available literature. It is observed that the electronic band structures of the ZnOS alloys show an exciting impact of sulfur (S) substitution in the ZnO. The ZnOS alloys, in CsCl type structure, display their metallic character. The static dielectric constants of the GeP, CsCl, and NiAs type’s polymorphs demonstrate that with increasing S concentration, polarization is enhanced. Moreover, the CsCl type phase of the ZnOS alloys exhibits the maximum value of the static dielectric constant along with showing metallic character. The optical results highlight the potential of S-doped ZnO in these structures as the highest absorption, reflectivity, and conductivity peaks shift towards low photon energies. The examination of the absorption spectra demonstrates that GeP-type ZnOS alloys are suitable for infrared to visible regime applications. On the other hand, NiAs-type ZnOS alloys are appropriate for use in the visible light regime.

The light spectrum differentially influences morphology, physiology and metabolism of Chrysanthemum × morifolium without affecting biomass accumulation

AbstractThe development of light emitting diodes (LED) gives new possibilities to use the light spectrum to manipulate plant morphology and physiology in plant production and research. Here, vegetative Chrysanthemum × morifolium were grown at a photosynthetic photon flux density of 230 μmol m−2 s−1 under monochromatic blue, cyan, green, and red, and polychromatic red:blue or white light with the objective to investigate the effect on plant morphology, gas exchange and metabolic profile. After 33 days of growth, branching and leaf number increased from blue to red light, while area per leaf, leaf weight fraction, flavonol index, and stomatal density and conductance decreased, while dry matter production was mostly unaffected. Plants grown under red light had decreased photosynthesis performance compared with blue or white light‐grown plants. The primary and secondary metabolites, such as organic acids, amino acids and phenylpropanoids (measured by non‐targeted metabolomics of polar metabolites), were regulated differently under the different light qualities. Specifically, the levels of reduced ascorbic acid and its oxidation products, and the total ascorbate pool, were significantly different between blue light‐grown plants and plants grown under white or red:blue light, which imply photosynthesis‐driven alterations in oxidative pressure under different light regimens. The overall differences in plant phenotype, inflicted by blue, red:blue or red light, are probably due to a shift in balance between regulatory pathways controlled by blue light receptors and/or phytochrome. Although morphology, physiology, and metabolism differed substantially between plants grown under different qualities of light, these changes had limited effects on biomass accumulation.

Weeds as Bioindicators of Ecological Conditions in Organic Carrot and Onion Crop

Summary The obtained results indicate the possibility of weed control in organic intercropping production systems of carrots and onions with the application of corn gluten, together with the ecological assessment of habitat based on bioindicator values of weed species. A total of 29 weed taxons are present in the intercoped and pure crops of carrots and onions, grown without (CO) and with the application of corn gluten (CO-G). Although floristically uniformed, 24 taxons (CO) and 23 taxons (CO-G), the total weediness on the CO-G variants was 24% higher. The highest value of fresh weed biomass was recorded on the treatment of pure onion crop with gluten application (2844.85 g/m2), while the lowest value was recorded on the treatment of intercropped carrot and onion (1004.99 g/m2). Ecological assessment of habitat, based on indicator values and abundance of weed species, indicates favorable climatic conditions with favorable temperature (Tx̄ - 4) and light (Lx̄ - 4) regime, which refers to temperate continental climate conditions (Kx̄ - 2,7). Soil indicators indicate slightly drier conditions (Fx̄ – 2,6), slightly acidic to neutral pH (Rx̄ – 3,3), rich in nutrients (Nx̄ – 4), with moderate humus content (Hx̄ – 3), moderate aeration (Dx̄ – 2,8) and locally salted (s) with the participation of salinity indicators in the amount of 54% (CO) and 40% (CO-G). The presence of heavy metals tolerance (m) indicators in the amount of 46% (CO-G) and 41% (CO) should not be neglected, which imposes the need for additional analysis of soil for heavy metal content. Based on the analysis of obtained indicator values, it can be concluded that these ecological conditions correspond to the development of carrots and onions and that the lowest values of fresh weed biomass were recorded on the treatment of intercropping of carrots and onions, without application of corn gluten.

Coupled carbon and nitrogen cycling regulates the cnidarian–algal symbiosis

Efficient nutrient recycling underpins the ecological success of cnidarian-algal symbioses in oligotrophic waters. In these symbioses, nitrogen limitation restricts the growth of algal endosymbionts in hospite and stimulates their release of photosynthates to the cnidarian host. However, the mechanisms controlling nitrogen availability and their role in symbiosis regulation remain poorly understood. Here, we studied the metabolic regulation of symbiotic nitrogen cycling in the sea anemone Aiptasia by experimentally altering labile carbon availability in a series of experiments. Combining 13C and 15N stable isotope labeling experiments with physiological analyses and NanoSIMS imaging, we show that the competition for environmental ammonium between the host and its algal symbionts is regulated by labile carbon availability. Light regimes optimal for algal photosynthesis increase carbon availability in the holobiont and stimulate nitrogen assimilation in the host metabolism. Consequently, algal symbiont densities are lowest under optimal environmental conditions and increase toward the lower and upper light tolerance limits of the symbiosis. This metabolic regulation promotes efficient carbon recycling in a stable symbiosis across a wide range of environmental conditions. Yet, the dependence on resource competition may favor parasitic interactions, explaining the instability of the cnidarian-algal symbiosis as environmental conditions in the Anthropocene shift towards its tolerance limits.

Sexual competition and light regimes interactively affect dimorphism and competitiveness of opposite sexes in Populus yunnanensis

Light, as the most important energy and environmental signal, exerts crucial impacts on plant-plant interactions and the composition of plant communities. However, little attention has been paid to understanding how females and males respond to sexual competition under different light conditions. In this study, we investigated morphological and physiological parameters between two sexes of Populus yunnanensis under intra- and intersexual competition in two light regimes, i.e., full light and shading conditions (equal to 55% full light). Under full-light conditions, males grown under intersexual competition exhibited greater above-ground biomass accumulation, specific leaf area (SLA), root-to-shoot ratio (R/S), non-structural carbohydrate (NSC) utilization efficiency, and a higher ability to maintain the balance of nitrogen (N) and phosphorus (P) content compared to females. These eco-physiological responses confer males with a competitive advantage over females under sufficient light conditions. In contrast, there were no significant sex-specific differences in biomass accumulation and relative competitive intensity (RCI) values under shade treatment. Under shading, the opposite sexes of P. yunnanensis exhibited mutual suppression of each other to varying degrees, showing similar competitive potential. These results demonstrate that the performance of plants in terms of morphology and physiology is strongly affected by patterns of sexual competition and light regimes. The asymmetry in sexual competition might be a crucial factor influencing the biased sex ratio of P. yunnanensis in natural habitats.

Impact of Different Light Conditions on the Nitrogen, Protein, Colour, Total Phenolic Content and Amino Acid Profiles of Cultured Palmaria palmata

The impact of different light conditions during culture on the nitrogen, protein, colour, total phenolic content (TPC) and amino acid profile of Palmaria palmata biomass was investigated. P. palmata was cultured using different light regimes, i.e., white (1 and 2), red, blue and green over 12 days. A significant decrease (p < 0.05) in total nitrogen (TN), non-protein nitrogen (NPN) and protein nitrogen (PN) was observed on day 6 while an increase was observed on day 12 in P. palmata samples cultured under blue light. The protein content (nitrogen conversion factor of 4.7) of the initial sample on day 0 was 15.0% (w/w) dw whereas a maximum protein content of 16.7% (w/w) was obtained during exposure to blue light following 12 days culture, corresponding to an 11.2% increase in protein content. Electrophoretic along with amino acid profile and score analyses showed light-related changes in protein composition. The lighting regime used during culture also influenced the colour parameters (lightness L*, redness a*, yellowness b* and colour difference ΔE) of milled algal biomass along with the TPC. Judicious selection of lighting regime during culture may allow the targeted production of sustainable high-quality proteins from P. palmata.

Light Quality Potentiates the Antioxidant Properties of Brassica rapa Microgreen Extracts against Oxidative Stress and DNA Damage in Human Cells.

Plants are an inexhaustible source of bioactive compounds beneficial for contrasting oxidative stress, leading to many degenerative pathologies. Brassica rapa L. subsp. rapa is well known for its nutraceutical properties among edible vegetable species. In our work, we aimed to explore an eco-friendly way to enhance the beneficial dietary phytochemicals in this vast world of crop-growing plants at selected light quality conditions. White broad-spectrum (W) and red-blue (RB) light regimes were used for growing brassica microgreens. The organic extracts were tested on keratinocytes upon oxidative stress to explore their capability to act as natural antioxidant cell protectors. Our results show that both W and RB extracts caused a notable reduction in reactive oxygen species (ROS) levels induced by H2O2. Interestingly, according to its higher contents of polyphenols and flavonoids, the RB was more efficient in reducing ROS amount and DNA damage than the W extract, particularly at the lowest concentration tested. However, at higher concentrations (up to 100 μg/mL), the antioxidant effect reached a plateau, and there was little added benefit. These findings confirm that RB light effectively increases the antioxidant compounds in Brassica rapa L. microgreens, thus contributing to their enhanced activity against oxidative-induced genotoxicity compared to microgreens grown under W light.