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Abstract

We report on the application of supplementary light-emitting diode (LED) lighting within a greenhouse for cultivation of red, green and light green leaf baby lettuces (Lactuca sativa L.) grown under natural illumination and high-pressure sodium (HPS) lamps (16-h; PPFD-170 μmol m−2 s−1) during different growing season. Supplementary lighting from blue 455/470 nm and green 505/530 nm LEDs was applied (16-h; PPFD-30 μmol m−2 s−1). Our results showed that to achieve solely a positive effect is complicated, because metabolism of antioxidant properties in lettuce depended on multicomponent exposure of variety, light quality or seasonality. The general trend of a greater positive effect of supplemental LED components on the vitamin C and tocopherol contents was in order: 535 > 505 > 455 > 470 nm; on the total phenol content: 505 > 535 = 470 > 455 nm; on the DPPH free-radical scavenging capacity: 535 = 470 > 505 > 455 nm; on the total anthocyanins: 505 > 455 > 470 > 535 nm. Further investigations are needed for understanding the mechanism and interaction between antioxidants and light signal transduction pathways.

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... According to various literature sources, phenolic compounds show plasticity in response to light quality, quantity, and duration, allowing plants to adapt to their changes and act as sunscreen, antioxidants, or both. Many studies related to the light quality concern UV-A and blue light as having the most effective impact on phenylpropanoid metabolism than the other light spectrum [6,11,14,19,22,24,29,30]. It was determined that such light stimulates the genes expression belonging to the phenylpropanoid pathway, which is involved in the biosynthesis of phenolic acids and flavonoids mediated by cryptochromes [11,22,24,29,31,32]. ...
... Meanwhile, chlorogenic acid content increased during spring cultivation when 455 nm LEDs light was used in the daytime and positively affected rosmarinic acid content in all cases. Other authors noticed the positive impact of longer blue wavelengths (450-470 nm) on the accumulation of phenolic compounds in leafy vegetables such as different lettuces varieties, pak choi, Chinese kale, basil, etc. depending on exposure duration till harvest, photoperiod during the daytime, intensity [6,11,14,19,33,34]. Various authors showed that the transcriptional levels of flavonoid biosynthetic genes are strongly affected by the time duration, amount, and blue or UV-A wavelength of light [24,31,33]. ...
... Therefore, there is comparatively little literature on its impacts on plants quality, including phenolic compounds. Few accessible reports showed that green light used as monochromatic or as part of a broader light combination frequently had no effect or reduced accumulation of phenolic compounds and can reverse the positive impact of monochromatic blue light [6,11,14,24,[36][37][38][39]. The green light had positive results in only a few cases. ...
Article
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The study aimed to determine the changes in phenolic compounds content in lettuce (Lactuca sativa L. cv. Little Gem) depending on the preharvest short-term daytime or nighttime supplemental light-emitting diodes (LEDs) to high-pressure sodium lamps (HPS) lighting in a greenhouse during autumn and spring cultivation. Plants were grown in a greenhouse under HPS supplemented with 400 nm, 455 nm, 530 nm, 455 + 530 nm or 660 nm LEDs light for 4 h five days before harvest. Two experiments (EXP) were performed: EXP1—HPS, and LEDs treatment during daytime 6 PM–10 PM, and EXP2—LEDs treatment at nighttime during 10 AM–2 PM. LEDs’ photosynthetic photon flux density (PPFD) was 50 and HPS—90 ± 10 µmol m−2 s−1. The most pronounced positive effect on total phenolic compounds revealed supplemental 400 and 455 + 530 nm LEDs lighting, except its application during the daytime at spring cultivation, when all supplemental LEDs light had no impact on phenolics content variation. Supplemental 400 nm LEDs applied in the daytime increased chlorogenic acid during spring and chicoric acid during autumn cultivation. 400 nm LEDs used in nighttime enhanced chlorogenic acid accumulation and rutin during autumn. Chicoric and chlorogenic acid significantly increased under supplemental 455 + 530 nm LEDs applied at daytime in autumn and used at nighttime—in spring. Supplemental LEDs application in the nighttime resulted in higher phenolic compounds content during spring cultivation and the daytime during autumn cultivation.
... Therefore, any variation in red or far-red radiation and their ratios is perceived by phytochromes [40], which may impact photo morphogenetic processes in plants. Red light has more potential in plant growth and production as compared to far-red light and is more desirable because [41] it increases plant yield [42], reduces nitrate concentration [43] and increases vitamin C concentration [44] in plants. Contrasting results of red light were observed where red light hindered the transition to flowering in basil [45], whereas it induced upward or downward leaf curling in tomato (Solanum Lycopersicum) [46]. ...
... In another study by Snowden et al. [52] and Bugbee [73], they tried to reveal that green light enters deeper into leaves and canopies, and thus fluctuating plant growth and development; however, its effects may decline with increasing photosynthetic fluxes. Samuolienė et al. [43] worked on baby leaf lettuce and found that under the combination of red and blue LEDs, green LED light of wavelength 530 nm promoted the accumulation of a-carotene and anthocyanins. However, significant effort will need to be put into the development of LED lighting models for different green vegetables and lettuce cultivars. ...
... It was found that red light increased the total anthocyanin content in "red rookie", whereas the anthocyanin content in "Kinshun" remained the same regardless of the light quality [58]. A general trend of the positive effect of supplemental LED light on the anthocyanin concentration in red and light-green leaf lettuce was found to be of the order 505 > 455 > 470 > 535 nm [43], which was in concordance with the study of Zhang and Folta [230], who reported the reversal of the effect of the blue light-induced accumulation of anthocyanin by green light. Similarly, green LED light was reported to decrease blue light-induced anthocyanin accumulation, while far-red and blue light were able to enhance anthocyanin accumulation with increasing intensity in kale, broccoli and beet microgreens [127]. ...
Article
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A reduction in crop productivity in cultivable land and challenging environmental factors have directed advancement in indoor cultivation systems, such that the yield parameters are higher in outdoor cultivation systems. In wake of this situation, light emitting diode (LED) lighting has proved to be promising in the field of agricultural lighting. Properties such as energy efficiency, long lifetime, photon flux efficacy and flexibility in application make LEDs better suited for future agricultural lighting systems over traditional lighting systems. Different LED spectrums have varied effects on the morphogenesis and photosynthetic responses in plants. LEDs have a profound effect on plant growth and development and also control key physiological processes such as phototropism, the immigration of chloroplasts, day/night period control and the opening/closing of stomata. Moreover, the synthesis of bioactive compounds and antioxidants on exposure to LED spectrum also provides information on the possible regulation of antioxidative defense genes to protect the cells from oxidative damage. Similarly, LEDs are also seen to escalate the nutrient metabolism in plants and flower initiation, thus improving the quality of the crops as well. However, the complete management of the irradiance and wavelength is the key to maximize the economic efficacy of crop production, quality, and the nutrition potential of plants grown in controlled environments. This review aims to summarize the various advancements made in the area of LED technology in agriculture, focusing on key processes such as morphological changes, photosynthetic activity, nutrient metabolism, antioxidant capacity and flowering in plants. Emphasis is also made on the variation in activities of different LED spectra between different plant species. In addition, research gaps and future perspectives are also discussed of this emerging multidisciplinary field of research and its development.
... The antioxidant and polyphenol contents can be stimulated by adding red light and blue light [15,44]. For varieties of baby leaf lettuces, it has been found that their nutritional quality is further affected by red and blue light [59,60]. Similarly, the red LED illumination (600 nm, 50 μmol m −2 s −1 ) has been found to augment the anthocyanin concentrations in red leaf cabbages [61] while adding supplemental farred has an adverse effect on the nutrient contents. ...
... Anthocyanins can be considered phenolics and antioxidants, found in some vegetables and fruits [65], and are responsible for their vibrant coloring. The anthocyanin concentration can be increased by using supplemental 505 nm green LED illumination with an HPS lighting system for baby leaf lettuces (Lactuca sativa L.) [59]. Similar results can Figure 3. Impact of different LED illumination spectra on the nutrient's parameters, namely, treatment antioxidant, treatment flavonoids, treatment phenols, treatment flavonoids, and control antioxidant, control flavonoids, control phenols for various vegetables and herbs in a grow chamber [55][56][57]. ...
... The antioxidant and polyphenol contents can be stimulated by adding red light and blue light [15,44]. For varieties of baby leaf lettuces, it has been found that their nutritional quality is further affected by red and blue light [59,60]. Similarly, the red LED illumination (600 nm, 50 µmol m −2 s −1 ) has been found to augment the anthocyanin concentrations in red leaf cabbages [61] while adding supplemental far-red has an adverse effect on the nutrient contents. ...
Article
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Vegetables and herbs play a central role in the human diet due to their low fat and calory content and essential antioxidant, phytochemicals, and fiber. It is well known that the manipulation of light wavelengths illuminating the crops can enhance their growth rate and nutrient contents. To date, it has not been easy to generalize the effects of LED illumination because of the differences in the plant species investigated, the measured traits, the way wavelengths have been manipulated, and the plants’ growing environments. In order to address this gap, we undertook a quantitative review of LED manipulation in relation to plant traits, focusing on vegetables and herbs. Here, we use standardized measurements of biomass, antioxidant, and other quantitative characteristics together with the whole range of the photosynthetic photon flux density (PPFD). Overall, our review revealed support for the claims that the red and blue LED illumination is more reliable and efficient than full spectrum illumination and increases the plant’s biomass and nutritional value by enhancing the photosynthetic activity, antioxidant properties, phenolic, and flavonoids contents. Although LED illumination provides an efficient way to improve yield and modify plant properties, this study also highlights the broad range of responses among species, varieties traits, and the age of plant material.
... It has been reported that after harvest, the intensity, duration, and quality of light have a significant impact on phytochemical accumulation [13]. Light affects pigment metabolism, enhancing the color of various vegetables, such as tomatoes, broccoli, and other crops [9,25]. In present study, carotenoid content was greatly increased by irradiation with red LED light. ...
... The result of our study is in accordance with the findings of Ngcobo et al. [9], who found that red light affects the concentration or presence of carotenoids in the postharvest of red tomato tissues, and who also proposed that phytochrome, a photoreceptor response to red wavelength, appears to promote carotenoid biosynthesis in green mature tomato tissues. Samuolienė et al. [25] showed that red LED light apparently had a stronger effect than blue on the color-altering steps of baby leaf lettuce. In contrast, the highest carotenoid content was detected in broccoli stored under continuous postharvest white-blue LED [12]. ...
... Anthocyanins are red plant pigments that, among many other roles, protect plants from photo inhibition and photo damage by absorbing solar radiation [25]. In this study, blue LEDs enhanced the concentration of anthocyanin in eggplant peel. ...
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Eggplant (Solanum melongena L.), one of the major vegetable crops, is recognized for its availability of numerous bioactive compounds and antioxidant activity. The accumulation of these compounds in plant tissues can be increased by exogenous stimuli, including light exposure. This study aimed at enhancing the antioxidant activity and bioactive compounds of eggplant using light-emitting diode (LEDs) irradiation after harvest. For this purpose, eggplant fruits were irradiated under LEDs at different wavelengths, including red (650–660 nm), blue (450–460 nm), or the combination of red and blue (red + blue) LEDs, for 48 h. The results indicated that red + blue LED exposure during postharvest significantly (p < 0.05) elevated the accumulation of bioactive compounds and antioxidant activity. The accumulation of major phenolic compounds, chlorogenic acid (58.59 mg/100 g FW), and gallic acid (14.25 mg/100 g FW) in the eggplant fruits was increased significantly under red + blue irradiation when compared with the control (under dark condition). The total phenolic (821.86 mg GAE/100 g FW) and the total flavonoid (595.98 mg CE/100 g FW) contents were shown to have a considerably high accumulation in the peels of eggplant after irradiation under red + blue LEDs, whereas the total carotenoid content was relatively high in the flesh of eggplant fruits. Consequently, red + blue LED irradiation can be considered as a convenient tool used for the postharvest of eggplant, with a positive effect in the increasing of important secondary metabolites. The obtained eggplant fruits proved to be a promising source of bioactive and antioxidant compounds for functional food production.
... Although the quantum yield of green/ yellow light for photosynthesis is quite low, plants can absorb 43% to 87% of the green light 20 and efficiently use this part of the energy for photosynthesis at the inner canopy level and in deeper layers of the leaf mesophyll 3,21 , and thus, supplemental green light (only at low levels) based on compound light has been shown to promote growth in lettuce 22 , sweet pepper 23 , and cucumber 24 . In addition, supplementing blue and/or red light with green light can also improve nutritional quality in lettuce 22,25 . Kim et al. 22,26 reported that the addition of waveband sections (500-600 nm) at lower input levels to red-blue LEDs had positive effects on lettuce morphology and dry matter accumulation. ...
... Studies have shown that monochromatic RB cause oxidative stress and destroy the cell membrane 36 . Samuolienė et al. 25 also showed partly similar results, where supplemental LED light enhanced the antioxidant capability of lettuce for protection from the photooxidative state. In the current study, higher O 2 − and H 2 O 2 levels under the supplemental Y and sole W conditions resulted in a high MDA content, and higher SOD, CAT, and POD activities were correspondingly required to remove ROS 40,41 . ...
Article
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Compound light is required for plant growth and development, but the response mechanisms of plants are undercharacterized and not fully understood. The present study was undertaken to evaluate the effect of supplemental light (green light, G; white light, W; yellow light, Y) added to red-blue light (RB) and sole W on the growth and photosynthesis of rapeseed seedlings. The results revealed that supplemental G/W improved the growth and photosynthesis of seedlings, but supplemental Y significantly reduced the photosynthetic rate and palisade tissue layer. Sole W caused similar responses in terms of growth, leaf development, oxidative damage, and antioxidant capability as supplemental Y. In total, 449, 367, 813, and 751 differentially expressed genes (DEGs) were identified under supplemental G, Y, and W and sole W, respectively, compared to RB. The DEGs under different lights were closely associated with pathways such as light stimulus and highlight response, root growth, leaf development, photosynthesis, photosynthesis-antenna proteins, carbohydrate synthesis and degradation, secondary metabolism, plant hormones, and antioxidant capacity, which contributed to the distinct growth and photosynthesis under different treatments. Our results suggest that Y is more likely substituted by other wavelengths to achieve certain effects similar to those of supplemental Y, while G has a more distinctive effect on rapeseed. Taken together, supplementation RB with G/W promotes the growth of rapeseed seedlings in a controlled environment.
... Likewise, B light is also important for plants to trigger the development of chloroplasts, photomorphogenesis, and stomatal opening [7]. Moreover, different combinations of colors/wavelengths of light increase the accumulation of various primary and secondary metabolites, such as vitamin-C, tocopherol, soluble sugar, and flavonoids, when compared to white light in different crop species [8][9][10][11]. Thus, R and B combinations are often used to produce better plant growth in agriculture [12]. Although previous studies investigated the effect of different light wavelengths on the growth and production of secondary metabolites in lettuce [11,13,14], a deeper understanding of genome-wide changes of gene expression is still largely unknown. ...
... R and B combination lighting is commonly used in indoor urban agriculture to increase yield and improve metabolite accumulation, such as chlorophyll and carotenoids [8][9][10][11]. Our results verified this by showing that RB promoted growth in lettuce and resulted in increased biomass with more leaves than those grown in FL. This is consistent with previous observations showing that R and B combination lighting, particularly at R:B = 3:1, was optimal for growth and increasing chlorophyll and flavonoid content [24][25][26]. ...
Article
Lettuce is commonly consumed around the world, spurring the cultivation of green- and red-leaf varieties in indoor farms. One common consideration for indoor cultivation is the light wavelengths/spectrum, which is an important factor for regulating growth, development, and the accumulation of metabolites. Here, we show that Batavia lettuce (Lactuca sativa cv. “Batavia”) grown under a combination of red (R) and blue (B) light (RB, R:B = 3:1) displayed better growth and accumulated more anthocyanin than lettuce grown under fluorescent light (FL). Anthocyanin concentration was also higher in mature stage than early stage lettuce. By performing a comparative transcriptome analysis of early and mature stage lettuce grown under RB or FL (RB or FL-lettuce), we found that RB induced the expression of genes related to oxidation-reduction reaction and secondary metabolite biosynthesis. Furthermore, plant age affected the transcriptome response to RB, as mature RB-lettuce had six times more differentially expressed genes than early RB-lettuce. Also, genes related to the accumulation of secondary metabolites such as flavonoids and anthocyanins were more induced in mature RB-lettuce. A detailed analysis of the anthocyanin biosynthesis pathway revealed key genes that were up-regulated in mature RB-lettuce. Concurrently, branching pathways for flavonol and lignin precursors were down-regulated.
... Anthocyanin biosynthesis is often associated with high light conditions [52], as well as ultraviolet radiation and blue light [53,54]. In lettuce plants, anthocyanin accumulation can be induced by supplementing 373-, 455-, 460-, 476-, 505-, 658-, and 660-nm light with different light sources such as HPS lamps, solar light, and white fluorescent lamps [55][56][57]. However, anthocyanin accumulation mechanisms and interactions with light signal transduction pathways, particularly outside of blue wavelength range, are not yet understood [57]. ...
... In lettuce plants, anthocyanin accumulation can be induced by supplementing 373-, 455-, 460-, 476-, 505-, 658-, and 660-nm light with different light sources such as HPS lamps, solar light, and white fluorescent lamps [55][56][57]. However, anthocyanin accumulation mechanisms and interactions with light signal transduction pathways, particularly outside of blue wavelength range, are not yet understood [57]. In the present study, we observed that 630-nm light affects purple coloration in lettuce leaves. ...
Article
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Red and blue light are the principal wavelengths responsible for driving photosynthetic activity, yet amber light (595 nm) has the highest quantum efficiency and amber-rich high pressure sodium lamps result in superior or comparable plant performance. On this basis, we investigated how lettuce plant growth and photosynthetic activity were influenced by broad and narrow light spectra in the 590–630 nm range, by creating amber and red light-emitting diode (LED) spectra that are not commercially available. Four different light spectra were outfitted from existing LEDs using shortpass and notch filters: a double peak spectrum (595 and 655 nm; referred to as 595 + 655-nm light) that excluded 630-nm light, 595-nm, 613-nm, and 633-nm light emitting at an irradiance level of 50 W·m−2 (243–267 µmol·m−2·s−1). Shifting LED wavelengths from 595 nm to 633 nm and from 595 nm to 613 nm resulted in a biomass yield decrease of ~50% and ~80%, respectively. When 630-nm light is blocked, lettuce displayed expanded plant structures and the absence of purple pigmentation. This report presents a new and feasible approach to plant photobiology studies, by removing certain wavelengths to assess and investigate wavelength effect on plant growth and photosynthesis. Findings indicate that amber light is superior to red light for promoting photosynthetic activity and plant productivity, and this could set precedence for future work aimed at maximizing plant productivity in controlled environment agriculture.
... Moreover, plants grown under different light qualities in in vitro environment consisted of enhanced growth, secondary metabolites, and active antioxidant enzyme metabolism (Kozai et al., 1997;Mengxi et al., 2011;Manivannan et al., 2015a). Recently, the usage of light-emitting diodes (LEDs) over the conventional cool white fluorescent light source has been increasing due to its advantages, such as less heat radiation, energy efficiency, monochromatic spectrum, and longer life span, thus offering a wide range of applications for the plant growers (Kim et al., 2004;Samuoliene et al., 2012;Batista et al., 2018). The application of different light qualities separately or in combination influences the physiology and metabolite contents. ...
... The light quality-mediated elicitation of secondary metabolites has gained importance in recent days, especially in medicinal plants (Alvarenga et al., 2015;Manivannan et al., 2015a). The light-mediated elicitation of phenols and flavonoids has been reported by Samuoliene et al. (2012) in lettuce. In this experiment, the contents of total phenols and flavonoids were found to be markedly higher in the blue LED treatment, followed by the red LED treatment (Figure 5). ...
Article
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The current study has determined the effect of red and blue lights on the enhancement of growth, antioxidant property, phytochemical contents, and expression of proteins in Scrophularia kakudensis. In vitro-grown shoot tip explants of S. kakudensis were cultured on the plant growth regulator-free Murashige and Skoog (MS) medium and cultured under the conventional cool white fluorescent lamp (control), blue light-emitting diodes (LED) light, or red LED light. After 4 weeks, growth, stomatal ultrastructure, total phenols and flavonoids, activities of antioxidant enzymes, and protein expressions were determined. Interestingly, blue or red LED treatment increased the shoot length, shoot diameter, root length, and biomass on comparison with the control. In addition, the LED treatments enhanced the contents of phytochemicals in the extracts. The red LED treatment significantly elicited the accumulation of flavonoids in comparison with the control. In accordance with the secondary metabolites, the LED treatments modulated the activities of antioxidant enzymes. Moreover, the proteomic insights using two-dimensional gel electrophoresis system revealed the proteins involved in transcription and translation, carbohydrate mechanism, post-translational modification, and stress responses. Taken together, the incorporation of blue or red LED during in vitro propagation of S. kakudensis can be a beneficial way to increase the plant quality and medicinal values of S. kakudensis.
... The antioxidant activity of F. saxatilis was estimated using DPPH and ABTS radical scavenging assays. The DPPH radical scavenging activity of F. saxatilis was consistent with that of the total phenol and flavonoid compounds and with previous studies, in which an increase in phytochemicals led to a significant improvement in radical scavenging activity when various combinations of LEDs were used (Samuolienė et al. 2012;Zhao et al. 2020;Manivannan et al. 2015;Oh et al. 2021). Therefore, it was concluded that the combination of R and B light at a ratio of 7:3 (R7B3) enhanced the antioxidant activity of F. saxatilis by increasing the content of functional substances, such as phenols and flavonoids. ...
Article
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Forsythia saxatilis is an endangered species endemic to Korea. Here, we determined the effects of light quality on the growth and antioxidant activity of F. saxatilis. Six different light conditions were used: white (W10, control); combined light-emitting diodes (LED) of white (W) and far-red (Fr) at 10:1 (W10Fr1); combined LED of red (R) and blue (B) at 5:5 (R5B5); combined LED of R and B at 7:3 (R7B3); combined LED of R, green (G), and B at 7:1:2 (R7G1B2); and a combined LED of R, G, B, and Fr at 7:1:2:1 (R7G1B2Fr1). Forsythia saxatilis shoot formation was the highest with R7G1B2 at 89%, whereas the greatest growth-promoting effects—that is, increase in plant height, leaf length and width, and fresh and dry weights of shoots and roots—were achieved with W10Fr1. The total phenol and flavonoid contents were the highest with R7B3. The activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) were the highest with R7B3 treatment. In summary, W10Fr1 treatment was found to be the most effective for the growth of F. saxatilis, whereas R7B3 was confirmed to be the most effective for maximizing antioxidant activity.
... On the other hand, Samuolienè et al. (2012) determined a positive trend of B and G LED light supplementation (30 µmol m -2 s -1 ) for 16 hours per day on vitamin C and tocopherol concentration in lettuce (Lactuca sativa L.) cultivated in a greenhouse compared to natural light intensity conditions. Moreover, Son and Oh (2015) showed that the use of R (600 -700 nm), G (500 -600 nm) and B (400 -500 nm) LED lights with a PPFD of 173 µmol m -2 s -1 for 12 hours per day for 18 days increased the production of biomass and secondary metabolites on lettuce treated with a greater proportion of R and B-lights, respectively. ...
Article
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The present study employed white (W), blue (B: 468 nm), red (R: 629 nm) and green (G: 524 nm) monochromatic LED lights for 26 days, from 11:00 to 18:00 h (7 h per day), with an average photosynthetic photon flux density (PPFD) of 26.0 m-2 s-1 on baby spinach leaves (Spinacia oleracea L.), cvs. Falcon F1 and Viroflay, grown in a hydroponic system. Regardless of the cultivar, the fresh and dry weights were positively influenced when the plants were irradiated by R-light in comparison to W-light. Independent of the cultivar, the leaves treated with Blight reached a significantly higher phenolic compound concentration and antioxidant capacity than plants irradiated with W-light. In addition, the green light increased total phenolic compound concentration. According to the results, the use of LED lights is a promising technique for the production of antioxidant compound-enriched leafy vegetables. Keywords LED light • biomass • spectrum • antioxidant capacity • hydroponic system • spinach Effect of LED light on the quality of spinach 99 Revista de la Facultad de Ciencias Agrarias-UNCuyo | Tomo 53-1-Año 2021 Resumen El presente estudio empleó luces LED monocromáticas blanca, azul (468 nm), roja (629 nm) y verde (524 nm) durante 26 días, desde las 11:00 hasta las 18:00 h (7 horas por día), con una densidad media de flujo fotosintético de 26,00 µmol m-2 s-1 sobre dos cultivares de espinaca (Spinacia oleracea L.) de hoja baby (Falcon F1 y Viroflay) cultivadas en un sistema hidropónico. Respecto del cultivar, los pesos fresco y seco fueron influenciados positivamente cuando las plantas fueron irradiadas con luz roja en comparación con las irradiadas con luz blanca. Independientemente del cultivar, las hojas tratadas con luz azul alcanzaron una concentración de compuestos fenólicos y capacidad antioxidante superiores a la de las plantas irradiadas con luz blanca. Además, la luz verde incrementó la concentración de compuestos fenólicos. De acuerdo con los resultados, el uso de luces LED es una técnica prometedora para la producción de hortalizas de hoja enriquecidas en compuestos antioxidantes. Palabras clave luces LED • biomasa • espectros • capacidad antioxidante • sistema hidropónico • espinaca
... Diverse monochromatic light function differently in dissimilar species for in vitro plant growth and development [24,25]. Some studies were also reported about the effects of white, green, far red, yellow and orange LEDs in plant micropropagation [25][26][27][28][29][30]. LEDs are found more efficient over fluorescent light for orchid PLB organogenesis [6,7,[31][32][33][34][35][36][37][38][39][40]. ...
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Dendrobium okinawense is an endangered epiphytic orchid, and there has been no scientific report so far on its propagation. Protocorm is mass of cell, and protocorm-like bodies (PLBs) look alike protocorm produced by vegetative explants in vitro. Regeneration of PLBs is the most efficient technique for the orchids micro-propagation. We used different light emitting diodes (LEDs) for the efficient PLB organogenesis of D. okinawense. PLBs regenartion under green and red LED surpassed respectively 81.1% and 71.6% in numbers, and respectively 80.8% and 57.8% in fresh weight over white fluorescent light. We manipulated the culture media by different concentrations of PCIB and HMI. PLBs organogenesis promoted by low concentration, it increased respectively 35.9% and 19.3% over control by 0.01 mg/L PCIB and 0.01 ml/L HMI in numbers. Green LED and PCIB independently produced mostly similar numbers of new PLBs. Interestingly, culture media with 0.01 mg/L of PCIB further increased 8.5% of the numbers of PLBs under green LED, whereas the culture media with 0.01 mg/L HMI reduced the number of PLBs under green LED. PLBs culture under green LED with very low concentrations of PCIB manipulated culture media can significantly increase their organogenesis of D. okinawense.
... In particular, the high ROS scavenging capacity of quercetin and kaempferol glycosides has been confirmed in some species, including lettuce [25] and Phillyrea latifolia [26]. Strategies to improve the nutraceutical content of indoor-grown crops are aimed at obtaining highly nutritional crops all year long, an important goal considering that in some lettuce cultivars [27] and in baby leaf lettuce [28], the concentration of phenolic compounds has been shown to change according to seasonality. In lettuce, as in most horticultural crops, red and blue light have been identified as the most efficient spectral regions for enhancing both growth and the concentration of nutraceutical compounds [29,30]. ...
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In indoor vertical farms, energy consumption represents a bottleneck for both a system’s affordability and environmental footprint. Although switching frequency (sf) represents a crucial factor in determining the efficacy of light emitting diodes (LED) lighting systems in converting electricity into light, the impact of sf is still underexplored. The aim of this work was to investigate the effect of LEDs sf on the productive and qualitative responses of lettuce (Lactuca sativa L.), also considering the resource use efficiency. Plants were grown for 14 days under red and blue LEDs (215 μmol m−2 s−1 and 16/8 h light/dark, with a red:blue ratio of 3) characterized by two different sf for the blue diode, namely high sf (850 kHz) and low sf (293 kHz). A fluorescent light (same light intensity and photoperiod) was included. LED sf did not alter plant morphological parameters, including fresh or dry biomass, leaf number, leaf area, or water use efficiency. A low sf increased the energy use efficiency (EUE) by 40% as compared to high sf. The latter enhanced the leaf antioxidant capacity, as a consequence of increased concentrations of caftaric and chicoric acids, isoquercetin, and luteolin, consistent with the upregulation of a few genes related to the biosynthetic pathway of phenolic compounds (4C3H and DFR). The study highlights that different sf may significantly affect the EUE as well as crop nutritional properties.
... For most higher plants, leaves are the major organs for photosynthesis and assimilate production. Plants have a remarkable ability to adapt their morphology and biochemistry in response to the prevailing environmental conditions (Terashima et al, 2006;Samuolien et al, 2012;Gong et al, 2015). Adaptations to reduced light intensities are generally categorized into shade avoidance or shade tolerance mechanisms (Gommers et al, 2013). ...
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Specific aspects of plant cultivation require tests under fully controlled environmental conditions with restricted energy supply, such as orbit-based space laboratories and low-light conditions. For these growing conditions, super dwarf plants have been developed as model crops, and a gibberellin- deficient Super Dwarf Rice genotype was proposed as a model crop for space flight plant experiments. We tested this genotype in a climate chamber experiment under different illumination and nitrogen supply levels to assess its suitability under scenarios with limited resource availability. A 25% reduction in illumination led to a 75% reduction in yield, mainly due to a 60% reduction in formed tillers and 20% reduction in grain weight, and a 80% reduction in illumination caused total yield loss. Leaf area under reduced illumination was significantly lower, and only marginal changes in the dimensions of leaves were observed. Plant photosynthesis was not significantly different between control and 75% illumination. This was explained by a higher photochemical efficiency under lower light conditions and a reduced mesophyll resistance. Therefore, we concluded that this genotype is well-suited for plant experiments under space and light-limited conditions since it kept its small stature and showed no shade avoidance mechanisms, such as leaf elongation, which would complicate experiments under low-light conditions. Nitrogen concentrations of 2.8 and 1.4 mmol/L led to no differences in plant growth. We concluded that a nitrogen concentration of 1.4 mmol/L is sufficient for this genotype under the light intensities.
... La enzima PAL se asocia con la producción de compuestos fenólicos en plantas, la cual es mayormente estimulada bajo la combinación de luz azul y roja (Heo et al., 2012). Sin embargo, el comportamiento de los resultados puede variar debido a que no solo depende del tipo del espectro de luz que inciden en las plantas, si no, también depende de la especie, la variedad y etapa de desarrollo (Samuolienė et al., 2012). ...
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El chile habanero es el cultivo hortícola de mayor im­portancia económica en la península de Yucatán. Este podría desarrollarse en ambiente controlado con iluminación LED y permitiría tener una producción continua, con un aumento exponencial de rendimiento y estar libre de plagas y enfer­medades. Los objetivos fueron evaluar el efecto de cinco proporciones de luz LED azul:roja y un testigo fluorescente sobre crecimiento en planta, concentración de pigmentos fotosintéticos, compuestos fenólicos y nutrimental en hoja; germinación de polen, grosor de hoja, anatomía de ovario y antera de chile habanero ‘Mayan Ba’alché’ bajo condiciones controladas de crecimiento. Los resultados mostraron que los tratamientos no indujeron un efecto en crecimiento de plan­ta. La luz roja favoreció el rendimiento de frutos y frecuencia estomática. La luz roja monocromática favoreció la concen­tración de pigmentos fotosintéticos, Mg y Mn e indujo menor concentración de P y Cu. La luz azul monocromática favoreció la concentración de compuestos fenólicos. El testigo indujo mayor concentración de K entre algunos tratamientos LED e incrementó la germinación de polen y el grosor de hoja al igual que la luz azul monocromática. La anatomía de los óvu­los en ovarios y el polen en anteras no presentaron ningún efecto por los tratamientos.
... Red and blue LEDs can act as a principal light source, with the potential to improve photosynthesis by stimulating the stomatal activity, which can enhance dry mass and yield (Sabzalian et al., 2014). Various studies have demonstrated that controlled amounts or specific spectra of light affect photosynthetic characteristics (Dong et al., 2014;Samuolienė et al., 2020), metabolism (Samuolienė et al., 2013;Lee et al., 2016), and antioxidant properties (Samuolienė et al., 2012;Lekkham et al., 2016). However, these experiments are typically performed in controlled environment chambers with constant irradiance during the day and abrupt transitions between light and dark at dawn and dusk. ...
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This study aimed to evaluate the effect of dynamic red and blue light parameters on the physiological responses and key metabolites in lettuce and also the subsequent impact of varying light spectra on nutritive value. We explored the metabolic changes in carotenes, xanthophylls, soluble sugars, organic acids, and antioxidants; the response of photosynthetic indices [photosynthetic (Pr) and transpiration (Tr) rates]; and the intracellular to ambient CO2 concentration ratios (C i /C a ) in lettuce (Lactuca sativa L. "Lobjoits Green Cos"). They were cultivated under constant (con) or parabolic (dyn) blue (B, 452 nm) and/or red (R, 662 nm) light-emitting diode (LED) photosynthetic photon flux densities (PPFDs) at 12, 16, and 20 h photoperiods, maintaining consistent daily light integrals (DLIs) for each light component in all treatments, at 2.3 and 9.2 mol m-2 per day for blue and red light, respectively. The obtained results and principal component analysis (PCA) confirmed a significant impact of the light spectrum, photoperiod, and parabolic profiles of PPFD on the physiological response of lettuce. The 16 h photoperiod resulted in significantly higher content of xanthophylls (neoxanthin, violaxanthin, lutein, and zeaxanthin) in lettuce leaves under both constant and parabolic blue light treatments (BconRdyn 16 h and BdynRdyn 16 h, respectively). Lower PPFD levels under a 20 h photoperiod (BdynRdyn 20 h) as well as higher PPFD levels under a 12 h photoperiod (BdynRdyn 12 h) had a pronounced impact on leaf gas exchange indices (Pr, Tr, C i /C a ), xanthophylls, soluble sugar contents, and antioxidant properties of lettuce leaves. The parabolic PPFD lighting profile over a 16 h photoperiod (BdynRdyn 16 h) led to a significant decrease in C i /C a , which resulted in decreased Pr and Tr, compared with constant blue or red light treatments with the same photoperiod (BconRdyn and BdynRcon 16 h). Additionally, constant blue lighting produced higher α + β-carotene and anthocyanin (ARI) content and increased carotenoid to chlorophyll ratio (CRI) but decreased biomass accumulation and antioxidant activity.
... Differences between red and green lettuce [28,54] and basil [55] in growth, antioxidant levels, and photosynthetic response to red LED parameters were reported, which highlighted that red (purple) cultivars are less sensitive to environmental impacts. Similarly, in our study, according the PCA analysis, the two species with red (amaranth) and green (turnip greens) leaves showed a distinct response under the same lighting conditions. ...
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To improve microgreen yield and nutritional quality, suitable light spectra can be used. Two species—amaranth (Amaranthus tricolor L.) and turnip greens (Brassica rapa L. subsp. oleifera (DC.) Metzg)—were studied. The experiment was performed in a controlled LED environment growth chamber (day/night temperatures of 24 ± 2 °C, 16 h photoperiod, and 50/60% relative humidity). Three emission wavelengths of a light-emitting diode (LED) were adopted for microgreen lighting: (1) white LED (W); (2) blue LED (B), and (3) red LED (R); the photosynthetic photon flux densities were 200 ± 5 µmol for all light spectra. The response to light spectra was often species-specific, and the interaction effects were significant. Morphobiometric parameters were influenced by species, light, and their interaction; at harvest, in both species, the fresh weight was significantly greater under B. In amaranth, Chl a was maximized in B, whereas it did not change with light in turnip greens. Sugar content varied with the species but not with the light spectra. Nitrate content of shoots greatly varied with the species; in amaranth, more nitrates were measured in R, while no difference in turnip greens was registered for the light spectrum effect. Polyphenols were maximized under B in both species, while R depressed the polyphenol content in amaranth.
... Vitamin C content was assessed spectrophotometrically (Samuoliene et al. 2012). Plant tissue (1.0 g) was accurately weighed out, and 10 ml of 5% oxalic acid was added to grind it into a homogenate. ...
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The growth and development and metabolism of plants have different physiological responses to different light qualities. To study the influence of light qualities on green onions, the impacts of LED light treatment on the growth and development as well as the nutritional components and flavor substances in green onions were studied under controlled conditions. Leaf area, plant height, dry matter accumulation, Dickson’s quality index (DQI), nutritional content, and volatile compounds under different light quality treatments were determined. The results indicated that the white and blue combined light (W/B: 3/1) treatment was the most beneficial to growth and nutrient accumulation and led to higher levels of sulfur compounds in the green onions than the other treatments. This shows that it is possible to control the contents of compounds that affect consumer preferences by adjusting the lighting conditions and to thereby increase the value and quality of seasoning vegetables.
... The lipid components from lettuce that have been most studied are the fat-soluble vitamins (FSVs) (Chun et al., 2006;Szymańska, Kruk, 2008;Samuoliene et al., 2012) and carotenoids (Kim et al., 2018), though the fatty acid (FA) compositions of some varieties have been reported (Kim et al., 2016). Unfortunately, the FA composition does not distinguish FAs coming from different lipid classes, so there is no identification, and no quantification of different lipid classes, such as triacylglycerols (TAGs), diacylglycerols (DAGs), and galactolipids (GALs). ...
Article
The compositions of molecular species of structural lipids and storage lipids of two types of lettuce leaves, romaine (green leaf) and Lolla Rossa (red leaf), are reported. Lettuce was harvested at two ages, three weeks (microgreens) and eight weeks (mature), and analyzed by liquid chromatography-mass spectrometry. Samples grown under natural light in a greenhouse were compared to those grown under grow lights. Compositions of molecular species of galactolipids (GALs), which are structural lipids, and triacylglycerols (TAGs) and diacylglycerols (DAGs), which are storage lipids, were examined relative to type (cultivar), age, and light source. GALs were most abundant, and the predominant molecular species were dilinolenoyl-monogalactosyldiacylglycerol (LnLn-MGDG) and dilinolenoyl-digalactosyldiacylglycerol (LnLn-DGDG), averaging 53.6 ± 1.4% and 33.7 ± 2.3% of galactolipids, respectively. TAGs containing linolenic acid (Ln) increased from three to eight weeks, especially LnLnL, LLLn, PLLn (P is palmitic acid and L is linoleic acid), and LnLnLn, with corresponding decreases in TAGs containing mostly linoleic acid, especially LLL, LLP, and LLO (O is oleic acid). α-Tocopherol started at similar levels in both varieties of greenhouse-grown lettuce, and it approximately tripled in Lolla Rossa, from 3.4 ± 0.3 μg/g to 9.9 ± 0.7 μg/g, by two LED lighting treatments.
... The plants under RL conditions were shown to accumulate various antioxidants, such as flavonoids, alpha tocopherol, ascorbic acid and sugars (Li & Kubota 2009;Samuoliene et al., 2016;Lu et al., 2012). For example, RL induces accumulation of a number of low molecular weight antioxidants in certain members of the Brassicaceae family (Bliznikas et al., 2012;Samuoliene et al., 2012;Son & Oh 2013). RL is also able to influence on the accumulation of secondary metabolites and alkaloids. ...
Article
The photosynthetic acclimation of extremophile Eutrema salsugineum plants to red light (RL) (14 days, 150 μmol photons m−2 s-1, 660 nm) and the expression of the key photoreceptor apoprotein genes, transcription factors (TFs) and associated with phytochrome system MIR (microRNA) genes were studied. RL exposure induced an increase in the content of anthocyanin and total phenolic compounds and the level of Chls was decreased. The photosystem 2 electron transport rate and the number of open reaction centres (qL) were not changed in RL plants, however, the levels of non-photochemical quenching (NPQ) and the regulated quantum yield of non-photochemical quenching Y(NPQ) were significantly higher in the RL plants. The rate of CO2 uptake was decreased by almost 1.4-fold but the respiration and transpiration rates, as well as the stomatal conductance were not changed in the RL plants. An increase in the expression of the photoreceptor apoprotein genes PHYA, PHYB and PHYC, the TF genes PIF4, PIF5 and miR395, miR408, miR165 and decreases in the levels of the transcripts of the TF gene HY5 and miR171, miR157, and miR827 were detected. The acclimation effect of photosynthetic apparatus to RL was accompanied by an increase of pigment content such as total phenolic compounds and carotenoids and it is due to the changes in the expression of the apoprotein phytochrome genes PHYA, PHYB, PHYC and phytochrome signalling TFs (PIF4, PIF5 and HY5) as well as MIR genes associated with phytochrome system.
... Differential growth, antioxidant and photosynthetic response of red and green lettuce [27,28] and basil [9] cultivars to different LED lighting parameters were reported, showing that red (purple) cultivars are less sensitive to environmental impacts. According to the PCA analysis, red and green leaf lettuce showed distinct response to the same lighting conditions in our study. ...
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In this study, we sought to evaluate and compare the effects of constant and dynamic lighting on red and green leaf lettuce (Lactuca sativa L. Red Cos and Lobjoits Green cos) cultivated in a controlled environment. Plants were illuminated with the combination of red 662 and 638 nm, blue 452 nm, and far-red 737 nm at 16 h photoperiod and constant daily light integral (DLI) of each component. Five constant or dynamic lighting treatments were performed: (BR) constant flux of both B452 and R662; (B*R) constant flux of R662, but the DLI of B452 condensed in 8 h in the middle of photoperiod doubling the PPFD of blue light; (BR*) constant flux of B452, but the DLI of R662 light condensed in the middle of photoperiod; (BdynR) constant flux of R662, but the flux of B452 varies in the sinusoidal profile during 16 h photoperiod, imitating diurnal increase and decrease in lighting intensity; and (BRdyn) constant flux of B452, but the flux of R662 varies in sinusoidal profile. The lettuce’s response to dynamic lighting strategies was cultivar specific. Dynamic lighting strategies, mimicking natural lighting fluctuations, did not have a remarkable effect on photosynthesis and antioxidative parameters, but the dynamic flux of blue light component had a pronounced effect on higher macro and microelement contents in lettuce leaves.
... Control GHH25% * GHH50% CGW25% CGW50% GPH25% GPH50% Tocopherols composition is presented in Table 3. γ-tocopherol was the most abundant vitamin E isoform, followed by αand δ-tocopherols, a result which agrees with the findings of Mou [40] who reported a similar profile of tocopherols for various lettuce types (except for the crisphead lettuce) although δ-tocopherol was not present. Similarly, Samuolienė et al. [58] suggested the content of the same two vitamin E isoforms (α-and γ-tocopherol) to be affected by light quality, whereas in another study all four tocopherols were detected [59]. Moreover, the CGW25% treatment increased significantly the overall tocopherols content, while in regard to individual tocopherols the GHH50% Sustainability 2020, 12, 8511 9 of 17 treatment increased α-tocopherol and that of GPH25% increased γand δ-tocopherol. ...
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The environmental burden from crop production byproducts is gradually increasing and necessitates the sustainable management of waste towards a circular economy approach. In the present study, three byproducts (cotton ginning waste (CGW), ground hazelnut husks (GHH) and ground peanut husks (GPH)) were evaluated in lettuce cultivation. For this purpose, the tested materials were incorporated in soil at two different rates (25% and 50% of total substrate volume) while a control treatment (no addition of byproducts) was also considered. Fresh weight per plant and total yield was the highest for the GHH50% treatment. The highest fat, protein, carbohydrates and energy content were observed for the CGW25% treatment. Chemical composition also differed among the tested byproducts where CGW25% treatment had the highest total tocopherols, sugars (sucrose, fructose, trehalose and total sugars) and organic acids content. The most abundant fatty acids were α-linolenic, linoleic and palmitic acid in all the tested treatments, while the highest antioxidant activity was observed for the GHH50% treatment. Regarding polyphenols, phenolic acids content was the highest in the GHH treatments, whereas flavonoids were the highest for the CGW25% treatment. No cytotoxicity against the PLP2 non-tumor cell line was observed, whereas only the GPH50% treatment showed moderate efficacy against HeLa, HepG2 and MCF-7 cell lines. The tested extracts also showed moderate antibacterial activities and only the extracts from the CGW50% treatment were more effective than the positive control against Trichoderma viride. In conclusion, the present results showed the great potential of using the tested byproducts as soil amendments for vegetable crops production, since they may improve the nutritional parameters, the chemical profile and the bioactivities of the final product. The suggested alternative use of the tested byproducts not only will increase the added value of crops but will also alleviate the environmental burden from bulky agroindustry byproducts.
... In the previous study, treatment with blue light LEDs shown to induce anthocyanin accumulation and total flavonoid content in Chinese herbal medicine during storage (Ren et al. 2014) and Chinese kale fruit (Brassica sp.) (Qian et al. 2016). Nevertheless, it has been reported that LED treatment has a positive influence on the anthocyanin accumulation in grapes (Vitis sp.) and leaf baby lettuce (Lactuca sativa) (Kondo et al. 2014;Samuoliene et al. 2012). The effect of different LED treatments blue, red, and green (385 nm, 470 nm, 525 nm, and 630 nm) in immature strawberries (Fragaria ananassa) at 5°C for 4 days was reported compared with control samples (Kim et al. 2011). ...
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Major losses of fresh horticultural produce transpire during postharvest storage due to prompt senescence and diseases. The traditional postharvest preservation techniques used after harvest are based on cooling and the application of chemical preservation techniques. As a residue-free physical sterilization and preservation method, light-emitting diode (LED) treatment, has recently been applied for postharvest storage of fruits and vegetables by numerous researchers. This paper reviews the recent applications of LEDs in postharvest storage of fresh produce, including its effect on physiological characteristics, secondary metabolism, nutritional attributes, ripening process, senescence, shelf-life improvement, and pathogenic microbial spoilage of fruits and vegetables. LED treatment has promoted the accumulation of different phytochemicals, such as phenolic compounds, vitamins, glucosinolates, chlorophyll, total soluble solids, and carotenoids. Changes in the nutritional content, anthocyanin content, antioxidant capacity, and ripening were also observed after the treatment. Reduction in microbial spoilage and delay senescence were evident after the LED exposure. The influence of LED light depended on the fruit and vegetable variety. Therefore, LED treatment is an efficient and promising strategy for extending the storage life of fruits and vegetables with enhanced nutritional values. Graphical abstract
... On the other hand, Samuolienè et al. (2012) determined a positive trend of B and G LED light supplementation (30 µmol m -2 s -1 ) for 16 hours per day on vitamin C and tocopherol concentration in lettuce (Lactuca sativa L.) cultivated in a greenhouse compared to natural light intensity conditions. Moreover, Son and Oh (2015) showed that the use of R (600 -700 nm), G (500 -600 nm) and B (400 -500 nm) LED lights with a PPFD of 173 µmol m -2 s -1 for 12 hours per day for 18 days increased the production of biomass and secondary metabolites on lettuce treated with a greater proportion of R and B-lights, respectively. ...
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The present study employed white (W), blue (B: 468 nm), red (R: 629 nm) and green (G: 524 nm) monochromatic LED lights for 26 days, from 11:00 to 18:00 (7 h per day), with a average of photosynthetic photon flux density (PPFD) of 26.00 m-2 s-1 on two baby leaves of spinach (Spinacia oleracea L.) cultivars (Falcon F1 and Viroflay) grown in a hydroponic system. Regardless of the cultivar, the fresh and dry weights were positively influenced when the plants were irradiated by R-light in comparison to W-light. Independent of the cultivar, the leaves treated with B-light reached a significantly higher phenolic compound concentration than plants irradiated with W-light. With respect to antioxidant capacity, plants treated with B-light showed a significantly higher antioxidant capacity than those treated with W-light. According to the results, the use of LED lights is a promising technique for the production of antioxidant compound-enriched vegetables. Highlights - The fresh and dry weights were positively influenced when baby leaves spinach were irradiated by red LED light. - Baby leaves spinach treated with blue LED light reached a significantly higher phenolic compound concentration and antioxidant capacity. - The green LED light increased total phenolic compound concentration in baby leaves spinach.
... Quando é realizada a produção de plantas em cultivo protegido, as instalações podem ser divididas em duas categorias principais, de acordo com a utilização da fonte de luz: estufas e casas de vegetação, estas utilizam a luz solar como fonte principal de energia, e os ambientes indoor totalmente fechados, que utilizam luz artificial, como fonte luminosa (Samuolienė et al., 2012). O uso de iluminação artificial e controlada, pode reduzir os efeitos negativos do excesso da luz e fornecer a quantidade de luz necessária para o crescimento da planta, melhorando assim as condições para a otimização das concentrações de fitoquímicos em vegetais produzidos em ambientes controlados (Gupta, 2017). ...
... Chang et al. [9] confirmed that blue LED light irradiation enhances L-ascorbic acid content while reducing reactive oxygen species accumulation in Chinese cabbage seedlings. Samuolienė et al. [10] showed that blue LED irradiation of baby leaf lettuce had a significant positive effect on its DPPH scavenging capacity and enhanced its antioxidant properties. lettuce had a significant positive effect on its DPPH scavenging capacity and enhanced its antioxidant properties. ...
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Freshly cut vegetables are susceptible to microbial contamination and oxidation during handling and storage. Hence, light-emitting diode technology can effectively inhibit microbial growth and improve antioxidant enzyme activity. In this paper, the freshly cut amaranth was treated with different intensities of blue light-emitting diode (LED460nm) over 12 days. Chlorophyll content, ascorbic acid content, antioxidant capacity, antioxidant enzymes activity, the changes in microbial count, and sensorial evaluation were measured to analyze the effects of LED treatment on the amaranth. Blue LED460nm light irradiation improved the vital signs of the samples and extended the shelf life by 2–3 days. The AsA–GSH cycle was effectively activated with the irradiation of 30 μmol/(m2·s) blue LED460nm light. According to the results, the LED460nm light could retard the growth of colonies and the main spoilage bacteria, Pseudomonas aeruginosa, of freshly cut amaranth.
... The red:blue ratio also affects phenolic compound levels, antioxidant activity, nitrate content, firmness and crispness in some products [38][39][40] . Green light increases phytonutrient concentrations (vitamin C, tocopherol and phenolic compounds) and inhibits anthocyanin biosynthesis 41,42 . ...
Article
Vertical farming can produce food in a climate-resilient manner, potentially emitting zero pesticides and fertilizers, and with lower land and water use than conventional agriculture. Vertical farming systems (VFS) can meet daily consumer demands for nutritious fresh products, forming a part of resilient food systems—particularly in and around densely populated areas. VFS currently produce a limited range of crops including fruits, vegetables and herbs, but successful implementation of vertical farming as part of mainstream agriculture will require improvements in profitability, energy efficiency, public policy and consumer acceptance. Here we discuss VFS as multi-layer indoor crop cultivation systems, exploring state-of-the-art vertical farming and future challenges in the fields of plant growth, product quality, automation, robotics, system control and environmental sustainability and how research and development, socio-economic and policy-related institutions must work together to ensure successful upscaling of VFS to future food systems.
... Thus, the overlap of green LEDs to the blue spectral region could cause a change in the equilibrium of activated and inactivated CRYs, which in turn could slightly enhance total PheC content. Several studies have demonstrated the positive effect of green light on ascorbic acid, anthocyanin, and total phenolic content in lettuce [65][66][67]. However, Zhang et al. (2021) [68] concluded that green light reduces stem elongation when partially replacing blue light independent of CRY signaling. ...
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Photosynthetically active radiation (PAR) is an important environmental cue inducing the production of many secondary metabolites involved in plant oxidative stress avoidance and tolerance. To examine the complex role of PAR irradiance and specific spectral components on the accumulation of phenolic compounds (PheCs), we acclimated spring barley (Hordeum vulgare) to different spectral qualities (white, blue, green, red) at three irradiances (100, 200, 400 µmol m−2 s−1). We confirmed that blue light irradiance is essential for the accumulation of PheCs in secondary barley leaves (in UV-lacking conditions), which underpins the importance of photoreceptor signals (especially cryptochrome). Increasing blue light irradiance most effectively induced the accumulation of B-dihydroxylated flavonoids, probably due to the significantly enhanced expression of the F3’H gene. These changes in PheC metabolism led to a steeper increase in antioxidant activity than epidermal UV-A shielding in leaf extracts containing PheCs. In addition, we examined the possible role of miRNAs in the complex regulation of gene expression related to PheC biosynthesis.
... In addition, the combination of green (G), R, and B lights can inhibit the B light response [37], making the suppression of leaf expansion of B light less effective [38]. The supplement of G LEDs to HPS lamp lighting enhanced fresh and dry weights, leaf area, and pigment concentration in tomato, sweet pepper, and cucumber [39]. The SFL sources were a combination of R light and shorter wavelengths of B and G lights, which resulted in a remarkable impact on tomato vegetative growth compared to the NSL, HPS, and control. ...
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Supplemental artificial light in greenhouses is fundamental to achieving sustainable crop production with high yield and quality. This study’s purpose was to investigate the efficacy of supplemental light (SL) sources on the vegetative and reproductive growth of cherry tomatoes. Four types of light sources were applied, including high-pressure sodium lamps (HPS), a narrow-spectrum LED light (NSL), and two specific full-spectrum LED lights (SFL1 and SFL2) with a shorter blue peak wavelength (436 nm) and/or green peak wavelength (526 nm). The control was the natural light condition. Shoot fresh and dry weight and leaf area in the SFL1 and SFL2 treatments were greater than those in the control. The HPS and NSL treatments also enhanced tomato growth, but they were less efficient compared to the SFL treatments. The SFL1 and SFL2 treatments showed higher fruit yields by 73.1% and 70.7%, respectively, than the control. The SL sources did not affect the effective photochemical quantum yield of photosystem II (Y(II)). However, they did trigger the increased electron transport rate (ETR) and non-photochemical quenching (NPQ). The SFL treatments enhanced tomato growth, fruit yield, and efficient use of light and energy, suggesting that the specific full spectrum based on the short-wavelength blue and/or green peak can be successfully applied for the cultivation of cherry tomato and other crops in greenhouses.
... In recent years, artificial light supplementation has been used to overcome short-term sunlight exposure in greenhouse cultivation during winter months [8][9][10]. Light-emitting diodes (LEDs) have been used as supplementary light sources in greenhouse cultivation because of their efficiency, environment-friendly performance, availability of varying light intensities, and long-term use [11,12]. ...
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Supplementary light exposure using light-emitting diodes (LEDs) promotes the growth of tomato plants in greenhouses. Owing to the biological clock in plants, determining the period during which they must be exposed to supplementary light is essential to enhance growth. In this study, we used red and blue LEDs (red:blue = 7:2) as the supplementary light source, to determine the effects of different light supplemental periods on the growth and photosynthetic characteristics of tomato seedlings. Light supplementation in the morning and evening promoted the growth of tomato plants to varying degrees, including the accumulation of photosynthetic products in the leaves. Light supplementation in the morning enhanced dry matter accumulation, root growth, and the contents of chlorophyll and carotenoids in the leaves. Although both morning and evening light supplementation increased the levels of gas exchange parameters and Rubisco activity in tomato leaves, these effects were more prominent after morning light supplementation. Furthermore, red and blue light supplementation in the morning pre-activated the key photosynthetic enzymes, promoted the synthesis and accumulation of photosynthetic pigments, increased the photosynthetic capacity of, and photosynthate production in, tomato leaves. These findings suggest that light supplementation in the morning is more effective in promoting the growth and development of tomato plants cultivated in greenhouses.
... In this study, we demonstrated that pretreatment of basil plants by LED lighting sources considerably enhanced proline and soluble sugar levels in both genotypes. Consistent with our current results, previous studies have shown that LED light treatment led to an increase in primary and secondary metabolisms in lettuce (Samuoliene et al. 2011(Samuoliene et al. , 2012Liu et al. 2018;Virsile et al. 2020), wheat (Monostori et al. 2018), sweet pepper (Klein et al. 2018), and lemon balm (Ahmadi et al. 2019). According to our results, increase in proline and soluble sugar levels in LEDexposed plants of two genotypes, especially R-irradiated plants under salinity, suggests the involvement of osmoregulation in basil plants (Fig. 4). ...
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In the present study, we evaluated a pretreatment with four LED light sources (red, blue, red + blue, and white) in two genotypes (green and purple) of basil on the growth parameters, stress oxidative markers, non-enzymatic antioxidants, osmoprotectant compounds, ion content, and polyphenolic profile under both control and salinity stress conditions. The results indicated that 150 mM of NaCl decreased biomass, RWC, and K⁺/Na⁺ ratio but increased the content of proline and antioxidant capacity in the leaves of both genotypes of basil grown under GH (greenhouse) conditions. The results suggested that RB LED-exposed plants in the green genotype and R LED-exposed plants in the purple genotype improved accumulation of shoot biomass, K⁺/Na⁺ ratio, proline and soluble sugars, glutathione and ascorbate, polyphenolic profile, and thioredoxin reductase activity in the leaves of basil under both control and salinity stress conditions. NaCl stress (150 mM) increased oxidative markers, which are responsible for disturbance of routine functions of various plant cellular modules. LED light pretreatments diminished these markers under both control and salinity stress conditions. It could be concluded that intensification of non-enzymatic antioxidant systems during light-mediated priming can diminish the deleterious effects of ROS induced by NaCl stress (150 mM) through preventing the lipid peroxidation, scavenging cytotoxic H2O2, and enhancement of antioxidant potentials. Therefore, usage of LED lighting systems as a pretreatment or to supplement natural photoperiods under both control and salinity stress conditions may be advantageous for increasing biomass and phytochemical accumulation in basil.
... Similar results of lower carotenoids accumulation under increasing light intensity have been found in mustard microgreens as the light intensity increased from 275 to 463 µmol m −2 s −1 [20,25,85]. However, with the role of carotenoids in plant photoprotection under higher photosynthetic photon flux density, its content would be expected to increase under higher photosynthetic photon flux density as evidence from other scientific works has shown [84,86,87]. A plausible hypothesis for these contradictory results related to carotenoid concentrations under various light intensities is suggested by Lefsrud et al. [88]. ...
Article
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Microgreens are edible seedlings of vegetables and flowers species which are currently considered among the five most profitable crops globally. Light-emitting diodes (LEDs) have shown great potential for plant growth, development, and synthesis of health-promoting phytochemicals with a more flexible and feasible spectral manipulation for microgreen production in indoor farms. However, research on LED lighting spectral manipulation specific to microgreen production, has shown high variability in how these edible seedlings behave regarding their light environmental conditions. Hence, developing species-specific LED light recipes for enhancement of growth and valuable functional compounds is fundamental to improve their production system. In this study, various irradiance levels and wavelengths of light spectrum produced by LEDs were investigated for their effect on growth, yield, and nutritional quality in four vegetables (chicory, green mizuna, china rose radish, and alfalfa) and two flowers (french marigold and celosia) of microgreens species. Microgreens were grown in a controlled environment using sole-source light with different photosynthetic photon flux density (110, 220, 340 µmol m−2 s−1) and two different spectra (RB: 65% red, 35% blue; RGB: 47% red, 19% green, 34% blue). At harvest, the lowest level of photosynthetically active photon flux (110 µmol m−2 s−1) reduced growth and decreased the phenolic contents in almost all species. The inclusion of green wavelengths under the highest intensity showed positive effects on phenolic accumulation. Total carotenoid content and antioxidant capacity were in general enhanced by the middle intensity, regardless of spectral combination. Thus, this study indicates that the inclusion of green light at an irradiance level of 340 µmol m−2 s−1 in the RB light environment promotes the growth (dry weight biomass) and the accumulation of bioactive phytochemicals in the majority of the microgreen species tested.
... Li & Kubota, 2009). When additional LED lighting was included in the lighting formula, supplemental green LED light (535 or 505 nm), or blue light (470 or 455 nm) had positive effects on the accumulation of vitamin C and tocopherol in the order 535 > 505 > 455 > 470 nm (Samuoliene et al., 2012). In addition to light quality, exposure to high light intensity resulted in the accumulation of bioactive compounds in lettuce, particularly chlorogenic acid, flavonols, anthocyanins, and vitamin C (Becker, Klaering, Schreiner, et al., 2014;García-Macías et al., 2007;Pérez-López et al., 2018;Shimomura et al., 2020). ...
Article
Lettuce is one of the most commonly consumed leafy vegetables worldwide and is available throughout the entire year. Lettuce is also a significant source of natural phytochemicals. These compounds, including glycosylated flavonoids, phenolic acids, carotenoids, the vitamin B groups, ascorbic acid, tocopherols, and sesquiterpene lactones, are essential nutritional bioactive compounds. This review aims to provide a comprehensive understanding of the composition of health-promoting compounds in different types of lettuce, the potential health benefits of lettuce in reducing the risks of chronic diseases, and the effect of preharvest and postharvest practices on the biosynthesis and accumulation of health-promoting compounds in lettuce.
... So far, no effects of light spectrum ratios on antioxidant capacity have been observed in holy basil. Samuoliene 64,65 reported that R light can improve antioxidant capacity in some lettuce cultivars and sweet basil 30 . Nevertheless, in two lettuce cultivars, flavonoid was enhanced by blue light 66,67 , and a similar experiment by Li and Kubota 25 showed high anthocyanin content induced by B light in red cross leaves. ...
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... The red:blue ratio also affects phenolic compound levels, antioxidant activity, nitrate content, firmness and crispness in some products [38][39][40] . Green light increases phytonutrient concentrations (vitamin C, tocopherol and phenolic compounds) and inhibits anthocyanin biosynthesis 41,42 . ...
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... In humans, they have been shown to reduce arteriosclerotic plaques and inflammation [5], and habitual consumption is associated with decreased mortality due to cardiovascular and cancer [6]. In plants, the phenolic compounds provide pigmentation and defend against pest attacks with a bitter flavor and astringent chemesthetic sensation [7][8][9]. ...
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... Anthocyanin levels and ascorbic acid concentration have been influenced by light quality applied during plant growth. The effect of blue and red radiation in increasing anthocyanin concentration was reported in numerous studies (Li and Kubota, 2009;Samuoliene et al., 2012;Nicole et al., 2016;Thoma et al., 2020). Moreover, a long photoperiod and low light intensity (18 h and 200 PPFD) increased the anthocyanin index in Red Oak and Red Salanova lettuce (Nicole et al., 2016). ...
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... It is possible that other photoreceptors still remain undiscovered. Photoreceptors are used by plants to obtain information about the quantity of light and the duration (periodicity) of irradiation, which consequently influence many metabolic reactions [13][14][15]. A particular plant species might also require spectral composition of light to be selected and adjusted for use in greenhouse production [16,17]. ...
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Major antioxidants and antioxidant activity in eight varieties of tomatoes were determined. Hydrophilic and lipophilic antioxidant activity (HAA and LAA) was determined by the ABTS assay and ascorbic acid and carotenoid contents were determined by HPLC-DAD. The HAA has far more significant impact on total antioxidant activity (83%) as compared with LAA. HAA was increasing during all ripening stages and was strongly correlated with ascorbic acid content (r = 0.83). During the ripening the LAA was increasing till the III. stage of maturity and then decreased. The main carotenoids determined in the red-fruit tomatoes were lycopene, β-carotene and lutein. The content of lycopene has been increasing equally during the ripening. β-Carotene and lutein were intensively synthesized between the I. and II. stage of maturity. Among ascorbic acid, α-tocopherol, lycopene, β-carotene and lutein standards ascorbic acid was determined as the most efficient antioxidant followed by α-tocopherol and β-carotene. Antioxidant activity of ascorbic acid, α-tocopherol, β-carotene and lutein grew equally with increasing concentration, however lycopene was the most effective in its lowest concentration. The analysis of two-component mixtures showed significant synergism between lycopene-lutein, lycopene-β-carotene and α-tocopherol-β-carotene.
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Effects of light and nutritional conditions on the ascorbic acid content in hydroponically grown lettuce of butterhead type (Luctuca sativa L. cv. Edogawa or Okayama) were investigated. With increasing levels of shading, the fresh weight and number of leaves decreased, the shape of leaves became narrower and ascorbic acid and sugars content decreased markedly, while nitrate nitrogen content inclined to increase. Plants grown in 1/4 strength standard nutrient solution were inferior in fresh weight and number of leaves to those grown in 1/2 strength solution. Though ascorbic acid and sugars content was higher for plants grown in 1/4 strength solution at higher light intensities, the effect of nutrient concentration gradually disappeared with increasing shading level.Diurnal changes in leaf constituents were studies on sunny and cloudy days. The contents of ascorbic acid, sugars and chlorophyll were higher in the daytime and lower during the night, while nitrate nitrogen content increased in the night time. These tendencies were more clear on the sunny day than on the cloudy day.The relations between the contents of ascorbic acid, sugars, nitrate nitrrogen etc. were discussed and possible techniques of practical use for improving the quality of hydroponically grown leaf vegetables were also discussed.
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Using UV-A, blue (B), green (G), red (R), and far-red (FR) light-emitting diodes (LEDs), we investigated the effects of different supplemental light qualities on phytochemicals and growth of ‘Red Cross’ baby leaf lettuce (Lactuca sativa L.) grown at a high planting density under white fluorescent lamps as the main light source inside a growth chamber. Photon flux added by supplemental LEDs for UV-A, B, G, R and FR were 18, 130, 130, 130 and 160μmolm−2s−1, respectively. Photosynthetic photon flux (PPF, 400–700nm), photoperiod, and air temperature (day/night) was 300μmolm−2s−1, 16h, and 25°C/20°C in all treatments including white light control. After 12 days of light quality treatment (22 days after germination), phytochemical concentration and growth of lettuce plants were significant affected by light treatments. Anthocyanins concentration increased by 11% and 31% with supplemental UV-A and B, respectively, carotenoids concentration increased by 12% with supplemental B, phenolics concentration increased by 6% with supplemental R while supplemental FR decreased anthocyanins, carotenoids and chlorophyll concentration by 40%, 11% and 14%, respectively, compared to those in the white light control. The fresh weight, dry weight, stem length, leaf length and leaf width significantly increased by 28%, 15%, 14%, 44% and 15%, respectively, with supplemental FR light compare to white light, presumably due to enhanced light interception by enlarged leaf area under supplemental FR light. Although the mechanisms of changes in phytochemicals under different supplemental light quality are not well known, the results demonstrated that supplemental light quality could be strategically used to enhance nutritional value and growth of baby leaf lettuce grown under white light.
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The aim of this work was to test 13 edible seeds for the levels of phenolic compounds and the antioxidant activity (TAC) at different germination states (dormant, imbibed and 7d sprouts). Selected seeds included mungbean, alfalfa, fava, fenugreek, mustard, wheat, broccoli, sunflower, soybean, radish, kale, lentil and onion. Accumulated phenolics (mg chlorogenic acid equivalent, CAE) and TAC (μg Trolox equivalent) on dry basis (DB) showed the general trend distribution of 7d sprouts>dormant seeds>imbibed seeds. In addition, the specific TAC (μg Trolox mg−1 CAE) increased only for imbibed seeds indicating a possible protection effect of the phenolic antioxidants to the emerging sprouts. Phenolic contents of 7d sprouts (DB) ranged from 490 (lentil) to 5676 (mustard)mg CAE 100g−1. Seven day sunflower sprouts had higher TAC on a DB (40202μgTroloxg−1) compared to other seeds (1456–25991) and a blueberry reference (35232). Increases in phenolics (DB) from dormant seed to 7d sprout differ among seeds, ranging from 2010% (mungbean) to −11% (kale), while increases in TAC (DB) ranged from 1928% (mungbean) to 0% (lentil). This study shows that germinated edible seeds are an excellent source of dietary phenolic antioxidants.
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Blue light has been suggested to participate in the acclimation of photosynthesis to growth irradiance. We analyzed the effects of blue light intensity on the photosynthetic properties of leaves with regard to acclimation to irradiance. Spinach (Spinacia oleracea L.) plants were grown under mixtures of blue and red light with blue-light photon flux densities (PFDs) of 0, 30, 100 and 150 µmol m−2 s−1 at a total photosynthetic PFD of 300 µmol m−2 s−1. The light-saturated rate of photosynthesis under white light, leaf N content per unit leaf area, leaf dry weight per unit leaf area and the ratio of cytochrome (Cyt) f content to light-harvesting chlorophyll-binding protein of photosystem II (LHCII) content were evaluated. The photosynthetic rate tended to increase with increasing blue-light PFD up to 100 µmol m−2 s−1, and this was associated with an increase in leaf N content per unit leaf area. However, the increase in leaf N content per unit leaf area did not necessarily result from an increase in leaf dry weight per unit leaf area. The Cyt f to LHCII content ratio increased linearly with increasing blue-light PFD up to 100 µmol m−2 s−1, indicating that plants grown under higher blue-light PFD up to this value resembled plants grown under higher irradiance in terms of N partitioning between electron-transport components and light-harvesting components. This result suggests that the level of blue light is involved only in the acclimation to relatively low growth irradiances at the chloroplast level.
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Lettuce is a popular leafy vegetable and plays an important role in American diet and nutrition. Crisphead lettuce has much lower nutrient content than leaf and romaine types. As the synthesis or absorption of many nutrients is light dependent, the lower nutritional value of crisphead lettuce is due to the enclosure of its leaves in a head structure. In addition to varietal differences, nutritional quality of lettuce may be influenced by environmental factors such as light, temperature, growing season, cultural practices, fertilizer application, and storage conditions. The moisture content of the plant also affects nutrient concentration. Enhancing the nutritional levels of vegetables would improve the nutrient intake without requiring an increase in consumption. Genotypic variation in germplasm suggests that genetic improvement of nutritional value is feasible in lettuce. However, breeding efforts for nutrition are often hampered by the lack of analytical capabilities in most crop improvement programs. Biotechnology has the potential to markedly increase the nutritional value of lettuce. The commercialization of transgenic lettuce may largely depend on progress in transgene expression, public acceptance, economic and marketing challenges, intellectual property issues, and risk assessment.
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Influence of light-emitting diode (LED) light on antioxidant activity of radiated pea seedlings was first studied using red (625–630 nm) and blue (465–470 nm) LED lights as light sources in an attempt to determine and compare the changes in chlorophyll and β-carotene contents, and Trolox equivalent antioxidant capacity (TEAC, μM). After radiation for 96 h, comparing to white light group, red light radiated seedlings displayed significant (p < 0.05) increases in stem length and leaf area, while blue light radiation significantly (p < 0.05) increased the stem length and seedling weight. Chlorophyll in leaves increased rapidly when seedlings were radiated by blue light but no significant (p > 0.05) difference was observed among light radiated seedlings after 96-h cultivation. β-Carotene content of LED radiated leaves was significantly (p < 0.05) higher in red light (54.47 ± 2.35 μg/g) group than in the others. TEAC value of ethanol and acetone extracts (50 mg/mL) of 240 pieces of red light radiated seedlings cultured for 96 h reached 106.48 and 81.68 μM, respectively, were higher than the other treatments. In conclusion, the contribution of red light to significant β-carotene expression and antioxidant activity for nutrition and health benefits and blue light to seedling weight and chlorophyll induction of radiated pea seedlings are emphasized.
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Whole grain products are recommended for healthy diets as being recognized sources of dietary fiber and antioxidant substances. In the present study, four cereals including barley, pearl millet, rye and sorghum which are adapted to the growing conditions in the United Arab Emirates were evaluated in terms of their composition of dietary fiber, resistant starch, minerals and total phenols and antioxidant properties. Antioxidant activity was evaluated on the basis of scavenging capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and 2,2′-azino-di-[3-ethylbenzthiazoline sulphonate] (ABTS+ radical cations). The adapted grains exhibited better nutritional quality compared to commercial hard and soft wheat flours, the main ingredients in grain-based food products. They were significantly rich in resistant starch, soluble and insoluble dietary fibers, minerals and antioxidants. Barley had the highest levels of phosphorus, calcium, potassium, magnesium, sodium, copper, and zinc, and the second highest content of iron following millet. Sorghum was exceptionally high in antioxidant activities followed by millet and barley. The antioxidant properties of the three grains were comparable to butylated hydroxytoluene. The nutritional data suggest that the selected grains, particularly barley and sorghum, hold promise as healthy food ingredients.
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A new simple and sensitive analytical spectrophotometric method is developed for the determination of ascorbic acid reduces methyl viologen to form a stable blue coloured free radical ion. This method has a sensitivity and lower limit detection of 0.1mugml(-1) of ascorbic acid (0.1ppm) which is comparable to the flow injection analysis reported earlier. Beer's law is obeyed over the concentration range of 1.0-10mugml(-1) of ascorbic acid per 10ml of the final solution (0.1-1.0mugml(-1)) at 600nm. The molar absorptivity and Sandell's sensitivity were found to be 1.5x10(5)+/-100lmol(-1)cm(-1) and 0.001mugcm(-2), respectively. The method has been applied to the determination of ascorbic acid in food, pharmaceuticals and biological samples.