Blue Fluorescent Lamps Research Articles

Features of pubertas of young egg chickens when grown under monochromatic and white lighting

The work was carried out in the Amur region at the Belogorsk poultry farm. In the period from 2015 to 2019, five experiments were carried out taking into account the seasonality. The aim of the study was to identify the influence of the spectral composition of light sources on the pubertation of replacement young egg chickens at the age of 15 weeks: the development of the pineal gland, pituitary gland and genital organs of the youngs. The study on replacement young egg crosses of Hisex White and Decalb White chickens was carried out. In the breeding workshop, four groups of day-old chickens were formed, 200 heads each. From one day of age to 15 weeks, young birds were kept under light of different colors in conditions of gradually decreasing daylight hours from 24 to 12 hours a day and an illumination level from 50-30 to 7-6 lux. White, yellow, green and blue compact fluorescent lamps were used as light sources. In young birds at the age of 30, 60 and 90 days, the live weight was determined by weighing 100 heads from each group. A 15-week-old bird was bled for β-estradiol content at a random selection of 30 birds from each group. For anatomical examination, 5 pullets from each group were sacrificed at the age of 15 weeks, taking into account the body weight required by the norm. The absolute mass of the pineal gland, pituitary gland, ovary, oviduct was determined in the bird, the length of the oviduct was measured. Regardless of the season of the year, the live weight of 90-day-old young in groups under white and yellow illumination had the upper values of the norm, with green and blue it could be at its lower border. Under white and yellow illumination, pullets at 15 weeks of age have higher serum β-estradiol levels. At anatomical examination in 15-week-old chickens under white and yellow lamps, the absolute mass of the pineal gland is less by 10.5 - 41.7% than under green and blue ones, and the mass of the pituitary gland, on the contrary, is more by 4.8 - 8.3%. Pullets with different color illumination did not have significant differences in the mass of the ovary and oviduct, as well as the length of the oviduct, the level of development of which corresponded to a given age. Under white and yellow lighting, the first signs of the onset of puberty at 15 weeks of age are slightly more pronounced than under green and blue light sources.

Diodos emissores de luz (LEDS) no cultivo in vitro de Eugenia involucrata

Esse trabalho objetivou avaliar o efeito do tipo de luz no cultivo in vitro de Eugenia involucrata. Os tratamentos consistiram do cultivo sob diodos emissores de luz (LEDs) de cor vermelho, azul, verde ou branco e lâmpadas fluorescentes. Nos cultivos sob LEDs branco e azul foram observadas as maiores médias de estabelecimento; sob o azul e lâmpadas fluorescentes, o maior número de folhas; sob o azul, o maior número de brotos; sob o branco, menor contaminação bacteriana; e sob o verde os piores resultados. LEDs azul, vermelho, branco e lâmpadas fluorescentes influenciam favoravelmente a propagação in vitro de E. involucrata.

The effects of light sources and packaging types on the storage stability of fresh lean and chuck beef meat during refrigerated storage

The fresh beef samples, which are vacuum packaged, wrapped with low-density polyethylene film, and unpackaged, were stored under different light sources which were red and blue light-emitting diode (LED) light, fluorescent and incandescent lamp at 4°C for 7 days. Changes in pH, color parameters, lipid oxidation as expressed by thiobarbituric acid reactive substances (TBARS) and microbiological properties of beef were determined during the storage period. The TBARS analysis for all treatments indicated that lipid oxidation levels gradually increased during storage (p < .05). However, the rate of increase in the TBARS level of samples under LED lights is much more than other groups (p < .05). The effect of the light source on the color values of the meat varies depending on the fat and moisture content of the meat (p < .05). The use of different light sources had no significant effects on the count of total mesophilic aerobic bacteria, coliform bacteria, mold, and yeast. It suggests that the use of blue LED light in storage equipment for vacuum packaged and wrapped meat may increase the shelf-life of meat. Practical applications The color of meat and meat products is an indicator of freshness for the consumer during meat shopping. The lighting system and packaging method affect the visual appearance and color of the fresh meat. The most commonly used light sources in the fresh meat storage system are incandescent, fluorescent, and light-emitting diode lamps. Meat is generally stored as wrapped with low-density polyethylene film, vacuum packaged, and unpackaged. This study provides detailed results about the effects of the beef type, light source, storage time, packaging form, and their interactions on oxidation stability, color properties, and microbiological properties. The results indicated that the lighting system would provide higher chemical and microbiological stability if a suitable packing form is preferred.

EFFECT OF PHOTOTHERAPY ON SERUM CALCIUM LEVELS IN NEONATAL JAUNDICE IN FULL TERM NEONATES

Introduction: The most prevalent anomalous physical finding during the first week of life is neonatal hyperbilirubinemia (NNH). It is estimated that more than two thirds of newborn babies have acquired clinical jaundice. It was also discovered that in the unconjugated hyperbilirubinemia of most neonates represents a common or exaggerated physiological syndrome. The physical immaturity of infants to handle increased production of bilirubin is referred to as Jaundice. This becomes potentially neurotoxic if severe unconjugated hyperbilirubinemia is left untreated. One of the routine strategies for treating hyperbilirubinemia is known as phototherapy. However it is not a harmless interference. This can produce negative results, such as dehydration, temperature volatility, blood flow redistribution, genotoxicity, rashes on the skin, loose skin, stools, damage to retinas, hypocalcemia and bronze baby syndrome. One of the lesser known but which has a potential adverse effect of phototherapy is hypocalcemia. A total serum calcium concentration of &lt; 7 mg / dl or ionised calcium concentration &lt; 4mg / dl (&lt; 1mol / L) is classified as neonatal hypocalcemia. Hypocalcemia increases the permeability of cells to sodium ions and increases the excitability of cell membranes.&#x0D; Material &amp; Methods: 60 full term neonates were included in present cross sectional study who was admitted to Neonatal Intensive Care Unit (NICU). Full term neonates who completed 37 weeks of gestation with unconjugated hyperbilirubinemia who require phototherapy. Under the normal protocol, traditional phototherapy equipment containing four blue light fluorescent lamps with wavelengths of 410-470 nm was mounted at a distance of 25-35 cm from the skin surface of neonates with entirely covered eyes and genitals. At 15μW / cm2 /nm at the level of the infant's skin, the irradiance during phototherapy was assessed and maintained consistently.&#x0D; Results: Among 60 neonates included in this study there were 27 (45%) male whereas 33 (55%) female neonates. In present study the mean levels of serum calcium before phototherapy was 9.21 with standard deviation of 0.83 while the serum calcium levels after phototherapy were 8.36 with standard deviation of 0.78. There was a statistically significant difference between serum mean calcium levels before and after phototherapy (p=0.001).&#x0D; Conclusion: A major issue is phototherapy induced hypocalcemia. Before beginning and during phototherapy for neonatal jaundice and close monitoring of neonates for signs of hypocalcemia, careful calcium status calculation should be carried out.. After phototherapy, there is a substantial reduction in the amount of serum calcium, but the risk of hypocalcemia in stable full-term neonates is minimal.

Making Locally Fabricated Phototherapy Devices Work Better.

The efficiency of a phototherapy (PT) device is a function of the irradiance delivered by the device at the surface of the skin. Because cost limits the ability of health care facilities in low- and middle-income countries to procure commercial PT devices, efforts have gone into local fabrication of devices for use in health care facilities in Nigeria. Evaluation of such fabricated devices is yet to be conducted. To identify and document essential features of locally fabricated phototherapy (FPT) devices in use in Nigeria. A cross sectional survey of locally FPT devices available in health facilities providing newborn health care services was conducted as part of evaluating neonatal jaundice management services in Kaduna State. Each FPT was characterized with respect to mobility/portability, adjustability, lamp type, number and color of lamps used. The irradiance of each device was measured using Model 22 Olympic BiliMeter™ at the facility's traditional PT distance and also at a distance at which optimum irradiance is delivered by the device. A total of 54 PT devices were in use. Thirty-two (59.3%) of these devices were locally fabricated while others were obtained from commercial sources. Of the fabricated devices 22/32 (68.8%) were non-adjustable while the remaining 10 devices were adjustable but with limited adjustability. Only 5/32 (15.6%) of the FPT devices used special blue fluorescent lamps. The majority, 68.8% (22/32) of the FPT devices used ordinary low-intensity blue lamps while the remaining 5/32 (15.6%) devices used white light fluorescent lamps. None of the devices used light emitting diodes as a PT light source. Only three fabricated devices offered irradiance (9.4, 13.6 and 33 µW/cm2/nm) at the facilities' traditional distances for PT. FPT devices in use in Kaduna, functioned sub-optimally because of technically inadequate designs. The devices will need to be designed to especially enable adjustability to vary distance between device and patient's skin and the use of lamps which offer high irradiance.

Ứng dụng đèn led trong vi nhân giống cây gừng (Zingiber officinale Rosc.)

Currently, fluorescent lamps are often used as lighting systems in the tissue culture. These lamps consumed a lot of power. Recently, the use of LED lamp systems for planting was being noticed because LEDs were more conducive to tissue culture and less power consumption. In this study, the effects of mineral content, sugar concentration and monochromatic light on ginger’s growth were investigated. The results showed that ginger plant cultured in SH medium (Schenk and Hildebrandt, 1972) had higher height and diameter than in other media. The experiment using different sugar concentration, explants get the best growth when they were cultured in medium supplemented with 30 g/l sucrose. The next experiment, explants were placed in different types of light sources including, red LED, blue LED, or combination of red with blue light in 9: 1; 8: 2; 7: 3; 6: 4; 5: 5 ratios, fluorescent lamps, red fluorescent lamps, blue fluorescent lamps. The results showed that the red LED was suitable for the growth of ginger. The plant height (4.55 cm), leaf area (2.66 mm2) and root diameter (3.83 mm) was significantly higher than that of the other treatments. In the nursery, plants under cultivation of red LED were good growth and a survival plantlet ratio obtained over 96%.

In vitro proliferation and ex vitro rooting of microshoots of commercially important rabbiteye blueberry (Vaccinium ashei Reade) using spectral lights

Efficient protocols for in vitro shoot growth and ex vitro root formation from in vitro-derived shoots under light-emitting diodes (LEDs) with simple ventilation were developed for rabbiteye blueberry cv. ‘Titan’. Red LEDs promoted shoot elongation while blue LEDs induced short shoots with enhanced accumulation of leaf chlorophyll contents. A combined treatment of 80% red with 20% blue LEDs was found the most suitable for plant growth, and more effective than 50% red mixed with 50% blue LEDs or fluorescent lamps as the control treatment. The use of ventilated vessels with ambient CO2 enrichment from a growth chamber resulted in healthy plants having greatly improved shoot length, leaf expansion, leaf chlorophyll contents and dry weight of both shoots and roots. In vitro-cultured shoots could be directly rooted at 100% under non-sterile conditions using a perlite-peat mixture with careful controls of high humidity. These results suggest that LEDs, particularly when coupled with ventilated vessels, should be used as a primary light source for replacing conventional fluorescent tubes in large-scale production of rabbiteye blueberries.

The effect of head covering in prevention of phototherapy-induced hypocalcemia in icterus newborns with gestational age less than 35 weeks.

Background:Hypocalcemia is one of the complications of phototherapy resulted from influence of phototherapy in melatonin secretion reducing corticosterone and ultimately increasing bone uptake. In this study, effect of head covering in prevention of this common and serious complication is studied.Materials and Methods:This prospective, randomized clinical trial study conducted on premature infants with gestational age <35 weeks with jaundice. Infants were divided into two groups (n = 43). The first group (intervention group) and the second group (control group) while on the cut, underwent phototherapy using four blue fluorescent lamps in distance of 35 cm. Eyes and genitalia were protected using appropriate clothing. In the first group, head was covered using cloth helmet with a suitable size. For both groups, serum calcium was measured before and 36 h after starting phototherapy.Results:Mean serum calcium before phototherapy in both intervention and control groups was 8.72 ± 1.12 and 8.79 ± 0.87 mg/dL, respectively, and the difference between groups was not significant (P = 0.76). After treatment, calcium level in both intervention and control groups was 8.9 ± 0.82 and 8.43 ± 0.91, respectively, and the difference between the two groups was significant (P = 0.015). Mean serum calcium levels after phototherapy in the intervention group was −0.17 ± 1.46 (increase) and it was 0.35 ± 0.71 (decrease) in the control group. According to t-test, the difference between the two groups was significant (P = 0.036).Conclusion:Head covering during phototherapy probably prevents from hypocalcemia.

ハボタンの白色蛍光灯照射下の栽培における昼温，夜温および昼夜温差が着色に及ぼす影響

ハボタンの紅色品種‘ウインターチェリー’および白色品種‘晴姿’を用い，着色に昼温，夜温および昼夜温差が及ぼす影響を，白色蛍光灯照射下で調査した．夜温の影響について調査した実験では，着色は，処理開始20日後までに，両品種とも，20／5°C（昼温／夜温）区および20／10°C区で認められ，20／15°C区では認められなかった．昼温の影響を調査した実験では，着色は，処理開始20日後までに，両品種とも，15／5°C区および20／5°C区で認められ，25／5°C区では認められなかった．昼夜温差を同一条件とした実験では，着色は，処理開始20日後までに，両品種とも，15／0°C区および20／5°C区で認められ，25／10°C区で認められなかった．すべての実験において，処理開始20日後における着色面積率は，20／5°C区が最も高かった．以上のことから，ハボタン‘ウインターチェリー’および‘晴姿’の着色を促す温度条件は，昼温20°C以下，夜温10°C以下であり，さらに，昼温20°C，夜温5°Cが最適であると考えられた．また，着色は，昼温が25°Cの高温であれば，夜温が10°C以下と低くても認められず，着色を促すには，昼温が夜温および昼夜温差よりも強く影響することが明らかとなった．

Performance of continuous stirred-tank reactors connected in series as a photocatalytic reactor system

Film-diffusion resistance significantly reduces the decomposition of organic compounds over an immobilized photocatalyst in the vicinity. To overcome this problem, the performance of a photocatalytic system consisting of five continuous stirred-tank reactors (CSTRs) in series was investigated. Each reactor was a square-shaped container with a glass plate immobilized with a film of TiO2 photocatalyst at the bottom. Two 4-W blacklight blue-fluorescent lamps fixed above the container provided UV light. A 10-ppm aqueous solution of 2,4-dinitrophenol (DNP) supplied continuously to the reactor was stirred by an impellor fixed to a shaft with a wind propeller at its upper end. The change in the DNP concentration in each reactor with increasing flow rate agreed with the result calculated by a mathematical model, constructed for the photocatalytic system, which included a mass-transfer coefficient expressed in terms of rotational speed. Hence, this model was used to simulate the performance of the reactor system. At sufficiently high rotational speeds, the conversion of DNP at the exit of the fifth CSTR was substantially higher than that at the exit of a single CSTR with the same liquid volume, and was close to the calculated value for a plug-flow reactor without film-diffusion resistance. At low rotational speeds, however, the DNP concentration remained remarkably high because of large film-diffusion resistance, demonstrating that the photocatalytic reaction requires sufficient liquid mixing to enhance the reaction rate. Thus, the system of five CSTRs in series is effective as a photocatalytic reactor system.

미세조류 4종(Chlorella vulgaris, Nitzschia sp., Phaeodactylum tricornutum, Skeletonema sp.)의 성장에 미치는 발광다이오드 단일파장의 영향

We investigated the effect of monochromatic light emitting diode (LED) on the growth of diatoms Nitzschia sp., Phaeodactylum tricornutum, Skeletonema sp. and green algae Chlorella vulgaris. The four microalgae species were cultured under blue LED (450 nm), yellow LED (590 nm), red LED (650 nm) and fluorescent lamp (mixed wavelengths). The maximum growth rates and cell densities of Nitzschia sp., P. tricornutum and Skeletonema sp. were highest under blue LED, followed by fluorescent lamp, red LED and then yellow LED, however those of C. vulgaris were highest under red LED. This result indicates that blue LED is favorable for the growth of diatoms. Thus, the growth of microalgae under monochromatic light might be species-specific or taxon-specific. Also, these results could be used as an important information in future for remediation of heavy metal contamination in the sediments using LED and microalgae.

The effect of hematocrit on the efficacy of phototherapy for neonatal jaundice

The therapeutic phototherapy action spectrum ranges from 420 to 500 nm. However, a recent report of improved efficacy of fluorescent "turquoise" light (~490 nm) as compared with blue light (~450 nm) underscores the need to define an optimal action spectrum for precision-targeted phototherapy using very narrow wavelength ranges. We used a current semi-empirical model of the optical properties of skin for robust calculations of the fraction of light absorbed by bilirubin at various wavelengths that could be confounded by hemoglobin (Hb), melanin, and skin thickness. Applying assumptions regarding the wavelength dependence of bilirubin photochemistry, "action spectra" were assembled from the calculated values. All the calculated action spectra displayed a peak between 472 and 480 nm (most at 476 nm), which is a significant shift from the well-reported 460 nm absorption peak of bilirubin. Of note, the relative amplitudes of the action spectra showed an inverse relationship with hematocrit (Hct). We speculate that a narrow range of light at 476 nm would be 60% more effective than blue (broadband) fluorescent lamps. Because Hb serves as a major competitor of bilirubin for light absorption, the calculations also predict that the efficacy of phototherapy is dependent on the Hct. A high Hct could reduce therapeutic efficiency.

Use of Red and Blue Light-Emitting Diodes (LED) and Fluorescent Lamps to Grow Microalgae in a Photobioreactor

High oil content microalgae are a source for biofuel production. They can be produced in open ponds or closed photobioreactors. To efficiently grow such microalgae, illumination for photosynthesis, CO2 consumption, and the pH and nutrient content of the growth medium must be monitored and precisely controlled. In a closed photobioreactor, illumination is the most critical parameter because it is the most expensive factor of algae production and must be operated 24 h per day. In this research, Chlorella kessleri (UTEX 398) microalgae were grown in photobioreactors. All parameters were identical, except the source and intensity of the illumination. The light sources included red light-emitting diodes (LED), blue LED, and fluorescent lights. Growth of the microalgae was observed for seven days and the effects of the three illumination sources on cell count, cell weight, and cell size were determined. In the first experiment, in which the current of all three light sources was the same, red LED produced the highest number of cells with the highest weight while blue LED light produced the largest cells. In the second experiment, in which the light intensity was the same for all three light sources, the highest weight was again achieved with the red LED. Thus, we suggest that most advantageous production system may be to use a red light initially to produce the desired cell concentration, then switch to a blue light to increase cell size.

Performance of TiO 2 photocatalyst supported on silica beads for purification of wastewater after absorption of reflow exhaust gas

The photocatalytic treatment of wastewater containing organic compounds in the exhaust gas from a reflow furnace is studied in a laboratory-scale batch recirculation type reactor system with a packed column of TiO 2/SiO 2 beads (TiO 2 supported on SiO 2 beads). A comparison is made between the photocatalytic activities of the TiO 2/SiO 2 beads under irradiations with UV light emitted from 6 W blacklight blue fluorescent lamps (BL) and germicidal lamps (GL). When the wastewater is treated over 24 h, the conversions on the TOC concentration base are 73 and 90% with UV irradiations from BL and GL, respectively, indicating that GL is more useful for the present photocatalytic treatment. Quantitative and qualitative analyses of the treated wastewater by GC/MS reveal that the photocatalytic reactor system can satisfactorily decompose not only aromatic but also aliphatic compounds into harmless substances (CO 2, H 2O and other mineral ions). Although several intermediates are present in the treated wastewater, their concentrations are very low. The TiO 2/SiO 2 photocatalyst can retain more than 80% of the original activity even after repeated use of three times.

Modelling of an annular photocatalytic reactor

This work deals with the photocatalytic oxidation of toluene at room temperature and atmospheric pressure in the gas phase. The differential equations of the reactor model are solved numerically with simultaneous estimation of the model parameters. Estimation of the kinetic data is performed using a modified differential method of data analysis and a Nelder–Mead method of nonlinear optimization for parameter estimation. The reaction is performed in an annular photoreactor using UVA black light blue fluorescent lamp. The experiments are carried out at different total flow rates of the reaction feed (20–160 cm3 min−1), two different inlet concentrations of toluene (2.67 and 5.24 g m−3) and at constant relative humidity (25%). A good agreement between the experimental data and theoretical predictions is obtained, supporting the applicability of the proposed models to describe the investigated process performed in laboratory annular photoreactor.

Visible-light-induced oxidative removal of nitrogen oxides in air by metal chloride-modified titanium (IV) oxide nanoparticles

Various metal chloride-modified titanium(IV) oxide (TiO2) (MCMT) samples were prepared by loading metal chloride on commercial TiO2 nanoparticles (Ishihara ST-01) having a large specific surface area and used for photoinduced oxidative removal of nitrogen oxides (NO x ) in air under irradiation of visible light and/or ultraviolet (UV) light. The NO x removal activity of MCMT samples under photoirradiation from a blue fluorescent lamp (BFL) with a UV cut filter decreased in the following order: RhCl3/ST-01>H2PtCl6/ST-01>RuCl3/ST-01>ST-01>IrCl4/ST-01>HAuCl4/ST-01, indicating that RhCl3. H2PtCl6 and RuCl3 fixed on TiO2 effectively worked as photosensitizers for NO x removal. NO x was almost quantitatively fixed as nitrate on RhCl3/ST-01 photoirradiated with BFL or blue light-emitting diodes. Under irradiation of both visible light and UV light from a white fluorescent lamp, RhCl3/ST-01 exhibited a higher level of removal of NO x and a much lower level of release of nitrogen dioxide than did bare ST-01, indicating that RhCl3/ST-01 effectively utilized both visible light and UV light and that two types of reaction (photosensitization by fixed RhCl3 and photocatalysis by TiO2) occurred over RhCl3/ST-01.

First Report of Fusarium langsethiae on Durum Wheat Kernels in Italy.

Durum wheat (Triticum durum Desf.) is one of the most widely grown crops in Italy, extending to approximately 1.5 million ha. Seedborne fungi, affecting both germination and commercial quality of the product, represent a threat to wheat production. Several Fusarium species produce mycotoxins, secondary metabolites harmful to humans and animals. In 2006, monitoring the health status of durum wheat kernels from central (Pollenza, MC) and southern Italy (Foggia; Gravina di Puglia, BA; Enna) was conducted. Kernels at the 11.3 Feeke's scale growth stage were analyzed with the deep freezing blotter test (1). Ten isolates morphologically similar to Fusarium poae were observed. For identification, monosporic isolates were transferred onto potato dextrose agar (PDA) and carnation leaf agar (CLA) to grow at 23°C with exposure to 12-h alternate cycles of darkness and near-UV light (Philips TLD 18W/08 Blacklight Blue Fluorescent Lamp, peak 360 nm). The shape and dimension of microconidia were similar to those of F. poae. The average radial daily growth rate (4.7 ± 1.0 mm day-1) of seven isolates at 23°C was significantly different (P < 0.05) from those of F. poae (8.8 ± 0.2 mm day-1) and F. sporotrichioides (9.4 ± 0.3 mm day-1). In addition to a slower growth rate, these isolates differed from F. poae because of a powdery appearance on PDA, the presence of polyphialides, the absence of macroconidia, and the lack of the peach-like odor. On the basis of the characters observed, the fungus was identified as F. langsethiae, a species recently described from several grains, including wheat (2). To confirm the diagnosis, the internal transcribed spacer (ITS) region of four isolates (ISPaVe ER-1399, ER-1400, ER-1401, and ER-1402) was amplified using universal primers ITS4 and ITS5 (3). The 546-bp product obtained was directly sequenced at the GenLab, Enea, Rome. A homology search using the BLASTn algorithm of all obtained sequences showed 100% identity with GenBank sequence AY680864, corresponding to F. langsethiae. One of these sequences (ISPaVe ER-1400) was deposited in GenBank with Accession No. EF526078. The DNAs of four isolates of F. langsethiae and one each of F. poae and F. sporotrichioides were amplified with the F. langsethiae-specific primers FlangF3 and LanspoR1 (4). The PCR conditions consisted of the initial denaturation at 94°C for 2 min, 35 cycles each of 30 sec at 94°C, 30 sec at 58°C, 1 min at 72°C, and a final extension at 72°C for 7 min. No amplification was obtained from F. poae and F. sporotrichioides, while a PCR product of the expected size (310 bp) was obtained from all F. langsethiae isolates, confirming their specific identification. To our knowledge, this is the first report of F. langsethiae on durum wheat in Italy. This species is known to produce the T2 and HT2 toxins, type A trichotecenes related to alimentary toxic aleukia in humans and haematotoxicity and immunotoxiciticy in animals. A large-scale monitoring of this fungus on durum wheat in Italy is in progress.

Effect of Light Quality on Growth and Vegetable Quality in Leaf Lettuce, Spinach and Komatsuna

The effects of light quality on biomass and internal quality of leaf lettuce, spinach and komatsuna were examined. The plants were grown hydroponically in an environmentally controlled room with a 12-h light period and under a light/dark temperature of 20±1°C/18±1°C and a photosynthetic photon flux density (PPFD) of 300 μmol m-2 s-1 under four light quality treatments, i.e., red light from red fluorescent lamps (R) or blue light from blue fluorescent lamps (B) or a mixture of R and B (RB) or white light from white fluorescent lamps (W). The irradiation of R compared with W increased shoot dry weight in komatsuna and decreased the nitrate content in spinach. Irradiation of B or RB compared with W increased the L-ascorbic acid content in leaf lettuce and komatsuna and decreased the nitrate content in leaf lettuce. Irradiation of B was not suitable for the spinach cultivation due to an extremely decreased shoot dry weight although the carotenoid content was slightly increased. Our data show that controlling light quality is useful to achieve higher productivity or higher nutritional quality of the commercial crops even under limited light intensity in controlled-environment agricultural facilities although the effective light quality treatment differs depending on the plant species.

Melatonin in Glycyrrhiza uralensis: response of plant roots to spectral quality of light and UV‐B radiation

Melatonin (N-acetyl-5-methoxytryptamine) is known to be synthesized and secreted by the pineal gland in vertebrates. Evidence for the occurrence of melatonin in the roots of Glycyrrhiza uralensis plants and the response of this plant to the spectral quality of light including red, blue and white light (control) and UV-B radiation (280-315 nm) for the synthesis of melatonin were investigated. Melatonin was extracted and quantified in seed, root, leaf and stem tissues and results revealed that the root tissues contained the highest concentration of melatonin; melatonin concentrations also increased with plant development. After 3 months of growth under red, blue and white fluorescent lamps, the melatonin concentrations were highest in red light exposed plants and varied depending on the wavelength of light spectrum in the following order red >> blue > or = white light. Interestingly, in a more mature plant (6 months) melatonin concentration was increased considerably; the increments in concentration were X4, X5 and X3 in 6-month-old red, blue and white light exposed (control) plants, respectively. The difference in melatonin concentrations between blue and white light exposed (control) plants was not significant. The concentration of melatonin quantified in the root tissues was highest in the plants exposed to high intensity UV-B radiation for 3 days followed by low intensity UV-B radiation for 15 days. The reduction of melatonin under longer periods of UV-B exposure indicates that melatonin synthesis may be related to the integrated (intensity and duration) value of UV-B irradiation. Melatonin in G. uralensis plant is presumably for protection against oxidative damage caused as a response to UV irradiation.

Light quality of continuous illuminating at night to induce floral initiation of Fragaria chiloensis L. CHI-24-1

A wild strawberry strain, Fragaria chiloensis CHI-24-1, produced inflorescences from both parent and asexually propagated daughter plants linked with runners when grown at 23 °C/20 °C (day/night) under a 24 h day-length (DL) of daylight plus nightly lighting by an incandescent lamp, but not under 8 or 16 h DLs. In the present study, the effect of light quality for continuous illuminating at night on floral initiation of CHI-24-1 plants grown under a 24 h DL was examined. The CHI-24-1 plants were grown under a 24 h DL consisting of natural daylight and continuous lighting at night by an incandescent, a blue fluorescent, a red fluorescent or a far-red fluorescent lamp for 40 days in summer and autumn. Also, the CHI-24-1 plants were grown for 40 days in a growth chamber at 25 °C/20 °C (day/night) with natural daylight and continuous lighting at night by red- and four types of far-red light-emitting-diodes (LEDs with peak wavelengths of 660, 700, 735, 780 and 830 nm). In both experiments, floral initiation of the parent and daughter plants was observed under a stereomicroscope. Although more than 50% of the parent and daughter plants initiated flower buds under the incandescent and far-red fluorescent lamps, about 15% and 0% of those initiated flower buds under blue and red fluorescent lamps, respectively. Floral initiation of the parent and daughter plants occurred under the far-red LED light source whose peak wavelength was 735 nm, but not under the red or the other far-red LEDs. From these results, it can be concluded that the effective light wavelength range of nightly continuous illuminating for floral induction in the CHI-24-1 plants is 735 nm in the far-red light region. Hence, the induction of floral initiation by nightly continuous far-red light (735 nm) appeared to be a response mediated by phytochrome.