• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.312-318
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• 2020

BACKGROUND: Photoreversibility, a reversion of the inductive effect of a brief red light pulse by a subsequent far red light pulse, is a property of photo responses regulated by the plant photoreceptor phytochrome B. Plants use photoreceptors to sense photo signal and to adapt and modify their morphological and physiological properties. Phytochrome recognizes red light and far red light and plays an important role in regulating plant growth and development. METHODS AND RESULTS: The reversal responses of growth and fruiting characteristics were investigated to increase the yield of oriental melon (Cucumis Melo L. var. Kumsargakieuncheon) by means of controlling light quality in a plastic house. Red (R:660nm) and far red (FR:730nm) lights were subsequently irradiated on the whole stems and leaves of the oriental melon plant during growing periods, using red and far red LEDs as light sources, from 9:00 PM daily for 15 minutes. The intensities of R and FR light were 0.322-0.430 μmol m-2s-1 and 0.250-0.366 μmol m-2s-1, respectively. Compared to R light irradiation, combination of R and FR light irradiation increased the length of internode, number of axillary stems, number of female flowers, and fruit number of oriental melons. The results of treatment with R were similar to R-FR-R light irradiation in terms of length of internode, number of axillary stems, number of female flowers, and number of fruits. When FR treatment was considered, R-FR and R-FR-R-FR light irradiation had similarities in responses. These reversal responses revealed that oriental melon showed a photoreversibility of growth characteristics, flowering, and fruiting. CONCLUSION: These results suggested the possibility of phytochrome regulation of female flower formation and fruiting in oriental melon. The fruit weight of the oriental melon was the heaviest with the R light irradiation, while the number of fruits was the highest with the FR light. With the FR light irradiation, the fruit weight was not significantly higher compared to that of the control. Meanwhile, the yield of oriental melon fruits increased by 28-36% according to the intensities of the FR light due to the increases of the number of fruits.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.4
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• pp.292-296
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• 2002

Soybean seeds were treated with blue, red and far-red lights for 0, 6, 12, and 24 hours during 24-hour imbibition before culture for 6 days. The soybean sprouts raised were classified by their hypocotyl lengths; normal (＞4cm), abnormal (＜4cm) and non-germination, and their lateral roots, hypocotyl diameters and component dry weights were measured. Red light treatment and dark imbibition reduced the abnormal soybean sprouts more than far-red and blue light treatments, meaning that the former treatments produced more commercial sprouts. The lateral roots were more formed in blue light and dark imbibition than the other light treatments, but were completely blocked by any light treatment lasted during the whole imbibition. Although any light quality treatment did not influence their primary root lengths, blue light one lengthened the hypocotyl more than the others treated during the imbibition, and far-red light enlarged its diameter. Despite this morphological change, component, total or economic yield was not significantly different among the light quality treatments during the imbibition.

• Journal of Bio-Environment Control
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• v.28 no.1
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• pp.86-93
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• 2019

Plant growth and morphology are affected by light environments. The morphogenesis and growth of the plants growing in plant factories are different from those grown under sunlight due to the effect of far-red light included in sunlight. The objective of this study was to compare the morphogenesis and growth of cucumber plants grown under artificial sunlight, high pressure sodium lamp (HPS), and HPS with additional far-red light (HPS+FR). The artificial solar (AS) with a spectrum similar to sunlight was manufactured using sulfur plasma lamp, incandescent lamp, and green-reducing optical film. HPS was used as a conventional electrical light source and far-red LEDs were added for HPS+FR. The optical properties of each light source was analyzed. The morphogenesis, growth, and photosynthetic rate were compared in each light source. The ratio of red to far-red lights and phytochrome photostationary state were similar in AS and HPS+FR. There were significant differences in morphology and growth between HPS and HPS+FR, but there were no significant differences between AS and HPS+FR. SPAD was highest in HPS, while photosynthetic rate was higher at AS and HPS. Although the photosynthetic rate in HPS+FR was lower than HPS, the growth was similar in AS. It was because canopy light interception was increased by longer petioles and larger leaf areas induced by FR. It is confirmed that the electrical light with additional far-red light induces similar photomorphogenesis and growth in sunlight spectrum. From the results, we expect that similar results will be obtained by adding far-red light to electrical light sources in plant factories.

• Asian Journal of Turfgrass Science
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• v.15 no.1
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• pp.15-20
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• 2001

Two types of annual bluegrass have been reported, and those consist of annual type (Poa annua ssp. annua) and perennial type (Poa annua ssp. reptans). As a weed, annual bluegrasses are commonly found in putting greens and fairways in many golf courses. Due to its strong competitiveness such as tremendous seed reproduction rate a year, prostrate growth habit, and no herbicide availability, annual bluegrasses have been considered as one of the most hard-to-control weeds in turf management systems. A growth chamber study was conducted to determine seed dormancy and to understand seed germination characteristics of annual bluegrass (Poa annua ssp. annua). Freshly harvested seeds showed 80 and 55% germination at 30 and $35^{\circ}C$, respectively, indicating that the optimum temperature of annual bluegrass is $30^{\circ}C$. However, the seed germination occurred only under light condition at any given temperature. This result demonstrated that light is prerequisite for the seed germination, and no primary dormancy of annual bluegrass seed exists. Secondary seed dormancy induced by unfavorable temperatures and dark condition was broken through 4 to 6 wk-storage at $4^{\circ}C$ with moisture, and the stored seeds germinated at $20^{\circ}C$ even under the dark. In red and far-red light trial, fresh seeds resulted in 40% germination under red while no seed germination occurred under far-red light condition, indicating that phytochrome Pr and Pfr could be related to annual bluegrass seed germination. When the far-red light replaced the red the germination was recovered, but this reversibility did not reach to the germination level under the red light only. This result implied that other lights than red and far-red would play an important role on seed germination of annual bluegrass.

• BMB Reports
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• v.28 no.5
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• pp.382-386
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• 1995

One of the reaction pathways in light-invoked signal transduction can be initiated through ion fluxes across the plasma membrane in higher plants. We isolated protoplasts from oat coleoptile and examined the effects of light on the membrane potential using a membrane potential-sensitive fluorescent probe (bisoxonol). Both red and far-red light initially induced a hyperpolarization in oat cells. Red light-induced hyperpolarization was effectively dissipated by 100 mM $K^+$, but the hyperpolarization induced by far-red light was not depolarized by any of the cations ($K^+$, $Ca^{2+}$, $Li^+$, $Na^+$) tested. The depolarization induced by red light and $K^+$ was inhibited by 200 mM TEA, which is a $K^+$ channel blocker. These results suggest that $K^+$ influx through the inward $K^+$ channel may be a depolarization path in the phytochrome-mediated signal transduction.

• Journal of Plant Biotechnology
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• v.31 no.3
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• pp.239-248
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• 2004

This experiment was carried out to confirm that phytochrome regulates anthocyanin bio-synthesis during cell suspension culture system of grape or not. In suspension culture of grape, maximum accumulation of anthocyanin was observed at the stationary phase under continuous white light condition. From mono-chromatic light interruption for 24h at the 4th or 7th day on the suspension cultured cells, the anthocyanin accumulation was highly enhanced at the light interruption at 7th day than 4th day under all monochromatic light treatment. However, the cell growth patterns were not affected by any light treatment. In the darkness, the anthocyanin synthesis was very low but remarkably increased by blue light or red light irradiation. However, the increase of anthocyanin accumulation by blue or red light was suppressed by far-red light in the suspension cells of grape. This suppression by far-red light on the anthocyanin synthesis also observed on the cells treated red or far-red light alternatively. These results implied that phytochrome regulation system may be involved in the anthocyanin biosynthesis of the suspension grape cells. By RNA expression analysis, chalcone synthase (CHS) gene was expressed highly by blue and red light but low by far-red light. The synergistic increase of CHS gene expression was also observed at the treatment of blue light followed by red for 24h. This result may explain the increase of anthocyanin accumulation in B/R treatment. Although the expression of phytochrome gene (PHYA or PHYB) was not highly increased by all light treatment (blue, red, and far-red light) the expression of both PHYA gene and PHYB gene was increased a little in cells treated red or far-red light. In grape suspension cells, the red light enhanced the anthocyanin synthesis, whereas the far-red light was suppressed. Although it was not confirmed whether or not phytochrome gene is activated in anthocyanin accumulating grape cells, we believed that anthocyanin biosynthesis in grape cells may be regulated under phytochrome signal transduction system.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.223-229
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• 2000

This study was conducted to analyze the opto-electric characteristics of light-emitting diodes(LED) designed for growth and morphogenesis control of transplant and to quantify the photon flux emittig from LED using a quantum sensor spectroradiometer. Difference in photon flux for blue and red LED between measured by a quantum sensor and measured by a spectroradiometer and numerically integrated was not observed. This result implies a spectroradiometer can be applied to quantify the photon flux emitting from far-red LED, which can not be measured using a quantum sensor. Since photon flux increases in proportion to wavelength, photon flux of LED modules arranged for red and far-red increased in proportion to wavelength, photon flux of LED modules arranged for red and rar-red increased gradually as the number of LED stick emitting far-red in LEd modules increased. Illumination of LED modules arranged for red and far-red decreased as the number of LED stick emitting far-red in LED modules increased. There was no difference in irradiance between LED modules arranged for red and far-red.

• Plant Resources
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• v.7 no.1
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• pp.77-86
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• 2004

The reduced ratio of red:far-red (R:FR) light acts as a measure of the proximity of competitors and plants can detect the potentially competing neighbor plants by perceiving reflected R:FR signals and initiate the response of “shade avoidance” before actual shading occurs. The phytochrome system is responsible for monitoring the changes in the R:FR and initiating the shade avoidance response. The response to low R:FR ratio was studied in a white aspen Populus alba clone ‘Bolleana’ using two filter systems: a clear plastic filter system that allows a R:FR ratio less than 1.0 to pass from adjacent border plant reflection; and a special commercial plastic that blocks FR light and creates a R:FR ratio above 3.0. The reduced R:FR signals enhanced the stem elongation in response to competition at the expense of relative stem diameter growth. Trees grown inside clear chambers were 27 ％ taller than trees grown inside the FR-blocking filter chambers. Stem taper of clear chamber trees was 16％ less than the FR-blocking filter trees. Low R:FR also induced 22％ more stem dry weight and 13％ greater petiole length per leaf compared to the FR-blocking filter trees. There were no statistically significant differences in leaf area, leaf number increment, and total dry weight between the two light filter treatments.

• Plant Biotechnology Reports
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• v.4 no.4
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• pp.303-309
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• 2010

Endoreduplication is a developmental process that is unique to plants and occurs in all plants. The present study aimed to assess endoreduplication in various explant tissues and regenerated somatic embryos of Doritaenopsis. We further investigated the effects of light quality on endoreduplication and somatic embryo proliferation. To this end, we studied endoreduplication in leaves and root tips from regenerated plantlets and somatic embryos and in developing somatic embryos under 4 types of lighting conditions: red light, red + far-red light, red + blue light, and white light. We found that the degree of endoreduplication varied in different explants, and that the choice of explants used also influenced the ploidy levels of the newly regenerated somatic embryos. The DNA content of the leaf (2C-8C) was less than that of the root tip (2C-16C) and somatic embryo (2C-64C). In terms of light quality, the combination of red and far-red light produced the highest number of somatic embryos, while maintaining a low degree of endoreduplication. The data obtained indicate that this light combination stimulates somatic embryogenesis in Doritaenopsis and may exert some control on endoreduplication during cell division. These findings can be applied to achieve a reduction in somaclonal variations for the purpose of mass proliferation and genetic improvement.

• Korean Journal of Weed Science
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• v.10 no.4
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• pp.305-311
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• 1990

Effects of light on germination of major weeds in upland fields were examined. Most weeds showed light positive response to germination at above 25$^{\circ}C$, but germination percentage was very low at lower temperatures. Red light promoted germination of Amaranthus lividus, Portulaca oleracea, and A. retroflexus, but far-red light inhibited germination. Germination resposnse of A. retroflexus, A. lividus, and P. oleracea showed reversible reaction to red/far-red light, and thus it seemed that phytochrome was involoved in seed germination, Echinochloa crusgali and Eleusine indica showed higher germination percentage under the conditions of continuous illumination of red, white, and bule lights, and thus it was estimated that blue light pigment (HIR, high irradiation reaction) related to long time illumination was involved in germination in addition to phytochrome.