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  • Author or Editor: Dong Woo Lee x
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This experiment was conducted to investigate the effects of artificial light sources for light period extension on growth and flowering of statice `Sophia' and `Early Blue'. The seeds were sown on 10 June in a plug tray with 128 plugs. The seedlings were grown at the highland (800 m above sea level) for 50 days, and transplanted on 30 July in 20-cm-diameter plastic pots. High-pressure sodium lamps (HPS) (220V, 400W), incandescent lamps (Il) (220V, 200W), and fluorescent lamps (Fl) (220V, 40W) for day length extension (16-h photoperiod) as compared with short day (8-h photoperiod) were tested. HPS gave the greatest photosynthetically active radiation (PAR), but Fl did the smallest. HPS or Fl as compared with Il showed high ratio of red/far-red light. The leaves of plant grown under HPS were effective for light absorbance and chlorophyll contents. HPS promoted photosynthesis as much as light period extension, while more respiration than photosynthesis occurred under Fl affected by low PAR. Long day condition as light period extension hastened flowering of statice, and HPS or Il were more effective than Fl on flowering among artificial light sources tested. The light compensation and saturation points of statice were 50 and 500 μmol·m–2·s–1, respectively. Photosynthesis hastened at high temperature, but amount of photosynthesis at vegetative stage showed much higher than flowering stage under the condition below 20 °C These results indicated that day length extension with HPS increased productivity and quality for cut flower of statice at the highland in Korea.

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Hanabusaya asiatica has beautiful flowers as ornamental pot plant. It's a famous Korean endemic perennial plant in Korea. Recently many research items has been studying for developing cultivation technology of H. asiatica as a new commercial pot plant. Many endemic plants have much problems associated with maintaining quality for commercial plant. In H. asiatica, as a result of accumulation of anthocyanin in the leaves at reproductive stage, the leaf veins turn to brownish black and whole leaves become to necrosis and dry after all. This study was carried out to find out the suitable method for preventing the accumulation of anthocyanin in leaves by light quality. H. asiatica was treated three light quality, blue, far-red + blue, far-red and control on the middle stage of vegetative growth. Light quality sources were made by diodes. Light quality treatments were done in growth chamber. The photoperiod was 16 hours. Light quality treatments were done for 4 hours as daylight extension after 12 hours lighting by fluorescent lamps. Far-red lighting treatment was very effective to prohibit the formation of anthocyanin in the leaves. Blue lighting treatment was increased the anthocyanin accumulation but blue lighting treatment with far-red showed preventing the formation of anthocyanin. In these results, far-red lighting was very effective for preventing the action of cryptochrome by blue lighting on the anthocyanin formation in the leaves of Hanabusaya asiatica.

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The principal bitter sesquiterpene lactones (BSLs; latucin, 8-deoxylactucin, and lactucopicrin) in six red and four green-pigmented leaf lettuce (Lactuca sativa L. var. crispa L.) cultivars were identified and quantified using high-performance liquid chromatography, proton nuclear magnetic resonance, and liquid chromatography–mass spectrometry and the contribution of each to the overall bitterness was determined. The concentration of each BSL and the total varied significantly among cultivars and there were significant differences resulting from leaf color (green versus red) and morphology (cut versus curled leaves) with red and curled leaf cultivars having higher BSL concentrations. The concentrations of lactucin, 8-deoxylactucin, and lactucopicrin ranged from 2.9 to 17.2, 2.8 to 17.1, and 8.8 to 36.1 μg·g−1 dry weight, respectively, with the total concentration ranging from 14.6 to 67.7 μg·g−1. Bitterness of the cultivars was assessed using a bitter activity value calculated using the concentration and bitterness threshold value for each BSL. Lactucopicrin was the primary contributor to bitterness as a result of its concentration and lower bitterness threshold; its relative proportion of the total bitterness activity value across all cultivars was over 72%. The concentration of individual BSLs differed with leaf location on the plant (i.e., basal, midstalk, and flower stalk). The concentrations in lactucin, 8-deoxylactucin, and lactucopicrin in flower stalk leaves were significantly higher (i.e., 2.9, 12.4, and 5.4 times, respectively) than in basal leaves, with the concentrations increasing acropetally. Genetic differences among cultivars and with leaf location on the plant contribute to the wide range in bitterness in lettuce.

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Growth response of `Sambok Honey' watermelon grafted onto different rootstocks, including four Citrullus rootstocks and three other cucurbitaceous rootstocks, was evaluated at low and normal temperature regimes. Marked reduction in plant growth rate was observed in plants grown at low temperatures as compared to those grown at normal or optimal temperatures. Relative growth reduction rates were 40% to 48% for vine length, 39% to 51% for total leaf area, 37% to 60% for shoot fresh weight, and 50% to 79% for shoot dry weight, respectively. Watermelon rootstock PI 482322 showed comparable plant growth as the most popular rootstock (Shintozwa pumpkin) even at low temperatures. `Sambok Honey' watermelon grafted onto watermelon hybrids `PI 271969 × PI 296341' and `PI 271769 × Calhoun Gray', showed comparable plant growth as FR Dantos bottle gourd rootstock. Index of growth ability at low temperature (IGALT), which was calculated on the basis of reduced rate of vine length, dry weight, and leaf area, was comparatively high in C. martinezii, Shintozwa, PI 482322, and `PI 271769 × PI 296341' rootstocks (50% or higher) and lowest in own-rooted `Sambok Honey' or in watermelon plants on `Knight' rootstock. Watermelon hybrids `PI 271969 × PI 296341' and `PI 271769 × Calhoun Gray' exhibited better or at least comparable growth at low temperatures as compared to `FR Dantos', thus confirming the feasibility of using watermelon rootstocks even in winter greenhouse conditions.

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The efficiency of volatile formaldehyde removal was assessed in 86 species of plants representing five general classes (ferns, woody foliage plants, herbaceous foliage plants, Korean native plants, and herbs). Phytoremediation potential was assessed by exposing the plants to gaseous formaldehyde (2.0 μL·L−1) in airtight chambers (1.0 m3) constructed of inert materials and measuring the rate of removal. Osmunda japonica, Selaginella tamariscina, Davallia mariesii, Polypodium formosanum, Psidium guajava, Lavandula spp., Pteris dispar, Pteris multifida, and Pelargonium spp. were the most effective species tested, removing more than 1.87 μg·m−3·cm−2 over 5 h. Ferns had the highest formaldehyde removal efficiency of the classes of plants tested with O. japonica the most effective of the 86 species (i.e., 6.64 μg·m−3·cm−2 leaf area over 5 h). The most effective species in individual classes were: ferns—Osmunda japonica, Selaginella tamariscina, and Davallia mariesii; woody foliage plants—Psidium guajava, Rhapis excels, and Zamia pumila; herbaceous foliage plants—Chlorophytum bichetii, Dieffenbachia ‘Marianne’, Tillandsia cyanea, and Anthurium andraeanum; Korean native plants—Nandina domestica; and herbs—Lavandula spp., Pelargonium spp., and Rosmarinus officinalis. The species were separated into three general groups based on their formaldehyde removal efficiency: excellent (greater than 1.2 μg·m−3 formaldehyde per cm2 of leaf area over 5 h), intermediate (1.2 or less to 0.6), and poor (less than 0.6). Species classified as excellent are considered viable phytoremediation candidates for homes and offices where volatile formaldehyde is a concern.

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