• FLOWER RESEARCH JOURNAL
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• v.16 no.2
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• pp.134-142
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• 2008

This work aims to obtain basic information for seed propagation of Hydrangea serrata for. acuminata. The germination percentage of the seeds taken on 15 November, 30 December, and 23 January was $90.0{\pm}4.16%$, $84.4{\pm}5.52%$, and $88.9{\pm}2.40%$, respectively. This suggest that seeds of Hydrangea serrata for. acuminata are non-dormant seeds. The optimum temperature for germination was $25^{\circ}C$ and light was necessary. Most of the growth parameters (shoot and leaf length, stem diameter, root length, no. of roots, T/R ratio, and fresh and dry wts.) were significantly greater at $25/20^{\circ}C$ and $25^{\circ}C$ than at the other temperatures. Low T/R ratio at relatively cool temperatures (15 and $20^{\circ}C$) was caused by suppressed top growth. In light quality treatment, red light (RL) significantly enhanced stem elongation. The greatest photosynthetic pigments (total chl, chl a/b, and carotenoid) were observed in seedlings grown in blue light (BL), followed by seedlings grown in RL+BL. When blue light was added, higher pigment contents were found. Effect of plug cell size (50, 72, 128, 162 and 200 cells) on the growth of seedlings was investigated. The highest top growth was observed in seedlings grown in 50 cell trays, followed by seedlings grown in 72, 128, 162, and 200 cell trays. However, there was no significant differences between 162 and 200 cell trays. Especially, smaller size leaves were observed in seedlings grown in smaller cell trays (lower volume and high plant density).

• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.38-45
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• 2015

BACKGROUND: For commercial production of greenhouse crops under shorter day length condition, supplementary radiation has been usually achieved by the artificial light source with higher electric consumption such as high-pressure sodium, metal halide, or incandescent lamps. Light-Emitting Diodes (LEDs) with several characteristics, however, have been considered as a novel light source for plant production. Effects of supplementary lighting provided by the artificial light sources on growth of Kale seedlings during shorter day length were discussed in this experiment. METHODS AND RESULTS: Kale seedlings were grown under greenhouse under the three wave lamps (3 W), sodium lamps (Na), and red LEDs (peak at 630 nm) during six months, and leaf growth was observed at intervals of about 30 days after light exposure for 6 hours per day at sunrise and sunset. Photosynthetic photon flux (PPF) of supplementary red LEDs on the plant canopy was maintained at 0.1 (RL), 0.6 (RM), and $1.2(RH){\mu}mol/m^2/s$ PPF. PPF in 3 W and Na treatments was measured at $12{\mu}mol/m^2/s$. Natural light (NL) was considered as a control. Leaf fresh weight of the seedlings was more than 100% increased under the 3 W, Na and RH treatment compared to natural light considering as a conventional condition. Sugar synthesis in Kale leaves was significantly promoted by the RM or RH treatment. Leaf yield per $3.3m^2$ exposed by red LEDs of $1.2{\mu}mol/m^2/s$ PPF was 9% and 16% greater than in 3W or Na with a higher PPF, respectively. CONCLUSION: Growth of the leafy Kale seedlings were significantly affected by the supplementary radiation provided by three wave lamp, sodium lamp, and red LEDs with different light intensities during the shorter day length under greenhouse conditions. From this study, it was suggested that the leaf growth and secondary metabolism of Kale seedlings can be controlled by supplementary radiation using red LEDs of $1.2{\mu}mol/m^2/s$ PPF as well as three wave or sodium lamps in the experiment.

• Korean Journal of Environmental Agriculture
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• v.36 no.3
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• pp.193-200
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• 2017

BACKGROUND: Plant growth under smart greenhouse (that is plant factory system) conditions of an artificial light type is significantly depending on the artificial light sources such as a fluorescent lamps or Light-Emitting Diodes (LEDs) with specific spectral wavelengths regardless of the outside environmental changes. In this experiment, characteristics on the growth and compound synthesis of kale seedlings affected by light qualities and intensities provided by LEDs were mentioned. METHODS AND RESULTS: The kale seedlings which developed 3~4 true leaves were exposed by fluorescent lamps or LEDs lights of red (R), blue+white (BW), blue+red (BR) with 50 (L) or $100(H){\mu}mol/m^2/s^1$ photosynthetic photon flux (PPF) under hydroponic culture system of deep flow technique for 50 days. Shoot fresh weight increased under the RH, BWH, and BRH treatments with higher PPF. Shoot elongation of the seedlings decreased, and polyphenol synthesis promoted by the higher light intensity conditions. Sugar synthesis in the leaves was above 2 times greater under the RH treatment of monochromic red light quality with $100{\mu}mol/m^2/s^1\;PPF$ than $50{\mu}mol/m^2/s^1\;PPF$. CONCLUSION: The results show that the control of light quality and intensity in the smart greenhouse conditions with artificial lights significantly affects the growth and compound synthesis in the fresh kale leaves with higher culture efficiency compared to the conventional soil culture under greenhouse or field conditions. Researches on the optimum light intensities of the LEDs with special spectral wavelengths are necessary for maximum growth and metabolism in the seedlings.