• Journal of Biosystems Engineering
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• v.37 no.5
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• pp.314-318
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• 2012

Purpose: This study was conducted to develop a measurement system for determining photosynthetic photon flux (PPF) distribution and illumination efficiency of LED lamps. Methods: The system was composed of a linear moving sensor part (LMSP), a rotating part to turn the LMSP, a body assembly to support the rotating part, and a motor controller. The average PPF of the LED lamp with natural cooling and water cooling was evaluated using the measurement system. Results: The PPF of LED lamp with water cooling was 3.1-31.7% greater than that with natural cooling. Based on the measured value, PPF on the horizontal surface was predicted. Illumination efficiency of the LED lamp was slightly increased with water cooling by 3.4%, compared with natural cooling. A simulation program using MATLAB was developed to analyze the effects of the vertical distance from lighting sources to growing bed, lamp spacing, and number of LED lamps, on the PPF distribution on the horizontal surface. The uniformity of the PPF distribution of the LED lamps was fairly improved with 15 cm spacing, as compared to the 5 cm spacing. By simulation, PPF of $217.0{\pm}27.9{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was obtained at the vertical distance of 40 cm from six LED lamps with 12 cm spacing. This simulated PPF was compared to the measured one of $225.9{\pm}25.6{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. After continuous lighting of 346 days, the relative PPF of LED lamps with water cooling and natural cooling was decreased by 6.6% and 22.8%, respectively. Conclusions: From these results, it was concluded that the measurement system developed in this study was useful for determining PPF and illumination efficiency of artificial lighting sources including LED lamp.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.529-534
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• 2013

Rotational lighting system for plant factory is the way to decrease high installation cost of the existing lighting system. A few of LEDs are used at the rotational lighting system in comparison with the existing lighting system to supply artificial lights to crops. At rotational lighting system, the manufacturing cost becomes very low by comparing with the existing lighting system. In this paper, the photosynthetic photon flux (PPF) is investigated in order that plants may grow. And PPF is analyzed with the rotational speed of blade and LED output by using the rotational lighting system prototype and quantum sensor. It is confirmed that constant PPF value of $200{\mu}mol{\cdot}m^{^-2}{\cdot}s^{^-1}$ is supplied with the blade rotation speed of 20rpm and LED output of IN 73%, CENTER 37% and OUT 50%. By comparing with the lighting system of existing plant factory, there is no difficulty to supply the light needed to grow plants by rotating a few of LEDs.

• Journal of Biosystems Engineering
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• v.33 no.2
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• pp.106-114
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• 2008

This study was performed to analyze the distribution of air current speed, $CO_2$ concentration, and photosynthetic photon flux (PPF) in a closed transplants production system (CTPS) for producing quality transplants. And the effect of PPF on the growth of potato (Solanum tuberosum L. cv. Dejima) plug seedlings was analyzed. Uniformity of the air current speed in CTPS was improved by installing perforated floors in duct for air circulating and by adjusting of air flow rate of the fan connected to air conditioning unit used in this study, Measured $CO_2$ concentrations were measured $409{\pm}13$, $950{\pm}25$, and $1,550{\pm}35\;{\mu}mol{\cdot}mol^{-1}$ for setting values of 400, 950, and $1,550\;{\mu}mol{\cdot}mol^{-1}$, respectively. Uniformity of PPF by adding each one the single fluorescent lamp of 20 W at both ends of the single fluorescent lamps of 40 W was highly improved. While the average PPF measured under the twin fluorescent lamps of 55 W installed at regular intervals of 10 cm was decreased by increasing the vertical distance from the lighting sources, the ratio of average PPF measured at both ends to PPF measured in the center was 74-79%. Five levels ($100{\pm}9$, $150{\pm}14$, $200{\pm}17$, $250{\pm}24$ and $300{\pm}31{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) of PPF were provided to investigate the effect of PPF on plant height, fresh weight and dry weight of potato plug seedlings produced in CTPS. Plant height was decreased by increasing PPF. Maximum fresh weight and dry weight were shown under PPF of $250{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Thus PPF of $250\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was enough to produce quality potato transplants under air temperature, photoperiod, and relative humidity of $20^{\circ}C$, 16/8 h, and 70%, respectively. It was concluded that quality indices such as plant height, fresh weight and dry weight could be improved by illuminating of adequate PPF from artificial lighting sources.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.535-539
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• 2010

The formation and elongation of runners, growth of runner plants, and transplant propagation rates of 'Maehyang' strawberry were investigated at various photosynthetic photon flux (PPF) levels. Strawberry plants having $3.1{\pm}0.4$ leaves and $7.0{\pm}1.1mm$ of crown diameter were used as propagules and were cultured for 35 days in 9 transplant production modules using fluorescent lamps as artificial lighting sources. Applied PPF levels were $137.4{\pm}2.1$, $217.0{\pm}1.0$, and $274.7{\pm}8.4{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as measured on the surfaces of empty shelves. The numbers of runners and runner plants per propagule were the greatest at $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPF. The runner plant propagation rate was 0.27 plant/day/propagule at $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, which was significantly greater than that of conventional propagation methods. Results indicate that high PPF levels promotes the formation of runners and runner plants of strawberry and that the rapid propagation method with high PPF levels can be feasible for production of vigorous transplants in a closed transplant production system.

• Journal of Bio-Environment Control
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• v.11 no.1
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• pp.40-44
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• 2002

A prototype of closed-type transplant production system(CTTPS) with fully environmental control was developed to produce massively quality transplants. Four photosynthetic photon flux(PPF) levels of 200,300,400 and 500$\mu$mol . m$^{-2}$ .s$^{-1}$ , four photoperiod levels of 1816 h,12/12h, 9/15 h and 6/18 h were provided to analyze the growth and development of cucumber plug seedlings(Cucumis sativus L., cv. Kyuewosalichungiang) as affected by PPF and photoperiod in a CTTPS. Effect of photoperiod on the growth and development of cucumber plug seedlings produced in a CTTPS was higher than PPF, Stem diameters dry weight of shoot and roots number of leaves, leaf with and length, and SPAD value of cucumber plug seedlings produced in a CTTPS were significantly high as compared to the control. But stem length of plug seedlings produced in a CTTPS was shorter than those of the control. Growth characteristics of cucumber plug seedlings raised at photoperiod of 6/18 h and PPF of 200$\mu$mol . m$^{-2}$ .s$^{-1}$ were similar to the those of the control. These results suggest that cucumber quality transplant can be produced at relatively short photoperiod and low PPF, It means that the electric energy consumed for the production of cucumber plug seedlings in a CTTPS can be saved.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.5
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• pp.11-18
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• 2010

This study was conducted to provide design data for deciding covering method in double layers greenhouse. The variation of photosynthetic photon flux (PPF) and heat flow in air inflated and conventional double layers greenhouse was analyzed. The PPF of air inflated double covering greenhouse was less than that of conventional greenhouse during summer season because the more PPF comes into conventional greenhouse through roof vent which was rolled up for ventilation. The air inflated double layers covering greenhouse was superior to conventional type in the aspect of controlling inside temperature down owing to lower irradiation. The PPF of air inflated greenhouse was greater than that of conventional greenhouse during winter season because the transmittance of conventional greenhouse decreased by dust collected on inside plastic film nearly closed for insulation. Considering the PPF not sufficient for tomato growing in winter, the air inflated double covering system with the greater transmittance was better than conventional covering system. When the inside air of air inflated greenhouse was injected into space between the double layers of covering, the PPF of air inflated greenhouse was much less than the conventional greenhouse because the transmittance of air inflated double covering decreased due to condensation of highly humidified inside air. It was concluded that the more dried outside air should be used for inflating double layers covering. The heat insulation performance of air inflated double covering system was superior to conventional double covering system when comparing the overall heat transfer coefficients for each covering method. However the differences among the overall heat transfer coefficients depending on difference between inside and outside temperatures of greenhouse were great, it is necessary to conduct additional experiment for investigating the overall heat transfer coefficient to design the double layers covering.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.383-390
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• 2014

This study was conducted to investigate the growth characteristics of cucumber scion and pumpkin rootstock under different levels of light intensity (photosynthetic photon flux, PPF) and plug cell size in a closed transplant production system with artificial lighting. Cucumber scion and pumpkin rootstock seedlings were grown under the combinations of three levels of PPF (PPF 165, 248, and $313{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and five types of plug tray (50, 72, 105, 128, and 200 cells in the tray) for nine days. The shoot dry weight and relative growth rate increased with increasing PPF and plug cell size. As PPF increased, cucumber scion and pumpkin rootstock seedlings had higher dry matter, lower specific leaf area, and lower hypocotyl length. The first true leaf of cucumber scion and pumpkin rootstock unfolded at eight and seven days after sowing, respectively, except the treatment using 200-cell plug tray. The unfolding of first true leaf of seedlings grown in 200-cell plug tray was delayed by one day. Accordingly, it was considered that the use of small cell size such as 200-cell plug tray would require more time for the production of scion and rootstock. Based on the results, we suggest that cucumber scion and pumpkin rootstock be grown in 105-cell to 128-cell plug tray for eight days and 72-cell to 105-cell plug tray for seven days, respectively, when using splice grafting method with root-removed rootstock. Additionally, higher PPF is suggested to improve the growth and quality of scion and rootstock.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.14-23
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• 2013

This study evaluated the influence of light quality and intensity during healing and acclimatization on the $CO_2$ exchange rate, growth, and morphogenesis of grafted pepper (Capsicum annuum L.) transplants, using a system for the continuous measurement of the $CO_2$ exchange rate. C. annuum L. 'Nokkwang' and 'Tantan' were used as scions and rootstocks, respectively. Before grafting, the transplants were grown for four weeks in a growth chamber with artificial light, where the temperature was set at $25/18^{\circ}C$ (light/dark period) and the light period was 14 hours $d^{-1}$. The grafted pepper transplants were then healed and acclimatized under different light quality conditions using fluorescent lamps (control) and red, blue, and red + blue light-emitting diodes (LEDs). All the transplants were irradiated for 12 hours per day, for six days, at a photosynthetic photon flux (PPF) of 50, 100, or 180 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. The higher PPF levels increased the $CO_2$ exchange rate during the healing and acclimatization. A smaller increase in the $CO_2$ exchange rates was observed in the transplants under red LEDs. At a PPF of 180 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, the $CO_2$ exchange rate of the transplants irradiated with red LEDs was lowest and it was 37% lower than those irradiated with fluorescent lamps. The $CO_2$ exchange rates of transplants irradiated with blue LEDs was the highest and 20% higher than those irradiated under fluorescent lamps. The graft take was not affected by the light quality. The grafted pepper transplants irradiated with red LEDs had a lower SPAD value, leaf dry weight, and dry matter content. The transplants irradiated with blue LEDs had longer shoot length and heavier stem fresh weight than those irradiated with the other treatments. Leaves irradiated with the red LED had the smallest leaf area and showed leaf epinasty. In addition, the palisade and spongy cells of the pepper leaves were dysplastic and exhibited hyperplasia. Grafted pepper transplants treated with red + blue LEDs showed similar growth and morphology to those transplants irradiated with fluorescent lamps. These results suggest that high-quality grafted pepper transplants can be obtained by healing and acclimatization under a combination of blue and red lights at a high PPF level.

• Horticultural Science & Technology
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• v.32 no.5
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• pp.600-606
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• 2014

The objective of this study was to determine the effects of seedling ages of scions and rootstocks for grafting and light intensity during their cultivation in a closed transplant production system on the growth and development of grafted cucumber transplants. Cucumber scions and rootstocks were cultivated under 5 photosynthetic photon flux (PPF) levels: 100, 140, 180, 230, and $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ in a closed transplant production system. The scions were grafted onto the rootstocks at 8, 9, 10, 11, and 12 days after sowing (DAS). Hypocotyl length of scions and rootstocks decreased significantly as PPF increased, and an increase in dry weight with increasing PPF was more pronounced in scions. After grafting, cucumber transplants were grown in a greenhouse until 22 DAS and were then transplanted for investigation of their growth and development. Plant height, leaf area, and fresh weight of cucumber transplants grafted at 8, 9, and 10 DAS were greater, but light intensity during cultivation of scions and rootstocks did not significantly affect the early growth of cucumber transplants after grafting. The number of female flowers in grafted cucumber after transplanting was highest when scions and rootstocks were cultivated under PPF 140 and $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and were grafted at 8 DAS. These results indicate that controlling environmental conditions in a closed transplant production system during the production of scions and rootstocks can advance grafting time and promote the growth and development of grafted cucumber transplants.

• Horticultural Science & Technology
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• v.29 no.3
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• pp.273-277
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• 2011

Fusarium oxysporum f. sp. fragariae (Fof), the causal agent of crown and root rot in strawberry, is the most serious soilborne disease of nursery plants in Korea. The possibility of infection by Fof through runner propagation from infected mother plants of strawberry cv. 'Kumhyang' was assessed in stolons and daughter plants hanging from raised beds. The number of daughter plants from an infected mother plant in plastic house and photosynthetic photon flux (PPF) system, 280 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was 2.7 and 3.8 plants after 58 days, respectively. However, healthy mother plants produced 6.5 and 8.4 daughter plants, respectively. The pathogen was detected in the uppermost portion of the stolon after 58 days, but was not detected further down the stolon. After 90 days, it was detected in all portions of the stolon between mother and $1^{st}$ daughter plant and in 60% of all $1^{st}$ daughter plants. The pathogen was not detected in the corresponding portions of the non-infected controls. These results show that infected mother plants can transmit Fof to their daughter plants without passing through the soil and $1^{st}$ daughter was used as mother plant in PPF system for propagating healthy plants.