• Horticultural Science & Technology
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• v.30 no.5
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• pp.586-595
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• 2012

This study was conducted to determine the effects of horticultural therapy (HT) program using hydroponics on work adjustment skills of students with mental retardation. Based on the critical role transitional model and special education curriculum for agriculture, especially hydroponics, HT program (total 22 sessions) using hydroponics procedure for Lettuce (Lactuca sativa L. 'Asia Heuk Romaine') was developed. Fourteen (10 males, 4 females) graded $1^{st}$ to $2^{nd}$ with intellectual disabilities were recruited from a special education class in a high school located in Inchon, Korea and then a special farm for hydroponics in Inchon, Korea was offered for the HT program. The students with intellectual disabilities participated in the HT program for 4-month (from September to December of 2011, twice a week, approximately 60 minutes per session). Before and after the HT program, the McCarron assessment neuromuscular development, emotional behavioral checklist, interpersonal negotiation strategies, and KEPAD picture vocational interest test were performed by the teachers and horticultural therapists. As the results, the students significantly improved motor performance (p = 0.002), emotional behavioral strategies (p = 0.00), and interpersonal negotiation strategies (p = 0.05). However, no significant difference between before and after the HT program for vocational interest was observed. In conclusion, the HT program using hydroponics, consists of simple and easy tasks so that it would be applicable for the students with intellectual disabilities positively affected to work adjustment skills by improving the motor performance, emotional behavioral strategies, and interpersonal negotiation strategies. Additionally, HT programs using hydroponics with various kinds of vegetables are required to develop and to apply in practical settings for improving work adjustment skills.

• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.963-974
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• 2015

This study was conducted to determine the effects of organic vegetable cultivation on the soil physical properties in 33 farmlands under plastic greenhouse in Korea. We were investigated 5~8 farms per organic vegetable crops during the period from August to November 2014. The main cultivated vegetables were leafy lettuce (Lactuca sativa L.), Perilla leaves (Perilla frutescens var. Japonica Hara), cucumber (Cucumis sativus L.), strawberry (Fragaria ananassa L.) and tomato (Lycopersicon spp.). We have analyzed soil physical properties. The measured soil physical parameters were soil plough layer, soil hardness, penetration resistance, three soil phase, bulk density and Porosity. The measurement of the soil plough layer, soil hardness and penetration resistance were carried out direct in the fields, and the samples for other parameters were taken using the soil core method with approximately 20 mm diameter core collected from each organic vegetable field. Soil plough layer was average 36 cm and ranged between 30 and 50 cm, and slightly different depending on the sorts of vegetable cultivation. The soil hardness was $0.17{\pm}0.15{\sim}1.34{\pm}1.02$ in the topsoil, $0.55{\pm}0.34{\sim}1.15{\pm}0.62$ in the subsoil. It was not different between topsoil and subsoil, but showed a statistically significant difference between the leafy and fruit vegetables. Penetrometer resistance is one of the important soil physical properties that can determine both root elongation and yield. The increase in density under leafy vegetables resulted in a higher soil penetrometer resistance. Soil is a three-component system comprised of solid, liquid, and gas phases distributed in a complex geometry that creates large solidliquid, liquid-gas, and gas-solid interfacial areas. The three soil phases were dynamic and typically changed in organic vegetable soils under greenhouse. Porosity was characterized as range of $54.2{\pm}2.2{\sim}60.3{\pm}2.4%$. Most measured soils have bulk densities between 1.0 and $1.6gcm^{-3}$. To summarize the above results, Soil plough layer has been deepened in organic vegetable cultivation soils. Solid hardness (the hardness of the soil) and bulk density (suitable for the soil unit mass) have been lowered. Porosity (soil spatial content) was high such as a well known in organic farmlands. Important changes were observed in the physical properties according to the different vegetable cultivation. We have demonstrated that the physical properties of organic cultivated soils under plastic greenhouse were improved in the results of this study.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.2
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• pp.122-128
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• 2001

In order to find out the effect of nitrogen fertilizers on soil pH, EC, $NO_3-N$ and lettuce growth, this study was conducted by pot experiment in plastic film house condition. The square-pot which was $42{\times}54.5{\times}22cm$ in length, width and height, respectively, was filled with two kinds of soils in different soil EC as $0.20dS\;m^{-1}$ and $1.13dS\;m^{-1}$. Seven kinds of nitrogen fertilizers (urea, potassium nitrate, calcium nitrate, ammonium nitrate, ammonium sulphate, complex fertilizer A(11-10-10) and complex fertilizer B(12-12-12)) were treated in same standard rate of nitrogen for lettuce, transplanted the six lettuce seedlings of 10 days grown per pot, and have been grown for 38~44 days with three times harvesting. Soil pH was increased with the potassium and calcium nitrate treatments and decreased with ammonium nitrate, ammonium sulphate, complex fertilzer A and B, and the pH of urea treatments was kept the same value as the pH of before experiment. The growing status of lettuce seedling were surveyed during the early period after transplanting and withering of seedling was occured in all treatments. The withering rates were 10% in soil of EC $0.20dS\;m^{-1}$ and 44% and 42% in complex fertilizer and ammonium sulphate treaments, respectively, in soil of EC $1.13dS\;m^{-1}$. $NO{_3}^-$ contents of lettuce were about $1,000{\sim}2,000mg\;kg^{-1}$ based on fresh weight and these contents were considered to be lower to compare the $NO{_3}^-$ level of EU countries.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.228-233
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• 2013

This study was conducted to examine the effect of light intensity and photoperiod of white LEDs as the artificial light source on the growth of leaf lettuce (Lactuca sativa L.) 'Seonhong Jeokchukmyeon' in a closed-type plant production system. Seedlings, transplanted at a density of $20cm{\times}20cm$ in a completely randomized design, were grown under white LEDs (FC Poibe Co. Ltd., Korea), at one of the 3 light intensities (100, 200, or $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$), and each with one of 3 photoperiods [12/12, 18/6, or 24/0 (Light/Dark)]. Plants were cultured for 22 days under the condition of $21{\pm}2^{\circ}C$, $60{\pm}10%$ RH, and $400{\pm}50{\mu}mol{\cdot}mol^{-1}\;CO_2$. The greatest leaf length and width, fresh and dry weights, and total anthocyanin content were obtained in the 24/0 photoperiod, regardless of the light intensity. Length of the longest root, fresh and dry weights, and number of leaves were greater in light intensity of $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ than 100 or $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Chlorophyll value was the greatest in the photoperiod 12/12 than 18/6 or 24/0. The results obtained suggest that plant grew the best kept by light intensity at 200 or $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and photoperiod of 12/12 or 18/6.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.4
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• pp.111-116
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• 2001

As part of the recycling methods, residual food through the anaerobic fermentation process was decomposed into methane gas and fermentation liquid. The research was conducted to measure the effect of application of fermentation liquid on chemical properties of soil and plant growth according to application rate and separate manure at the base of nitrogen in fermentation liquid. The fermentation liquid contained 0.52% nitrogen was applied in treatments by standard fertilizer. The treatments were composed of the control only with chemical fertilizer and N-50, N-100-4, N-100-8 were each of applied with 50, 100(6 times), 100(3 times)% of fermentation liquid contrast to standard fertilizer. Properties of fermentation liquid was high EC because of waster soluble organic compounds as well as much of salts and also contained a lot of suspended solid. The changes of soil chemical properties little occurred in before and after of experiment but EC and content of ex. Ca in soil were increased. Fresh weigh in treatments applied with fermentation is high than that of control but the difference between treatments little showed. The above result means if fermentation liquid be used instead of chemical fertilizer the volume of used fermentation liquid will be reduced by 50% of present standard fertilizer.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.242-248
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• 1992

This study was carried out to investigate the effects of root-zone temperature in hydroponics on the plant growth and nutrient uptake of lettuce(Lactuca sativa L), tomato (Lycopersicon esculentum Mill), and cucumber (Cucumis sativus L). Respiration rate in roots increased with increase in root-zone temperature. At $10^{\circ}C$ of root-zone temperature, respiration rate in lettuce root was higher than those in tomato and cucumber. Increasing rate of root respiration in tomato with increase in root-zone temperature was greater than those in lettuce and cucumber. The lowest dry weight and leaf area of the crops studied were obtained at $10^{\circ}C$ of root-zone temperature, but they were not different between 20 and $30^{\circ}C$. Increase in root-zone temperature generally resulted in increase in T/R ratio and net assimilation rate. At the low root-zone temperature, root growth and leaf area of tomato and cucumber were severely affected. Relative growth rates of lettuce and cucumber were also greatly reduced by the low root-zone temperature. Contents of N, P, K, Ca, and Mg in the crops increased as root-zone temperature increased from 10 to $20^{\circ}C$, whereas only Ca content in tomato and cucumber increased with increase in root-zone temperature to $30^{\circ}C$. Remarkably low contents of P and Mg in the crops were found at the low root-zone temperature. Inhibition of plant growth and nutrient uptake due to low root-zone temperature was much greater in cucumber than in lettuce and tomato.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.225-236
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• 2019

BACKGROUND: Hydroponics is one of the methods for evaluating plant production using the inorganic nutrient solutions, which is applied under the artificial light conditions of plant factory system. However, the application of the conventional inorganic nutrients for hydroponics caused several environmental problems: waste from culture mediums and high nitrate concentration in plants. Organic nutrients are generally irrigated as a supplementary fertilizer for plant growth promotion under field or greenhouse conditions. Hydroponic culture using organic nutrients derived from the agricultural by-products such as dumped stems, leaves or immature fruits is rarely considered in plant factory system. Effect of organic or conventional inorganic nutrient solutions on the growth and nutrient absorption pattern of green and red leaf lettuces was investigated in this experiment under fluorescent lamps (FL) and mixture Light-Emitting Diodes (LEDs). METHODS AND RESULTS: Single solution of tomatoes (TJ) and kales (K) deriving from agricultural by-products including leaves or stems and its mixed solution (mixture ration 1:1) with conventional inorganic Yamazaki (Y) were supplied for hydroponics under the plant factory system. The Yamazaki solution was considered as a control. 'Jeockchima' and 'Cheongchima' lettuce seedlings (Lactuca sativa L.) were used as plant materials. The seedlings which developed 2~3 true leaves were grown under the light qualities of FL and mixed LED lights of blue plus red plus white of 1:2:1 mixture in energy ratio for 35 days. Light intensity of the light sources was controlled at 180 μmol/㎡/s on the culture bed. The single and mixture nutrient solutions of organic and/or inorganic components which controlled at 1.5 dS/m EC and 5.8 pH were regularly irrigated by the deep flow technique (DFT) system on the culture gutters. Number of unfolded leaves of the seedlings grown under the single or mixed nutrient solutions were significantly increased compared to the conventional Y treatment. Leaf extension of 'Jeockchima' under the mixture LED radiation condition was not affected by Y and YK or YTJ mixture treatments. SPAD value in 'Jeockchima' leaves exposed by FL under the YK mixture medium was approximately 45 % higher than under conventional Y treatment. Otherwise, the maximum SPAD value in the leaves of 'Cheongchima' seedlings was shown in YK treatment under the mixture LED lights. NO₃-N contents in Y treatment treated with inorganic nutrient at the end of the experiment were up to 75% declined rather than increased over 60 % in the K and TJ organic treatment. CONCLUSION: Growth of the seedlings was affected by the mixture treatments of the organic and inorganic solutions, although similar or lower dry weight was recorded than in the inorganic treatment Y under the plant factory system. Treatment Y containing the highest NO₃-N content among the considered nutrients influenced growth increment of the seedlings comparing to the other nutrients. However effect of the higher NO₃-N content in the seedling growth was different according to the light qualities considered in the experiment as shown in leaf expansion, pigmentation or dry weight promotion under the single or mixed nutrients.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.77-84
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• 2021

This study attempted to find a way to maintain the quality of mixing baby wild leaf vegetables with existing baby leaf vegetables in various ratios. The crops for mixing baby leaf vegetables were Peucedanum japoincum Thunberg and Ligularia stenocephala, as wild vegetables, and red romaine, which is widely used in young leafy vegetables. The mixing ratio of red romaine and wild vegetables was red romaine 0: mantilla oil 5: L. stenocephala ratio 5 (R0: P5: L5), red romaine 3.3: P. japoincum 3.3: L. stenocephala ratio 3.3 (R3.3: P3.3: L3.3), red romaine 5: P. japoincum 2.5: L. stenocephala 2.5 (R5: P2.5: L2.5), red romaine 8: P. japoincum 1: L. stenocephala 1 (R8: P1: L1), red romaine 10: P. japoincum 0: L. stenocephala 0 (R10: P0: L0). All treatments were packaged in OTR (oxygen transmittance) 10,000 cc m-2·day-1·atm-1 film and stored for 27 days at 2℃/85% RH conditions. Fresh weight, carbon dioxide, oxygen, and ethylene concentrations of the baby leaf packages were examined approximately every 3 days, and visual quality, chlorophyll content, and chromaticity were examined on the 27th day of storage. The oxygen and carbon dioxide concentration in the packages were affected by the respiration rate of the crop. As the mixing ratio of lettuce, which had a low respiration rate, increased, the oxygen concentration in the packages was higher and the carbon dioxide concentration was lower. Oxygen concentration decreased significantly after 15 days, but was remained above 16%, and on the contrary, carbon dioxide concentration was kept at 1-4% until the 15th, and then gradually increased to 2-5% on the 27th day. The concentration of ethylene was maintained at 3-6 µL·L-1 until the end of storage (27th day). Visual quality score measured at the end of storage was slightly less than 3.0, which is the limit of marketability of all treatments. Although there was no significant difference, the chlorophyll content (SPAD) of red romaine and P. japoincum were most similar with an initial value in R8:P1:1 treatment, and L. stenocephala was higher value in R8:P1:L1 and R5:P2.5:L2.5 treatments at the end of storage. The leaf color (L∗, a∗, b∗, chroma) of the three crops at end of storage compared with the heat map showed the least change in the R5:P2.5:L2.5 and R8:P1:L1 treatments at the end of storage. Among them, R8:P1:L1 treatment maintained the highest chlorophyll content, the second lowest ethylene concentration, and adequate carbon dioxide concentration of 2-3%. Therefore, it is judged that the mixed ratio of red romaine 8: P. japoincum 1: L. stenocephala 1 (R8: P1: L1) is most suitable for the mixed package of baby leaf vegetables of these three crops.

• Korean Journal of Organic Agriculture
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• v.7 no.1
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• pp.115-127
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• 1998

Under the visual judgement of consumers, to reduce nitrate intake through vegetables, this experimentation analyzed the content of nitrate, in heading leaf vegetables such as chinese cabbage(Brassica campestris L. ssp. perkinensis (Lour.) Rupr), cabbage(Brassica oleracea L. var. capitata) and lettuce(Lactuca sativa L.) by the leaf number. And the result is summarized as follows In the nitrate content change by the leaf number, the nitrate content is increased as it goes by from inner leaf to outer leaf and the nitrate content in leaf midrib is higher than that in leaf blade. In case of chinese cabbage, the nitrate content in the leaf midrib from the most inner leaf to the most outer leaf changed 40-3,177ppm and in the leaf blade it changed 40-2,887ppm. But the nitrate content in the leaf blade of cabbage from the most inner leaf to the most outer leaf changed 89~2,297ppm and in the leaf blade it changed 25~765ppm. In case of lettuce, the nitrate content change of the leaf midrib by the leaf position was 419~4,349ppm, and in the leaf blade it changed 260~2894ppm. It was conclude that the outer leaf of chinese cabbage, cabbage and lettuce should be removed to keep the lower nitrate intake by population before it is consumed.

• Korean journal of applied entomology
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• v.47 no.4
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• pp.365-368
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• 2008

Adult longevity and fecundity of the foxglove aphid, Aulacorthum solani Kaltenbach, were studied at $12.5{\sim}25^{\circ}C$ with $60{\sim}70%$ RH under 16L:8D and the results were put together to build a life table. The longevity of foxglove gradually increased with decreasing temperature below $25^{\circ}C$. Also total fecundity increased with decreasing temperature and highest fecundity was 74.1 nymphs per female at $15^{\circ}C$. However, daily fecundity increased with increasing temperatures up to $20^{\circ}C$ showing 2.9 nymphs per day and thereafter decreased. Net reproduction rate ($R_0$) was highest of 58.7 at $15^{\circ}C$. The intrinsic rate of increase per day ($r_m$) and the finite rate of increase per day (${\lambda}$) were highest of 0.27 and 1.32, respectively and the doubling time (Dt) was shortest of 2.52. the mean generation time (T) was 10.99 at $22.5^{\circ}C$.