• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2007.05a
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• pp.261-265
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• 2007

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.3
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• pp.113-121
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• 1994

Since it is difficult to expect the normal production of plants in greenhouses during hot summer season in Korea, certain provisions on the control of extreme environmental factors in summer should be considered for the year-round cultivation in greenhouses. This study was carried out to find a method to suppress the temperature rising of nutrient solution by cooling, which is able to contribute to the improvement of the plant growth environment in hydroponic greenhouse during hot summer season. A mechanical cooling system using the counter flow type with double pipe was developed for cooling the nutrient solution efficiently. Also the heat transfer characteristics of the system was analysed experimentally and theoretically, and compared with the existing cooling systems of nutrient solution. The cooling capacities of three different Systems, which used polyethylene tube in solution tank, stainless tube in solution tank, and the counter flow type with double pipe, were evaluated. The performance of each cooling system was about 41 %, 70% and 81 % of design cooling load in hydroponic greenhouse of 1 ,000m$^2$ on the conditions that the flow rate of ground water was 2m$^3$/hr and the temperature difference between two liquids was 10 ˚C According to the results analysed as above, the cooling system was found to have a satisfactory cooling capability for regions where ground water supply is available. Fer the other regions where ground water supply is restricted, more efficient cooling System should be developed.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.348-353
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• 2009

Organic materials reveal the remarkable absorption and high buffer capacity for nutrient. Hence, organic materials need some different nutrient management skill from inorganic one. The objective of this study was to evaluate the effect of EC level of nutrient solution on the yield and quality of cut rose grown in the mixed substrate of coir and perlite. 3 EC levels of nutrient solution was treated, which were 0.7, 1.0, 1.3 times of standard solution (Aichiken solution, Japan) for cut rose hydroponics. EC of the standard solution was changed by season following as 1.4 (Apr.~June), 1.0 (July~Aug.), 1.4 (Sep.~Oct.), and $1.6dS{\cdot}m^{-1}$ (Nov.~Mar.) subsequently. The supply of nutrient solution was controlled by the signal of water potential at -5kPa using frequency domain reflectometry (FDR) sensor. As the results, marketable yield was similar for all treatments until 3rd harvest, but was decreased in high EC level from 4th harvest to 7th harvest as final. 0.7 times of standard solution decreased the ratio of unmarketable rose having short stem below 70cm and increased the ratio of high quality rose having long stem above 91cm. The flower weight and stem diameter of cut rose was higher in the low EC treatment than the others.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.348-351
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• 2007

This study was conducted to find out the change of infernal quality, such as vitamin C and nitrate contents in some leaf vegetables grown hydropoincally in different nutrient conditions. Pak-choi (Brassica camperistis L. spp. chinesis Jusl.), chungchima (Lactuca sativa L. var. crispa cv. Chungchima) and romaine (Lactuca sativa L. var. longifolia Lam.) lettuces were cultivated for 2 weeks in 4 different nutrient solutions, such as tap water; no-nutrient, added $NH_4$, discarded $NO_3$, and supplied Yamazaki' solution for lettuce as a control. The growth of leaf vegetables was not different among nutrient solution treatments except tap water. The nitrate content showed the highest in control, and followed by $+NH_4$ treatment, $-NO_3$ and tap water treatment, regardless of kind of vegetables. The vitamin C content in 3 different vegetables showed the opposite result against nitrate content so that the treatment that showing the highest vitamin C content was tap water in romaine and chungchima lettuces, and $-NO_3$ treatment in pak-choi. The vitamin C and the nitrate content showed high correlations; $r=-0.614^*$ in pak-choi, $-0.651^*$ in romaine lettuce, and $-0.804^{**}$ in chungchima lettuce.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.90-98
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• 1999

This study was conducted to select proper substrate and nutrient solution concentration for favorable growth and quality in common thyme (Thymus vulgaris L.). The growth of common thyme was better in deep flow culture (DFT) than in other substrate cultures. As the nutrient solution concentration rose, the ratio of dry matter increased, while the fresh weight and the number of lateral shoots decreased. The contents of total chlorophyll and vitamin C were higher in DFT than others. Ca, K, P were showed high contents in cocopeat, but Mg content was the highest at half-fold concentration in DFT. Common thyme showed low content of nitrate in DFT compared with that in other substrate culture. DFT was the most effective system for pronoting growth and quality of common thyme. The optimal concentration of nutrient solution in common thyme was half-fold(EC=1.2mS/cm) of herbs nutrient solution by European Vegetable R&D Center.

• Journal of Bio-Environment Control
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• v.2 no.1
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• pp.9-15
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• 1993

Chinese white cabbage, Chinese flat cabbage, lettuce, garland chrysanthemum, and green perilla were grown in nutrient solution culture to investigate the effects of various media and nutrient solutions. The culture media were sand, mixed substrate(peatmoss : sand= 1 : 1), and non-media(deep-flow culture). The nutrient solutions were Cooper's, Hoagland's, and Yamazaki's solution. Plants were grown under different treatments for three weeks. Generally, the growth was greatest in non-media culture and followed mixed substrate culture, and poorest in sand culture. In non-media culture, the growth of Chinese white cabbage, Chinese flat cabbage, lettuce, and green perilla was good in Yamazaki's solution. And regardless of nutrient solution, garland chrysanthemum was good in non-media culture. Relative chlorophyll was not different among the treatments.

• Journal of Bio-Environment Control
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• v.5 no.1
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• pp.50-56
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• 1996

This experiment was carried out to investigate the effects of new material, bioceramic powder in the nutrient solution(0.02%) and foliar spray(0.2%) on the growth and fruit quality of aeroponically grown tomato(Lycopersicon esculentum MILL. cv. Seokwang). Plant height was lowered, but root growth was increased both treatment of bioceramic powder into the nutrient solution and foliar spray. Cluster growth of tomato plants increased up to 14% over than that of control in the plot of foliar spray with bioceramic powder. Total plant dry weight also increased when bioceramic powder was treated both into the nutrient solution and foliar spray. T/R ratio was reduced by the treatment of bioceramic powder, but NAR and RGR showed the highest in the plot of foliar spray treated with 0.2% bioceramic powder than that of the other plots. Cumulative fruit fresh and dry weight were reduced when bioceramic powder was treated into nutrient solution but foliar spray produced more cumulative fruit fresh and dry weight than that of control. It was shown that treatment of bioceramic powder into the nutrient solution and foliar spray could be improved sugar degree without reducing fruit yields.

• Journal of Bio-Environment Control
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• v.4 no.1
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• pp.25-31
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• 1995

This study was carried out to investigate the effect of the concentration of nutrient solution on the growth of tomato(Lycopersicon esculentum Mill. cv. seokwang) in substrate culture. The substrates used in the experiment were perlite, vermiculite, and peatmoss. Tomato plants were treated with different concentrations of nutrient solution, viz. 0.5, 1.0, 2.0, 3.0, and 5.0mS/cm at seedling stage and transferred to different treatments, 1.0, 2.0, and 3.0mS/cm after transplanting in each substrate. As the concentrations of nutrient solution increased from 0.5 to 3.0mS/cm at seedling stage, the $CO_2$ assimilation rates of seedlings increased in all three substrate culture. Beyond this range, the $CO_2$ assimilation rates of seedlings decreased. By increasing the concentrations of nutrient solution, plant height, leaf length, leaf width, stem diameter, and top dry weight increased in perlite and were high at 2-5mS/cm in vermiculite. On the other hand, in peatmoss, the best result was shown at 3.0mS/cm. Therefore, the adequate concentration of nutrient solution on early growth of seedlings differed among substrates and was shown to be 3.0-5.0mS/cm in perlite, 2.0-5.0mS/cm in vermiculite, and 3.0mS/cm in peatmoss. Generally, as the concentrations of nutrient solution increased from 1.0 to 3.0mS/cm after transplanting, dry weight increased significantly in all three substrate culture. However, dry weights of tomato plants grown under high concentration of 5.0mS/cm slightly increased both at seedling stage and after transplanting.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.3
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• pp.107-115
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• 2008

Herbs and plants widely used for the ecological restoration were selected for germination rate analysis under treatment of microorganisms to determine ideal treatment conditions and medium for enhanced germination rate. Albizzia julibrissin, when submerged in a nutrient medium or distilled water, presented a decrease in germination period rather than increase in germination rate. When treated with microorganism culture solution (JM-2) for 24 hours, 90% germination was achieved in two days, which is sufficient evidence to conclude that such treatment accelerates the germination of Albizzia julibrissin. Germination period decreased for Lespedeza cyrtobotrya samples submerged in microorganism solution for 15 and 48 hours, however, increases in germination rates were not observed. Sample treated in the solution for 24 hours had increased germination rate and enhanced germination period. Microorganism solution treatment had a negative effect on germination for Lespedeza cuneata, unlike Lespedeza cyrtobotrya and Albizzia julibrissin. Microorganism treated seeds of Lepsedeza cuneata had a lower germination rate than that of the control with no treatment. However, submerging treatments in a nutrient medium or distilled water for 24 to 48 hours were proven effective with higher germination rates than control sample with no treatment. Herbs and plants widely used for the ecological restoration were selected for germination rate analysis under treatment of microorganisms to determine ideal treatment conditions and medium for enhanced germination rate. Albizzia julibrissin, when submerged in a nutrient medium or distilled water, presented a decrease in germination period rather than increase in germination rate. When treated with microorganism culture solution (JM-2) for 24 hours, 90% germination was achieved in two days, which is sufficient evidence to conclude that such treatment accelerates the germination of Albizzia julibrissin. Germination period decreased for Lespedeza cyrtobotrya samples submerged in microorganism solution for 15 and 48 hours, however, increases in germination rates were not observed. Sample treated in the solution for 24 hours had increased germination rate and enhanced germination period. Microorganism solution treatment had a negative effect on germination for Lespedeza cuneata, unlike Lespedeza cyrtobotrya and Albizzia julibrissin. Microorganism treated seeds of Lepsedeza cuneata had a lower germination rate than that of the control with no treatment. However, submerging treatments in a nutrient medium or distilled water for 24 to 48 hours were proven effective with higher germination rates than control sample with no treatment.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.385-391
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• 2013

In this study, the availability of slurry composting and biofiltration (SCB) solution as an alternative for synthetic nutrient solution was determined by monitoring the growth, fruit yield, and fruit quality of cherry tomato (Solanum lycopersicum L. 'Unicon'). Treatments for nutrient solution were consist of SCB 1/2N, 1N, 2N, and commercial nutrient solution 1N (CNS 1N) based on nitrogen concentration (218.32 $mg{\cdot}L^{-1}$) of cherry tomato nutrient solution (control 1N). All nutrient solution including SCB solution (440~520 mL per day) was supplied to rock wool medium using a timer. After 31 days of transplanting, fresh and dry weights of shoots, leaf area, plant height, stem diameter, SPAD value and number of node were measured. After measuring growth characteristics of tomato plants, total fruit yield, ratio of marketable fruit yield, fruit weight, total soluble solids content, total acidity, total phenolic concentration, and antioxidant capacity were determined once a week for 7 weeks. As a result, among the SCB treatments, SCB 1/2N was similar to control 1N and CNS 1N in terms of fresh and dry weights of shoots, leaf area, stem diameter, number of node, and SPAD value. Increased N concentration of SCB inhibited the growth of tomato plants. Total fruit yield of SCB 1/2N was 47% of that of control 1N which showed the best result. Percentage of marketable fruit yield in SCB 1/2N was about 58%. Soluble solids contents, total acidity, total phenolic concentration and antioxidant capacity was the highest in SCB 2N and the other treatments were not shown any difference. Blossom-end rot rarely occurred in control 1N and CNS 1N while SCB treatments without Ca induced the physiological disorder of 7~19%. In conclusion, SCB 1/2N was good for the vegetative growth of cherry tomato plants but reduced yield and quality of fruit compared with control 1N and CNS 1N. Thus, it is possible to apply SCB solution to grow cherry tomato plants hydroponically but in the consideration of fruits yield and quality additional supply of several minerals would be required.