• Korean Journal of Plant Resources
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• v.28 no.4
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• pp.546-549
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• 2015

This study was carried out to investigate the effect of simple hydroponic culture in cultivation of grafted cactus. The results obtained are as follows: Growth indexes of grafted cactus cultivars, such as scion diameter, fresh weight, and scion hardness were improved in simple hydroponic culture compared with soil culture regardless of cultivars. Stem rot and rate of non-graft take were lower in simple hydroponic culture than in soil culture, but no significant difference was monitored between cultivars. Time for harvesting was fast in simple hydroponic culture compared with soil culture. Marketable yield increased in simple hydroponic culture.

• Journal of Biosystems Engineering
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• v.28 no.4
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• pp.335-342
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• 2003

A simple disposable thick-film potentiometric strip has been developed and evaluated for hydroponics application. The strip consisted of low ion-selective electrodes (ISE) fabricated by screen-printing technology. The electrochemical responses of ion sensors for nitrate, ammonium, potassium, and magnesium were measured with specially designed 16-channel low voltage signal transducers. The analytical characteristics of the sensors were comparable with those of conventional ISE sensors. The thick-film sensors exhibit linear relationships over five concentration decades. The concentration of N $O_3$ - ion in standard solution can be determined by direct potentiometric measurements without any conditioning before measurements. However, measurement of $K^{+}$, N $H_4$$^{+}$, and $Mg^{2+}$ ionic concentrations in nutrient solutions seems not feasible.

• 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.

• 전자공학회논문지 IE
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• v.45 no.4
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• pp.19-26
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• 2008

The purpose of this paper is to build a system applicable to floriculture, hydroponics and vinyl house agriculture by a development of remote control equipments using programmable logic controllers (PLC). Remote factory automation and home automation systems have been developed and used due to the rapid progress in the fields of information and automation; however, the systems are so expensive that their applications have not been feasible in agriculture. So we have developed simple modules for PLC to replace the expensive conventional systems. The developed systems have potentials to be applied to automation systems in agricultural industry. Technologies for motor control, microprocessor, PLC programming and wireless interface are developed and implemented in the form of application modules of our systems, and our system is applicable to the remote form automation of floriculture and hydroponics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.657-659
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• 2022

Hydroponics and aquaponics are attracting attention as they enable automated farm management and stable production thanks to the spread of smart farms. There are issues that need to be addressed in applying smart farm, but one of them is to be able to respond flexibly to demand by automatically deciding when to ship, which requires a method for automatically determining the growth level of crops. In this paper, we focused on the simple fact that the area and volume occupied by crops increase with the growth of them, and showed that it is possible to monitor the growth process of crops with 2D and 3D cameras, and to determine the degree of growth of crops by calculating the area and volume. It is necessary to verify the method by applying it to various environments and crops, but in the case of common crops in hydroponics and aquaponics, it is possible to determine the growth level through the analysis of the acquired image through 2D and 3D camera.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.321-321
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• 2017

Water availability in rainfed lowlands (RFL) is strongly affected by climate change. In RFL, rice plants are exposed to soil moisture fluctuations (SMF) but rarely to simple progressive drought as widely believed. Typical RFL field is characterized by a about 5-cm thick high bulk density hardpan layer underneath the cultivated layer at about 20 cm depth that impedes deep root development. Root system has the ability to develop in response to changes in SMF, known as phenotypic plasticity. We hypothesized that genotypes that can adapt to RFL have root plasticity. The roots can sharply respond to re-wetting after drought period and thus penetrate the hardpan layer when the hardpan is wet and so becomes relatively soft, and thus access water under the hardpan. This study aimed to identify CSSLs derived from a cross between Sasanishiki and Habataki which adapted to such RFL conditions. We used 39 CSSLs together with the parent Sasanishiki, which were grown in hydroponics and pot under transient soil moisture stresses (drought and then rewatering), and compared with continuously well-watered (WW) (control) up to 14 days after sowing (DAS), and 20 DAS, respectively. Based on the results of hydroponics and pot experiments, we selected a few lines, which were grown in the soil-filled rootbox with artificial hardpan layer and without artificial hardpan. For the rootbox without artificial hardpan, plants were grown under WW and transient soil moisture stresses for 49 DAS. While the rootbox with artificial hardpan, the plants were grown under WW (control) and SMF (WW up to 21 DAS, 1st drought (22-36 DAS), rewatering (37-44 DAS), and followed by 2nd drought (45-58 DAS)). Among the 39 CSSLs, only CSSL439 (SL39) consistently showed significantly higher shoot dry weight (SDW) than Sasanishiki under transient soil moisture stress conditions as well as SMF conditions in all the experiments. Furthermore, under WW, SL39 consistently showed no significant differences from Sasanishiki in shoot and root growth in most of traits examined. SL39 showed significantly greater total root length (TRL) than Sasanishiki under transient soil moisture stress, which is considered as phenotypic plasticity in response to rewatering after drought period. Such plastic root development was the key trait that effectively contributed to root elongation and branching during the rewatering period and consequently enhanced the root to penetrate hardpan layer when the soil penetration resistance at hardpan layer reduced. In addition, using the rootbox with artificial hardpan layer ($1.7g\;cm^{-3}$, heavily compacted), SL39 showed greater root system development than Sasanishiki under SMF, which was expressed in its significantly higher TRL, total nodal RL, and total lateral RL at hardpan layer as well as at below the hardpan layer. These results prove that SL39 has plasticity that enables its root systems to penetrate hardpan layer in response to rewatering. Under SMF, such root plasticity contributed to its higher gs and Pn.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.314-321
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• 2007

This study was conducted to select leaf vegetables suitable for cultivation in apartment verandas and simple and easy fertigation method for home gardening. In order to develop the convenient fertigation method, hydroponics, wick irrigation, and overhead irrigation methods were compared. For the wick irrigation, two types of nutrient sources were used; one was slow release fertilizers mixed with medium and the other one was nutrient solution filled in container located under pots. The growth of leafy lettuce, leaf mustard, and leaf beet was better in both of the wick irrigation methods rather than in overhead irrigation and hydroponics. The wick irrigation method is very easy, so that it is expected to bring a good result from the cultivating and managing point of view, if it brings with commercialized system along with slow release fertilizer. As a result of investigation of environment such as temperature, relative humidity, and irradiance level in apartment verandas in autumn the highest irradiance level during a day was just 48% and 35% in verandas facing south and feeing southeast, respectively, comparing to that in greenhouse. The light environment was investigated as a limiting factor for vegetable growing in verandas. Therefore, to select the vegetables showing good growth under low irradiance environment, nine leaf vegetables such as romaine lettuce, lent lettuce, head lettuce, endive, pak-choi, leaf mustard, garland chrysanthemum, leaf beet, and Chinese chive were grown under 0%, 50%, 70%, 90% shading. Among them, Chinese chive showed the best growth under low irradiance levels. Endive showed line growth reduction according to shading degree, however, even under 90% shading condition, it showed good growth. And then leafy lettuce, garland chrysanthemum, and pak-choi followed. Therefore, these results will be of help in selecting vegetables for veranda gardening with different light levels.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.170-179
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• 2012

We examined pretreatment methods eliminating potassium and sodium efficiently for coir bag used in hydroponics by analyzing drainage coming from coir bags. In the first experiment we investigated for six coir bags with the high market shares. The three types of pretreatment were washing coir bags with only water for 7 days (W7S0), washing with water for 4 days and further with nutrient solution for 3 days (W4S3), and washing with only nutrient solution for 7 days (W0S7). In the second experiment we tested reproducibility of the experiment results for Bio Grow and coco Mix among six coir bags used in the first experiment to verify the results. As a result, the best pretreatments for the pH stabilization were W4S3 and W0S7. The EC value of the drainage was stabilized to less than 1.0 that is the same as EC of the supply solution on the fourth day in all treatments. The nutrients of the drainage in W7S0 was stabilized in 3~4 days but calcium and magnesium were depleted. We assessed that washing longer than 4 days was waste of water. The stabilization of coir bags in W0S7 was similar to it in W4S3, but washing with the nutrient solution for 7 days seemed to be uneconomical. The reproducibility experiment for two coir bags ensured the results in the first experiment. Therefore, the pretreatment method, which is the most simple to implement and economic, seems to wash with water for 3 days and then with the nutrient solution for 1 day before planting on coir bag.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.153-158
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• 2013

This research was carried out to investigate silicon (Si) uptake levels by six potted plant species from a nutrient solution supplemented with $K_2SiO_3$. Uniform rooted plants of Dendranthema grandiflorum Ramat., Spathiphyllum patinii N.E. BR., Kalanchoe blossfeldiana, Hedera helix L., Dianthus caryophyllus L., and Euphorbia pulcherrima Willd. were grown in 350 mL boxes, one plant per box, containing a nutrient solution supplemented with either 0, 2.7, or 5.4 mM Si as $K_2SiO_3$. The nutrient solution in each container was adjusted to EC $1.5mS{\cdot}cm^{-1}$ and pH 5.6. The solution in each container was aerated by an 1 m-long polyethylene tube, all connected to a vacuum pump. After 15 days of cultivation in a glasshouse Si contents in the roots and shoots were measured using the colorimetric molybdate method and amount of remaining Si in the nutrient solution was measured using the ICP-AES to calculate the amount of absorption. A simple regression analysis was performed to observe the changes in Si contents in the roots and shoots as affected by concentration of Si supplied to the solution. Among the six species tested, carnation had the greatest and poinsettia the lowest tissue levels of Si concentration in the root, whereas carnation had the greatest and kalanchoe the lowest tissue levels of Si concentration in the shoot. Based on the Si content in the whole plant, Si uptake levels by poinsettia, kalanchoe, and chrysanthemum were low, whereas those by spathiphyllum were intermediate, and those of English ivy and carnation were high. These results indicated that the uptake level of Si by the plant vary depending on plant species.