• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.72-80
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• 2023

Melons, a rich source of vitamins and fibers, are commonly grown in the soil. Hydroponic cultivation could improve yield and quality of melon and selection of substrate volume and the kind of substrates is important for hydroponic cultivation of melons. This study investigated the effect on melon growth according to volume of granular rockwool and substrates of coir and rockwool slab. 'Geumsegye' melon (Cucumis melo L. cv. Geumsegye) was cultivated hydroponically according to volume of granular rockwool to 1.0, 1.5, 2.0, 3.0, and 4.0 L, and was also cultivated using coir and rockwool slabs. Logistic model was applied to estimate the growth characteristics of melons such as plant height, leaf length, leaf width, and the characteristics of fruit. The growth characteristics of melons were significantly increased at 4.0 L compared to those grown of 1.0 L volume of on granular rockwool, and the results were the highest in coir and rockwool slabs. Melons grown in rockwool slabs showed the largest fruit fresh weight, fruit length, and fruit width. During hydroponic cultivation, growth characteristics of melon appropriate at the 4.0 L volume of granular rockwool, and the highest at coir and rockwool slabs. This study provides a basis for understanding the effect of root zone environment to the growth characteristics and fruit quality of non-netted melon.

• Journal of Bio-Environment Control
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• v.7 no.1
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• pp.71-77
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• 1998

The root-zone environment is an important factor to the plant growth and it is closely related to the thermal characteristics of the root media. In this study thermal characteristics of root media with ambient environmental conditions were analyzed. The temperatures of nutrient solution as well as inside air of culture bed were measured in Nutrient Film Technique(NFT) and Deep Flow Technique(DFT) systems, and also the temperatures of root media measured in aggregate culture systems , The temperature of nutrient solution of NFT system with as low as 3$\ell$/min of flow rate was 3$^{\circ}C$ higher than that with 5 $\ell$/min of flow rate in the daytime, and the temperature of inside air was 2$^{\circ}C$ higher at night. And the temperature of nutrient solution of DFT system with as low as 0.8 cm of water level was 1-2$^{\circ}C$ higher than that with 1 8 cm in the daytime, and the temperature of inside air was almost same at night. The root-zone temperatures in the perlite and rockwool granulate systems with film mulching were 3$^{\circ}C$ higher than those without film mulching in the daytime. However, the rockwool slab system with film mulching showed the same trend as rockwool granulate system, but relatively higher temperature than any other medium because of the exposure of media surface to the ambient air. Additionally the temperature below the plant was measured 3$^{\circ}C$ lower than that between plants.

• Journal of Bio-Environment Control
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• v.33 no.2
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• pp.114-119
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• 2024

Rockwool substrate has superior physicochemical characteristics and is often used in crop cultivation. However, rockwool substrate has the disadvantages of high purchase cost and difficulty in disposal. Reuse of substrate can compensate for these disadvantages. Substrate must be disinfected and rehydrated during reuse, and various physicochemical changes during this process must also be considered. This study was to compare the physical properties of two types of rockwool substrates (reused and unused) and to evaluate the reuse potential of rockwool substrate by analyzing the chemical properties of the reused rockwool substrate during the rehydration process. The experiment on substrate physicochemical properties comparison was conducted from March to August 2023 using used rockwool substrates in tomato cultivation and unused rockwool substrates. Drainage time, drainage volume, and substrate weight were measured using load cells installed at the top and bottom of the irrigation monitoring system. The reused rockwool substrate weight and density were higher than those of the unused rockwool substrate, while the average drainage time after irrigation was 1.5 times longer for the reused rockwool than for the unused rockwool. The salinity concentration in different parts of the reused rockwool substrate was found to be lower in the reused rockwool substrate compared to the unused rockwool substrate. The electrical conductivity of the drainage was at its peak at the beginning of the drainage and decreased exponentially as the drainage volume increased. Change in electrical conductivity of the drainage over the irrigation time showed an exponential decay pattern. Through the experiments, the potential reusability of the rock wool substrate was assessed by conducting a comparative analysis of its physicochemical properties.

• Journal of Bio-Environment Control
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• v.5 no.1
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• pp.43-49
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• 1996

This study was conducted to investigate the effects of artificial zeolite and various ion exchangers supplemented in rockwool on the ion exchangability of muskmelon. The results obtained were as follows ; Plant height was higher in the treatment of Ca type artificial zeolite as of 131.2cm than that of control as of 124cm, and same trends were shown in fresh weight of leaf and stem. Fruit weight was increased by supplement of artificial zeolite, but there were no significant differences in the sugar degree and external appearance as influenced by supplementing artificial zeolite. Supplement of artificial zeolite stabilized the pH and increased the ion exchange capacity of nutrient solution. Nutrient absorption was more favorable and led to growth promotion. This study was demonstrated that supplement of artificial zeolite in rockwool slab was improved the stabilization of root environment and increased ion uptake of muskmelon plant.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.238-243
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• 2009

To investigate the characteristics of moisture content (MC), moisture distribution and starting point of drainage in a rockwool slab culture, time domain reflectometry (TDR) sensors were used in a drip irrigation system. MC values ($0{\sim}100%$) measured by TDR sensors in a slab were compared to those by loadcells. Seventy two seedlings of paprika (Capsicum annuum L.) were cultured for $5{\sim}6$ months in a green-house and the starting point of irrigation was determined by the average value of three TDR sensors which were inserted diagonally across the slabs under the plants. MCs as a standard for starting point of irrigation by TDR were determined with 40%, 50%, and 60%. Distribution of MCs in a slab measured with five TDR sensors equally spaced from two irrigation points were not much different when the MC in the slab increased from zero to saturation point. The saturated MCs in the slab were presented at $58{\sim}65%$ and the drain was started when the MC became around $50{\sim}55%$. At the saturated MC in the slab, TDR sensors presented 100% but the values from the loadcell showed 90% at the same time. However, measurement errors between two methods for MC remarkably decreased with a decrease in the MC in a slab. Especially when the MC was maintaining below 60%, the errors between TDR and loadcell methods for measuring MC in the rock-wool slab were less than 5%. There were no significant differences in number of fruits and fresh and dry weights of fruits when they were cultured under the different MC conditions with three irrigation regimes (40%, 50%, and 60%). These results indicated that the MC control by TDR sensors in a rock-wool based paprika culture can be suggested as a method to determine the starting point of irrigation for a soilless culture system.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1997.05a
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• pp.11-16
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• 1997

본 연구는 양액재배에서 영양진단에 기초한 배양액관리를 하기 위해 유효한 수단으로 이용되고 있는 신속하고 간편하며 정확한 즙액분석 방법(질산태질소의 정량방법, 인산정량방법, 즙액추출법, 추출비율, 마쇄시간 및 샘플채취 부위 등)들에 관한 비교검토를 하였다. 'Earl's Favorite 춘계 F$_1$호'를 1993년 1월 11일에 파종하여 본엽 3~4매의 묘를 스티로폼베드내 암면슬라브에 정식하여 비순환방식으로 재배했다. 즙액분석법은 결핍이나 과잉증상이 외관적으로 나타나기 전에 신속하고 간이한 즙액분석법에 의해 작물체의 영양상태를 진단하여 대응이 가능하다고 판단되었다. 즙액분석시 질산태질소의 분석에는 자외부흡광도법, 인산분석에는 바나드몰리브덴산법이 추천되었고, 추출비율은 1:4로, 엽병의 마쇄시간은 60초, 그리고 채취 부위는 일정부위로 하는 것이 바람직하다고 판단되었다. 그러나 샘플채취시간에 대해서는 채취시간에 따른 차이가 크기 때문에 앞으로 보다 상세한 검토가 요청되었다.

• Journal of Bio-Environment Control
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• v.23 no.2
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• pp.139-143
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• 2014

This study was conducted to investigate the effect of cultivation period and rockwool block size on the growth and early yield of paprika transplants grown in a closed transplant production system. Paprika seeds were sown and germinated in three different size of rockwool blocks ($45{\times}40{\times}35$, $70{\times}70{\times}60$, $100{\times}100{\times}65mm$) and cultivated in a closed transplant production system for 23, 30, and 37 days after sowing. Paprika transplants were cultivated using $100{\times}100{\times}65mm$ rockwool blocks in a greenhouse following a conventional and typical production method for comparing with the growth of paprika transplants grown in a closed transplant production system. Also, we transplanted paprika transplants grown for 23, 30, and 37 days in a closed transplant production system and greenhouse to rockwool slabs and investigated fresh weight of fruits and yield 125 days after sowing. The growth of paprika transplants grown in $70{\times}70{\times}60mm$ rockwool blocks in a closed transplant production system was highest, and the quality of paprika transplant grown in a closed transplant production system was better than in a greenhouse. Rockwool block size and cultivation period in a closed transplant production system did not affect fresh weight of fruits, however, yield was largest when paprika transplants were cultivated using $70{\times}70{\times}60$ and $100{\times}100{\times}65mm$ rockwool blocks for 23 days in a closed transplant production system. These results suggest that decreasing rockwool block size and cultivation period can be strategically used to enhance transplant quality and yield of paprika, as paprika transplants were cultivated in a closed transplant production system.

• Journal of Bio-Environment Control
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• v.33 no.1
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• pp.37-44
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• 2024

This study was conducted to validate the growth and productivity of cucumber hydroponics using coir as the medium, different types of nutrient solutions and formal methods, in order to select the most efficient cultivation method. The nutrient solutions consisted of culture solution (S) and raw water (W), the planting methods were rockwool cube seedlings (RC), rockwool plug seedlings (RP), and slab directly seedlings (DS). The reference date was set the sowing date. The initial growth showed a significant increase in the culture solution treatment, the differences among treatments decreased as the growth period lengthened. There was no apparent correlation between the planting methods and growth, but different results were observed among the same planting methods depending on nutrient solution used. Similarly, productivity followed a similar trend, with significantly higher harvest in the culture solution treatment during the initial harvest period of 6-8 weeks after sowing, but the harvest gap among treatments were diminished in the after period. The cumulative harvest was significantly higher in the culture solution treatment due to the initial difference in harvest quantity. Plant growth and fruit productivity exhibited a similar trend, showing a linear relationship. There was no correlation among the planting methods, but direct seedling with the culture solution showed the highest initial growth and harvests due to stable nutrient and moisture supply in the initial root zone. Therefore, it is believed that direct seeding method on the culture solution medium would be most advantageous for plant growth and productivity. Additionally, it is expected to contribute to cost effectiveness from an economic perspective through simplification of the cultivation process, labor costs and production cost reduction

• Horticultural Science & Technology
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• v.29 no.1
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• pp.29-35
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• 2011

Individual ion concentrations and ionic contributions to EC reading in the circulated nutrient solution are the important factors to be considered for stable EC-based closed-loop soilless culture. This study was conducted to determine appropriate ion-analysis intervals of the circulated nutrient solutions based on ion concentration, ion balance, and ion electrical conductivity under different renewal intervals in EC-based nutrient control systems for sweet peppers (Capsicum annum L. 'Fiesta') in early growth stage. Average node numbers of the plants were 13 and 18 when the experiment started and finished, respectively, and three plants were grown in each rockwool slab. Four different renewal intervals of circulated nutrient solutions such as 1, 2, 3, and 4 weeks were used as treatment. Nutrient solutions were supplied to the plants based on integrated radiation. Drainage was collected into drain tanks after irrigation ended in the day and then mixed with fresh water until the EC reaches 2.69 $dS{\cdot}m^{-1}$. The replenished nutrient solution was supplied to the plants in the next day. Ion concentrations of the individual ions periodically analyzed in the circulated nutrient solutions showed no significant differences among the treatments during the experimental period. Ion concentrations of $K^+$, $Ca^{2+}$, $Mg^{2+}$, $Na^+$, $NO_3{^-}$, ${SO_4}^{2-}$, ${PO_4}^{3-}$, and $Cl^-$ varied within 5-8, 11-14, 2.0-2.7, 0.5-0.6, 14-19, 4-5, 1-4, and 0.3-0.5 $meq{\cdot}L^{-1}$, respectively. Ion balance showed a consistent tendency over all the treatments and especially $K^+$ : $Ca^{2+}$ and ${SO_4}^{2-}$ : ${PO_4}^{3-}$ played great roles in the cation and anion balances in the nutrient solutions, respectively. Activity coefficients of ions such as $K^+$, $NO_3{^-}$, and $H_2PO_4{^-}$ varied within 0.8-0.9 and those of $Ca^{2+}$, $Mg^{2+}$, ${SO_4}^{2-}$ varied within 0.5-0.6, showing little changes with time. Ionic contributions of $K^+$ and $NO_3{^-}$ to EC reading were the greatest followed by $Ca^{2+}$, ${SO_4}^{2-}$, and $Mg^{2+}$ in the order. From the results, we thought that allowable ranges in ion concentration, ion balance, and subsequent individual ionic contributions to EC reading would be obtained within 4-week renewal interval of nutrient solution in EC-based closed-loop soilless culture for sweet pepper plants.