• Research in Plant Disease
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• v.24 no.2
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• pp.145-152
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• 2018

During 2015-2017, we surveyed the incidence of viral infections of tomato and paprika growing in greenhouses in Cherwon province, Korea. In 2015 and 2016, we collected leaves and fruits from tomato and paprika plants growing in greenhouses. We detected viruses in the samples collected using specific primer sets for Broad bean wilt virus 2 (BBWV2), Cucumber mosaic virus (CMV), Pepper mild mottle virus (PMMoV), Pepper mottle mosaic virus (PepMoV), and Tomato spotted wilt virus (TSWV). We detected PMMoV, CMV, and TSWV in the samples, and CMV and TSWV were the most prevalent. For the prevention of future viral diseases, we then surveyed the routes of infection by these viruses in tomato and paprika plants growing in greenhouses in Cherwon province in 2017. Leaf and fruit samples were collected from seedlings and crops two and four months after transplanting into greenhouses. As a result, we found that TSWV was transferred from seedlings to plants, and outbreaks of the virus occurred at the early stage of cultivation. On the other hand, we found that CMV was a virus indigenous to the soil of some towns in Cherwon province, and thus outbreaks of this virus occurred at the middle stage of cultivation.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.279-285
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• 2019

To estimate daily canopy photosynthesis, accurate estimation of canopy light interception according to a daily solar position is needed. However, this process needs a lot of cost, time, manpower, and difficulty when measuring manually. Various modeling approaches have been applied so far, but it was difficult to accurately estimate light interception by conventional methods. The objective of this study is to estimate the spatial distributions of light interception and photosynthetic rate of paprika with time by using 3D-scanned plant models and optical simulation. Structural models of greenhouse paprika were constructed with a portable 3D scanner. To investigate the change in canopy light interception by surrounding plants, the 3D paprika models were arranged at $1{\times}1$ and $9{\times}9$ isotropic forms with a distance of 60 cm between plants. The light interception was obtained by optical simulation, and the photosynthetic rate was calculated by a rectangular hyperbola model. The spatial distributions of canopy light interception of the 3D paprika model showed different patterns with solar altitude at 9:00, 12:00, and 15:00. The total canopy light interception decreased with an increase of surrounding plants like an arrangement of $9{\times}9$, and the decreasing rate was lowest at 12:00. The canopy photosynthetic rate showed a similar tendency with the canopy light interception, but its decreasing rate was lower than that of the light interception due to the saturation of photosynthetic rate of upper leaves of the plants. In this study, by using the 3D-scanned plant model and optical simulation, it was possible to analyze the light interception and photosynthesis of plant canopy under various conditions, and it can be an effective way to estimate accurate light interception and photosynthesis of plants.

• Horticultural Science & Technology
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• v.32 no.1
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• pp.46-52
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• 2014

This study was conducted to compare colony forming unit (CFU) of microorganisms in closed and open soilless culture systems for estimating the possibility for potential disease occurrence. Samples were collected at four different positions in four commercial greenhouses with closed or open soilless culture system using rock wool or coir as substrate, respectively. The distance between sampling positions was 3 cm starting from the substrate and the surface area of each position was $25cm^2$. The CFU of fungi was significantly higher in the open system, while that of bacteria was not significantly different but showed relatively lower in the closed system. Samples collected at the plastic surface of the substrates where little environmental effects occurred from drainage showed lower CFU than any other positions. The principal component analysis showed that samples collected on the drainage pathway highly affected the changes in microbial population in the greenhouse. These results indicated that greenhouses with closed soilless culture are expected to have more advantageous conditions for restraining the microbial growth, resulting in the lower potential of disease occurence in greenhouse ecosystem.

• Horticultural Science & Technology
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• v.30 no.6
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• pp.680-685
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• 2012

The objective of the experiment was to investigate the effect of two growing areas in the greenhouse on the plant growth characteristics, physiological responses and yield attributes of the 'Cupra' sweet pepper. Two growing areas of the greenhouse were as follows, central part area (CA) and north part area (NA). Daily average temperature of the CA was $1.6^{\circ}C$ higher than those of NA. Plant height, number of internode, and SPAD value in the CA were significantly higher than NA both six weeks and twelve weeks after planting. Net photosynthesis of the sweet pepper leaves of the CA was significantly higher than those of NA. The total fruit yield of the sweet pepper was 20% higher in plants grown for CA than that of NA. These results suggest that air temperature in the greenhouse influenced plant growth characteristics, net photosynthesis and total yield of sweet pepper whether pepper plants were grown as CA or as NA.

• Korean journal of applied entomology
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• v.40 no.2
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• pp.149-153
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• 2001

We surveyed on the host plants of Fungus gnat, Bradysia app. and found 21 species in the greenhouse and field. These are as follows: Cucumis sativus L., Cucumis melo L., Citrullus lanatus T., Cucurbita moschata F., Lycopersicon esculentum M., Capsicum annuum L (Pepper), Capsicum annuum L (Paprika), Lillium longiflorum T., Dianthus caryophyllus L., Rosa hybrida H., Gerbera jamesonii B., Chrysanthemum morifolium R, Phalaenopsis schilleriane R., Gladiolus grandiflours H., Zingiber officinale R., Cnidium officinale M., Canavalia gladiata DC., Angelica utilis M., Polygonatum odoratum D., Pinus densiflora S., and Pinus thunbergii P. Fungus gnat larvae cause damages to the root and promote decay and wilt by feeding on the roots and burrowing in plant tissue.

• The Korean Journal of Pesticide Science
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• v.9 no.4
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• pp.391-400
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• 2005

This study was undertaken to survey the pesticides used under the greenhouse cultivation of 9 vegetable crops including cucumber, tomato, strawberry, eggplant, hot pepper, paprika, lettuce, perilla leaves and green onion in the Southern area during the period of 2003-2004. The total number of farmers investigated was 202 which consisted of 124 conventional growers and 78 environment-friendly growers. The farmers were requested to record with respect to the crop's name, cultivation acreage, growing practices (conventional/environment-friendly), use purpose, pesticide kinds, usage quantity and application time of pesticides. The average usage quantity of pesticides for the 9 crops was 3.30 kg ai/ha in conventional growing and 0.47 kg ai/ha in environment-friendly growing. The average application time of pesticides was 11 times in conventional and 2 times in environment-friendly growing, with more than 90% cases as a foliar application. The number of active ingredients of pesticides was 34 in conventional and 10 in environment-friendly growing on the average per crop. The purpose of pesticide application was as a fungicide in 56% cases and as an insecticide in 43% cases.

• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.166-172
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• 2018

This study set out to conduct a field survey with smart greenhouse-based farms in seven types to figure out the actual state of smart greenhouses distributed across the nation before selecting a system to implement an optimal greenhouse environment and doing a research on higher productivity based on data related to crop growth, development, and environment. The findings show that the farms were close to an intelligent or advanced smart farm, given the main purposes of leading cases across the smart farm types found in the field. As for the age of farmers, those who were in their forties and sixties accounted for the biggest percentage, but those who were in their fifties or younger ran 21 farms that accounted for approximately 70.0%. The biggest number of farmers had a cultivation career of ten years or less. As for the greenhouse type, the 1-2W type accounted for 50.0%, and the multispan type accounted for 80.0% at 24 farms. As for crops they cultivated, only three farms cultivated flowers with the remaining farms growing only fruit vegetables, of which the tomato and paprika accounted for approximately 63.6%. As for control systems, approximately 77.4% (24 farms) used a domestic control system. As for the control method of a control system, three farms regulated temperature and humidity only with a control panel with the remaining farms adopting a digital control method to combine a panel with a computer. There were total nine environmental factors to measure and control including temperature. While all the surveyed farms measured temperature, the number of farms installing a ventilation or air flow fan or measuring the concentration of carbon dioxide was relatively small. As for a heating system, 46.7% of the farms used an electric boiler. In addition, hot water boilers, heat pumps, and lamp oil boilers were used. As for investment into a control system, there was a difference in the investment scale among the farms from 10 million won to 100 million won. As for difficulties with greenhouse management, the farmers complained about difficulties with using a smart phone and digital control system due to their old age and the utter absence of education and materials about smart greenhouse management. Those difficulties were followed by high fees paid to a consultant and system malfunction in the order.

• Journal of Biosystems Engineering
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• v.35 no.5
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• pp.343-349
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• 2010

Rapid on-site sensing of nitrate-nitrogen and potassium ions in hydroponic solution would increase the efficiency of nutrient use for greenhouse crops cultivated in closed hydroponic systems while reducing the potential for environmental pollution in water and soil. Ion-selective electrodes (ISEs) are a promising approach because of their small size, rapid response, and the ability to directly measure the analyte. The capabilities of the ISEs for sensing nitrate and potassium in hydroponic solution can be affected by the presence of other ions such as calcium, magnesium, sulfate, sodium, and chloride in the solution itself. This study was conducted to investigate the applicability of two ISEs consisting of TDDA-NPOE and valinomycin-DOS PVC membranes for quantitative determinations of $NO_3$-N and K in hydroponic solution. Nine hydroponic solutions were prepared by diluting highly concentrated paprika hydroponic solution to provide a concentration range of 3 to 400 mg/L for $NO_3$-N and K. Two of the calibration curves relating membrane response and nutrient concentration provided coefficients of determination ($R^2$) > 0.98 and standard errors of calibration (SEC) of < 3.79 mV. The use of the direct potentiometry method, in conjunction with an one-point EMF compensation technique, was feasible for measuring $NO_3$-N and K in paprika hydroponic solution due to almost 1:1 relationships and high coefficients of determination ($R^2$ > 0.97) between the levels of $NO_3$-N and K obtained with the ion-selective electrodes and standard instruments. However, even though there were strong linear relationships ($R^2$ > 0.94) between the $NO_3$-N and K concentrations determined by the Gran's plot-based multiple standard addition method and by standard instruments, hydroponic $NO_3$-N concentrations measured with the ISEs, on average, were about 10% higher than those obtained with the automated analyzer whereas the K ISE predicted about 59% lower K than did the ICP spectrometer, probably due to no compensation for a difference between actual and expected concentrations of standard solutions directly prepared.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.411-417
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• 2017

Environmental and growth factors such as light intensity, vapor pressure deficit, and leaf area index are important variables that can change the transpiration rate of plants. The objective of this study was to compare the transpiration rates estimated by modified Penman-Monteith model and artificial neural network. The transpiration rate of paprika (Capsicum annuum L. cv. Fiesta) was obtained by using the change in substrate weight measured by load cells. Radiation, temperature, relative humidity, and substrate weight were collected every min for 2 months. Since the transpiration rate cannot be accurately estimated with linear equations, a modified Penman-Monteith equation using compensated radiation (Shin et al., 2014) was used. On the other hand, ANN was applied to estimating the transpiration rate. For this purpose, an ANN composed of an input layer using radiation, temperature, relative humidity, leaf area index, and time as input factors and five hidden layers was constructed. The number of perceptons in each hidden layer was 512, which showed the highest accuracy. As a result of validation, $R^2$ values of the modified model and ANN were 0.82 and 0.94, respectively. Therefore, it is concluded that the ANN can estimate the transpiration rate more accurately than the modified model and can be applied to the efficient irrigation strategy in soilless cultures.

• Journal of Bio-Environment Control
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• v.26 no.1
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• pp.1-6
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• 2017

The paprika has emerged as one of the highest-income crops by increase in dimestic and export demand in the greenhouse crops. Nevertheless, there is no standard for fertigation in soil, because general culture system is soilless culture. This study was conducted to establish the optimum nitrogen and potassium application level for paprika fertigation. Four different levels of nitrogen and potassium were applied, treatment levels were 0.5, 1.0, 1.5, 2.0 times of pimiento fertilization recommendations based on soil testing. Experiment to instigate the optimum amounts of nitrogen and potassium were carried out in 2012 and 2013, respectively13. Nitrogen application : stem diameter of 0.5 times was significantly lower than other treatments, but stem length was not affected by nitrogen fiertigation levels. Number of fruit and yield of first fruiting group harvest were not significant difference. but those of the second fruiting group were decreased by increasing nitrogen level beyond 1.0 times treatment and were the lowest in 0.5 times treatment. Overall, the optimum level of nitrogen for fertigation was judged 1.0 times of pimiento fertilization recommendations based on soil testing. Potassium application : Growth was no signigicant trend except stem length. Number of locule, fresh thickness and sugar content were not significant difference. Number of fruit and yield were not significant difference at the first and second fruiting group harvest. But those were significant difference at third fruiting group harvest, maximum yield was obtained by 1.5 times fertigation level. The optimum level of potassium for fertigation was judged 1.5 times of pimiento fertilization recommendations based on soil testing.