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http://dx.doi.org/10.12791/KSBEC.2022.31.4.409

Development of Continuous Monitoring Method of Root-zone Electrical Conductivity using FDR Sensor in Greenhouse Hydroponics Cultivation  

Lee, Jae Seong (Department of Horticulture and Breeding, College of Life Science and Biotechnology, Andong National University)
Shin, Jong Hwa (Department of Horticulture and Breeding, College of Life Science and Biotechnology, Andong National University)
Publication Information
Journal of Bio-Environment Control / v.31, no.4, 2022 , pp. 409-415 More about this Journal
Abstract
Plant growth and development are also affected by root-zone environment. Therefore, it is important to consider the variables of the root-zone environment when establishing an irrigation strategy. The purpose of this study is to analyze the relationship between the volumetric moisture content (VWC), Bulk EC (ECb), and Pore EC (ECp) used by plant roots using FDR sensors in two types of rockwool media with different water transmission characteristics, using the method above this was used to establish a method for collecting and correcting available root-zone environmental data. For the experiment, two types of rockwool medium (RW1, RW2) with different physical characteristics were used. The moisture content (MC) and ECb were measured using an FDR sensor, ECp was measured after extracting the residual nutrient solution from the medium using a disposable syringe in the center of the medium at a volumetric moisture content (VWC) of 10-100%. Then, ECb and ECp are measured by supplying nutrient solution having different concentration (distilled water, 0.5-5.0) to two types of media (RW1, RW2) in each volume water content range (0 to 100%). The relationship between ECb and ECp in RW1 and RW2 media is best suited for cubic polynomial. The relationship between ECb and ECp according to volume moisture content (VWC) range showed a large error rate in the low volume moisture content (VWC) range of 10-60%. The correlation between the sensor measured value (ECb) and the ECp used by plant roots according to the volumetric water content (VWC) range was the most suitable for the Paraboloid equation in both media (RW1, RW2). The coefficient of determination the calibration equation for RW1 and RW2 media were 0.936, 0.947, respectively.
Keywords
calibrated equation; FDR sensor; electrical conductivity (EC); moisture content (MC); rockwool; volumetric water content (VWC);
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