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Pohang, South Korea

Choi E.-Y.,Korea University | Yoon Y.-H.,68 Chungwondae ro | Choi K.-Y.,Kangwon National University | Lee Y.-B.,University of Seoul
Horticulture Environment and Biotechnology | Year: 2015

Open hydroponic systems are the most widely used hydroponic systems in Korea. However, water drainage from the open hydroponics often causes significant environmental pollution due to agrochemicals and loss of water and nutrients. The objectives of this study were to show the potential application of an irrigation schedule based on threshold values of volumetric substrate water content tomato (Solanum lycopersicum L. ‘Betatini’) cultivation in a commercial hydroponic farm. This study was performed for minimizing effluent from coir substrate hydroponics using a frequency domain reflectometry (FDR) sensor-automated irrigation (FAI), as compared with conventional timer-irrigation (TIMER) from the farmer’s experience. The irrigation volume and retained water volume in the substrate of the TIMER during autumn to winter cultivation were 6.1-fold and 2-fold higher, respectively, than those of the FAI with slightly higher fruit weight and no difference in plant growth in the TIMER. This resulted in 1.9-fold higher water use efficiency (WUE) in the FAI. The irrigation volume and retained water volume in the substrate of TIMER during spring to summer were 3.2-fold and 1.8-fold higher, respectively, than those of the FAI with no difference in fruit weight or plant growth between the two treatments, which led to a 1.9-fold higher WUE in FAI. Approximately 61% fertilizer cost savings and a substantial decrease in drained solution volume were observed for FAI compared to those with TIMER. The use of the FAI technique for a least-drainage hydroponic system can be achieved in a large-scale hydroponic farm, resulting in efficient and environmentally sustainable use of water and fertilizer. © 2015, Korean Society for Horticultural Science and Springer-Verlag GmbH. Source

Choi E.-Y.,Korea University | Park H.-I.,68 Chungwondae ro | Ju J.-H.,68 Chungwondae ro | Yoon Y.-H.,68 Chungwondae ro
Horticulture Environment and Biotechnology | Year: 2015

This study was performed to investigate boron (B) distribution within various parts of tomato plants (Solanum lycopersicum L. ‘Super Momotarou’) grown under either B supply (adequate, 0.5 mg·L−1) or no B (0 mg·L−1) condition. The objective was to examine how B supply affects plant growth, photosynthetic activity and the morphological response of the entire root system. When the plants were grown for 36 days under the B supply treatment, B concentration was greatest in the order of the leaf (54.3 μg·g−1), fruit cluster (27.8 μg·g−1), petiole (24.7 μg·g−1), and stem (14.1 μg·g−1). However, B deficient supply altered the B distribution so that the greatest concentration was found in the stem (7.82 μg·g−1); then the petiole (8.20 μg·g−1), the fruit cluster (5.5 μg·g−1), and lastly in the leaf (4.11 μg·g−1). No B treatment resulted an approximately 46% decrease in the calcium content of the leaf and an 87% decrease in the potassium content of the fruit cluster. No B treatment also led to a severe decrease in photosynthetic rate, stomatal conductance and transpiration, with an increase in the water vapor saturation deficit at the leaf surface. Microscopic investigation of the stomata 36 days after transplant revealed that a majority of the stomata in the epidermal layer of B-deficit leaves were closing. The total dry weights of the leaves, leaf petioles and stems of B-deficit leaves decreased by 36, 43, and 27%, respectively, at 22 days after transplant, and decreased by 60, 69, and 60%, respectively, at 36 days after transplant, compared to the values for the B-sufficient leaves. A 10-fold lower fruit cluster dry weight was also observed in the B-deficit plants. Under no B supply, the total root length at 35 days after transplant decreased by about 56%, while the average root diameter increased by 20%. This was associated with a significant decrease in the root length, which ranged between 0 and 0.2 mm in diameter, alongside a significant increase in the root length, which ranged larger than 0.9 mm in diameter. One explanation for this finding is that limited B availability leads to a lack of translocation of B to the leaf and reproductive tissues, and this alteration of B partitioning may then affect fruit quality as well as root growth. An improved understanding of B partitioning in plant tissues may help to improve B management and, in the long term, improve crop yields. © 2015, Korean Society for Horticultural Science and Springer-Verlag GmbH. Source

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