• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.181-187
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• 2002

The overall objective of this study was to improve tomato fruit quality, while maximizing yield. The variety of 'Momotaro' was grown in the basic nutrient solution of 1.6 dS.m$^{[-10]}$ which was supplemented by three levels of seawater with EC 1.0, 2.0 or 3.0 dS.m$^{[-10]}$ . Tomato plants were cultivated in cool seasons. Plant growth characteristics were compared between treatments, and fruits were classified to analyse fruit quality characteristics according to ripening stages： MG, Br, Br＋3, Br＋5, Br＋7 and Br＋10. Adding seawater generally did not affect the shoot growth parameters such as plant height, leaf length, leaf width, internode length and chlorophyll content. Adding seawater negatively affected yield parameters such as the height and weight of fruit, marketable fruit weight per plant and marketable fruit yield. Therefore, the more yield reduction was obtained with the increasing level of seawater treatment. Fruit quality was improved by seawater treatment. The degree of the effect for $^{\circ}$Bx degree and sugars were the highest with the EC of seawater 2.0~3.0 dS.m$^{[-10]}$ , and at the Br＋5~Br＋7 of ripening stages. The relative abundance of tomato flavor, volatile components, was not generally affected by the seawater treatment with an exception of 6-methyl-5-hepten-2-one. The relative abundance of most volatile components increased as ripening progressed. The increment began at the Br stage and showed the highest increment at the Br＋5~Br＋7 stages. The results from these experiments suggest that seawater treatment of EC 3.6 dS.m$^{[-10]}$ for hydroponics is good for improving tomato quality. Fruit quality is the best at the Br＋5~Br＋7 ripening stages. It is considered that these results may be applied far use in hydroponic culture to improve fruit quality with minimum yield reduction.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.247-252
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• 2011

Electrical conductivity, drainage, and irrigation amount of nutrient solution are important factors for determination of the mixing ratio of fresh and reused nutrient solutions in closed-loop soilless culture. Generally a fixed mixing ratio is applied in commercial scale greenhouses using solar radiation-based irrigation system. Although it ensures continuous supply of fresh nutrient solution in the mixing process, occasional discharge of the drainage is inevitably required. This study was conducted to compare the nutrient replenishing effect under different mixing processes and to investigate appropriate mixing process. For this experiment, a fixed mixing ratio (FR), modifiable mixing ratio (MR), and open-loop (OP) as control were applied. Mixing ratio was determined by a set value of EC for dilution of collected drainage in FR and the set values of 1.0 and $2.0dS{\cdot}m^{-1}$ were used as treatments (FR 1.0 and FR 2.0), respectively. In MR, mixing ratio was determined based on EC and volume of drainage within irrigation volume per event. The volume of drainage stored in the drainage tank tended to increase in FR 1.0. Although such trend was not observed in FR 2.0 and MR, the volume of drainage stored in MR was lower than that in FR 2.0. The ion balance of $Mg^{2+}:K^+:Ca^{2+}$ or $SO^{2-}_4:NO^-_3:PO^{3-}_4$ in the drainage and reused nutrient solution changed within a narrow range regardless of treatment.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.348-353
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• 2009

Organic materials reveal the remarkable absorption and high buffer capacity for nutrient. Hence, organic materials need some different nutrient management skill from inorganic one. The objective of this study was to evaluate the effect of EC level of nutrient solution on the yield and quality of cut rose grown in the mixed substrate of coir and perlite. 3 EC levels of nutrient solution was treated, which were 0.7, 1.0, 1.3 times of standard solution (Aichiken solution, Japan) for cut rose hydroponics. EC of the standard solution was changed by season following as 1.4 (Apr.~June), 1.0 (July~Aug.), 1.4 (Sep.~Oct.), and $1.6dS{\cdot}m^{-1}$ (Nov.~Mar.) subsequently. The supply of nutrient solution was controlled by the signal of water potential at -5kPa using frequency domain reflectometry (FDR) sensor. As the results, marketable yield was similar for all treatments until 3rd harvest, but was decreased in high EC level from 4th harvest to 7th harvest as final. 0.7 times of standard solution decreased the ratio of unmarketable rose having short stem below 70cm and increased the ratio of high quality rose having long stem above 91cm. The flower weight and stem diameter of cut rose was higher in the low EC treatment than the others.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.432-436
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• 2002

This study was conducted in 2001 to determine the influence of seed-piece size (SPS) and number (SPN) per mini-tuber produced by hydroponics on growth and yield of potato (Solanum tuberosum L.). Treatments consisted of the combination of six SPS (3, 5, 7, 9, 11, 13g/seed-piece) and four SPN (whole tuber, and two, three, and four pieces/tuber). Percentage sprout emergence at transplanting was higher for seed pieces weighing 7 to 13 g (83.0 to 85.4%) and for three and four pieces per tuber (85.4 and 84.8%). As SPS were increased from 3 to 9 g/piece, total yields markedly increased from 2,052 to 2,924 kg/10a and seed tuber (31 to 250 g) yield from 1,589 to 2,428kg/10a with no further increase with SPS. As SPN was increased from one to three/ tuber, total yields increased from 1,918 to 2,982 kg/10a and seed tuber yields from 1,422 to 2,579 kg/10a with no further increase with SPN. Average tuber weight increased with SPS (46.3 to 71.5 g/tuber) and SPN (56.5 to 64.9 g/tuber).

• Horticultural Science & Technology
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• v.28 no.6
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• pp.1072-1077
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• 2010

Plant diseases including gray mold caused by Botrytis cinerea are often reduced when calcium compounds are used as alternative materials in paprika. However, much less information is available about the effects of calcium compounds on controlling of $B.$ $cinerea$. Seven calcium compounds such as calcium sulfate dihydrate, calcium chloride, calcium nitrate, calcium oxide, calcium hydroxide, calcium carbonate, and calcium hydride were evaluated for their effectiveness against $B.$ $cinerea$ on potato dextrose agar medium. The pH of selected calcium compounds was higher (pH 8.2-10) than that of the control (pH 6.6). Calcium carbonate, calcium oxide, calcium hydride, and calcium hydroxide among seven calcium compounds were more effectively inhibited the growth of $B.$ $cinerea$ than other calcium compounds. In the case of spraying the spore suspension on paprika applied with the selected four calcium compounds and supplied with the selected calcium supplements in a hydroponic culture system, the paprika treated with calcium compounds showed less severity of disease than those untreated plants. On the basis of our results, we propose that the suppressive effects of calcium compounds on $B.$ $cinerea$ in paprika resulted from the supply of calcium and a certain degree of salt stress.

• Journal of Bio-Environment Control
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• v.12 no.2
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• pp.89-94
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• 2003

This study was conducted to identify the effect of recycling method of drained solution on the concentration of drained solution, and growth and yield of tomato in the recycling system. The recycling methods of drained solution were composed of control, MEC (measurement of EC) and ANS (analysis of nutrient solution). The plant height in the early growth stage was not different among the treatments, but plant fresh weight and dry weight were higher in the MEC or the ANS than in the control. The growth including fruit number, fruit weight, and yield of tomato in the ANS as compared with the control was favorable. The EC of drained solution tended to decrease in the early growth stage, but that of drained solution increased in the late growth stage. It was low in the MEC and the ANS as compared with the control. The pH of drained solution was maintained by 6.2 to 6.5 throughout the growth period in the MEC and the ANS, but the pH of the control increased up to 7.2 at the late growth stage. The N and K concentrations of drained solution tended to decrease in the early growth stage, while those of P, Ca and Mg increased. In the late growth stage, concentrations of N, P, Ca and Mg tended to decrease, but that of K in the ANS was very low. Concentrations of N, P, K, Ca and Mg were lower in the MEC and the ANS than in the control.

• Journal of Bio-Environment Control
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• v.5 no.1
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• pp.65-70
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• 1996

Water potential which is an physical chemistry and thermodynamic indicator expressed water status of plant root, stem and fruit could be use as a useful indicator for growth control of hydroponically grown muskmelon plant. Linear relationship was observed between EC and water potential of nutrient solution, consequently increment of EC related to the decreasing water potential and resulted with the alteration of water potential and solute potential of upper leaves. Rapid reduction in growth was observed in over 5${\mu}{\textrm}{m}$ of Cu concentration in the media and same tendency was recorded in the shoot fresh weight, root dry weight and chlorophyll content. Increment of Cu concentration in the nutrient solution leads to lower the growth rate and then the water potential of upper leaves. Turgor pressure was not affected the growth of hydroponically grown muskmelon and also Cu concentration of nutrient solution was not recognized the direct relationship to the growth characteristics of muskmelon. These results demonstrated that water potential of nutrient solution can be use as an useful indicator for water physiological comparison of plant growth in hydroponically grown muskmelon.

• Journal of Bio-Environment Control
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• v.16 no.1
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• pp.13-20
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• 2007

This study was conducted to collect the basic data fo the development ot hydroponic technique and the efficient promotion of water culture. We have also analysed the water culture associated domestic patent application informations searching for on-line internet site with an admission fee (http://www2.wips.co.kr) from the year 1983 to January, 2006. Fifty nine patent applications related to the hydroponics were searched for in this study. Main patent contents applied were as followed in the order of that nineteen applications about the hydroponic equipments by 32.2%, thirteen applications about the materials used in water culture by 22.0%, eleven applications about the composition of nutrient solution by 18.6%, nine applications about the cultural methods by 15.3%, and seven applications about the cultural media by 11.9%. The compositions of nutrient solution and the cultural methods intended for specific crops were increased in number following five applications about tomato plants and four applications about potatoes. Thirty three patents (55.9%) were mainly applied before the year 2000. Main patent contents were the compositions of nutrient solution before the year 2000 in contrast to the cultural methods and substrates after the year 2000.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.1
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• pp.31-37
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• 2010

Two field experiments were carried out in 2002 to evaluate effects of the sizes of tubers produced through a wick-based hydroponics on growth and yield of seed potatoes (Solanum tuberosum L. 'Dejima'). Nine sizes of seed tubers (<1, 1~3, 3~5, 5~7, 7~10, 10~20, 20~30, 30~50, and 50~80 g) were used in spring crop. In fall crop, however, tubers except for the 1 g and 50~80 g wereused with tubers 7 and 15 g produced through aeroponics. Emergence rate greatly increased as tuber size was increased up to 10~20 g and then leveled off in both croppings. The number of days from planting to emergence in spring crop was about 34 days regardless of tuber size, while that in fall crop decreased from 34 to 16 days as tuber size increased from 1~3 to 30~50 g. The number of stems per plant, stem length and diameter, and leaf size tended to increase with tuber size. As the seed tuber size increased up to 10~20 g, the number of tubers per plant, average tuber weight, total and seed tuber yields linearly increased and then slowly increased with seed tuber size. Total and seed potato yields were not significantly different between tubers produced through a wick-based hydroponics and an aeroponics when similar sized tubers were planted in the fall cropping.

• Horticultural Science & Technology
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• v.35 no.1
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• pp.30-37
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• 2017

This study was conducted to determine the effects of various growth substrates on the growth and flowering of hydroponically grown Freesia hybrid 'Gold Rich'. Perlite, peat moss and a perlite: peat moss mixture (1 : 1 ratio, v / v) were used as the growing media. The greatest plant height before flower bud differentiation was attained using mixed medium compared to the others. The type of medium used did not influence leaf number, mineral content or SPAD value in leaves. Flowering began at 137 days after planting in mixed medium, which was 13 days earlier than in perlite medium. The whole plant fresh weight was 21.3 g heavier in mixed medium than in perlite medium (40.9 g). A similar result was obtained for shoot length, with the highest value (96.6 cm) obtained in mixed medium, i.e., 20 cm higher than in perlite medium (76.6 cm). Floret number per plant was also the highest in mixed medium (14.4), i.e., 1.7 - times higher than in perlite medium. Therefore, among the substrates tested in this experiment, we recommend using mixed perlite: peat moss medium (1 : 1 ratio, v / v) for hydroponic culture of freesia, as the use of this medium improved the physical properties of the plants, producing the best results in terms of plant growth and cut-flower quality.