• Korean Journal of Soil Science and Fertilizer
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• v.35 no.3
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• pp.153-161
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• 2002

The installation of subsurface drainage equipment is required for generalized use of paddy field and to improve soil productivity. The internal drainage of paddy field has improved root condition from the increasing of oxygen supply and removing noxious elements. This experiment was carried out to determine the effects of fertilization and drainage system on soil characteristic, growth and lodging trait of rice in paddy soil. A subsurface drainage system was installed a depth of 0.8m. Three fertilizer treatments were applied : 1) Conventional fertilized plot, 2) Controlled-release fertilized plot, 3) No-fertilized plot. In conventional plot, 110 kg N (as urea 46%), 45 kg P (as fused phosphate 20%) and 57 kg K (as potassium chloride 60%) per hectare fertilizers were applied. Controlled-release fertilizer was applied by 70% of N compared to the conventional plot. During the rice cropping, the water depth decrease was two times higher in subsurface drainage(SD) plot than non-drained(ND) plot. After harvesting of rice, the bulk density of sub-soil(10-20cm depth) was lower in SD plot than ND plot. After the experiment, the surface soil pH was high at SD plot but sub-soil was high at ND plot. Organic matter content was higher in all soil layer for SD plot than fro ND plot. Available $P_2O_5$ was not different between SD and ND plot for surface soil, but was high for SD plot for sub soil. The $NH_4{^+}-N$ content of soil, shoot dry matter, total nitrogen and $K_2O$ of rice plant were greater after panicle formation stage in SD plot. Total nitrogen content, $P_2O_5$ and $K_2O$ of rice root were high in SD plot after heading. Though the gravity center and 3rd internode length were greater, pulling force of rice root was higher in SD plot than ND plot. Rice yield in SD plot were low at conventional and controlled-release fertilized plot because of the greater field lodging, but yield in SD plot was high at no-fertilized plot. This study indicates that the fertilization level should be decrease on subsurface drainage system for rice cropping.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.383-390
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• 2014

This study was conducted to investigate the growth characteristics of cucumber scion and pumpkin rootstock under different levels of light intensity (photosynthetic photon flux, PPF) and plug cell size in a closed transplant production system with artificial lighting. Cucumber scion and pumpkin rootstock seedlings were grown under the combinations of three levels of PPF (PPF 165, 248, and $313{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and five types of plug tray (50, 72, 105, 128, and 200 cells in the tray) for nine days. The shoot dry weight and relative growth rate increased with increasing PPF and plug cell size. As PPF increased, cucumber scion and pumpkin rootstock seedlings had higher dry matter, lower specific leaf area, and lower hypocotyl length. The first true leaf of cucumber scion and pumpkin rootstock unfolded at eight and seven days after sowing, respectively, except the treatment using 200-cell plug tray. The unfolding of first true leaf of seedlings grown in 200-cell plug tray was delayed by one day. Accordingly, it was considered that the use of small cell size such as 200-cell plug tray would require more time for the production of scion and rootstock. Based on the results, we suggest that cucumber scion and pumpkin rootstock be grown in 105-cell to 128-cell plug tray for eight days and 72-cell to 105-cell plug tray for seven days, respectively, when using splice grafting method with root-removed rootstock. Additionally, higher PPF is suggested to improve the growth and quality of scion and rootstock.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.376-382
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• 2014

This work was conducted to investigate the variation of growth and yield among three generations ($TC_0$, $TC_1$, and $TC_2$) in the field cultivation of virus-free sweetpotato (Ipomoea batatas) plants. Virus-free generations of three cultivars ('Matnami', 'Shinhwangmi', and 'Yeonhwangmi') were cultivated with $75{\times}25cm$ planting density on May 20th, covered with black vinyl film. At 30 days after planting, vine growth in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant, and vine length in $TC_0$ showed the highest growth among treatments. At harvesting time after 120 days, vine diameter, number of node, and number of branch in $TC_0$, $TC_1$, and $TC_2$ were more increased than farmer's plant, but were not statistically significant. Fresh weight of shoot in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant, but was not statistically significant among generations or cultivars. Number of tuber per plant and mean weight of tuber in $TC_0$ and $TC_1$ showed significant increasement, but that in $TC_2$ did not show significant difference as compared to the farmer's plant. Weight of tuber per plant in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant. Marketable yield, percentage of marketable tuber, and percentage of small tuber (40 to 200g) in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant. The large tuber over 300g showed the lowest percentage in $TC_0$. Marketable yield in $TC_2$ was significantly decreased as compared to $TC_0$, and was not significantly different as compared to the farmer's plant. Marketable yield in 'Matnami' was highest among cultivars. From this results, Farmers are required to renew every three years to maintain the yield and quality of virus-free plants. However, the exchange period of virus-free plants is desirable to renew every 2 or 3 years according to the degree of virus reinfection.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.173-178
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• 2013

Experiments were conducted to investigate the optimum concentration of nutrient solution for strawberry 'Maehyang' bred domestically for exportation in hydroponics. Nutrient solutions for strawberry, which was made by Yamazaki, were supplied electrical conductivity (EC) 0.6, 0.8, 1.2, and $1.8dS{\cdot}m^{-1}$ after planting on cocopeat medium during the experiment period. Growth of shoot of strawberries did not show any statistical differences among treatments. Fruit length showed the longest in EC 0.8 and $1.2dS{\cdot}m^{-1}$, followed by 0.6 and $1.8dS{\cdot}m^{-1}$ in the first and third cluster. It showed the shortest in EC $1.8dS{\cdot}m^{-1}$ in the second cluster but there were no significant differences among treatments in the fourth cluster. Fruit diameter did not show significant differences among treatments in the first and second cluster but was the longest in the lowest concentration EC $0.6dS{\cdot}m^{-1}$ in the third cluster. The shortest was in EC $1.8dS{\cdot}m^{-1}$ in the fourth cluster. The heaviest mean fruit weight appeared in EC 0.8 and $1.2dS{\cdot}m^{-1}$, and the lightest was in EC $1.8dS{\cdot}m^{-1}$ in the first cluster and also lightest in EC $1.8dS{\cdot}m^{-1}$ but no significant differences was found among other treatments in the second & third cluster. Also the fruit weight was significantly light in plants grown in EC $1.8dS{\cdot}m^{-1}$ than $0.6dS{\cdot}m^{-1}$ in the fourth cluster. Soluble solids content of fruit was the highest in EC $0.6dS{\cdot}m^{-1}$ in all cluster. As a result, we came to the conclusion that the optimum EC for strawberry 'Maehyang' was EC 0.8 - $1.2dS{\cdot}m^{-1}$ during low temperature season. This result will be utilized as an indicator for strawberry hydroponics.

• Journal of Bio-Environment Control
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• v.26 no.3
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• pp.227-234
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• 2017

This study aimed to investigate the nutrient solution developed by based on nutrient-water absorption rate of strawberry 'Maehyang' by comparing growth and yield for 8 months with 5 kinds of nutrient solution with different ion composition. Strawberry plants were planted at elevated bed and supplied with five kinds of nutrient solutions (RDA), Yamazaki, PBG, University of Seoul (UOS) and NewUOS from one month onwards. Five types of nutrient solution were supplied to the strawberry plants associated with EC $1.0dS{\cdot}m^{-1}$, pH 6.0, $150{\sim}300mL{\cdot}plant^{-1}$ per day. At 60 days after planting, leaf width and leaf petiole of the strawberry plants showed significant differences among nutrient solution types and photosynthesis was higher in RDA and NewUOS nutrient solution and lower in PBG nutrient solution. The EC of the drainage on vegetative growth stage was $0.7{\sim}0.8dS{\cdot}m^{-1}$, which is lower than the supplied EC level, and to $1.0-1.2dS{\cdot}m^{-1}$, afterwards. The pH of the drainage was higher in Yamzaki solution as 6.2~6.8, while the pH of the UOS nutrient solution was lower in 5.1~5.2. Nitrate content was most absorbed in vegetative growth stage and after flower clusters development. The potassium uptake was highest at the NewUOS followed by UOS and Yamazaki nutrient solution. At six months after -planting fresh weight and dry weight of shoot and root were higher in UOS and NewUOS nutrient solution than other nutrient solutions, and the dry matter ratio was lower at 43.5% in Yamazaki nutrient solution and 30.6% in NewUOS nutrient solution than other solutions. Length, width, weight, and sugar content of the strawberries harvested from December to February were unaffected by treatment, but yield was higher in NewUOS nutrient solution due to increasing fruit number and average weight. From March to May, number of fruit was higher in Yamazaki nutrient solution. In conclusion, there was no difference in the growth of 'Maehyang' when 5 nutrient solutions were grown under hydroponics. But in order to improve the marketability, the NewUOS nutrient solution is appropriate to use from planting to February and it is suitable to use Yamazaki nutrient solution after March when temperature is high and the amount of fruit set per inflorescence.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.388-398
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• 2020

Watermelon yield mainly depends on soil water content controlled by irrigation in a plastic greenhouse. In this study, we investigated the effect of different soil moisture contents affected by irrigation starting point on growth, yield, and physiological responses of small-sized watermelons. Irrigation was initiated at 5 different levels of soil water content as a starting point with soil moisture detecting sensor after 14 days of transplanting, and stopped at 7 ~ 10 days before harvest. These treatments were compared with the conventional periodic irrigation as control. When soil had the lowest moisture content (-50 kPa), the overall shoot growth was retarded, but the root length and root dry weight increased. The photosynthetic parameters (photosynthetic rate, stomatal conductance, and transpiration rate) of watermelon leaves decreased significantly in the lowest soil moisture content (-50 kPa). On the other hand, the photosynthetic rates of watermelon leaves grown with irrigation starting point between -20 and -40 kPa were observed to be higher than those of other treatments. Fruit set rate and marketable fruit yield increased significantly at -30 kPa and -40 kPa. Proline, abscisic acid (ABA), total phenol and citrulline, which are known to contribute to stress tolerance under drought condition, increased as soil water content decreased, particularly, the largest increases were recorded at -50 kPa. From these results, it was found that an appropriate water supply adjusted with an irrigation starting point between -30 and -40 kPa could help to keep favorable soil water content during the cultivation of small-sized watermelons, promoting the marketable fruit production as well as inducing the vigorous plant growth and reproductive development.

• Ocean and Polar Research
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• v.27 no.2
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• pp.125-133
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• 2005

This study described the phonology and reproductive potential of four species of Korean seagrasses, Zostera caespitosa, Z. caulescem, Z. Japonica and Z. marina. Z. caespitosa and Z. caulescens sampled from a mixed stand at the subtidal area of Yulpo Bay, Geojedo of the South Sea of Korea in November 2002 and August 2003. Z japonica and Z. marina occurred at the depth between the middle intertidal and shallow subtidal (<1m below mean sea level) of Seungbongdo (in Yellow Sea) samples collected in February and October 2003. The sexual reproductive phase of the four Zostera species was apparently different in timing of flowering, reproductive period, fruiting and seed maturing. Z. caespitosa flowered from February to early May $(10-16^{\circ}C)$, and its seed production completed in early May. The reproductive shoots of Z. caulescens began to appear in January $(9^{\circ}C)$, and its flowering followed from February to June $(10-19^{\circ}C)$. The flowers of Z. japonica were observed from July to September $(18-22^{\circ}C)$, and its seeds matured from August to September. The most commonly I marina flowered from April to August $(7-21^{\circ}C)$ and developed into seeds in July. Z. caulescens, the largest plant, had the highest number of seeds per shoot and longest spadix length. Z. marina, which was intermediate In size, recorded the highest reproductive potential. The study indicates that the reproductive phase and potential of the four species of seagrass from Korea are highly related to water temperature, and the populations of these species show a perennial lifespan with a low sexual reproductive input.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.597-603
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• 1997

Orostachys japonicus, Wasong as herb medicine, has been artificially cultivated as an anti-tumor medicinal. The experiment was carried out to examine the effect of natural daylength as control or night-break treatment (NB) imposed at June 20, July 18 or Aug. 15 on its growth, dry weights of leaf and bract, stem, floret and root, and morphological characters including bolting and floret flowering. After a plant was grown in a 15cm plastic pot containing a 2 : 1 soil : peat moss mixture on May 23, three treatments with above differing night-break had been imposed around midnight up to Nov. 7. The plants were sampled 3 times at the same day forced to night-break and then done 6 times by 2-week interval after the final NB. Plant height and inflorescence length of all the NB increased with delayed NB but declined in comparison with the natural daylength. No. of leaves including bracts showed similar response to plant height although NB given before July 18 showed less leaves and bracts. Stem diameters of NB were continuously increased to middle Sept. to middle Oct. while that of natural daylength decreased after middle Oct. Natural daylength or NB given on Aug. 15 had greater fraction, shoot and total dry weights resulting from increment of leaf and bract up to Aug. or of floret, stem and root after Sept. The earlier NB, the later formation of florets and the less number of flowering florets whereas in natural daylength florets on inflorescence begun to be formed from middle Sept. were sharply increased up to middle Oct. when all the plants were flowered. Bolting was not formed in the plant of the earliest NB of June 20, and thereby no anthesis of florets up to early Nov. It was concluded that year-round cultivation of Orostachys japonicus plants was possible through controlling the NB timing because its bolting and flowering of florets separately occurred.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.132-137
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• 2011

BACKGROUND: This experiment was carried out to evaluate the effect of potassium fertigation on the growth and yield of fourteen years-old 'Campbell Early' grapevine (Vitis labrusca L.) on a sandy loam soil. METHODS AND RESULTS: Potassium application (125 kg/ha/yr) was top-dressed as 30% of annual potassium application in all treatments and the remainders were drip-irrigated with 0 (0% of total K, K0 level of the remainder), 25 (17.5% of total K, K1/4 level of the remainder), 50 (35% of total K, K1/2 level), and 100mg/L (70% of total K, K1 level) in the intervals of 2 times a week for 12 weeks and the effect of K drip fertigation was compared to control treatment in which the K remainder was applied with surface application as additional fertilizer. The growth of stem diameter, leaf number and shoot length were highest in K1/2 (50 mg/L K), but K of mineral contents was lowest in K0. Yield of grapevine was no difference in 2008, but significantly higher K1/2 than other treatments in 2009. However, fruit quality (color degree, brix, acid contents) was no difference among the treatment. CONCLUSION(s): From the results, It is expected that K1/2 levels of fertigation based on soil testing could be more efficient to get optimum yield and save potassium fertilizer than control (surface application) treatments when grapevine was drip-irrigated at open field condition.

• Journal of Plant Biotechnology
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• v.40 no.2
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• pp.79-87
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• 2013

The aim of this study was to establish plant regeneration from leaf explants of Sedum tosaense Makino, which is globally rare and endangered species. The leaf explants of S. tosaense were cultured on the MS medium supplemented with different concentration of BA and NAA for callus induction. Callus induction was showed the highest (100%) on MS medium containing $2.0mg{\cdot}L^{-1}$ BA and $1.0mg{\cdot}L^{-1}$ NAA. The highest number of shoots were regenerated when callus were cultured on MS medium containing $2.0mg{\cdot}L^{-1}$ BA and $1.0mg{\cdot}L^{-1}$ NAA for 5 weeks. The axillary bud were cultured on the MS media supplemented with combination of BA and NAA for in vitro propagation. The highest number of adventitious shoot (7.9 per explants) formed at $1.0mg{\cdot}L^{-1}$ NAA and $2.0mg{\cdot}L^{-1}$ BA. For rooting, MS medium supplemented with or without $2.0g{\cdot}L^{-1}$ activated charcoal was tested. The optimal results were observed using MS medium supplemented with $2.0g{\cdot}L^{-1}$ activated charcoal, on which 85.7 (No. of root), 4.6 cm (length of root). 1,200 ppm $CO_2$ and 350 ppm $CO_2$ were supplied for make certain the effects of $CO_2$ on pre-acclimatization by photoautotrophic culture. 1,200 ppm $CO_2$ treatment was established higher than 350 ppm $CO_2$ treatment. Soil acclimatization of in vitro plantlets was the best in mixture soil consisted of peat moss and perlite with 100% survival rate and they showed the maximum growth.