• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.836-841
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• 2012

Distributions and growth of submerged plants with water level were investigated in a flood control reservoir around Dongbok Lake. In adddition, the total amount of biomass and uptakes of plants per unit area ($m^2$) in the flood control reservoir were investigated. The total vegetation area was $156,871m^2$ in the Dongbok flood control reservoir ($209,160m^2$) before flooding. By July 11, the Dongbok flood control reservoir was flooded during rainy season except for upper area. Dominant plants were CRXDM (Carex dimorpholepis Steud), ECHCF (Echinochloa crusgalli), POLHY (Polygonum hydropiper L) and BROTE (Bromus tectorum L) which occupied 75% of the flood control reservoir. The total amounts of organic matter uptakes per unit area ($m^2$) with distribution rates by CRXDM, ECHCF, POLHY and BROTE under different submerged plants were 65.5, 6.8, 7.0 and 13.0%, respectively. The total amount of nitrogen uptakes per unit area ($m^2$) with distribution rates at different submerged plants were in the order of CRXDM ($1.30g\;m^{-2}$) > POLHY ($0.34g\;m^{-2}$) > BROTE ($0.30g\;m^{-2}$) > ECHCF ($0.25g\;m^{-2}$). The total amounts of phosphorus uptakes per unit area ($m^2$) with distribution rates at different submerged plants were great in the order of CRXDM (51.8%) > BROTE (17.7%) > POLHY (10.3%) > ECHCF (9.6%). Thus, the results of this study suggest that O.M, T-N and T-P by submerged plants in Dongbok Lake were strongly influenced at water quality in flood control reservoir.

• Journal of Radiation Protection and Research
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• v.22 no.3
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• pp.171-181
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• 1997

A mixed solution of $^{54}Mn$, $^{60}Co$, $^{85}Sr$ and $^{137}Cs$ was applied to the soil of culture boxes in a greenhouse 2 days before transplanting red pepper and at 3 different times during its growth for investigating transfer factors ($m^2/kg-dry$) for its green and red fruits. Transfer factors varied with radionuclide, application time and harvest time by factors of about $20{\sim}100$. They decreased mostly in the order of $^{85}Sr>^{54}Min>^{60}Co>^{137}Cs$ while $^{54}Mn$ and $^{60}Co$ was higher than $^{85}Sr$ when time lapse between application and harvest was short. Transfer factors of $^{85}Sr$ and $^{137}Cs$ at the last application were lower than those at the previous one by factors of $3{\sim}20$ depending on harvest time. Variations in $^{54}Mn$ and $^{60}Co$ transfer factors with application time after transplanting were comparatively low. Transfer factors of $^{54}Mn$, $^{60}Co$ and $^{85}Sr$ mixed with topsoil before transplanting were up to $3{\sim}9$ times higher than those for the application onto soil surface 2 days after transplanting while there was no difference in $^{137}Cs$. The present results can be referred to in estimating root-uptake concentrations of the radionuclides in red pepper fruit and taking proper measures for its harvest and consumption at the event of an accidental release during the growing season of red pepper.

• Journal of Bio-Environment Control
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• v.25 no.1
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• pp.63-70
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• 2016

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 for tomato (Solanum lycopersicum L. 'Samsamgu') cultivation in a commercial hydroponic farm during spring to summer cultivation. This study was performed for minimizing effluent from coir substrate hydroponics using a frequency domain reflectometry (FDR) sensor-automated irrigation, as compared with an integrated solar-radiation (IR) and conventional timer-irrigation (TIMER) after transplanting. In results, no significant difference in daily irrigation volume was found among the treatments until 88 days after transplant (DAT). However, during the 88 to 107 DAT, the daily irrigation volume was in the order of IR (2125 mL) > TIMER (2063 mL) > FDR (1983 mL), and during the 108 to 120 DAT, it was in the order of IR (2000 mL) > TIMER (1664 mL) > FDR (1500 mL). The lowest drainage volume was observed in the FDR treatment with the order of IR (12~19%) > TIMER (4~12%) > FDR (0~7%) during the entire growing period. A lower irrigation volume in the FDR treatment after 88 DAT may be due to the sensor's detecting capacity for less water absorption by plant after completing fruit maturity with apical pruning and removal of lower leaves, while a higher irrigation volume in the IR treatment may be due to gradual increase in integrated solar-radiation amount as closer to summer season. There was no significant difference in plant growth and fruit yield among the treatments; however, a 11% and 18% of higher soluble sugar content was observed in the FDR than that of TIMER and IR treatment. respectively.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.244-252
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• 2009

This research aims at comparison of climatic conditions of sweet pepper's greenhouse between Korea (KOR) and the Netherlands (NL) to find out the reason of much lower yield in KOR than NL focus-ing on greenhouse climatic conditions. Hence, greenhouse climate data were obtained from each one commercial glasshouse in both countries. The crops (cv. 'Derby') were grown on rockwool slab with two stems per plant with 3.75plants/$m^2$ in KOR and three stems per plant with 2.5plants/$m^2$ or four stems per plant with 1.875plants/$m^2$ in NL. Even though plant density was differed but stem density was on the same to 7.5stems/$m^2$. There was no significantly difference on weekly growth of sweet pepper plant both countries, whereas harvested nodes to whole nodes of NL's plant was more than two times higher compared to KOR. The averaged daily global radiation during the whole growing periods was 14.5MJ/$m^2$/day in KOR and l2.1MJ/$m^2$/day in NL. Averaged 24h temperature was similar to both glasshouse as $21.6^{\circ}C$ in KOR and $21.2^{\circ}C$ in NL during the whole growing periods, however the variance was higher in KOR than NL. Humidity deficit (HD) was observed higher in KOR during the whole growing periods. Averaged day $CO_2$ concentration was measured contrary pattern in both countries because of heating to greenhouse on NL winter season. Averaged 24h temperature and day $CO_2$ concentration to daily global radiation was regular pattern in NL, whereas there are large scatter in KOR. Consequently, more irregular greenhouse climate condition in KOR could be induced irregularly crop growth.

• Korean Journal of Plant Resources
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• v.31 no.5
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• pp.489-497
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• 2018

In Korea, common and Tartary buckwheat are cultivated mainly in spring and fall, however the available buckwheat varieties are still very limited. In this study, we have evaluated buckwheat germplasm for agronomic traits and compared flavonoids contents in different cultivation period and collection area. In common buckwheat, the number of days from sowing to flowering was 40 and 31 days and from sowing to maturity took 90 and 69 days in spring and fall cultivation, respectively. The number of nodes and branches were higher in spring cultivation while the hundred seed weight was higher in fall cultivation. The average flavonoids contents in common buckwheat were 0.20 mg/g dry weight (DW) and 0.40 mg/g DW in spring and fall cultivation, respectively. The highest flavonoids content was detected in Jeonnam accessions with 0.29 mg/g DW and 0.43 mg/g DW during spring and fall cultivation, respectively. The flavonoids contents were varied from 1.5 to 2.5 times according to the collection area. These results suggest that the agronomic traits and flavonoids contents were vary depending on the cultivation environment and germplasm collection area. Therefore, it is necessary to select the material by considering the characteristics of the germplasm for breeding of new varieties.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.517-524
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• 2014

As an assessment of substantial equivalence and environmental risks of branchless chrysanthemum GM lines (LeLS69, LeLS76, LeLS80) developed in Korea, we investigated their degree of branchlessness and developmental characteristics including growth and flowering, as well as the stability of populations of insect pests and soil microbes. The GM lines were compared with a control variety, 'Jinba'. LeLS80 showed the highest level of branchlessness among the three GM lines, whereas abnormal axillary buds developed in lines LeLS76 and LeLS69. There were no significant differences between the growth characteristics of 'Jinba' and the GM lines. The branchlessness LeLS80 was increased during the summer season, suggesting that it is a useful germplasm for developing elite branchless cultivars. These GM lines showed no significant differences in the occurrence of five insect pests including aphids, mites, leaf miners, thrips, and whiteflies. Similarly, for soil microbes including bacteria and actinomycetes, there were no significant differences between 'Jinba' and the GM lines. However, there was a higher occurrence of fungi in the GM lines compared to 'Jinba'. Our findings suggest that 'Jinba' and the GM lines are substantially equivalent, although further monitoring studies are needed to confirm this.

• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.2
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• pp.86-92
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• 1989

This experiment was conducted to find out the effect of soil improvement on the changes of soil physical properties and the silage yield of corn in the newly-reclaimed sloped land. Corn (Suweon 19) was cultivated under the six different treatments at Songjeong loam, 20 percent slope, during 1985 to 1987 and various soil physical properties and silage yield were investigated. Growing Degree Days of corn during the growing season were $820.6^{\circ}C$ in 1985, $810.2^{\circ}C$ in 1986, and $812.4^{\circ}C$ in 1987. The changes of soil bulk density were high variances by different treatments in 1st year, but sluggish in 2nd year. In 3rd year, the control plot was the highest, but the integrated improvement plot was the lowest than the other plots. Soil hardness was reduced in subsoiling and integrated improvement plot with deep plowing, and water stable aggregates and air permeability were higher in these plots. Moisture retention was no differences between treatments. Dry matter yield of corn was decreased in the 2nd year than the 1st year, but increased in the 3rd year. Increasing ratio of yield was in the order of integrated improvement > subsoiling > lime > phosphate > compost > control plot. Correlation among the dry matter yield and soil physical properties were significant at 1%, but moisture retention of soil was not significant at 5%.

• Journal of Radiation Protection and Research
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• v.20 no.4
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• pp.255-263
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• 1995

Root uptakes of $^{54}Mn,\;^{60}Co,\;^{85}Sr\;and\;^{137}Cs$ by rice were studied through a greenhouse experiment in which the upper 20 cm of the culture box was filled with an acidic loamy-sandy soil and a mixed solution of the radionuclides was applied to the surface water on the soil 2 days before, and 5 different times after, transplanting. Percent uptakes of the radionuclides to rice tops varied $3.4{\sim}13.7%,\;0.03{\sim}0.1%,\;0.6{\sim}1.5%,\;0.02{\sim}0.15%$, respectively, with application time. Among radionuclides, soil-to-plant transfer factors decreased, on the whole, in the order of $^{54}Mn>^{85}Sr>^{60}Co{\geq}^{137}Cs$, and among plant parts, in the order of straw > chaff > hulled seed. Transfer factors $(m^2/kg-dry)$ in hulled seed were, depending on application time, $1.2{\times}10^3{\sim}5.0{{\times}10^3\;for\;^{54}Mn,\;1.6{\times}10^5{\sim}2.6{\times}10^4\;for\;^{60}Co,\;1.1{\times}10^4{\sim}7.6{\times}10^4\;for\;^{85}Sr\;and\;5.2{\times}10^5{\sim}7.0{\times}10^4\;for\;^{137}Cs$. The highest factors of all the radionuclides in straw came from the application at 67 days after transplanting while those of $^{54}Mn,\;^{60}Co\;and\;^{85}Sr$ in hulled seed appeared at later applications. The data from this studv can be referred to in assessing the radiological impact of an accidental contamination during the rice growth.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.87-90
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• 2013

The average annual and winter ambient air temperatures in Korea have risen by $0.7^{\circ}C$ and $1.4^{\circ}C$, respectively, during the last 30 years. Due to climate change, the occurrence of abnormal weather conditions has become more frequent, causing damage to vegetable crops grown in Korea. Hot pepper, chinese cabbage and radish, the three most popular vegetables in Korea, are produced more in the field than in the greenhouse. It has been a trend that the time for field transplanting of seedlings is getting earlier and earlier as the spring temperatures keep rising. Seedlings transplanted too early in the spring take a longer time to resume the normal growth, because they are exposed to suboptimal temperature conditions. This experiment was carried out to figure out the change of cellular tissue of chinese cabbage under the condition of low temperature to provide the information regarding the coming climatic change, on the performance of 'Chunkwang' chinese cabbage during the spring growing season. In our study, plant height, number of leaf, chlorophyll and leaf area was lower at the open field cultivation than heating house treatment after transplanting 50 days. Especially in fresh weight, compared with heating treatment, open field and not heated treatment were notably low with the 1/3 level. Of damage symptoms due to low temperature cabbage leaves about 10 sheets when $-3.0^{\circ}C$ conditions in chinese cabbage was a little bit of water soaking symptoms on the leaves. $-7.4^{\circ}C$ under increasingly severe water soaking symptoms of leaf turns yellow was dry. Microscopy results showed symptoms of $-3.0^{\circ}C$ when the mesophyll cell of palisade tissue and spongy tissue collapse, $-7.4^{\circ}C$ palisade tissue and spongy tissue was completely collapsed. The result of this study suggests that the growers should be cautioned not to transplant their chinese cabbage seedlings too early into the field, and should be re-transplanting or transplanting other plants if chinese cabbage are exposed to suboptimal temperature conditions ($-3.0^{\circ}C$ or $-7.4^{\circ}C$).