• The Journal of Engineering Geology
• /
• v.22 no.4
• /
• pp.387-398
• /
• 2012

Korean agricultural areas that employ water curtain cultivation (WCC) have recently suffered extensive groundwater shortages due to an increase in the number of facilities. The primary focus of this study is to measure the daily groundwater use and discharge rates in the Cheongweon and Chungju pilot areas, while the second focus is to estimate the total amount of groundwater used in WCC areas nationwide in Korea. Taking into consideration several factors, including motor type, outflow abilities of wells, records of daily minimum temperatures below $0^{\circ}C$, and the number of running wells according to weather variations, we estimated that $53,138m^3/ha$ of groundwater had been used in the 4-hectare Cheongweon pilot area during the winter period of late 2011 through early 2012. On a prorated areal basis, we can calculate that the total groundwater used nationwide was 0.57 billion $m^3$ in WCC areas of $10,746m^2$. This value is equivalent to 33.7% of the total agricultural groundwater use (1.69 billion $m^3$) in Korea. During 9-22 February 2012, the daily water discharge rate in the 4-ha Cheongweon pilot area ranged from 2,079 to $2,628m^3$, averaging $2,341m^3$. Combining this value with meteorological records for 94 days with a daily minimum temperature below $0^{\circ}C$ results in an estimated groundwater volume of $54,990m^3/ha$ for the pilot area during the 2011-2012 winter period. The total amount of groundwater used nationwide in WCC areas would then be 0.59 billion $m^3$, equivalent to 34.9% of the total agricultural groundwater use in Korea. In the Chungju area, the groundwater discharge rate was estimated to be less than 805 $m^3$/ha. This value, combined with weather data for 108 days with a daily minimum temperature below $0^{\circ}C$ in this area, can be applied to infer that the total groundwater volume used in WCC areas nationwide is no more than 55% of the total agricultural groundwater use in Korea.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.5
• /
• pp.500-507
• /
• 2016

This study was undertaken to improve the survival and early life growth rates of cold-water fish by culturing rotifer (Brachionus plicatilis) with low-temperature tolerance. The enrichment experiment was carried out at different temperatures and over different time intervals. Cultivation of the rotifer at low temperatures was repeated, with the selected and cultured as the water temperature was gradually lowered from $20^{\circ}C$ to $10^{\circ}C$. Enrichment of the rotifer was completed using A, S, SCV and SCP. Enrichment was carried out after 6, 12 and 24 hours at three different temperatures (10, 15 and $20^{\circ}C$). In the growth experiments, the rotifer increased to approximately triple their original size, from $350{\pm}7.9ind./ml$ to $1,064{\pm}5.7ind./ml$ at $10^{\circ}C$ over 50 days. The fatty acid composition of the four enrichment materials was species-specific, with the highest ratios belonging to eicosapentaenoic acid (EPA, C20:5n-3) and docosahezaenoic acid (DHA, C22:6n-3) in SCP. The fatty acid composition of the rotifers was affected by the enrichment materials. The EPA (% of total fatty acid) was more than 2 % in SCP, which showed a higher ratio than the other enrichment materials. DHA was higher in S reaching 12.40 % at $15^{\circ}C$ for 24 hours. The highest levels of EPA (3.09 %) and DHA (11.65 %) were obtained after the rotifers were enriched with S at $20^{\circ}C$ for 12hours.

• Horticultural Science & Technology
• /
• v.35 no.1
• /
• pp.1-10
• /
• 2017

We investigated growth, clove development, and photosystem II activity in garlic (Allium sativum L.) grown under different day/night temperature regimes using Soil-Plant-Atmosphere - Research (SPAR) chambers to determine the optimum cultivation temperature and to assess the impact of temperature stress on garlic. In the early stages of growth, plant growth increased markedly with temperature. At harvest time, however, the pseudostem diameter decreased significantly under a relatively low day/night temperature range ($14/10-17/12^{\circ}C$), suggesting that these temperature conditions favor regular bulb growth. At harvest time, the bulb diameter and height were great at $14/10-23/18^{\circ}C$, whereas the bulb fresh weight and number of cloves per bulb were greatest at $17/12-20/15^{\circ}C$. However, the number of regularly developed cloves per bulb was highest at the relatively low temperature range of $14/10-17/12^{\circ}C$, as were the clove length and fresh weight. The photochemical efficiency ($F_v/F_m$) and potential photochemical efficiency ($F_v/F_o$) of photosystem II in the leaves of garlic plants were higher at $14/10-20/15^{\circ}C$ and lower at temperatures below $14/10^{\circ}C$ or above $20/15^{\circ}C$, implying that the $14/10-20/15^{\circ}C$ temperature range is favorable, whereas temperatures outside this range are stressful for garlic growth. Furthermore, at temperatures above $20/15^{\circ}C$, secondary growth of garlic, defined as lateral bud differentiation into secondary plants, continuous growth of the cloves of the primary plants, or the growth of bulbil buds into secondary plants, was enhanced. Therefore, to achieve commercial production of fresh scapes and bulbs of garlic, it may be better to grow garlic at relatively low temperature ranges of $14/10-17/12^{\circ}C$.

• Journal of Bio-Environment Control
• /
• v.29 no.2
• /
• pp.110-119
• /
• 2020

This study investigates the improvement in the performance of a temperature and humidity measuring system developed by Company A using the Aspirated Radiation Shield (ARS). The shield has been used in the industry and its accuracy was verified recently. The study also experimentally examines the impact of the wind speed of the ARS device on temperature and humidity. The results are summarized as follows. Before the improvement of the system, the temperature of Company A's system was up to 10.2℃ higher than that measured by the ARS device, and the measured relative humidity was approximately 20.0% lower. After improving the system, the temperature and relative humidity of nodes 1 and 2 were found to be almost identical. The temperature deviations including the maximum, mean, and minimum temperatures between those measured in node 2 and by ARS were approximately 0.2 to 0.7℃, respectively; further, the values measured by ARS tended to be slightly lower or higher. In terms of relative humidity, the ARS measurements yielded values approximately 10.0% higher immediately after sunset; otherwise, the values were approximately 1.9% lower. Moreover, when node 1 was set to minimum-middle, middle-maximum, and maximum, the deviations including the maximum, mean, and minimum temperatures of nodes 1 and 2 were 0.1 to 0.4℃, 0.0 to 0.2℃, and 0.0 to 0.5℃, respectively. The deviations including the maximum, average, and minimum temperatures of the three points of node 1 and the ARS ranged from 0.2 to 0.5℃, 0.1 to 2.2℃, and 0.1 to 1.1℃, respectively, indicating that the temperature deviation according to the wind speed was negligible. In addition, considering the results of the previous study with those from this study, the optimal wind speed to improve the temperature deviation is considered to be in the range of 1.0~2.0 m·s^-1.

• Journal of Aquaculture
• /
• v.2 no.2
• /
• pp.91-106
• /
• 1989

Chlorella has been used as a very useful food for rearing rotifer which is an important live food for early stages of fish and crustancean larvae. But Chlorella does not grow well in higher or lower temperature such as during summer or winter season in this country. Therefore, cooling or heating facilities are needed for Chlorella culture during summer or winter, but it costs too much for the commercial scale fish farmers. To solve this problem, the growth rates of 34 different species of phytoplanktons were examined at the various levels of temperatures, salinites and light intensities to select suitable species as the food for rotifers for summer and that for winter. After the suitable species were selected, growth comparisons of rotifer groups which were fed the selected species of phytoplanktons against rotifer group fed Chlorella as a control were done. Fatty acid compositions of the selected phytoplanktons and rotifer groups which were fed these selected phytoplanktons were examined. It was revealed that Nannnochioris oculata was optimum for rotifers in summer season and Phaeodactylum tricornutum was suitable for that in winter season. The optimum temperature, salinity and light intensity for former phytoplankton were $28^{\circ}C$, $33\%_{\circ}$ and 5,000 lux and those for later were $10^{\circ}C$, $30\%_{\circ}$ and 8,000 lux, respectively. In the higher temperature condition, the growth of N. oculata fed rotifer group was better than Chlorella ellipsoidea fed group. In the lower temperature condition, however, the growth of Chlorella fed rotifer group was slightly better than P. tricornutum fed group. Between two selected phytoplanktons, N. oculata has the highest content of linolenic acid (18 : 3 $\omega$ - 3, $\omega$ - 6) which is essential fatty acid for marine fish larvae. A rotifer group which was fed this plankton also showed the highest linolenic acid content among the other rotifer groups.

• Korean journal of applied entomology
• /
• v.38 no.2
• /
• pp.123-128
• /
• 1999

Recently, entomopathogenic nematodes have received a considerable attention as biologicalcontrol agents. For in vitro cultivation, storage and transportation of nematodes, oxygen supply isextremely impotant due to its limited solubility and mass transfer problem. The oxygen uptake rates(OURs) of four different Steinernema species were measured in a 5L bioreactor at varying temperatures.The OURs of the Steinernema spp. were below 0.5 x mmolO'||'&'||' . min in the range of 13-17$^{\circ}$C. TheOURs (mmo102/L - min) of S. glaseri Dongrae and S. carpocapsae Pocheon strains were 0.4 x lo-', 0.75x lo-\ulcorner at 21$^{\circ}$C, 1.5 x lo-\ulcorner, 3.2 x 10-2 at 25"C, and 2.8 x lo-', 5.8 x lo-\ulcorner at 29"C, respectively. However,the OURs were not significantly altered by the agitation speed of 50-150 rpm. The specific oxygenuptake rates (qol) of S. glaseri NC, S. glaseri Dongrae, S. glaseri Mungyeong and S. carpocapsaePocheon strains were 0.3 x 0.5 x 0.3 x and 0.2 x mmolO~/cell min at 25"C,respectively. As the nematode size and temperature were increased, the qo, was also increased.the qo, was also increased.

• Journal of Bio-Environment Control
• /
• v.18 no.4
• /
• pp.326-331
• /
• 2009

This study was carried out to evaluate the effects of row cover materials supported by flexible FRP frames with three kinds of non-woven fabric, and five kinds of net in leaf vegetable cultivation. Leaf radish (Raphanus sativus L.), Chinese cabbage (Brassica rapa L. ssp. pekinensis) were sown on May 21, 2003, and leaf lettuce (Lactuca sativa L.) was planted at the same date in Agricultural Research Center for Climate Change, Jeju, Korea. Net coverings showed higher light transmittance than in non-woven fabric coverings. The average air and soil temperatures increased by $0.3{\sim}1.0^{\circ}C$ in net coverings and $0.5{\sim}3.0^{\circ}C$ in non-woven fabric coverings, respectively. There was no difference in relative humidity among the covering materials. All the vegetables showed higher growths and yields in non-woven coverings than in non-covering. The yields increased 81% in leaf lettuce, 58% in leaf radish, and 93% in Chinese cabbage, respectively. In addition, the insect damages were considerably reduced in the row covering plots than in the control, especially in non-woven fabric coverings.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.65 no.3
• /
• pp.192-198
• /
• 2020

Root extension is the most important growth change that occurs during cultivation. We analyzed growth changes according to young seedling age, temperature, and the degree of root cutting in order to identify factors affecting rooting after transplanting. Root cutting did not affect plant height growth rate, root growth rate was increased in plants that experienced root cutting, and 14-day-old seedlings exhibited a higher growth rate than 7-day-old seedlings. Growth temperature experiments revealed that elongation was high at 25℃ and 28℃, but tended to be low at 18℃, and root elongation was high at 22-28℃ for 7-day-old seedlings and 22-25℃ for 14-day-old seedlings. Nitrogen absorption decreased in the following growth temperature order: 25, 28, 22, 18℃, and differences in nitrogen absorption under different growth temperatures tended to be lower in 7-day-old seedlings. The amount of nitrogen taken up by roots did not differ significantly between the short root treatment and the control, and 7-day-old seedlings tended to start nitrogen absorption faster than 14-day-old seedlings. Root vitality was highest in short-rooted 7-day-old seedlings with 3 cm of root remaining, and vitality also tended to be high in short-rooted 14-day-old seedlings.

• Research in Plant Disease
• /
• v.25 no.4
• /
• pp.196-204
• /
• 2019

Rice panicle blast occurred severely in southern provinces of Korea in 2014. The proportion of panicle blast incidence area to cultivated area of rice were 11.0% and 14.6% in Jeollanam-do and Gyeongsangnam-do, respectively. To identify the causal factors of the outbreak, we investigated weather conditions in August, amount of cultivated area of mainly grown cultivars, and nitrogen contents in plants with different disease incidences in 2014. 'Saenuri,' 'Ilmibyeo,' 'Unkwang,' 'Dongjin 1 ho,' 'Nampyeongbyeo,' and 'Hwangkeumnuri' were mainly grown cultivars. Monthly average of daily air temperature in August 2014 was 3.2℃ and 3.1℃ less than 2018 in Haenam and Miryang, respectively. Rainfall in August 2014 was 70.0% and 42.0% greater than 2018 in Haenam and Miryang, respectively. The numbers of blast warning days in August calculated nationwide using a forecast model for blast infection were higher in 2014 than in 2018, and they were in high level throughout the country in 2014. Nitrogen contents in plant samples from high-incidence plots were significantly higher than those from low-incidence plots. Consequently, excessive use of nitrogen fertilizers was the main factor for the disease outbreak at the level of specific farms, in addition to the collective cultivation of susceptible cultivar, low temperatures and frequent rainfalls in August.

• Journal of fish pathology
• /
• v.6 no.2
• /
• pp.205-218
• /
• 1993

On the development of hirame(Paratichtys olivaceus) culture, outbreak of scuticociliata infection was reported to cause severe damage in Japan. To establish effective measures for isolation and cultivation of this ciliate, we tried to culture this pathogenic ciliate using medium for bacteria and fish cell lines in vitro. Scuticociliata from the brain tissues of infected fish was aseptically inoculated to CHSE-214 cells cultured in MEM-10 without antibiotic. Scuticociliata grew well and the number of ciliate reached $10^6\;cells/ml$ at temperatures of $15^{\circ}C$ to $20^{\circ}C$ for 10d. The number of ciliate cultured in the cell lines is 10 times higher than the numbers cultured in the liquid medium alone. This ciliata could be cloned by dilution method. Scuticociliata isolated could grow well on 42 different cell lines that were established from marine fish, warm freshwater fish, and salmonids. This ciliate could be preserved in liquid nitrogen for more than 6 months. Subsequently, we observed the optimal temperature and salinity for growth, and tested the sensitivities of this organism to formaldehyde, flagyl(Metronidazole), Ekuteshin(Combination compound of sulfamonometoxin and ormethoprim), and ozonixation. Optimal temperature for growth was $25^{\circ}C$ and salinity was 1.0 to 1.5%. Washed scuticociliata was killed by formaldehyde at the concentration of 50ppm for 10min, but was not completely killed even at a high concentration of 400ppm for 20min in MEM-5. Flagyl and Ekuteshin can inhibit the growth of scuticociliata at the concentration of 1,000 and $100{\mu}g/ml$ in MEM-10, respectively. More than 99% of this scuticociliata could be killed by ozonization at a dose equivalent to $1.0mg/\ell$ oxidant for 30sec in sea water. Isolated scuticociliata showed the pathogenicity to the cultured hirame by artificial infection(I. P. injection, $10^5\;cells$/fish). The number of scuticociliata in the water could be counted by most probable number(MPN) method using tissue culture, and the minimum detectable number was $1.8\;cells/\ell$. The number in the reservoir tank for water supply to the culture tank was 110 cells/l. After cleaning by elimination of the sediments from of the reservoir tank and disinfected with formaldehyde, number of scuticociliata decreased and was counted less than $1.8\;cells/\ell$ and infection rate of cultured hirame was decreased.