• Journal of Bio-Environment Control
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• v.23 no.3
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• pp.229-234
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• 2014

We analyzed drainage water from coir substrate in which cucumber plants were grown in winter and elucidated changes in pH, EC, and major nutrients according to the growth stages to recommend nutrient solution management appropriate to each growth stage. From the analysis of drainage solution the growth stages of cucumber were desirable to be divided into two, planting to fruit setting and fruit setting to harvest in case of nutrient solution management. The time required was about 3 weeks from planting to the first fruit setting and thereafter 7~10 days more until the first harvest. Approximately every 3~4 days were needed until the upper flowers bloomed. The time required from fruit setting to harvest was not different much among flowers as cucumber plants grew. From the experimental results, EC of supplied solution was recommended to maintain a little high to $3.0dS{\cdot}m^{-1}$ until before fruit setting and lower a little to $2.0{\sim}2.3dS{\cdot}m^{-1}$ after that. Of course, the amount of solution supply should be increased as plants grew. In case of each nutrients, the recommendation of concentrations of nitrogen, phosphorus and calcium were 700, 60, and $110mg{\cdot}L^{-1}$ each until before fruit setting, and then 660, 50, and $100mg{\cdot}L^{-1}$ each after fruit setting. The concentrations of potassium and magnesium are recommended to start from 400 and $80mg{\cdot}L^{-1}$ until fruit setting and lower a little after that.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1181-1186
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• 2013

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 study examined the influence of air temperature during seedling growth on the time required to reach the first fruit maturity and yield of hot pepper. Seedling plants of 'Super Manita' hot pepper was grown in temperatures $2.5^{\circ}C$ and $5.0^{\circ}C$ lower than the optimum temperature (determined by the average of temperatures for the past 5 years). Seedlings were transplanted into round plastic containers (30-cm diam., 45-cm height) and were placed in growth chambers in which the ambient temperature was controlled under natural sunlight. The growth of seedlings under lowered temperatures was reduced compared to the control. The mineral (K, Mg, P, N) concentrations in the leaf tissues were higher when plants were grown with the ambient temperature $2.5^{\circ}C$ lower than the optimum, regardless of changes in other growth parameters. Tissue calcium (Ca) concentration was the highest in the plants grown with optimum temperature. The carbohydrate to nitrogen (C/N) ratio, which was the highest (18.3) in the plants grown with optimum temperature, decreased concomitantly as the ambient temperature was lowered $2.5^{\circ}C$ and $5.0^{\circ}C$. The yield of the early harvested fruits was also reduced as the ambient temperature became lower. The first fruit harvest date for the plants grown with optimum temperature (June 27) was 13 days and 40 days, respectively, earlier than that in plants grown with $2.5^{\circ}C$ (July 10) and $5.0^{\circ}C$ (Aug 6) lower ambient temperatures. The fruit yield per plant for the optimum temperature (724 g) was the greatest compared to those grown with $2.5^{\circ}C$ (446 g) and $5.0^{\circ}C$ (236 g) lower temperatures. The result of this study suggests that the growers should be cautioned not to transplant their hot pepper seedlings too early into the field, since it may delay the time of first harvest eventually reducing total fruit yield.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.2
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• pp.89-94
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• 1998

A field experiment was carried out to determine the effects of chemical drying agents at mowing on the field drying rate of alfalfa (cv. Vernal) and rye (cv. Koolgrazer) for hastening hay manuf8cture. In alfalfa; chemicals ($K_2CO_3$ 2% $K_2CO_3$ 3% $Na_2CO_3$ 2% $CaCO_3$, 2% $K_2CO_3$2% + $Na_2CO_3$, 1% only water spray and control) were treated at early bloom stage in 1995. Chemicals ($K_2CO_3$, 2%, $Na_2CO_3$, 2% $CaCO_3$, 2% and control) were applicated at different harvest stages (early heading, heading and bloom) in rye, 1996. The drying rate of alfalfa by $K_2CO_3$ treatment among chemicals was higher than control, and the duration of field dry was shortened by one day with $K_2CO_3$ application, but there was no difference in drying efficiency between $K_2CO_3$ 2% and $K_2CO_3$ 3%. In rye, however, no moisture reduction by chemicals was observed. The days required for field dry were 6, 4, and 3 days at warly heading heading and bloom stage respectively; regardless of chemical drying agents and conbol. The nutritive value of rye hay with chemicals at baling was very slightly higher than control, but there was no significant difference. Also, no difference of hay quality was found among drying agents. In conclusion, $K_2CO_3$can enhance the field drying rate of alfalfa hay, but the drying efficiency was not high, particularly in rye hay. Harvesting at early heading to heading stage was desirable for manufacture of high quality rye hay.

• Korean journal of applied entomology
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• v.16 no.1 s.30
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• pp.55-63
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• 1977

As the important pathogens of potato storage diseases, Fusarium solani, F. reseum, F. oxysporum, and Erwinia carotovora were isolated from rot potato tubers. The cut potato pieces of the three cultivars, Epicure, Irish Cobbler, and Superior were held in moist chambers of $4^{\circ},\;14^{\circ},\;24^{\circ},\;and\; 34^{\circ}C$ and 7 days and then rated for suberin and periderm development. The cut potato pieces thus treated were inoculated with the four organisms and held at $24^{\circ}C$ for 9 days and then rated for decay. As the temperature and period of holding increased, more suberin and periderm were developed with decrease in decay. Although there were differences in pathogenicity of the organisms, varietal reaction and protective barrier development, the effect of temperature and holding period had greater importance for decay prevention. At $4^{\circ}C$ within 7 days of holding period the potato pieces developed no protective barrier with severe decay. It is required to avoid placing cut potatoes directly in cold storage of the low temperature. At $34^{\circ}C$ the pieces developed abundant protective barriers even though decay occurred in somecases. Practically no decay was found with moderate protective barrier development after 3 days and 5 days at $24^{\circ}C\;and\;14^{\circ}C$, respectively. Since the potato pieces decayed occasionally during the holding period when they were held at the higher temperature, the holding at $14^{\circ}C$ for longer than 5 days is considered to be feasible for prevention of storage rots.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.273-278
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• 2008

This study set out to investigate the changes to the growth, yield, and flavonoid contents of mungbean according to different seeding times from mid May to mid July in the southern region of Korea. Days to first flowering, days to first maturing, and cultivation period were shorter at later seeding time than earlier seeding time. But later the seeding time was, days from first maturing to first harvesting, days required between harvesting increased. Number of pods at first harvesting and yield of mungbean were highest when seeded at late June, showing increase in yield 14% more than at early June as standard seeding time. However number of seeds per pod and 1,000-seed weight at first harvesting were highest when seeded at mid July. The number of harvesting was smallest at two times when seeded at June or mid July. The contents of average vitexin and isovitexin in mungbean were highest in the order of mid July, late June, and mid May. In particular, their contents reached its highest point in the seeds of the second harvest. Considering the results of the cultivation period, yield, harvesting times, vitexin and isovitexin contents, the proper seeding time of mungbeans in the southern region of Korea will be from late June to mid July.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.4
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• pp.454-459
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• 2016

Pre- or post-harvest processing is required to mitigate the risk of norovirus infection mediated by shellfish or seafood. We investigated the environmental resistance of human norovirus (HuNoV) under various conditions of temperature, salinity, and pH in seawater. Male-specific coliphage (MSC) was as the reference virus for all tests. At 4℃, HuNoV GII4 spiked into seawater was continually detected by RT-PCR for 35 days, regardless of salinity or pH level. It maintained nearly stable concentrations, meaning HuNoV can sustain a viral population in seawater long enough to be accumulated by shellfish and other filter feeders during winter. MSC was also stable at 4℃ although viral infectivity dropped sharply after 28 days. The effects of salinity and pH on MSC were indistinct. At 25℃ the detectable period of HuNoV GII4 by RT-PCR in seawater decreased to about one-third or half of the period at 4℃. High salinity (32 psu) and alkaline pH (8.5) were also unfavorable for sustaining HuNoV abundance at 25℃ in seawater. The resistance patterns of MSC to high temperature, high salinity, and alkaline pH were more dramatic and viral infectivity decreased over time, almost in direct proportion to experimental days. MSC was undetectable after 12 days under all salinities and pH levels at 25℃.

• Journal of Bio-Environment Control
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• v.6 no.1
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• pp.27-33
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• 1997

This experiment was carried out to investigate the effects of limited nutrient supply during 21 days before and after pollination stage on the growth, fruit quality and nutrient uptake of muskmelon in rockwool culture. Muskmelon, cv. Earl's Favorite seeds sowed on rockwool cube and transplanted on rockwool slab($90\times15\times7.5cm$) when 2 to 3 true leaf appeared on Sep. 6, 1991. Three kinds of nutrient composition recommended by Shizuoka university, combinated with the composition of Otsuka house A and composition Shizuoka III. One half of calcium nitrate(Ca(NO$_3$)$_2$.4$H_2O$) for limiting nitrogen supply during 21 days was treated and then fertigated the nutrient composition recommended by Shizuoka university up to harvest time. Trickling nozzles(Netafim Co. Israel) were used for fertigation of nutrient solution and noncirculating system was employed. Temperature was maintained $18^{\circ}C$ in night but 23 to $25^{\circ}C$ for 10 days after pollination for softening the fruit. The drainage ratio of nutrient solution was adjusted 20 to 30 percent. Fertigated and drained amount, and the pH and EC of nutrient solution were recorded. The concentrations of mineral elements including N, P, K, Ca, and Mg were analyzed and compared among treatments. In both autumn and winter cultivation, the limitation of nutrient supply by adjustment of nutrient composition(NO$_3$-N : 8meㆍ$\ell^{-1}$) caused the nutrient deficiency in muskmelon plant due to the limited nutrient supply. After pollination nutrient limitation by the lowering the nitrate retarded the over thickening of upper leaves of muskmelon but plant height and fresh weight of fruit were higher in the plot of nonlimited nutrient supply. The phenomena were attributed to the differences of the amount of nutrient uptake due to the limited time of nutrient solution, duration of nutrient supply and concentration of nutrient solution. These results suggested that increasing nutrient supply in the pollination stage was favorable for better appearance of fruit and improving fruit quality. Further trials would be required for the incre-ment of sugar degree of muskmelon grown in rockwool.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.222-222
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• 2022

Improving the taste of rice in the breeding process is one of the important goals. However, it takes a lot of time and effort to select lines with good grain quality. MAS related to rice quality can help quickly and accurately select the elite lines in breeding programs. QTL qTV9, derived from Wandoaengmi 6, has been reported as a marker associated with improved glossiness of rice (Park et al., 2019). To confirm the function of QTL qTV9, 186 RILs derived from Hwayeong/Wandoaengmi6 were cultivated on ordinary planting cultivation for five years. The average DTH of Hwayeong and Wandoaengmi 6 was not significant at 99 and 97 days, respectively, but the averages of TV (toyo value) were 72.6 and 86.0, respectively. The DTH and TV of RIL vary from year to year. In 2017-2018, the average DTH was 98 days, which was significantly higher than the other three years. In 2018 and 2021, the average TV was 79.5 and 86.5, respectively, which were significantly higher than in other years. As a result of correlation analysis, DTH in the different years showed highly significant positive correlations (r = 0.71-0.92) from 0.71 to 0.92, whereas TV showed positive but weaker correlations (r = 0.42-0.71). The correlation between DTH and TV in each year was significant but weak (r = 0.25-0.64) and there was no correlation in 2017. The TV (77.6-88.7) of RILs with QTL qTV9 was significantly higher than that of RILs without qTV9 (72.6-84.9) for all five years. As a result of analyzing TV by DTH group, the TV of the lines with qTV9 in DTH groups (93-97) and (98-103) showed a significantly higher trend for all 5 years. And TV was not significant in DTH groups A, B, E, and F. This may have been influenced by factors such as insufficient populations between groups or differences in harvest timing. This study is expected to be used as data for improving the glossiness of cooked rice in breeding programs, and further study of the QTL qTV9 marker is required.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.4
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• pp.330-338
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• 1999

Extensive research has been conducted on effects of drought stress on growth and development of soybean but information is rather restricted on the limited-irrigation system by way of precaution against a long-term drought condition in the future. The experiment for limited-irrigation was conducted in transparent vinyl shelter at Asian Vegetable Research and Development Center (AVRDC), Taiwan in 1997. Two soybean varieties, Hwangkeum and AGS292, improved in Korea and AVRDC, respectively were used for this experiment. The relationships between normalized transpiration rate (NTR) and fraction of transpirable soil water (FTSW) in both varieties were similar that the NTR was unchanged until FTSW dropped to about 0.5 or 0.6. At FTSW less than those values, NTR declined rapidly. Days required to harvest in both varieties were significantly prolonged at IR6 treatment compared to any other treatments. Daily mean transpiration rate was significantly higher at IR5 treatment, as averaged over varieties. Similarly, water use efficiency was also high at 1R5 treatment. In both varieties, seed yield was the greatest at the IR5 treatment, as compared to any other limited-irrigation treatments, due to the increased seed number and high transpirational water use efficiency. The indices of input water and seed yield for the different limited-irrigation treatments against control indicated that Hwangkeum produced 59.6% or 60.7% of seed yield using 36.1% or 44.9% of input water, as compared to control, by irrigation at only R5 or R6 stages, respectively. The AGS292 produced 56.1% of seed yield with 35.4% of input water of control, when irrigated at R5 stage. The results of this study have elucidated that the limited irrigation at R5 stage in soybean can be minimized yield loss with such small quantity of water under the environment of long-term drought stress and the expected shortage of agricultural water in the future.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.338-343
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• 2007

This experiment was conducted to improve light environment of oriental melon cultivation in winter season. Three polyolefin (J-1, J-2 and J-3), two polyethylene (K-1 and K-2) films and K-3 commonly used in farmhouses, with different film thickness, ultraviolet ray interception and infrared ray absorption ratio were used. Heat conservation of J-2 was highest, compare to K-3, J-3 and J-1. Early growth of J-1, J-2 and J-3 were faster than K-3, and Days required to harvest of K-3 were shortened about 10 days. Marketable yield of K-3 was 991kg per 10a, those of J-1, J-2, J-3, K-1 and K-2 were increased 21%, 37%, 24%, 13% and 4% compare to K-3, respectively. Especially, harvesting of J-1, J-2, J-3 and K-1 were focused on early (50%) and middle stage (40%). Polyolefin with higher heat conservation improved growth and harvesting in early and shortened days to harvesting in winter season.