• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.23-24
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• 2001

Iro-ochi as has been called by Nori (Porphyra) farmers is biologically a bleaching phenomenon and has been one of the serious problems in Nori cultivation in Japan. Especially in the last Nori cultivation season, Iro-ochi gave an extremely serious damage to the Nori production in Ariake Bay, Kyushu, Japan, which attracted considerable socio-economic attention in Japan. As early as in late 1960s, we already made fundamental studies on Iro-ochi of Porphyra. (omitted)

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.3
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• pp.220-225
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• 1991

Four cropping systems, soybean mono-cropping, Cassia tora mono-cropping, soybean-C. tora companion cropping and soybean-C. tora intercropping, were compared for number of soil nematodes and soybean growth in upland field in 1986. Soybean was cultivated as an after-crop of four different cropping systems from 1987 to 1989, and observations were continued. Soil nematode was not found in C. tora mono-cropping plot from mid growing season of C. tora while many nematodes were found in soybean mono-cropping plot in 1986. A few nematodes were found for 3 years in soybean field after one season cultivation of C. tora in 1986. Number of nematodes was lower in soybean-C. tora companion and inter-cropping plots compared with soybean mono-cropping, and was also lower for 3 years in soybean field after one season companion and inter-cropping culture in 1986 compared with continuous soybean cultivation plot. No root nodule was formed on C. tora root, but number of root nodules of soybean plant grown in C. tora companion and inter-cropping plots was not different with soybean mono-cropping plot. Number of pods. number of seeds and seed weight per soybean plant grown in C. tora companion and inter-cropping plots were almost same with soybean mono-cropping plot. When soybean was cultivated in field after one season C. tora mono, companion or inter-cropping, pod and seed number, and seed weight per plant were higher than continuous soybean cultivation field.

• Korean journal of applied entomology
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• v.61 no.2
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• pp.335-347
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• 2022

We investigated the emergence patterns of Chilo suppressalis (Lepidoptera: Crambidae) adults using sex pheromone traps in the three northeastern areas, Dandong (40°07'N 124°23'E) (Liaoning province), and Gongzhuling (43°30'N 124°49') and Longjing (42°46'N 129°26'E) (Jilin province), China, in 2020 and 2021. Two times of adult flight seasons were isolated clearly during the rice growing periods in the all areas, in which the first season from mid May to late July, and the second season from mid July to mid September were observed. The adult emergence seasons in the areas at higher latitude were later than that at lower latitude. Using the adult emergence data during the first flight seasons, the second flight seasons were estimated through insect phenology modelling, and compared with the observed data. Temperature-dependent life history models (developmental rate, development completion, survival rate, adult aging rate, total fecundity, oviposition completion, and adult survival completion) were collected or constructed for each life stage of C. suppressalis, in which the data from the four previous studies were used. Those models were combined in an insect phenology estimation software, PopModel, and operated for the observed areas. In the results, the phenology modelling operated with the models based on the data of shorter larval periods in the previous studies estimated more accurately the second flight seasons. In 2021, we investigated the change of damaged hill ratios of rice with observing the adult emergence at Dandong and Longjing, 2021. The increase periods of damaged hill ratios of rice were observed two times during the total rice cultivation season, which may be caused by different generations of C. suppressalis larvae.

• Journal of The Korean Society of Grassland and Forage Science
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• v.20 no.4
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• pp.243-250
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• 2000

Selection of oat variety according to cultivation period is an important to increase productivity of forage crop. To investigate the growth characters and dry matter productivity of oats according to cultivation period, early-maturing oat(EM0) and medium-maturing oat(MM0) variety were sown in spring and autumn at central district of Korea. When oats were cultivated in spring, MMO variety was longer 8 cm in leaf length and wider 5 mm in leaf width than 25 cm and 12 mm of EM0 variety, rexpectively. but in autumn, those were not different between maturities of oat varieties. Plant length of MMO variety was longer 7 cm than that of EM0 Variety in spring cultivation, but in autumn, plant length of EM0 variety was longer 14 cm than that of MMO variety. Heading dates were 20th to 22th May in EM0 variety, and 30th May to 10th June in MMO variety in spring cultivation, and ear of EM0 variety emerged 30th Oct. to loth Nov. but that of MMO variety did not emerge at harvesting day in autumn cultivation. In Spring cultivation, dry matter(DM) yield of EM0 variety was 7,349 kg/ha that was less 56% than 11,466 kg/ha of MMO variety, but In Autumn, was more 15% than 6,575 kg/ha of MMO variety. In conclusion, selection of oat variety in spring and autumn cultivation can be different with cropping system of forage crop, and this trial is suggesting that oat variety could be sown MMO variety in spring and EM0 variety in autumn at central district of Korea. (Key words : Oat variety, Productivity, Cultivation season)

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.320-320
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• 2017

Recently, the rice growing time was extended by the global warming. This study was conducted to investigate the possibility of rice double cropping system in southern Korea. The first transplanting was with six cultivars ('Kilala397', 'Baekilmi', 'Joun', 'Hanseol' and 'Jungmo1031') on April 15. All cultivars could be harvested at the end of July. Adaptable cultivars for the first cultivation were 'Kilala397', Baekilmi' and 'Joun'. The rice yields at the first cultivation was about 95% of local average yield. Although the yield was slightly less, the first cultivation was considered to have economic benefits, because of the high market price of rice. In the second transplanting was with five cultivars ('Manjong', 'Joun', 'Deabo', 'Jinok' and 'Kilala397') on April 15. All cultivars could be harvested in early November. Adaptable cultivars for the second cultivation were 'Jinok' and 'Kilala397'. The rice yields at the second cultivation was about below the 60% of local average yield, because there was the less growth than normal season cultivation. Consequently, southern Korea' annual rice double cropping system is considered to have no economic value yet. However, the research should be continued considering the temperature rise of global warming.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.801-807
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• 2011

This study was carried out to evaluate effect of consecutive application of organic matter on soil chemical properties and dehydrogenase, acid phosphatase activity in non-volcanic ash soil during three cropping season. Organic matter mixture and organic fertilizer (MOF, $2,000kg\;10a^{-1}$), food waste compost (FWC, $2,000kg\;10a^{-1}$), and pig manure compost (PMC, 2,000, 4,000, and $6,000kg\;10a^{-1}$) were applied for each cropping season. Soil pH values were increased after three cropping season in all treatment. In the soils of the increased application of PMC, soil pH, total-nitrogen, available phosphate, exchangeable cations (K, Ca, and Mg), and heavy metal (Zn and Cu) contents were increased. In addition, Soil dehydrogenase activity was significantly increased in proportions to PMC application rate and cropping season during potato cultivation period. The activity was two times higher in PMC ($4,000kg\;10a^{-1}$) than control after the third cropping season. Soil dehydrogenase activity was in order of PMC>FWC>NPK+PMC>MOF. Acid phosphatase activity was higher in PMC ($6,000kg\;10a^{-1}$) than other treatment. Soil Zn content and dehydrogenase activity showed linearly correlation, which were MOF ($R^2$=0.427), FWC ($R^2$=0.427) and PMC ($R^2$=0.411, p<0.01), respectively. This study demonstrated that soil chemical properties and enzyme activity could be affected greatly by consecutive application of different organic matter in the potato cultivation field.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.205-211
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• 2012

BACKGROUND: Generally, nitrogen (N) fertilization higher than the recommended dose is applied during vegetable cultivation to increase productivity. But higher N fertilization also increases the concentrations of nitrate ions and nitrous oxide in soil. In this experiment, the impact of N fertilization was studied on nitrous oxide ($N_2O$) emission to standardize the optimum fertilization level for minimizing $N_2O$ emission as well as increasing crop productivity. Herein, we developed $N_2O$ emission inventory for upland soil region during red pepper and Chinese milk vetch cultivation. METHODS AND RESULTS: Nitrogen fertilizers were applied at different rates to study their effect on $N_2O$ emission during red pepper and Chinese milk vetch cultivation. The gas samples were collected by static closed chamber method and $N_2O$ concentration was measured by gas chromatography. The total $N_2O$ flux was steadily increased due to increasing N fertilization level, though the overall pattern of $N_2O$ emission dynamics was same. Application of N fertilization higher than the recommended dose increased the values of both seasonal $N_2O$ flux (94.5% for Chinese cabbage and 30.7% for red pepper) and $N_2O$ emission per unit crop yield (77.9% for Chinese cabbage and 23.2% for red pepper). Nitrous oxide inventory revealed that the $N_2O$ emission due to unit amount of N application from short-duration vegetable field in fall (autumn) season (6.36 kg/ha) was almost 70% higher than that during summer season. CONCLUSION: Application of excess N-fertilizers increased seasonal $N_2O$ flux especially the $N_2O$ flux per unit yield during both Chinese cabbage and red pepper cultivation. This suggested that the higher N fertilization than the recommended dose actually facilitates $N_2O$ emission than boosting plant productivity. The $N_2O$ inventory for upland farming in temperate region like Korea revealed that $N_2O$ flux due to unit amount of N-fertilizer application for Chinese cabbage in fall (autumn) season was comparatively higher than that of summer vegetables like red pepper. Therefore, the judicious N fertilization following recommended dose is required to suppress $N_2O$ emission with high vegetable productivity in upland soils.

• Korean Journal Plant Pathology
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• v.14 no.3
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• pp.253-259
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• 1998

Effects of soil disinfection, fungicide application, and narrow ridge cultivation on ginger rhizome rot development were examined in two naturally-infested fields at Seosan, Choongnam province. Soil disinfection treatments were assigned to main plots, and fungicide and ridge treatments to sub-plots in a split plot design with three replications. The rhizome rot started in late July, and progressed rapidly until late September with the peak incidence in mid-august to early September. Soil disinfection by dazomet application showed the most prominent inhibition effects in both fields, where the disease was reduced by the treatment from 17.5% to 4.8% in one field, and from 51.0% to 2.2% in the other field. Three to five applications of fungicide metalaxyl-copper during the growing season inhibited the disease by 89.7% in one field, but less effectively in the other field. Narrow ridge cultivation reduced the disease effectively by 78.1% and 63.9%, compared to the unridged control plots in each field, respectively. Germination rate of seed-rhizomes and growth of ginger plants were similar between treatments, except when the plots received improper aeration after applying dazomet, and then the germination rate was significantly reduced. The greatest yields were obtained in the disinfected plots, regardless of rhizome rot incidence, except one control plot with very little disease. Ginger yield was negatively correlated with disease severity. However, the yield of ridge plots averaged 58∼59% compared to those of the unridged plots, due mainly to the half planting rate of the ridge plots. In spatial progress, the disease in the disinfected plots started from a single focus of the inoculum, and spread into the adjacent areas only, whereas in the untreated plots, the disease started from many foci that were distributed over the plot, and rapidly progressed to make an epidemic during the season. The soil density of P. myriotylum in the disinfected plots was not changed or, if not, increased slightly during the season. However, in the untreated plots it increased rapidly to reach the density 3 to 5 times greater by the end of the season.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.2
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• pp.91-99
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• 2017

The objective of this research was to investigate runoff characteristics of suspended solid (SS) and chemical oxygen demand (COD) from a paddy field watershed during storm events in the growing and non-growing seasons. Average of event mean concentration (EMC) of pollutants were 56.9 mg/L for SS and 23.9 mg/L for COD in the non-growing season and 50.3 mg/L for SS and 11.9 mg/L for COD in the growing season. The average EMC of SS in the study area was much lower than that in the uplands irrespective of cultivation, suggesting that paddy fields control soil erosion. This may be because flooding and wet soil in the growing season, and rice straw residue and stubble on the topsoil in the non-growing season reduce soil erosion. The changing tillage practice from fall tillage to spring tillage avoids soil erosion due to shortening of the tilled fallow period. However, the average EMC of COD in the non-growing season was about twice as much that in the growing season likely due to the runoff of organics like rice straw residues. The relationship between SS and COD loads and stormwater runoff volume was expressed by power function. The exponent for SS was higher than that for COD, suggesting that SS load increased with stormflow runoff more than COD load did. The mean SS and COD loads per storm during the non-growing season were much lower than those in the growing season, and therefore non-point source pollution in the growing season should be managed well.

• Food Science and Biotechnology
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• v.16 no.2
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• pp.306-310
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• 2007

Setoka (Tangor Norin No.8) is a superior tangor cultivar cultivated in a greenhouse on Jeju Island, and its ${\beta}-cryptoxanthi$n content was determined during the ripening season (September 2005 to March 2006). The ${\beta}-cryptoxanthi$n content of the peel of Setoka fruits was higher than that of the flesh. Also, the ${\beta}-cryptoxanthi$n content in both peel and flesh gradually increased through the ripening season from the beginning of pigmentation, and then decreased slightly late in the ripening season. The ${\beta}-cryptoxanthi$n content in the peel of Setoka fruits varied throughout the season with values of 0.02 (Sep), 0.67 (Nov.), 2.27 (Dec.), 2.88 (Jan.), 2.27 (Feb.), and 2.13 mg% (Mar.). The ${\beta}-cryptoxanthi$n content in Setoka fruit flesh increased throughout the ripening season with values of 0.05 (Sep.), 0.22 (Nov.), 0.57 (Dec.), 0.80 (Jan.), and 0.91 mg% (Feb).