• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.3
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• pp.155-160
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• 2007

This experiment was conducted to compare the agronomic characteristics and productivity in induced vetch cultivars at paddy field of Cheonan (National Institute of Animal Science) and Naju (Jeollanam-Do Agricultural Research and Extension) from 2004 to 2006. The vetch cultivars used in this study were 6 varieties ('VV4712', 'Welta', 'Penn-02', 'Ostsaat', 'Oregon com.', 'Sander 2'). At the Naju region, the most fast flowering date variety was Chinese milk vetch, Sander 2 was very late as 20th May. The average dry matter (DM) content was 21.7%. Vetch cultivars were severely different. 'Oregon com.' showed the highest DM yield by 5,406 kg/ha but the DM yield of 'Ostsaat' was low by 4,852 kg/ha. At the Cheonan region, the most fast flowering date variety was Korean milk vetch, Sander 2 was very late as 25th May. The average dry matter (DM) content was 16.9%. Vetch cultivars were severely different. 'Welta' and 'Ostsaat' showed the highest DM yield by 2,173 kg/ha and 1,883 kg/ha respectively, but the DM yield of 'VV4712' was low by 1,079 kg/ha. Crude protein (CP) content of vetch was 11.5%. 'Sander 2' showed the highest CP content by 14.4% and Chinese milk vetch showed the highest content by 19.3%. Average acid detergent fiber (ADF), neutral detergent fiber (NDF) and total digestible nutrient (TDN) content were 26.8%, 42.2% and 67.5%, respectively. The results of this experiments indicated that the productivity of vetch cultivar varied from winter hardness, therefore we will consider the winter hardness as main factor when induce vetch cultivars. According to the results obtained from this study, it is suggested that 'Oregon com.' at the Naju region and 'Welta' and 'Ostsaat' at the Cheonan region would be recommendable for fall sown 'vetch' for dry matter production.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.303-310
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• 2015

The diamondback moth, Plutella xylostella, overwinters in some protected areas in Korea. Using a sex pheromone trap, the adults were monitored since the occurrence of the overwintering populations. In Andong, P. xylostella exhibited four adult peaks in a year. Biological characters, such as cold tolerance, insecticide susceptibility, and developmental rate, were analyzed and showed a significant variation among different local overwintering populations. Population genetic variation was assessed with molecular markers, in which the initial high genetic variation among the overwintering populations decreased with the progress of seasons. These results suggests that there may be a significant migration of P. xylostella to decrease the genetic variation among the different local populations that are different in biological characters.

• Proceedings of the Korean Aquaculture Society Conference
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• 2005.05a
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• pp.66-67
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• 2005

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.12-16
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• 1991

So as to compare the differences of major agronomic traits according to fall plant types, two cultivars and eight lines which were derived from the same pedigree, were planted and analyzed. The heading and mature times, and culum length of erect plant types were earlier or longer, but the spike number per ㎡ and yield were smaller than the those of prostrate types. Also, 1000 grain weith, assortment rate and light penetration rate in erect types were greater than in prostrate types. The heading time was positively correlated with mature time and yield, but negatively correlated with culum length, 1000 grain weight, assortment rate and light penetration rate. Yield was negatively correlated with light penetration rate. If the lines with prostrate types in fall season, fast regrowth after wintering and rapid elongation of stem were bred and selected, it will be of great benefit in the area requiring sever winter hardiness.

• Korean Journal of Organic Agriculture
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• v.21 no.1
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• pp.61-68
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• 2013

This study was conducted to evaluate overwintering of hairy vetch (Vicia villosa Roth), biomass, and inorganic N concentration in soil to verify the adaptability of eight cultivars of hairy vetch into country. Winter survival rate was higher for the hairy vetch cultivars, such as Hungvillosa or Ostsaat, than those of Minnie, Oregon common, and TTF1, which affected amount of biomass of each hairy vetch, with higher biomass observed in Hungvillosa or Ostsaat cultivar. There were no significant difference for the mineral nutrients of each hairy vetch cultivar. Inorganic N concentration in soil was increased at 10 days after mowing by application of Hungvillosa and Ostsaat cultivars that had highly produced N content from the raw materials.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.561-567
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• 2011

Cold tolerance of the native Rhododendron species which are on the verge of extinction in Korean nature were compared with the introduced species and its mechanism were studied physiologically with the investigation of the leaf angle, leaf curling, and photosynthetic activity. The degree of cold tolerance measured with the leaf burning after winter season was higher in the native species, Rhododendron brachycarpum and Rhododendron brachycarpum var. roseum than all the introduced species. 'Nova Zembla', an introduced species, showed high sensitivity to the low temperature. Changes in leaf angle by the low temperature were bigger in 2 native species and 'Parker's Pink' than the other introduced species and small comparatively in 'Nova Zembla' and 'Cunningham's White' cultivar. Leaf curling also occurred strongly in 2 native species by the low temperature. While, it was comparatively little and mild in the other introduced species. Therefore these results suggested that the leaf movement such as leaf angle change and curling adapted to the low temperature is positively related to the cold tolerance of 2 native species. By the way, such relationship is not explainable in the cold-sensitive 'Parker's Pink' cultivar showing comparatively stronger leaf movement. Photosynthetic activity measured before the winter season was high in the cold-tolerant R. brachycarpum and its recovery after winter season was faster in the 2 native species and the introduced 'Cynosure' cultivar than the other introduced species. They were the lowest in the most cold-sensitive 'Nova Zembla'. This phenomena occurred similarly even in the stomatal conductivity, suggesting that the movement of water from the roots to the leaves is better and then the leaf burning after winter season become small in the cold-tolerant species. The recovery of photosynthetic activity and stomatal conductivity was comparatively slower in the cold-sensitive 'Parker's Pink'. From the above results, leaf behavior adapted to the low temperature during the winter season and water movement to the leaves are related collectively to the cold tolerance represented as the leaf burning in the Rhododendron species is suggested.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.355-365
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• 2014

It has been unclear whether the diamondback moth, Plutella xylostella can overwinter in Korean field conditions. This study determined overwintering conditions of P. xylostella by conducting field exposure tests based on its cold tolerance and monitoring overwintering populations by direct examination of overwintering larval habitats and capturing adults with sex pheromone traps. In addition, the overwintering populations were analyzed using polymorphic genetic markers to trace their sources. When all immature stages of P. xylostella were exposed to $-5^{\circ}C$, which was the temperature much above their supercooling points, they significantly suffered with direct cold injuries, where larval stage was most tolerant to the cold injury. However, the exposure to $5^{\circ}C$ for a long period (4 weeks) did not give any significant cold injury to nonfeeding stages, while this treatment gave lethality to larval stage without diet. When all developmental stages of P. xylostella were exposed to open field conditions during winter, they exhibited significant decreases of survival rates. However, some protected and indoor conditions reduced the cold injuries and the diet provision significantly increased larval survival rates. Adult monitoring with sex pheromone during winter period indicated that the first captures were observed at similar periods at different locations (${\approx}260$ Km apart). The overwintering adults were captured until early April. Genetic variation of these overwintering populations was analyzed with polymorphic molecular markers, indicating significant genetic divergences among the overwintering populations. This study indicates that P. xylostella can overwinter in southern Korean fields or some protected greenhouses with host plants.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.2
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• pp.167-176
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• 1999

Shoot morphological characteristics were affected by plant population densities in alfalfa. Shoots per plant, yield per shoot, yield per plant, and stem diameter increased with decreasing alfalfa population density. Winter survival was maximized at a plant population of $45plants\;m^{-2}$ or less. The grams of TNC per root increased as the stand density decreased. The lowest LT 50 occurred at the lowest stand density ($16plants\;m^{-2}$ having 25 cm plant spacing) and the highest LT 50 was attained at the highest stand density($494plants\;m^{-2}$ having 4.5 cm plant spacing). There were no differences in shoot morphology, winter survival, and cold hardiness in between 'Algonquin'and 'Vernal'. From this study, high stand density of alfalfa ($278plants\;m^{-2}$ or more) appears to be of little advantage compared to low stand density in terms of winter survival and cold hardiness.

• Korean Journal of Ecology and Environment
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• v.50 no.2
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• pp.266-274
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• 2017

We surveyed the habitat use and food materials of the endangered Swan Goose (Anser cygnoides) during the wintering period at the Seocheon tidal flat. The bird wintered about six months from October 2014 to early April 2015 at the flat. They showed a remarkable change in choosing their feeding habitat and prey. They stayed entirely at sedge grass patches on Songrim tidal flat during the early wintering period (October), while after November they gradually moved to Janggu bay and used rice paddy fields as well as sedge patches on the tidal flats as their feeding site. The dietary analysis showed the sedge grass (Bolboschoenus sp., Cyperaceae) was the main dietary source during the entire wintering period. Interestingly, the proportion of Cyperaceae on feces decreased slightly over wintering time, while the proportion of Fabaceae increased relatively since November. These results suggest that the Swan Geese switched their habitat and food sources in response to the change of food availability. The Seocheon tidal flat area is the important wintering site for Swan Geese and sedge grass patches in the area need to be managed as the main feeding area for the wintering Swan Geese.

• Korean Journal of Environment and Ecology
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• v.31 no.2
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• pp.135-151
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• 2017

Waterbirds were surveyed once a week from Oct. 2015 to Apr. 2016 to study the conditions of temperature of staying waterbirds on Wonju-Stream. The population staying on Wonju-Stream was in inverse proportion to the temperature change; birds increased as the temperature went down, and showed the highest peak counts on the 16th(27-Jan) survey, which was the lowest in temperature. decreasing as the temperature rose. The total population of Wonju River water birds increased with increasing freezing rate in proportion to the freezing rate of nearby reservoirs and tributaries. To clarify the relation of the numbers of the birds to temperature fluctuation, the correlation of the first period of wintering (1st~16th) and that of the later period(17th~27th) as well as the whole period was surveyed, based on the 16th which was the lowest in temperature. While most wintering waterbirds showed a negative correlation to the temperature, Egretta garzetta, Phalacrocorax carbo, and Ardea cinerea were positive in temperature relativity. Anas poecilorhyncha was in the highest relation to temperature fluctuation showing (7D/H3A(r=-0.960, P<0.000000001)) at 1-16 correlation(Cor.), with the whole wintering waterbird species showing the maximum correlation at 4D/LA in the every correlation(1~27Cor.(r=-0.942, P<0.01), 1~16Cor.(r=-0.947, P<0.01), 16~27Cor.(r=-0.958, P<0.01)). Each waterbird showed the correlation to the temperature variation(AT, HT, LT) and th duration(1D~7D) depending on the species differently. Most species demonstrated a bigger correlation to the lowest temperature rather than to the highest temperature. During the first half period of the wintering with the temperature falling it showed a high correlation to the temperature at the duration of 4D~7D, While it was for D1~D3 during the next half period.