• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.1
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• pp.23-29
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• 2018

'Dakyeong' (Avena sativa L.), a winter oats for forage use, was developed by the breeding team at National Institute of Crop Science, RDA in 2016. It was derived from a cross between 'CI7505'(IT133304) and 'Swan'(IT197920). Subsequent generations followed by the cross were handled in bulk and pedigree selection programs at Iksan and Jeonju, respectively. After preliminary and advanced yield test for 2 years, 'SO2004009-B-B-10-8-3-9', designated as a line name of 'Gwiri91', were subsequently evaluated for earliness and forage yield during 3 years in four parts such as Jeju (upland), Yesan (upland), Iksan (upland), and Jeonju (paddy), from 2014 to 2016, and finally named as 'Dakyeong'. Cultivar 'Dakyong' has leaves of dark green color, thick diameter culm and long grain of brown color. Over 3 years, the heading date of 'Dakyeong' was about 5 days earlier than that of check cultivar 'Samhan' (April 30 and May 5, respectively), and their average forage dry matter yield harvested at milk-ripe stage was higher 12% ($15.7tone\;ha^{-1}$) than $14.0tone\;ha^{-1}$ of check cultivar. Cultivar 'Dakyeong' was lower than the check cultivar 'Samhan' in terms of the protein content (6.1% and 7.0%, respectively) and total digestible nutrients (62.1%, and 62.5%, respectively), while the TDN yield was more than the check ($7.79tone\;ha^{-1}$ and $7.64tone\;ha^{-1}$, respectively). Fall sowing cropping of 'Dakyeong' is recommended only in areas where average daily minimum mean temperatures in January are higher than $-6^{\circ}C$, and it should not be cultivated in mountain areas, where frost damage is likely to occur.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.1
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• pp.26-32
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• 2014

'Dahan' (Avena sativa L.), a winter oat cultivar for forage use, was developed by the breeding team at the Department of Rice and Winter Cereal Crop, National Institute Crop Science (NICS), Rural Development Administration (RDA) in 2011. It was derived from an original cross between $F_1$[Sprinter/73625] and 'Gwiri26'. Subsequent generations followed by the cross were handled in bulk and pedigree selection programs at Suwon. A line, 'SO99027-GB-B-113-4-4-3', was selected for cold tolerance and good agronomic characteristics and as a line name of 'Gwiri75'. The line 'Gwiri75' was subsequently evaluated for cold tolerance and forage yield during 3 years in four region such as Yesan, Iksan, Kimjae, and Jeju, from 2009 to 2011 and finally named as 'Dahan'. Though similar in heading date to the check cultivar Samhan, 'Dahan' had tall plant length and lodging resistance. It's average forage dry matter yield harvested at milk-ripe stage was 15.6 ton $ha^{-1}$, compared with 14.1 ton $ha^{-1}$ of check cultivar. Cultivar 'Dahan' was lower to the check cultivar 'Samhan' in protein content (8.4% and 9.9%, respectively), while it was superior to the check cultivar in total digestible nutrients (TDN) (60.8% and 59.3%, respectively), and in TDN yield $ha^{-1}$ (9.5 ton and 8.4 ton, respectively). Fall sowing of 'Dahan' is recommended only in the areas where daily minimum mean temperatures are averaged higher than $-7^{\circ}C$ in January, and excluded in mountain area where frost damage is presumable.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.1
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• pp.1-9
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• 2006

Regardless of the recent observed warmer winters in Korea, more freeze injuries and associated economic losses are reported in fruit industry than ever before. Existing freeze-frost forecasting systems employ only daily minimum temperature for judging the potential damage on dormant flowering buds but cannot accommodate potential biological responses such as short-term acclimation of plants to severe weather episodes as well as annual variation in climate. We introduce 'dormancy depth', in addition to daily minimum temperature, as a complementary criterion for judging the potential damage of freezing temperatures on dormant flowering buds of grape vines. Dormancy depth can be estimated by a phonology model driven by daily maximum and minimum temperature and is expected to make a reasonable proxy for physiological tolerance of buds to low temperature. Dormancy depth at a selected site was estimated for a climatological normal year by this model, and we found a close similarity in time course change pattern between the estimated dormancy depth and the known cold tolerance of fruit trees. Inter-annual and spatial variation in dormancy depth were identified by this method, showing the feasibility of using dormancy depth as a proxy indicator for tolerance to low temperature during the winter season. The model was applied to 10 vineyards which were recently damaged by a cold spell, and a temperature-dormancy depth-freeze injury relationship was formulated into an exponential-saturation model which can be used for judging freeze risk under a given set of temperature and dormancy depth. Based on this model and the expected lowest temperature with a 10-year recurrence interval, a freeze risk probability map was produced for Hwaseong County, Korea. The results seemed to explain why the vineyards in the warmer part of Hwaseong County have been hit by more freeBe damage than those in the cooler part of the county. A dormancy depth-minimum temperature dual engine freeze warning system was designed for vineyards in major production counties in Korea by combining the site-specific dormancy depth and minimum temperature forecasts with the freeze risk model. In this system, daily accumulation of thermal time since last fall leads to the dormancy state (depth) for today. The regional minimum temperature forecast for tomorrow by the Korea Meteorological Administration is converted to the site specific forecast at a 30m resolution. These data are input to the freeze risk model and the percent damage probability is calculated for each grid cell and mapped for the entire county. Similar approaches may be used to develop freeze warning systems for other deciduous fruit trees.