• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.495-500
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• 2003

To establish the dual-purpose barley cultivation for forage by clipping before overwintering and grain next year, an experiment was conducted to clarify the effect of clipping times and cultivars haying different winter habits in rice-barley cropping system at paddy field in southern Korea. Barley showed more forage yield by clipping once only on December 10 than that of twice-clipping on November 10 and December 10. Among experimented cultivars, Saegangbori (winter habit II) and Keunalbori (winter habit IV) produced higher forage yield in one time clipping than the others. On the contrary, higher total digestive nutrients(TDN) was gained from twice-cut plants. Barley clipped once or twice headed and matured without serious delay as compared to the conventionally sown barley. In spite of clipping in November and/or December, barley produced grain yield similar to that of the conventional. Conclusively, it was regarded that cultivars having II-III winter habit were suitable for dual-purpose barley cultivation for forage in winter season and grain harvest next year.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.218-224
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• 2009

In organic fanning systems, integration of cover crops into cropping system are recommended to improve the soil quality, to prevent soil erosion, and to provide biological control of weeds. The aim of the present study was to evaluate the optimal seeding dates of major cover crops. To know optimal seeding dates, crimson clover, alfalfa, rye and hairy vetch were sown on 20. Sep., 27. Sep., 4. Oct., 11. Oct., 18. Oct., 25. Oct. Rye could germinate and grow well in all the tested sowing dates. Hence, it was concluded that the sowing of rye could be conducted later in fall or more earlier in spring than any other cover crops tested in this study. Growth and ground covering capacity were significantly decreased by late sowing in alfalfa and crimson clover. For safe overwintering, alfalfa and crimson clover should be sown before late September. Similarly, field emergence of hairy vetch was found to be sensitive to soil temperature, however, its growth and ground covering capacity after overwintering was enough to compensate the delay in sowing. Germination tests in laboratory revealed that hairy vetch grew faster at $25^{\circ}C$ compared to $20^{\circ}C$. The result suggested that germination and growth rate of hairy vetch was rapidly decreased at low temperature. Therefore, it is recommended that hairy vetch should be sown as soon as possible in September for improving stand establishment after overwintering.

• 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 applied entomology
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• v.48 no.2
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• pp.165-170
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• 2009

This study was conducted to investigate specific stages and distribution of overwintering nymphs of green rice leafhopper, Nephotettix cincticeps by measuring head capsule width. The nymphal head capsule width of the 1st instar to the 5th instar was 0.381, 0.502, 0.673, 0.979 and 1.128 mm, respectively. lts coefficient variation was 5.3, 4.0, 3.0, 4.5 and 5.3%, respectively. Growth ratio of each instar was not significantly different among 2nd to 4th instars as 1.31 to 1.34, but for the 5th instar it decreased as 1.28. The logarithm of the nymphal head capsule width was regressed as a function of the stage number of insects, resulting in LogY = 1.4627 + 0.1192X ($r^2= 0.9993$). Also fitness to the Dyar's law for the nymphal head capsule width of each instar was 98% or over and the Dyar's constant (K) was 1.316. The occurrence of N. cincticeps was maximum at the end of January with 195 individuals/0.25 $m^2$. The most abundant instar in the overwintering N. cincticeps population was 4th instar accounting for over 90%. Population of the 5th instar began to increase from mid-March, and adults began to occur in early April.

• Korean Journal of Ecology and Environment
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• v.49 no.2
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• pp.110-123
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• 2016

In order to obtain scientific information for the conservation of Utricularia japonica Makino, rare plant species, we investigated life history, phenology, growth and distribution in the east coastal region of Korea. Seven habitats of U. japonica were confirmed in this study. Turion of U. japonica rests overwinter at the bottom and ripens at the water surface and then usually germinate and sprout when the water warms in spring. A single shoot grown from turion divided into several shoots. Shoot decomposition started in October and formed a new turion at the end of the decomposed shoot. Flowering period was from early July to late October. Percentage of flowering ramets was significantly low as 6.3%. U. japonica showed the fastest growth rate from April to July, the maximum growth in August and the highest biomass in October. U. japonica tended to be concentrated in larger ramets in the water depth of 50 cm~150 cm in Cheonjin lake. The main factors affecting the growth of U. japonica were water temperature and turbidity. The establishment and growth of U. japonica in Cheonjin lake were determined by responses to water temperature with seasonal change and to light conditions caused by the different plants. These conditions affect the temporal and spatial distribution of U. japonica and population change. The findings of this study would be helpful to provide the basic information needed for the conservation and restoration of U. japonica.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.1
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• pp.78-85
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• 1987

In order for Paldanghomil (winter rye) to be investigated if its grain yield is able to be produced after clipping just before winter season for forage utilization this experiment was carried out under the four sowing dates of four locations in Korea (Chunchon, Suwon, Hwasung and Chungju). In rye clipping plot earlier sowing showed taller plant height, more number of tillers/㎡ and higher forage yield before winter season, indicating the highest forage yield (1803 kg/10a) in Chunchon by sowing of September II. Forage yield of rye before winter season was mainly influenced by plant height and number of tillers/㎡, showing more effect of plant height. Rye plants were more or less affected on winter damages, late heading and short culm by clipping before winter season. Analysis of variance indicated that only number of spikes/㎡ among grain yield components showed the high significance according to the clipping method, and that there showed little variation for other yield components due to the sowing date and clipping method. There showed more grain yield in non-clipping rather than that of clipping plot, indicating the difference of 46kg/10a. This was resulted from short culm and severe winter damages caused by clipping before winter season. Of the grain yield components, number of spikes/㎡ was greatly influenced for grain yield by analysis of stepwise regression. Therefore, grain yield of rye was able to produce after forage utilization before winter season due to the appropriate crop and soil managements, by resulting from the little variation in grain yield between clipping or non-clipping plots and from the higher grain yield by the early sowing.

• Research in Plant Disease
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• v.16 no.2
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• pp.109-114
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• 2010

The occurrence factors of Rice stripe virus (RSV) in Chungcheongbukdo were analyzed by investigating the viruliferous insect rate (VIR) of overwintered small brown plant hopper (SBPH), the population density of SBPH, the infection rate of natural host plants, and the occurrence rate of RSV on rice paddy fields at the 3 areas of Cheongwon, Jincheon, and Boeun in 2008 and 2009. The average VIR of overwintered SBPH was 0.0% in 2008 and 1.1% in 2009. From SBPH collected on early June in 2009, VIR was higher as 1.4% at Jincheon and 4.2% at Boeun than those of overwintered SBPH, and this higher VIR might relate stronlgy with the adult population of SBPH immigrated from China. The populations of SBPH at Cheongwon, Jincheon and Boeun in 2008 were 3.8, 7.5 and 20.8 Head/$m^2$, respectively. However, those of Cheongwon and Jincheon increased up to about two folds as 8.4 and 13.1 in 2009. No RSV was detected on the natural host plants including barley. The factors involved in RSV occurrence were affected negatively by the low VIR of overwintered SBPH, the low population of overwintered SBPH, the low infection rate of RSV on the natural host plants, and the clean cultivation environment in Chungcheongbukdo.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.2
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• pp.177-182
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• 2004

This experiment was conducted to compare the agronomic characteristics and productivity inintroduced vetch cultivar at the experimental field of Grassland and Forage Crops Division, National Livestock Research Institute from 1999 to 2000. The experiment was arranged in a randomized block design with three replications. The vetch cultivar used in this study were 8 cultivar(Haymaker plus, Common, Capello, Namoi, Victa, Aneto, Popany, Korean milk vetch). Namoi, Victa and Aneto cultivar were died during winter. The cultivar having the fastest flowering date was Korean milk vetch while the flowering date of Common was the latest as 22th May. The average dry matter(DM) content was 14.7% and crude protein(CP) content was 20.9%. Common showed the highest CP content by 23.1% and Korean milk vetch showed the lowest content by 18.0%. Average acid detergent fiber(ADF) and neutral detergent fiber(NDF) content were 33.5 and 42.5% respectively. All cultivar showed the first grade of RFV(relative feed value). The productivity of vetch cultivar were severely different according to the winter hardness. Common showed the highest DM yield by 8,664kg/ha, but the DM yield of Capello and Popany were low by 3,004 and 2,114kg/ha, respectively. The yield of CP and TDN(total digestible nutrient) also was high at Common. The results of this experiments indicated that the productivity of vetch cultivar was effected greatly depending on winter hardness, therefore it was thought winter hardness is the main factor for introducing vetch cultivar.

• Korean journal of applied entomology
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• v.42 no.2
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• pp.111-118
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• 2003

The population density of the Cotton caterpillar, Palpita indica (Saunder) larvae was gradually increased until 10th October and then decreased rapidly after that time at the watermelon culture of rain sheltered house. After 15th October, many larvae went to soil and molted to pupae for the hibernation. Most of pupae were found in pF 2.4 soil moisture condition, but none in pF 1.5 hydro-morphic soil. Most of the pupae were found below 5cm and there was no pupa below 10cm from the soil surface. The sex ratio of the overwintering pupae was 1.09 : 1.00. For the monitoring of the cotton caterpillar adults using sex pheromone compounds, different mixture ratios of each pheromone compound were investigated with (E)-11-hexadecenal and (E, E)-10,12-hexadecadienal. Seven versus three ratio of (I)-11-hexadecenal and (E, E) -10,12-hexadecadienal was more attractive than any other ratio, and then followed by 6 : 4, 8 : 2, 9 : 1, and 5 : 5 mixtures. As a result of monitoring with 7 : 3 mixture of (E)-11-hexadecenal and (E, E)-10,12-hexadecadienal, occurrence peaks of cotton caterpillar adults showed 4 times per year. The first time of adult appearance was late July in 2000 and middle July in 2001 and the highest number was collected on late September.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.354-361
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• 2012

This study was conducted to evaluate on the freezing tolerance of introduced blueberry cultivars in Korea and to investigate availability of portable timber moisture meter for simple and rapid diagnosis of blueberry-shoot damage by freezing during wintering. Frost tolerance of blueberry cultivars showed big difference that rates of blueberry-shoot death were widely distributed from about 0% to 100% after wintering. Optical density in TTC reduction of blueberry twig treated low temperature was low in order of $-40^{\circ}C$ < $-21^{\circ}C$ < $4^{\circ}C$. Hardiness evaluation of visible injury in the cross-sectional surface color did not agree with that of rates of blueberry-shoot death during wintering. Lowest water content of blueberry stem measured by timber moisture tester during wintering was about 15%. During wintering, water contents of blueberry stems were higher at lower part of tree, but were low at end part of stems, and then when the blueberry grew again for spring, the water content gradually increased to 20~40%. Water content of blueberry stem with freezing injury during wintering decreased to under 5% by desiccation. Therefore it is assummed that the moisture content of blueberry stem injured by freezing during wintering was about under 14%, and it is expected that portable timber moisture meter could be available for rapid diagnosis of blueberry freezing injury in field.