• Korean Journal of Medicinal Crop Science
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• v.6 no.2
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• pp.160-164
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• 1998

Angelica gigas has been a major medicinal crop in Korea for a long time. This study was to determine optimum seeding time and bolting response by shifting seeding time between November 10, 1993, and August 10, 1994 using promising line, Suwon 2. Days to emergence were similar among seeding times from April 10 to August 10 in Suwon. Seedling duration was shortened 92 days when seeded on July 10 compared with the conventional seeding time of April 10. Productivity of seedling ranging from 0.31 to 0.70cm in diameter was highest of 730 plants per $m^2$ in July 10 seeding. When seeded in July 10, bolting rate was 2.4 percent as compared with 2.6 percent in conventional seeding (April 10). The optimum seeding time was July 10. Seedling quality, survival rate after planting in field, and root yield were greatly influenced by seeding time.

• Korean Journal of Medicinal Crop Science
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• v.10 no.5
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• pp.419-422
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• 2002

Korean angelica(Angelica gigas Nakai), a oriental medicinal plants is important and in great demand in Korea. This crop is a biennial which is to die after flower, so as could not harvest the root. A new variety 'Anpung' was developed from the selection of the local collecting population by medicinal crop team at NCES in 2001. This showed stable bolting during its cropping year and have high quality and yield potential. The color is greenish purple in stem and red purple in flower. It was longer in plant height and root length, thicker in root diameter, more leave and latheral roots comparing with the check variety 'Manchu'. The dry root was 72 g/plant showing heavier than check variety of 65 g/plant. It showed such low bolting rate as 0.5%, on the other hand 49.3% in landrace when it cultured by transplanting with heating nursery seedlings, and $0{\sim}15%$ with field nursery seedlings. The dry root yield of the variety was averaged 3,630 kg/ha out yielding the check variety by 11% at the three regional yield test from 1999 to 2001. Finally, 'Anpung' showed higher content of extracts up to 46.3% in 'Anpung' and 45% in check variety, decursin and decursinol contents was 3.48% and 2.79%, showing slightly higher than check variety.

• Korean Journal of Medicinal Crop Science
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• v.2 no.2
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• pp.146-148
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• 1994

The most important subject in cultivation of A. gigas NAKAI would be how to decrease the bolting rate. Belcause the decrease and poor of the yields and quality is imevitable in such field where the bolting rate is high. This study was carried out to investigate the time of flower-bud differentiation as a part of improvements of cultivation method. Shoot apex was fixed in Farmer's solution(ETOH 3:Acetic acid 1), thin paraffin ribbon was made, and the tissue was stained by Safranin solution. Differentiation time of flower-bud in A. gigas differed greatly from individuals by the seedling size, generally begun from middle of May to late of June, it was time that two leaves spread. In this results, Photoperiocid types of A. gigas NAKAI were regarded as LI type or LS type of dull-photosensitivity.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.326-332
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• 2011

The growth and bolting characteristics of spring Chinese cabbage cultivars at two night-time temperature treatments such as $5^{\circ}C$ and $10^{\circ}C$ during seedling stage were investigated to establish a safe environmental management strategy for raising seedlings. The low night-time temperature treatments were applied at 5, 10, and 15 days after sawing and the treatment durations were 5, 10, and 15 days in each of treatment beginning. The growth of seedlings in all the tested cultivars were linearly reduced as the treatment duration was extended and no symptoms of bolting were found. The reduction rate in seedling growth of 'Chunkwang' reached to 59.3% at most by 15 days of $5^{\circ}C$ treatment when it be compared to that of control. However, no symptoms of bolting were shown in the treatments of two night-time temperatures until the harvest at 90 days after sawing, indicating that the vernalization effect by low night-time temperature could be mitigated by subsequent day-time optimal temperature management. This study showed that the major spring Chinese cabbage cultivars require more ultimate level of low night-time temperature treatment for the vernalization than this study. It is also supposed that the optimal day-time temperature management can reduce or delay the rate of bolting, even if the seedlings were exposed to short-term low temperature below $5^{\circ}C$ during night-time.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.1
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• pp.58-65
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• 1993

The purpose of this study is to determine the evolution of carbon and nitrogen concentrations in relation to dry matter and crude protein accumulation in the leaves of forage rape(Brassica napus Subsp. oleifera, CV. Swiss) during the growth period. Field-grown plants were sampled at intervals throughout fall, winter, early and late spring. During over-wintering period(from Nov. 7 1991 to Feb. 4 1992), the carbon concentration in the leaves increased from 382 mg to 435 mg g DM$^{-1}$ , while the concentrations of nitrogen and crude protein significantly decreased. There was little accumulation of fresh and dry matter in the leaves. On early spring growth from 4 Feb. to 30 Mar. marked carbon loss 37 mg. day$^{-1}$ and slight nitrogen accumulation occurred with the increase of fresh weight in the leaves. From spring growth to bolting stage(from 31 Mar. to 16 Apr.) the greatest accumulation of fresh and dry matter was observed and carbon and crude protein concentrations increased with a linear manner. After bolting stage the concentrations of carbon, nitrogen, hydrogen and crude protein in the leaves significantly decreased until late blooming stage, and the decreasing rate was prominent in nitrogen (45.7%) and crude protein(46%). From the results above it is recommended that fertilizer will be applied before early spring growth, and that optimal utilization period is a bolting stage. For the serious modification of the internal C/N balance during the overwintering period.

• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.2
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• pp.75-80
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• 2019

Oilseed rape is known to crop having low nitrogen use efficiency (NUE) but requires high levels of N fertilizer. NUE is associated with N remobilization from source to sink organ, consequently affects seed yield. Remobilization of leaf N is also related to transport of C/N metabolites in phloem. However, interaction between seed yield and phloem transport was not fully documented. In response to seed yield, N and C metabolites and their transport into seed from bolting to pod filling stage investigated in two contrasting genotypes (Capitol and Pollen) cultivated under ample (HN) or limiting nitrate (LN) supply. Seed yield was significantly reduced in N limitation and its reduction rate was much lower in Capitol than in Pollen compared to HN treated plants. Amino acid and protein content was higher in Capitol than in Pollen at bolting stage. They gradually decreased during plant development but not significant between two cultivars and/or two treatments. Glucose, fructose and sucrose content were 1.8-,1.6- or 1.25-fold higher in LN condition than in HN condition, respectively. Amino acid and sucrose content in phloem were largely higher in Capitol than in Pollen under LN condition. These results indicate that the higher seed yield might be related to greater transport ability of amino acid and sucrose in phloem under LN condition.

• Horticultural Science & Technology
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• v.29 no.4
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• pp.293-297
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• 2011

This experiment was conducted to elucidate the effects of mulching materials and removing time of the transparent polyethylene (PE) film on the growth of garlic at Uiseong experimental field, Korea. The experimental mulching materials comprised of transparent polyethylene film (0.025 mm) and net polyethylene (NPE). Plant height and leaf number of garlic were highest at PE treatment when the PE removing date was March 18 and this treatment also promoted the no. of cloves. Length of leaf sheath and bolting rate were highest and bulb weight loss rate was lowest at PE + NPE treatment when the PE removing date was March 18. But clove number was the lowest in this treatment compared to conventional PE film treatment. Conventional mulching method accelerated secondary growth rate but bulb weight loss was vice versa. There were statistically no differences in bulb diameter among treatments but conventional treatment positively focused on bulb diameter. Whenever PE film remove can suppress weeds compared to no mulching treatment but the dry weight of weeds were increasing trends as the removal dates of PE film were delayed. Transparent PE or PE + NPE treatments can be recommended to grow best quality garlic when PE film removing date is March 18.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.3
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• pp.186-191
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• 1995

This study was conducted to evaluate the effect of herbicides on weed control, growth characteristics and yield in rapes, after direct seeding it to the field. All herbicides treated had no effect on the emergence period, bolting rate of rapes. The major weeds were Cerastium holosteoides var. hallaisanense, Stellaria media Villars, Larnium ampleicaule L., Lobelia chinensis Lour., Geranium wilfordii Maxim. and Capsellu bursa-pastoris (L.) Medicus. Rapes yield were increased somewhat more with alachlor-G, herbicide than the other hehicides and by hand weeding. Alachlor-G and alachlor-Ec were had no i j u r y but butachlor- G and simajin-Wp were slightly harmful for the rapes with recommended concentration. On the other hand all hehicides were harmful in the double dosage level.

• Korean Journal of Plant Resources
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• v.8 no.3
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• pp.247-252
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• 1995

This study examines the effects of the planting time of mother bulb and mulching materials for the seed production of onion on the amount of seed production, and the following results are obtained : Growth, bolting rate, flowering rate, floret numbers per scape and fertilization rate are best in the case of the seed production under transparent vinyl mulching between Sept. 10 and Sept. 25, and seed yield per plant and seed yield per 10a are increased in the case of the seed production under transparent vinyl mulching between Sept. 10 and Sept. 25, so it is found that it is appropriate to plant the onion mother bulb under the transparent vinyl mulching between Sept. 10 and Sept. 25 in the southern areas of Korea.

• Geomechanics and Engineering
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• v.29 no.2
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• pp.99-111
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• 2022

Instability of bolted rock mass has been a major hazard in the underground coal mining industry for decades. Developing effective support guidelines requires understanding of complex bolted rock mass failure mechanisms. In this study, the dynamic failure behavior, mechanical behavior, and energy evolution of a laboratory-scale bolted specimens is studied by conducting laboratory static-dynamic coupled loading tests. The results showed that: (1) Under static-dynamic coupled loading, the stress-strain curve of the bolted rock mass has a significant impact velocity (strain rate) correlation, and the stress-strain curve shows rebound characteristics after the peak; (2) There is a critical strain rate in a rock mass under static-dynamic coupled loading, and it decreases exponentially with increasing pre-static load level. Bolting can significantly improve the critical strain rate of a rock mass; (3) Compared with a no-bolt rock mass, the dissipation energy ratio of the bolted rock mass decreases exponentially with increasing pre-static load level, the ultimate dynamic impact energy and dissipation energy of the bolted rock mass increase significantly, and the increasing index of the ratio of dissipation energy increases linearly with the pre-static load; (4) Based on laboratory testing and on-site microseismic and stress monitoring, a design method is proposed for a roadway bolt support against dynamic load disturbance, which provides guidance for the design of deep underground roadway anchorage supports. The research results provide new ideas for explaining the failure behavior of anchorage supports and adopting reasonable design and construction practices.