• Korean Journal of Plant Resources
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• v.37 no.2
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• pp.203-213
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• 2024

In this study, we investigated the growth and physiological responses of Iris laevigata Fisch. to shading treatments in order to suggest optimal light conditions for ex-situ conservation of the northern lineage plants. For this purpose, a control plant receiving full sunlight and different shading treatments (50%, 75%, 95%) were installed, and leaf mass per area, chlorophyll content and fluorescence response, and photosynthetic characteristics were investigated. I. laevigata developed leaves with higher photosynthetic efficiency to adapt to lower light intensity as shading levels increased. Chlorophyll content increased with increasing shading levels, and leaf mass per area decreased with increasing leaf area. The chlorophyll fluorescence responses Fv/Fm and NPQ did not change with shading, and the activity of the carbon fixation system did not differ between treatments. I. laevigata exhibited a light-saturation point equivalent to that of sun plants and maintained photosynthetic capacity similar to that of controls up to 75% shading. The apparent quantum yield of I. laevigata decreased significantly at 95% shading, indicating adaptation to lower light conditions. It seems that the photosynthetic capacity of I. laevigata decreases when grown under 95% shading level compared to full sunlight, and it is judged that the longer the light is restricted by continuous shading, the more unfavorable the growth will be.

• Journal of Plant Biotechnology
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• v.45 no.3
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• pp.266-272
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• 2018

A Polygonatum stenophyllum Maxim. is an important endangered plant belonging to the family Liliaceae. A method was developed for the rapid micropropagation of P. stenophyllum through plant regeneration from rhizome (1-year, 3-years, and 5-years) explant-derived calli. The rhizome segments were cultured in Murashige and Skoog (MS) medium supplemented with varying concentrations of 2,4-D (0, 0.5, 1.0, $1.5mg{\cdot}L^{-1}$) for callus induction. In media supplemented with $0.5mg{\cdot}L^{-1}$ of 2,4-D, 87% of 3-years rhizome produced callus. Subsequently, the callus was transferred to 1/2MS medium supplemented with various concentrations of IAA, IBA, NAA, and 2,4-D (0, 0.1, 0.5 and $1.0mg{\cdot}L^{-1}$) for adventitious shoot formation. The highest percentage of adventitious shoot induction (57%) was observed in 1/2MS medium containing $0.5mg{\cdot}L^{-1}$ of NAA. Elongation of the adventitious shoot was achieved in 1/2MS medium supplemented with $0.1mg{\cdot}L^{-1}$ of BA. Rooting was achieved in 1/2MS medium without any hormones. It is hypothesized that the stated in vitro propagation protocol will be useful for conservation and mass propagation of the endangered Polygonatum stenophyllum Maxim. for bioresources.

• Korean Journal of Plant Resources
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• v.20 no.4
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• pp.367-374
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• 2007

This study was carried out to establish the micropropagation system of Bupleurum latissimum Nakai that is a Korean native endangered species. Callus were induced from the leaf, petiole and floral bud and the percentage of callus formation was highest in the floral bud on the MS medium containing 2.0 mg ${\cdot}$ $L^{-1}$ 2,4-D. Especially, callus induced from floral bud was formed 77.8% and the percentage of shoot formation was 42.6% on the MS medium containing 2.0 mg ${\cdot}$ $L^{-1}$ 2,4-D plus 1.0 mg ${\cdot}$ $L^{-1}$ TDZ. For simultaneously callus formation and shoot regeneration, 1/2 MS medium was more effective than MS medium. The percentage callus formation, shoot regeneration and rooting were 46.3%, 13.0%, 13.0% in 1/2 MS medium, respectively. Soot regeneration from callus was good in 1/2 MS medium supplemented with 2.0 mg ${\cdot}$ $L^{-1}$ 2,4-D plus 1.0 mg ${\cdot}$ $L^{-1}$ BA where percentage of shoot regeneration was 74.1 %, and the number of shoot per explant was 2.4. The percentage of rooting was lowest (57.8%) in control while it was highest (97.8%) in 1.5 mg ${\cdot}$ $L^{-1}$ NAA. In acclimatization of regenerated plantlets, the percentage of survived plantlets was highest (86.1%), and plant height, root length and fresh weight were good in the soil for horticulture.

• Korean Journal of Plant Resources
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• v.36 no.4
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• pp.381-389
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• 2023

The germination characteristics of Pseudolysimachion kiusianum var. diamantiacum (Nakai) T.Yamaz., a rare and endemic plant designated by the Korea Forest Service, were investigated according to light conditions, temperature, and pretreatment. As a result of the germination experiment according to light conditions, it was determined that P. kiusianum is a photoblastic seed that does not germinate at all in dark conditions. The optimum germination temperature of the seeds was found to be 20-25℃, considering the final germination rate and germination time. Three growth regulators (IAA, GA₃, kinetin) and two inorganic salts (KNO₃, KCl) were pretreated to improve the germination rate of P. kiusianum seeds. The growth regulators IAA and kinetin had no significant effect on improving the germination rate of P. kiusianum seeds. On the other hand, GA₃ significantly increased the final germination percentage and germination rate regardless of the concentration, especially the treatment of more than 500 mg·L^-1 at 20℃ was more than 4 times more effective than the untreated. The inorganic salts KNO₃ and KCl had no significant effect on the seeds of P. kiusianum at low concentrations, but at higher concentrations (40 mM and 300 mM, respectively), they improved the germination rate and germination age by 2 times compared to the untreated. The results of this study will be useful for the mass propagation of P. kiusianum, which has the potential to be utilized as a native plant for restoration.

• Korean Journal of Plant Resources
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• v.37 no.1
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• pp.79-86
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• 2024

This study was conducted to determine the conditions for breaking dormancy in the seeds of the North Korean plant resource, Trollius macropetalus, and to investigate its germination characteristics. The morphological characteristics and viability of T. macropetalus seeds were examined. Germination characteristics were investigated based on temperature conditions (15/6℃ & 25/15℃), cold stratification treatment, and GA₃ treatment. The results showed that cold stratification treatment had no effect on breaking the dormancy of T. macropetalus. GA₃ treatment significantly increased the germination rate of T. macropetalus and also improved the mean germination days and germination speed. However, compared to the 15/6℃ condition, the effectiveness of GA₃ treatment for T. macropetalus decreased under the 25/15℃ condition. It was determined that T. macropetalus have a nondeep-type morpho-physiological dormancy. The most effective conditions for breaking dormancy were found to be the 15/6℃ temperature condition and GA₃ treatment at 500 mg·L^-1. The findings of this study are expected to provide valuable information for the mass propagation of T. macropetalus, which has potential applications in landscaping and pharmaceutical materials.

• Journal of Plant Biotechnology
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• v.42 no.4
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• pp.380-387
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• 2015

Aronia (Aronia melanocarpa, Black chokeberry) is an important cash crop in domestic agriculture. We investigated the effects of plant growth regulators on shoot proliferation and rooting using in vitro tissue culture. The most effective shoot multiplication was observed on WPM (woody plant medium) supplemented with 1.0 mg/L zeatin ($8.3{\pm}1.0$ shoots/explant), while the highest rooting rate was obtained from half-strength WPM with 3.0 mg/L IBA (8.8 roots/explant). The rooted plantlets all survived in the artificial soil mixture (with a mixture of peat moss : perlite : vermiculite, 1:1:1, v/v/v) and grew up relatively uniform, ranging from 14 to 16 leaves, 8 to 10 cm in stem height, and 2.3 to 2.8 mm in stem diameter. While experimenting with 5 different varieties of Aronia, we found out that each variety had different characteristics of shoot proliferation and rooting. The total numbers of proliferated shoots per variety is as follows: $17.4{\pm}0.8$ for Nero, 14 to 15 for Purple and Mackenzie, and 10 for both Viking and Odamamachiko. Rooting rates were also various depending on the variety: 88% of Odamamachiko, 80% of Viking and Purple, and 76% of Nero and 60% of Mackenzie shoots rooted. The survival rate of the rooted plantlets was from 92% to 100%, varying by type. Further growth appeared to be better in auxin-treated plantlets, compared to untreated ones. Our results showed the possibility of establishing an effective in vitro micropropagation system for Aronia melanocarpa.

• Composites Research
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• v.18 no.6
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• pp.26-33
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• 2005

The mechanical properties of composite materials may severely degrade in the presence of damage. Especially, the high-velocity impact such as bird strike, a hailstorm, and a small piece of tire or stone during high taxing, can cause considerable damage to the structures and sub-system in spite of a very small mass. However, it is not easy to detect the damage in composite plates using a single technique or any conventional methods. In this paper, the PVDF(polyvinylidene fluoride) film sensors were used for monitoring high-velocity impact damage initiation and propagation in composite laminates. The WT(wavelet transform) and STFT(short time Fourier transform) are used to decompose the sensor signals. A ultrasonic C-scan and a digital microscope are also used to examine the extent of the damage in each case. This research shows how various sensing techniques, PVDF sensor in particular, can be used to characterize high-velocity impact damage in advanced composite.

• Korean Journal of Plant Tissue Culture
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• v.28 no.3
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• pp.171-178
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• 2001

This study was investigated to establish a regeneration system of plant via adventitious bud formation from leaf explant cultures of strawberry (Fragaria ananassa Duch). Effects of plant growth regulators (2,4-D, BAP), agar sucrose and myo-inositol on adventitious bud formation were investigated. When the leaf explants were cultured on MS medium supplemented with 0.1 mg/L 2,4-D and 3 mg/L BAP, the adventitious bud formation was most promoted. The adventitious bud formation was not induced from leaf explants cultured on MS medium containing 2,4-D alone. Adventitious bud formation was enhanced to almost 3 times on medium with low level of agar concentration (0.4%) in comparison with those on the medium with high level of agar (1%), but almost of shoot was vitrificated on the medium. Therefore, the normal adventitious bud formation from leaf explants was most effective on the medium containing 0.05 mg/L 2,4-D,1 mg/L BAP, 0.8% agar, 30 g/L sucrose and 100 mg/L myo-inositol. Thus, the mass propagation of healthy strawberry could be established using leaf explants.

• Geomechanics and Engineering
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• v.14 no.3
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• pp.271-281
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• 2018

A jointed rock slope stability evaluation was simulated by a discontinuous deformation analysis numerical method to investigate the process and safety factors for different crack distributions and different overloading situations. An optimized method using Discontinuous Deformation Analysis for Rock Failure (DDARF) is presented to perform numerical investigations on the jointed rock slope stability evaluation of the Dagangshan hydropower station. During the pre-processing of establishing the numerical model, an integrated software system including AutoCAD, Screen Capture, and Excel is adopted to facilitate the implementation of the numerical model with random joint network. These optimizations during the pre-processing stage of DDARF can remarkably improve the simulation efficiency, making it possible for complex model calculation. In the numerical investigations on the jointed rock slope stability evaluations using the optimized DDARF, three calculation schemes have been taken into account in the numerical model: (I) no joint; (II) two sets of regular parallel joints; and (III) multiple sets of random joints. This model is capable of replicating the entire processes including crack initiation, propagation, formation of shear zones, and local failures, and thus is able to provide constructive suggestions to supporting schemes for the slope. Meanwhile, the overloading numerical simulations under the same three schemes have also been performed. Overloading safety factors of the three schemes are 5.68, 2.42 and 1.39, respectively, which are obtained by analyzing the displacement evolutions of key monitoring points during overloading.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.1 s.1
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• pp.157-163
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• 2001

The objective of the present study is to predict the characteristics of the fire and smoke propagations in a clean room. Numerical calculations have been performed by using the finite volume method to obtain temperature and velocity distributions in the clean room. In odor to account for the turbulent flow characteristics, the standard $k-{\varepsilon}$ model is used. From this study, it was found that the fire propagation could be fully developed only after 150 seconds when the ventilation system in the clean room was off. And the smoke mass fraction showed a similar distribution as the gas temperature. Since the simulated fire was proceeded up to $20{\sim}30%$ of the room within 60 seconds. it could be recommended that the occupants should be evacuated from the room within 30 seconds.