• Korean Journal of Medicinal Crop Science
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• v.7 no.3
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• pp.155-161
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• 1999

This study was carried out to develop the propagation system using in vitro induced- microtubers of yams (Dioscorea alata L.). Effects of kinds of media, mineral composition, sucrose concentration (0, 2, 4, 6, 8, 10%), photoperiod (0, 8, 12, 16, 24h), and growth regulators (NAA, IAA, ZR, JA-Me, ABA) on the development of microtubers, roots, and shoots in nodal stem segment cultures of D. alata L. were evaluated. Microtuberization in nodal stem segment occurred on all the media supplemented with growth regulator and sucrose. Among basic media, 1/2MS medium was the best in microtuber induction. NAA was shown to be the most effective among the growth regulators. Optimal NAA concentration was 1mg/l. The microtuberization was the highest at the concentration of 6% sucrose. When the nodal stem segment were cultured under darkness, the tuberization was increased markedly compared to those cultured under light condition. It was also noticeable that the culture in medium with NAA produced only microtubers and roots, but no shoots, in nodal segments. In this study, the optimal medium composition for microtuberization in nodal stem segment was found to be 1/2MS medium supplemented with 1mg/l NAA and 6% sucrose under dark condition at $25^{\circ}C$.

• Journal of Korea Foresty Energy
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• v.2 no.2
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• pp.1-12
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• 1982

To study tile comparison of aboveground biomass of Pinus rigida Mill. of 18-year-old, plantations located in Whaseong, Yuseong and Wanju district were selected. Ten sample trees in each district selected taking account of DBH distribution were felled carefully to minimize loss of branches and stem analysed by 1m lag segment sectioned from base . The tree height and DBH were measured for sample trees in total growing within $200m^2$ experimental plot. The diagram of oven-dry weight distribution of stem, branch and needle for each 1m segment was constructed. The logarithmic regression equations between dry weight of each component and the two variables, $DBH^2$ and tree height, combined term were presented. The standing crops in the sample stand was estimated to be as much as 23.88, 54.09 and 42.68 tons of dry matter, above ground , per ha in Whaseong, Yuseong anf Wanju district respectively. Annual net production was estimated at 253,657 and 3.65 tons per ha per year respectively. The net assimilation rate was 1.65,1.95 and 1.81 kg/kg/yr in Whaseong, Yuseong and Wanju district respectively. The efficency of leaf to produce stem was 0.99, 1.12 and 1.30 kg/kg/yr respectively.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.162-167
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• 2016

This study was carried out to investigate proper stem cutting position and air temperature to regenerate roots from cuttings of bitter gourd. 'NS454' (NS) and 'Dragon' (DR) cultivars were tested and the cutting position was cut at the 3rd node in the stem (treatment I) and cut at the central part (stem segment) between 3rd leaf and 4th leaf in the stem (treatment II). The air temperature was maintained at 18, 23, 28 and $35^{\circ}C$ in the growth chambers, respectively. The photosynthetic photon flux at the ground of a chamber was maintained in approximately $150-200{\mu}mol\;m^{-2}s^{-1}$ during the 16-hour photoperiod. The relative humidity in the chambers was maintained over 85%. After 10 days of cuttings, regardless of cutting position, DR and NS cultivars showed 100% the survival rate in the $18^{\circ}C$ or $23^{\circ}C$ treatments, however, most of plants $18^{\circ}C$ treatment had not rooting. In the $28^{\circ}C$ treatment, regardless of cutting position, DR and NS cultivars showed 100% of the rooting rate. In the $23^{\circ}C$ treatment, for DR cultivar, the node cutting showed 90% of rooting rate and the stem segment cutting showed 40% rooting rate. For NS cultivar, the node cutting showed 50% of rooting rate and the stem segment cutting showed 40% rooting rate. DR and NS cultivars have high rooting rate, while the rooting rate remarkably decreased in the $35^{\circ}C$ treatment. For DR cultivar, the stem segment cutting showed 5.3 of the highest rooting number and the node cutting showed 2.7 rooting number in the $28^{\circ}C$ treatment. NS cultivar was not significantly different the rooting regardless of cutting position. The results suggested that cutting at the stem segment cutting of bitter gourd is an effective cutting method for increasing survival rate and the air temperature should be maintained at $28^{\circ}C$.

• Journal of Plant Biotechnology
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• v.31 no.1
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• pp.49-53
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• 2004

Shoot formation was investigated from in vitro cultivation of exotic hybrid poplar (Populus koreana ${\times}$ P. trichocarpa) with a specific stomatal character occurring both upper and lower surface of leaves. Two different explants (stem and leaf segment) of Peace poplar were cultured on half strength Murashige and Skoog (MS) basal medium supplemented with the various concentrations of thidiazuron as a plant growth regulator. Most adventitious shoots were produced from excised ends of stem or mid-veins of leaf segments. The highest average numbers of shoots were 7.1 and 5.3 with the treatments of 0.02mg/L TDZ in both explants of stem and leaf segment. The highest shooting rates were achieved to 83.3％ and 47.6％ with the concentrations of 0.01mg/L and 0.02mg/L TDZ by axillary bud and leaf cultures, respectively.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.133-133
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• 2017

Lodging is one of the important constraints in rice production. The lodging destroys the canopy structure, and sharply reduces the capacity of photosynthetic rate and dry matter production. In cereal crops, stem lodging can be classified into two types: stem breaking type and stem bending type. To improve stem lodging resistance, it is important to reveal strong culm traits of superior lodging resistant varieties. There are large varietal differences in parameters associated with the bending moment at breaking (M) and flexural rigidity (FR). The indica variety Takanari possesses large M due to its large section modulus (SM) despite of its small bending stress (BS), while Takanari also has large FR due to its large secondary moment of inertia (SMI) and Young's modulus (YM). To identify quantitative trait loci (QTLs) and the corresponding genes associated with the parameters for M ($=SM{\times}BS$) and FR ($=SM{\times}YM$) should enable to develop lodging resistant varieties, efficiently. In order to identify QTLs for cell wall materials such as cellulose, hemicellulose and lignin associated with BS and YM, a set of Chromosome Segment of Substitution Lines (CSSLs) consisted of 37 lines with chromosome segments of Koshihikari in the genetic background of Takanari were used. Takanari had large M and small BS as compared with Koshihikari. The QTLs for BS were estimated on chromosomes 3, 5, 6, 8, 9, 10, 11 and 12. Koshihikari alleles increased BS in these QTLs. Takanari had a large FR due to its large SMI and YM as compared with Koshihikari. The YM was increased by substitution of the Koshihikari chromosomal segments on chromosomes 2, 10 and 11. Other QTLs estimated on chromosomes 7 and 12 that Koshihikari alleles contributed to the decrease of YM. For lignin, only one major QTL for lignin density was detected on chromosome 11. Hollocellulose densities were increased by the substitution of Koshihikari segments on chromosomes 5 and 11. On the other hand, these were decreased on chromosomes 1 and 3 by substitution of Koshihikari segments. QTLs for cellulose density were estimated on chromosomes 1, 3 and 5 by substitution of Koshihikari segments. For hemicellulose, QTL on chromosome 3 showed that hemicellulose density decreased by the substitution of Koshihikari segment. However, hemicellulose densities on chromosomes 5, 8 and 11 showed the opposite effects. The QTLs for hemicellulose, cellulose, and hollocelulose densities identified on chromosome 5 overlapped with that for bending stress, indicating the positive effect of Koshihikari segment on increasing bending stress. These results suggest that some QTLs for the densities of cell wall materials contribute to increasing bending stress and Young's modulus, and could be utilized to improve the lodging resistance for both types of breaking and bending in rice varieties.

• Journal of Life Science
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• v.12 no.3
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• pp.306-316
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• 2002

The ultrastructural change of sciatic nerve and immunohistochemical changes of NGF, PCNA were studied at the transplanted segment of intravascular cultured neural stem cell in the rat sciatic nerve by 5 months after the sciatic nerve transection. The transplanted intravascular neural stem cells were differentiated into Schwann reals at the 20th day and these cells began to regenerate by the proliferation and hypertrophy. There were many remyelinating Schwann cells in the transplanted nerve in term of stimulation. According to NGF finding, we suggest preexisting Schwann cells may induce the differentiation of neural stem cells into regenerating Schwann cells. Electron microscopic changes were the remyelinating appearance, the increase of intraaxonal microtubules and enlarged mitochondria and contacting tell processes each other.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.205-212
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• 1987

To examine the morphogenetic response, stem segments of 8 Populus spp. and 3 different explants of P. nigra var. italica were cultured on MS (Murashige and Skoog 1962) and WPM (Woody Plant Medium) medium containing various phytohormones. The results obtained were as follows: 1. Shoot regeneration and development from stem segment of 8 Populus spp. showed a quite difference according to the section and the species. All of the species of Leuce and Tacamahaca section did not form adventitious buds, while most of explants showed axillary or dormant bud elongation after 4 weeks. But P. nigra var. italica of Aigeiros section showed a successful adventitious bud formation (mean 5.4 buds per explant). 2. Leaf, petiole, and internode segment of P. nigra var. italica showed a quite differences according to media and ex plants upon the morphogenetic response. Adventitious bud formation from leaf was more abundant and readily initiated on the abaxial side than on the adaxial side. Mean number of 103 adventitious buds per explant was obtained from abaxial side of leaf segment cultured on WPM medium containing $0.2mg/{\ell}$ BAP for 5 weeks. 3. 2,4-D (2,4-dichlorophenoxy acetic acid) supplemented to media appeared to be negative upon the adventitious bud formation of P. nigra var. italica, while it promoted callus formation from all explants. Especially, NAA (${\alpha}$-naphtalene acetic acid) or NAA combination with BAP (6-benzylaminopurine) promoted root regeneration from the all explant of P. nigra var. italica in this study.

• Journal of Korean Neurosurgical Society
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• v.30 no.1
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• pp.66-72
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• 2001

Apatient with multiple dissecting aneurysms of a posterior inferior cerebellar artery trunk who presented with SAH is reported. A 58-year-old woman presented with sudden occipital headache, dizziness and vomiting. The intial vertebral angiography revealed a suspicious pearl and string sign at the proximal posterior inferior cerebellar artery(PICA) segment. After 2 weeks, follow up angiography showed a progression of the proximal PICA dissection and newly developed dissecting aneurysm of the distal PICA segment. A far lateral suboccipital transcondylar appoach confirmed two dissecting aneurysms at distant sites of the PICA trunk. The dissection segments were wrapped with muslin wrap, which preserved the flow through the PICA and brain stem perforators. The angiographys at 3 weeks and 6 months after operation revealed serial disappearance of the dissecting aneurysms which is distal to proximal. The diagnosis, course and treatment of the dissecting aneurysms of the PICA are discussed with literature review.

• Korean Journal of Medicinal Crop Science
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• v.2 no.2
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• pp.154-161
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• 1994

This experiment was carried out to establish micropropagation system in Fritillaria thunbergii Miq. Through the culture of bulblet scales, stems, node-buds and shoot tips with special reference to the effect of physiological age of explant and plant growth regulators on bulblet formation. Number of formed bulblets was significantly increased in node-bud or stem tissue compared to scals segments and on the medium supplemented with kinetin than BA containing medium. Optimum levels of kinetin for bulblet formation from node-bud taken from above 3 cm shoot length and stem segments excised from below 3 cm shoot length were 5.0 mg /L and $1.0{\sim}3.0\;mg$ /L kinetin, respectively. Interesting phenomenon was observed, the direct formation of bulblets from the axilliary bud of cultured explants. Bulblet forming capacity in stem tissue was depended on stem age, young stem had high regeneration ability compared to old stem taken from above 10 cm shoot length. 1.0 mg /L kinetin was optimum concentration for the formation of bulblets from old stem segments. Stem tissue taken from underground growing plant was promoted coampare to shoot tips or bulb scale segments. Optimum concentration of sucrose was $5{\sim}7%$. Summariged above results revealed that effective explant for micropropagation was stem and /or node-bud tissue excised from less than 3 cm plant height compared to those of bulb scale segments which showed high contamination after culture. Maximum multiplication rate of young stem and /or node-bud segment was about 20 times. Kinetin requirement for stimulation of bulblet formation from cultured explant depended on source of explants but favorable levels of kinetin for organogenesis ranged from 1.0 mg /L to 5.0 mg /L.

• Korean Journal of Medicinal Crop Science
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• v.4 no.2
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• pp.126-131
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• 1996

Plant regeneration from the stem tissue of Houttuynia cordata Thunberg was investigated. The medium supplemented with the combination of 2, 4-D 1 mg/L and kinetin 0. 5 mg/L was the most effective for the embryogenic callus formation. The internode segment produced more callus formation than the leaf segment. ${\frac{1}{2}}\;MS$ medium was the most effective for the embryogenic callus formation. The medium supplemented with the 1% activated charcoal produced the whole plant directly without the callus formation from the nodes. The medium supplemented with the combination of NAA 0. 2 mg/L and BA 1 mg/L was the most effective for the plant regeneration from the embryogenic callus.