• Korean Journal of Plant Tissue Culture
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• v.27 no.2
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• pp.143-148
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• 2000

This study was carried out to know the optimum dose of gamma-ray for the induction of mutation in vitro and the characteristics of the mutants induced by gamma-ray in persimmon (Diospyros kaki Thunb.). The LD50 (50% lethal dose) for in vitro shoots of the cultivar, Nishimurawase was between 1 krad and 2 krad and about 1 krad for the cultivar, Ichikikeijiro. As the dose of gamma-ray increased, the length of shoots decreased and necrosis of buds increased. For the cultivar, Nishmurawase, 37.5∼58.3% shoots rooted and the rooting rate and the number of roots per shoot was low in high gamma-ray. The irradiated young plants which were grown in the growth cabinet for 6 weeks were shorter in shoot length and had more branches than non-irradiated plants. The survival rate of irradiated plants grown in the green house for 3 months was 33%, while 77% for control plants.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.5
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• pp.90-97
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• 2009

Sedum takesimenses among the Korean Native Genus Sedum was selected as evergreen ground covers during winter in the central districts of Korea. In order to obtain basic information for production as a pot flower with good quality, the effects of pinching frequencies on growth and flowering of S. takesimense were investigated. S. takesimense plant height became much shorter and numbers of lateral shoots were increased with increased pinching. Shoots of S. takesimense treated with 30% pinching during 2004 and 2005 showed greater length and less number of lateral shoots than those with 60% pinching. Leaves of S. takesimense treated with 70% shading showed a dark green color and had a longer shoot length and a lower number of shoots than cultivation under full sunlight. Therefore, Korean native S. takesimense will be utilized as ground cover treated with 70% shading or under a tree. Therefore, S. takesimense will be promising as ground cover materials in the central districts of Korea.

• Korean Journal of Plant Resources
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• v.26 no.4
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• pp.511-515
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• 2013

Hypocotyls explants of melon seedling were cultured on Murashige and Skoog's (MS) medium supplemented with 1 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D) and 0.5 mg/L benzyl aminopurine (BA) for 6 weeks to produce somatic embryos. In somatic embryos produced through intervening bright yellow friable (BYF) from the explants, somatic embryos with two-cotyledon (26%) and horn-type cotyledon (74%) were observed. The procambial strand of cotyledons was originated from circular procambial tissues of lower hypocotyls. The circular procambial independently divided into two procambial strand at the edge of cotyledonary-node, and then connected to each cotyledon to form somatic embryos with two-cotyledon. When cotyledon was horn-type, the circular procambial strand in lower hypocotyls would continuously remain connected to the cotyledon. However, somatic embryos with two or horn type cotyledon formed an abnormal shoot apex without the tunica-corpus structure or dome shape in the inter-cotyledonary area. These results demonstrated that the variation of cotyledon in somatic embryos was closely related to procambial tissue differentiation and shoot apical formation.

• Journal of Plant Biology
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• v.3 no.2
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• pp.29-34
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• 1960

From the view point of phytopathological anatomy, the author has tried to study the effect of the shoot cluster disease virus on the internal structure of vascular tissues of chinese date tree (Ziziphus jujuba var. inermis Rehd.) comparing healthy checks and diseased plants. The materials were collected at the several sites, Kumgock-Ri, Masuc-Ri, Kyungi-Do, and near the campus of Korea University and around the area of Chongam-Dong, Seoul City, from August 15th to September 5th 1959. The leaf materials of healthy and diseased plants are fixed and aspirated in two kinds of killing solutions, formalin-acetic acid alcohol solution and Craf III solution. Sections were cut at 5-10$\mu$ thickness and stained with the double staining reagents of safranin and fast green. In this experiment the author has observed that there are marked structural changes in the infected plants in contrast of healthy checks. As figures 3-7 show that the following characteric changes have taken place on infected plants: 1) the arrangement of irregularly developed sieve elements in phloem, 2) the degeneration of phloem elements, 3) the irregular arrangement of epidermis in mid-vein, 4) more necrosis is observed among the parenchymatous cells, 5) abundant accumulatin of starch grains in parenchymatous cells, . In contrast to the above irregularities caused by the virus disease, the healthy checks appear normal structures as shown in figures 1 and 2. In adding to the all features noted above, the author could also observe an interesting feature that the xylem elements in mid-vein vascular bundle tissues are considerably disorganized to show the unspecialized vessel elements, the irregularly arranged xylem elements. However, this kind of irregularities which occur in xylem under the virus infection has not been reported previously. The features noted on the internal structure of vascular bundle under the condition of infection by the shoot cluster disease on chinese date trees appear to be more or less closely similar to the symptoms of the bunchy-top of banana and the yellow dwarf disease of barley in respect to the fact that whether phloem necrosis takes place as a primary symptom or a secondary symptom. In all these disease, primary histological changes of hypoplasia and hypertrophy are preceeded by the necrosis of phloem.

• Journal of Applied Biological Chemistry
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• v.55 no.2
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• pp.95-101
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• 2012

Nutritional components of Ojuk leaf tea and Ojuk shoot tea prepared from the leaves and shoots of black bamboo (Phyllostachys nigra Munro) by tea manufacturing process were evaluated. In addition, the extraction yield of water soluble components from these teas in the general tea brewing condition (water extraction in $80^{\circ}C$ for 10 min.) and the contents of polyphenol and flavonoid were compared with not only the dried raw materials, but also green tea and mate tea. Finally, offline and online scavenging activities against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and di(phenyl)-(2,4,6 trinitrophenyl)iminoazanium free radicals were investigated to evaluate the antioxidant activity and explore the components showing ABTS free radical scavenging activity from tea infusion. These results demonstrated that these teas from black bamboo contain various nutritional components and can be used as traditional tea beneficial to human health.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.221-221
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• 2022

Chromosome breakage occurred by DNA methylation inhibitor. Zebularine is known as DNA methylation inhibitor and suitable for water solubility among different DNA methylation inhibitors as 5-Azacytidine and 5-aza-2'-deoxycytidine. We used zebularine as mutagen according to different methods by roots absorption and seed imbibition. After zebularine treatment, DNA methylation inhibitor, we observed mitotic chromosome behavior what is different according to two different treatment methods. First, seed imbibition treatment in 1,000 μM of zebularine solution for 72 hours in dark conditions. The second treatment to seedlings of Keumkang was also treated in 1,000 μM of zebularine solution for 72 hours after germination. Root and shoot showed different elongations in each treatment. Root absorption treatment(3.01±0.48, 2.00±0.26) showed the shortest elongation in root and shoot than control(8.16±0.61, 4.03±0.48) and seed imbibition treatment(4.33±0.80, 2.48±0.36). It can be explained root tip meristematic cell activity was damaged by DNA methylation inhibitor. Primary root tips were collected in DW for 24 hours at low temperature(0℃) and fixed in fixation solution for 3 days to chromosome observation in mitosis. Mitotic index, chromosome structure and chromosome aberration were observed by phase-contrast microscope. Mitotic index of the control(0.29) showed twice mitotic cells as the treated groups(imbibition 0.15, absorption 0.14). Observation of chromosomes showed some short chromosomes and loosen chromosomes affected by zebularine. It is considered because of zebularine damage DNA in mitosis. We observed "gap by chromosome breakage" in chromosomes that have loose parts between centromere and telomere. It seems demethylation of zebularine occurs chromosome breakage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.386-395
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• 2006

The core questions for determining nitrogen topdress rate (Npi) at panicle initiation stage (PIS) are 'how much nitrogen accumulation during the reproductive stage (PNup) is required for the target rice yield or protein content depending on the growth and nitrogen nutrition status at PIS?' and 'how can we diagnose the growth and nitrogen nutrition status easily at real time basis?'. To address these questions, two years experiments from 2001 to 2002 were done under various rates of basal, tillering, and panicle nitrogen fertilizer by employing a rice cultivar, Hwaseongbyeo. The response of grain yield and milled-rice protein content was quantified in relation to RVIgreen (green ratio vegetation index) and SPAD reading measured around PIS as indirect estimators for growth and nitrogen nutrition status, the regression models were formulated to predict PNup based on the growth and nitrogen nutrition status and Npi at PIS. Grain yield showed quadratic response to PNup, RVIgreen around PIS, and SPAD reading around PIS. The regression models to predict grain yield had a high determination coefficient of above 0.95. PNup for the maximum grain yield was estimated to be 9 to 13.5 kgN/10a within the range of RVIgreen around PIS of this experiment. decreasing with increasing RVIgreen and also to be 10 to 11 kgN/10a regardless of SPAD readings around PIS. At these PNup's the protein content of milled rice was estimated to rise above 9% that might degrade eating quality seriously Milled-rice protein content showed curve-linear increase with the increase of PNup, RVIgreen around PIS, and SPAD reading around PIS. The regression models to predict protein content had a high determination coefficient of above 0.91. PNup to control the milled-rice protein content below 7% was estimated as 6 to 8 kgN/10a within the range of RVIgreen and SPAD reading of this experiment, showing much lower values than those for the maximum grain yield. The recovery of the Npi applied at PIS ranged from 53 to 83%, increasing with the increased growth amount while decreasing with the increasing Npi. The natural nitrogen supply from PIS to harvest ranged from 2.5 to 4 kg/10a, showing quadratic relationship with the shoot dry weight or shoot nitrogen content at PIS. The regression models to estimate PNup was formulated using Npi and anyone of RVIgreen, shoot dry weight, and shoot nitrogen content at PIS as predictor variables. These models showed good fitness with determination coefficients of 0.86 to 0.95 The prescription method based on the above models predicting grain yield, protein content and PNup and its constraints were discussed.

• Journal of Environmental Policy
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• v.12 no.4
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• pp.119-132
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• 2013

Hosta longipes is one of the most popular ornamental perennials in use in Korea today, and is mainly used as a groundcover plant in urban shaded places. In this study, the pytoremediation effect of Hosta longipes was tested using four concentrations (Control, 100, 250 and $500mg{\cdot}kg^{-1}$) of Cd, Pb and Zn in soil. The plants were planted in $300mm{\times}200mm{\times}250mm$ drainless-containers, which were filled with a artificial amended soil for 7 months. The results showed that the contents of heavy metals cadmium and lead in the shoot of Hosta longipes increased with increasing heavy metal concentration levels exception of zinc. The amount of zinc, cadmium, and lead accumulated in roots were increased with heavy metal concentration levels up in soil. The shoot/root ratios(TF; translocation factor) values were found to be more than 80% of total Zn, Cd, and Pb take up by Hosta longipes. These results indicated that root is the major part for accumulation of heavy metal. The removal contents of zinc, cadmium, and lead increased significantly with the increasing heavy metal concentration in the soil, which was planted with Hosta longipes. The heavy metal concentration accumulation in plant/soil ratios (BF; bioaccumulation factor) values for three metals were found to be more than 30% in cadmium and lead, but lower in zinc treatments. The different responses of Hosta longipes suggest that in heavy metal contaminated soils the plant adsorbs available metals depending on the concentration soils in which they are present. Therefore, this species can be an efficient phytoremediator for soils contaminated with cadmium and lead in urban shaded places.

• Asian Journal of Turfgrass Science
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• v.22 no.2
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• pp.133-140
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• 2008

The growth of root and shoot normally decline dramatically in mid-summer of Korea, moreover the cool-season turfgrassgrass eventually wither to death over $30^{\circ}C$. The increase of air temperature also drives the heat of soil, that makes stress on root system. The heat stress affects physiological mechanisms of hormonal unbalance that stimulates shoot growth, photosynthesis, and transpiration. To solve those problems, many studies have been carried out to control soil moisture and OM content to decrease soil temperature for dissolving the growth retardant by heat stress. This study initiated to analyze the change of soil temperature with soil moisture, and the effect of soil depth and moisture content on heat transmit and thermal changes on turfgrass growth(productivity, green color, and damage by dryness and high temperature). Kentucky bluegrass plots prepared with 25%, 33%, 40% soil moisture treatments. Soil temperature was measured every five min. with four thermo-sensors at 12 and 2 cm soil depth. The most acceptable growth showed at 33% soil moisture, but the worst result showed at 40%. The soil moisture seriously affected on the growth of Kentucky bluegrass, however the quality of turfgrass may acceptable if we can control soil moisture down to 33% when the flooding season of monsoon.

• Asian Journal of Turfgrass Science
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• v.21 no.2
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• pp.155-161
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• 2007

This study was initiated to evaluate the growth characteristics of creeping bentgrass cultivars during the sprlng season. The green-up of 'CY' and 'T-1' were about 2 weeks earlier than the other cultivars followed by 'Penn A' 'Crenshaw', 'L> 'Penncross' > 'Putter' > 'Dominant' > 'SR1020' in that order. 'T-1' and 'CY-2' had the highest chlorophyll content while 'Penncross' had the lowest during the spring. 'Crenshaw' and 'Penn A-4' showed the highest shoot density in this research, followed by 'CY-2', 'L-93', 'T-1', 'Putter', 'Dominant', 'SR1020', and 'Penncross' in that order. In case of root length, 'CY-2' and 'L-93' were the best cultivars, but 'Penncross' was worst during the spring. 'CY-2' had the best visual quality among the cultivars, 'T-1' and 'Crenshaw' also classified as high visual quality group whereas 'SR1020', 'Dominant' and 'Penncross' were grouped in relatively low quality. In conclusion, 'CY-2', 'T-1' and 'Crenshaw' were the best cultivars in terms of growth characteristics in spring. Conversely, 'SR1020' and 'Penncross' were the poorest cultivars. These results can be more useful for management or constructing of golf courses. However, this research was performed with little compaction stress. More information is needed on the tolerance to compaction stress of these bentgrass cultivars.