• Journal of The Korean Society of Grassland and Forage Science
• /
• v.37 no.2
• /
• pp.161-167
• /
• 2017

This experiment was conducted to comparison study on the productivity for certified varieties of import adaptability of silage corn in Pyeongchang area. Total eight varieties (Gangpyeongok, 31N27, 32P75, 32W86, P3156, P3394, DK 689 및 DK 729) were evaluated. The experimental design was 8 treatment of randomized block with three replications. Corn varieties were cultivated in experimental field of Pyeongchang campus, SNU from 1 May to 2 September, 2015 and plot size was $15m^2$. Plant height of 32W86 and ear height of Gwanpyeongok was the highest (p<0.05). Tasseling and silking date was 27 July-3 August and silking occurred after 1-3 day of tasseling. Average day to silking was 92 days and that of 31N27 variety was short (p<0.05). The varieties of DeKalbo Company (DK 689 and DK 729) required more times to silking. Average GDD (growth degree day) of eight varieties was $1,023^{\circ}C$ and P3352 was the lowest GDD. In the trials of resistance evaluation, P3394 was strong in disease, P3156 was the highest in insect. All varieties did not show the lodging and variety of DK 729 showed the highest stay green score (p<0.05). Average dry matter content was 30.77%, it showed higher trend in DM. 32W86 was the highest DM content among the varieties, but there was no significant difference among varieties (p>0.05). The weight per ear was the highest in 32W86 and the lowest in Gwanpyeongok. The ration of ear to whole plant was higher in 32W86 and P3394, but it was not found the significant difference (p>0.05). Average yield of fresh and DM was 59,017 and 13,476 kg/ha, respectively. DK 689 showed higher DM and TDN yield than others, but there was not significant difference (p>0.05). According to results, the difference of productivity was not found among certified variety of import adaptability of silage corn. The varieties Gwanpyeongok, 32W86 and 32P75 would be recommendable in Pyeongchang area for stable cultivation.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.5
• /
• pp.597-603
• /
• 1997

Orostachys japonicus, Wasong as herb medicine, has been artificially cultivated as an anti-tumor medicinal. The experiment was carried out to examine the effect of natural daylength as control or night-break treatment (NB) imposed at June 20, July 18 or Aug. 15 on its growth, dry weights of leaf and bract, stem, floret and root, and morphological characters including bolting and floret flowering. After a plant was grown in a 15cm plastic pot containing a 2 : 1 soil : peat moss mixture on May 23, three treatments with above differing night-break had been imposed around midnight up to Nov. 7. The plants were sampled 3 times at the same day forced to night-break and then done 6 times by 2-week interval after the final NB. Plant height and inflorescence length of all the NB increased with delayed NB but declined in comparison with the natural daylength. No. of leaves including bracts showed similar response to plant height although NB given before July 18 showed less leaves and bracts. Stem diameters of NB were continuously increased to middle Sept. to middle Oct. while that of natural daylength decreased after middle Oct. Natural daylength or NB given on Aug. 15 had greater fraction, shoot and total dry weights resulting from increment of leaf and bract up to Aug. or of floret, stem and root after Sept. The earlier NB, the later formation of florets and the less number of flowering florets whereas in natural daylength florets on inflorescence begun to be formed from middle Sept. were sharply increased up to middle Oct. when all the plants were flowered. Bolting was not formed in the plant of the earliest NB of June 20, and thereby no anthesis of florets up to early Nov. It was concluded that year-round cultivation of Orostachys japonicus plants was possible through controlling the NB timing because its bolting and flowering of florets separately occurred.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.5
• /
• pp.515-521
• /
• 1997

Tobacco plant was grown for 40 days hydroponically in nutrient solutions composed of different forms of nitrogen, like NO$_3$$^{[-10]}$ -N, NH$_4$$^{＋}$-N, and a mixed formulation of NO$_3$$^{[-10]}$ -N and NH$_4$$^{＋}$-N. Uptake response, nitrate reductase, and glutamine synthetase activity at growth stage were investigated to understand the basic knowledge of nitrogen metabolism. The better growth of shoot and root was observed in the mixed nutrient solution than NO$_3$$^{[-10]}$ -N or NH$_4$$^{＋}$-N, alone. The plant growth in NH$_4$$^{＋}$-N nutrient solution was poor due to ammonium toxicity. The pH of nutrient solution containing NO$_3$$^{[-10]}$ -N increased up to 40 days after transplanting. But the pH of solution containing NO$_3$$^{[-10]}$ -N decreased drastically to 3.42 at 20 days after transplant. The pH in the mixed formulation dropped to pH 3.64 at 30 days after transplant and showed re-increase. It is assumed that nitrogen of NH$_4$$^{＋}$-N form was taken up preferentially at early stage and NO$_3$$^{[-10]}$ -N form was taken up preferentially at middle stage in the treatment with the mixed solution. The result indicates that the relative proportion of nitrogen forms affected the uptake patterns at each growth stages. The contents of chlorophyll and soluble protein were high with the mixed solution. Total nitrogen content was the highest in NH$_4$$^{＋}$-N solution and the content also increased by the application of the mixed type of nitrogen. The amount of nitrate in leaves was high in NO$_3$$^{[-10]}$ -N treatment and the amount of ammonium was high in NH$_4$$^{＋}$-N treatment. The activity of nitrate reductase or glutamine synthetase was highest in the leaves grown in mixed nutrient solution than in those with any other single of nitrogen form.

• Journal of Animal Science and Technology
• /
• v.46 no.6
• /
• pp.917-924
• /
• 2004

Using PCR-RFLP haplotyping for the mitochondrial DNA(mtDNA) fragment containing the NADH dehydrogenase 2 gene(ND2) and three tRNA genes(tRNA-Met, tRNA-Trp and tRNA-Ala), we characterized the genetic diversity of five pig breeds including Jeju native pigs. mtDNA polymorphisms showing distinct cleavage patterns were found in the pig breeds. Two digestion patterns were detected when HaeIII- and Hinfl-RFLP, and four in the Tsp5091-RFLP analyses. Combining the three restriction enzyme digestion patterns found in five different pig breeds, four mtDNA haplotypes were observed and the haplotype frequencies were significantly different by the pig breeds. A monomorphic haplotype, mtWB, was observed in both Korean wild boars and Large White pigs. Both Duroc and Landrace pigs contained two haplotypes suggesting their multiple maternal lineages. Jeju native pig has two haplotypes(mtJN and mtJD). Of these, mtJN is identified as a Jeju native pig specific haplotype. This study suggested that more than two progenitor populations have been taken part in the domestication process of the Jeju native pig population, and/or probably subsequent crossing with other pig breeds from near east Asia. Unlike with our prediction, there was no direct evidence under molecular levels on the maternal introgression of Korean wild boar in the domestication of Jeju native pigs. In conclusion, specificity of mtDNA haplotypes related to pig breeds win be useful for identifying the maternal lineage as wen as constructing the genealogical pedigree in pigs.

• Journal of Animal Science and Technology
• /
• v.50 no.4
• /
• pp.573-580
• /
• 2008

This study was aimed to investigate that training of horses is related with the activity of superoxide dismutase(SOD) in erythrocyte of racing horses. The SOD activity was assayed from erythrocyte of six Thoroubred horses having final stage of training, about 21 month-old, 474~509 kg body weight for race trainig. During 7 weeks of training period from 24th Sep. to 6th Nov, horses were bled very carefully 4 times at 1st Oct, 16th Oct, 30th Oct. and 6th Nov. As the training period passed, erythrocyte of the horses have gradually increased the MnSOD activity(p<0.05) and lowered the CuZnSOD activity. The plasma ceruloplasmin and peroxidase activities, and lactate levels were reduced gradually while peroxide and glucose levels gradually increased. The calculated oxygen consumption(Eaton, 1995) for training of horses were linearly related with the MnSOD activity(r=0.650, n=32) but negatively with CuZnSOD activity in erythrocyte and lactate levels(r=－349, n=32) in plasma. Also, peroxide levels in plasma of horses had positive relation with the MnSOD activity in erythrocyte(r=0.616, n=48). In conclusions, as the training is progressed, the raised MnSOD activity in erythrocytes and peroxide levels in plasma indicated balances between oxidant and antioxidants for the protection from ROS during race of horses. The results showed that the MnSOD activity in erythrocyte and peroxide levels in plasma may be used as marker for the intensity of training racing horses.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.21 no.4
• /
• pp.233-246
• /
• 2001

The purpose of this study was to suggest the possibility of utilizing the wildflower pasture for promoting public interest. Growth characteristics, botanical composition, fauna distribution on wildflower pastures were observed. The experimental design included two treatments: native wildflower pasture(NWP, turf grasses 6 species + native wildflower 11 species) and introduced wildflower pasture(lWP, turf grasses 6 species + introduced wildflower 9 species). The field trials were carried out on the experimental pasture plots at Chungnam National University from 1997 to 2000. The results obtained are as follows: 1. The flowering of wildflower was maintained continuously from May to September, and the colors of wildflowers; varied seasonally during this period. With native flowers, however, Hemerocallis fulva, Belamcanda chinenis and Aster koraiensisi showed problems in lately germination and early establishment. Meanwhile, Introduced wildflower showed not only excellent germination and early establishment compared to native flowers species but also maintained brighter colors. But Coreopsis tinctoria, Achillea mi/lefolium and Rudbeckia bicolor had colonized at a higher height or possessed stronger rhizome. 2. The appropriate species of turf grass which maintained continuous seasonal distribution are thought to be tall fescue, perennial ryegrass. Kentucky bluegrass in NWP and IWP. 3. Botanical composition of wild flower in NWP was arranged in the order of Achillea sibirica > Lotus corniculatus var. Japonicus > Dianthus chinensis > Plantago asiatica > Taraxacum pla~ycarpum > Viola mandshurica > Aster koraiensis > Vicia tetasperma > Lespedeza stipulacea > Hemerocallis fulva, respectively. The highest seasonal distribution of native wildflower, Achillea sibirica was in spring and summer, Lotus corniculatus var. Japonicus was in autumn. Botanical composition of wild flower in IWP was arranged in the order of Achillea millefolium Coreopsis tinctoria > Silene armeria > Coreopsis lanceolata > Rudbeckia bicolor > Sanguisorba oficinalis > Centaurea cyanus > Chrysanthemum leucanthemum > Dianthus petraeus, respectively. The highest seasonal distribution of introduced wildflower, Silene armeria was in spring, Achillea millefolium was in summer, and Coreopsis tinctoria was in autumn.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.1 no.2
• /
• pp.127-134
• /
• 1999

This study was performed to obtain the basic data to present rational silvicultural tending plan. It makes these widely distributed pine-oak mixed stand and each of pure stand in middle province on object of this study and do comparative analysis of light condition about stand parameter and natural regeneration according to each slope(north, west and south) conditions of location in central part of South Korea. Sample plots for pine-oak mixed stand and pine and oak pure stand were established on each of southern, northern and western slopes based upon site and growth conditions of the slope. Sample plot was a circle of 0.05ha with a diameter of 25.24 m. A sample plot has between 30 and 40 tree in it. Total 23 sample plots were established; 9 pure pine stands, 8 pine-oak mixed stands. and 6 pure oak stands across lower, middle, upper parts of slopes. Relative light intensity within a stand was' measured by crown- photo(fish-eye lens; 180$^{\circ}$) system through fish-eye lens and by comparing each plot with the denuded through PAR-sensor. The crown closure ratio of pure pine stand (75%) shows much lower than that of mixed stand (90.9%) and pure oak stand (93%). The relative light intensity within a stand showed an opposite result. The crown closure of mixed stands tended to become gradually low as the slope moves from the north to the south, but the relative light Intensity within the stand tended to rise. By analyzing the relationship between the relative light intensity within a stand and stand parameter, light intensity within a stand tended to decrease as the diameter and N/ha increase. Number of oak seedlings and light intensity within a stand is in a straight-line regression relation. In particular, the number of oak seedlings was the highest in mixed stands on the southern slope. But no single pine seedling was found. The unfavorable conditions of l0cm thick litter layer and low relative light intensity in a stand (ranging between 4% and 8%) is considered to prevent pine seeds from germinating.

• Korean Journal of Environmental Agriculture
• /
• v.20 no.3
• /
• pp.155-161
• /
• 2001

This study was carried out to investigate cytotoxicity of paraquat or bentazone on NIH 3T3 fibroblasts, toxicity of paraquat or bentazone, and compensatory effects of 3-Methylcholanthrene(3-MC) on the rat liver. In order to MTT assay, the $5.0{\times}10^4$ cell/mL of NIH 3T3 fibroblast in each well of 24 multidish were cultured. After 24 hours, the cells were treated with solution of paraquat or bentazone(1, 25, 50, 100 ${\mu}M$ respectively). After the NIH 3T3 fibroblast of all groups were cultured in same condition for 48 hours. MTT assay were performed to evaluate the cytotoxicity of cell organelles. Paraquat or bentazone $MTT_{50}$ were 1668.97 ${\mu}M$ and 1506.97 ${\mu}M$, respectively. These $IC_{50}$ of paraquat or bentazone were decided low cytotoxicity by Borenfreund. In order to observe the toxicity and compensatory effects of paraquat or bentazone on the rat liver, Sprague-Dawley male rats were used as experimental animals and divided into paraquat or bentazone only treated group and simultaneous application group of paraquat or bentazone and 3-MC. At 30 min and 1, 3, 6, 12, 24, 48 and 96 hrs interval after each treatment, the animals were sacrificed by decapitation and liver were immediately removed, immersed in fixatives, and processed with routine method for light microscopic study. Paraffin sections were stained with H-E, PAM and Best Carmine. Under the light microscope, degenerative changes of hepatic lobules were frequently observed in portal area from 3 hrs after paraquat or bentazone treatment. All hepatic cells were induced degenerative change at 12 hrs and more severe degenerative change at 48 hrs after paraquat or bentazone treatment. Especially, hepatic cells of bentazone only treated group were distinctly showed pyknotic. Glycogen granules were increased in portal area at 3 hrs, all hepatic cells at 12 hrs and remarkably increased at 48 hrs after paraquat or bentazone treated group. But hepatic cells of bentazone only treated group were regeneration at 48 hrs from portal area and glycogen granules of hepatic cells of paraquat or bentazone and 3-MC combination treated group showed in central area only at 48 hrs. The results indicate that 3-MC may be decrease paraquat or bentazone cytotoxicity on the rat liver.

• Journal of Gifted/Talented Education
• /
• v.14 no.4
• /
• pp.125-149
• /
• 2004

The purpose of this study is to provide basic information on the current status of elementary school teachers' perception of gifted education. For this purpose, this study wi1l analyze elementary school teachers' perception of the gifted education (i.e., general perception of gifted education, characteristics of gifted children, identification of gifted children, programs for gifted education, and teachers of gifted education). A questionnaire survey was used for the purpose and research questions of this study. The questionnaire used in this study was constructed by taking into account the results of surveys conducted in previous studies and the literature on gifted education. Before conducting the research, a preliminary inquiry was made to identify problems that may occur while the subjects were participating in the survey, as well as to determine the appropriateness of the questionnaire and the amount of time needed. The preliminary inquiry was conducted with ten randomly selected elementary school teachers who did not participate as subjects in the actual research. The results were later used as initial data for the actual research. The subjects of this study were teachers who were teaching in8 elementary schools under each office of education in Seoul. This process was conducted for 180 elementary school teachers from April to May 2004. The results were analyzed using SPSS (Statistical Package for Social Science) Ver. 10.1, a software program for statistical research. After the data were analyzed, the following conclusions were arrived at: 1. The result of the genera1 perception of gifted education by elementary school teachers were positive and reasonably high. The level of their perception of detailed information or knowledge, however, was relatively low. 2. As for their perceptions of the emotional characteristics of gifted children, t11e results showed a low level of understanding of the characteristics of gifted children. 3. As for their perceptions of identification of gifted children, the results showed a high level of understanding of the appropriate time to provide special education to gifted children and of the methods to identify such. On the other hand, their understanding of the identification of gifted children in an actual class was poor. 4. The respondents' level of perceptions of programs for gifted education was very low since many subjects did not have any experiences with such programs. 5. The results showed a very positive response to receiving training on gifted education, though they were very reluctant to be assigned as teachers of gifted education because of the excessive work that is associated with such and their lack of capability in handling gifted children.

• Korean Journal of Food Science and Technology
• /
• v.35 no.5
• /
• pp.905-913
• /
• 2003

The physicochemical properties of rice flour roasted at various temperatures and times were analyzed, and the quality characteristics of tarakjuk made from these roasted rice flours were investigated. As roasting temperature and time increased, rice flour showed decreasing moisture, protein content, and glucose the major reducing sugar of rice flour. Total amino acid content did not show any significant changes, but the amount of free amino acids and individual amino acids, such as lysine, tryptophane, and tyrosine, decreased. A decrease in L value and increases in a and b values from both roasted rice flour and tarakjuk was observed. Reduced crystallinity and gelatinization temperatures of roasted rice flour were investigated with X-ray diffractogram and DSC, respectively. The thermal transitions between $100.6{\sim}127.6^{\circ}C$ of tarakjuk by DSC are considered to be due to the melting of amylose-lipid complex. As the roasting temperature and time of rice flours increased, tarakjuk showed lower viscosity and higher spreadability. Sensory characteristics, such as nutty flavor, color intensity, and gritty texture increased significantly. Tarakjuk made from rice flour roasted at $185^{\circ}C$ for 25min showed the highest score on overall preference. From the above results, roasted rice flour produced more preferable tarakjuk than nonroasted flour in terms of sensory quality.