• Journal of dental hygiene science
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• v.11 no.5
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• pp.411-416
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• 2011

Streptococcus mutans (S. mutans) is the major causative bacteria in dental caries. Xylitol is effective anticarious natural sugar substitute by inhibiting the virulence of S. mutans. However, long-term xylitol consumption leads to the emergence of the xylitol-resistant (XR) strains which means xylitol is no more inhibited their growth. We therefore confirmed the general characteristics and the virulence factors of the xylitol-sensitive (XS) and XR S. mutans for different concentrations of xylitol. S. mutans KCTC 3065 was maintained in TYE medium containing 0.4% glucose with 1% xylitol during 30 days at $37^{\circ}C$, 10% $CO_2$ to form XR strain. The strains were transferred to new medium every 24 hr and the same procedures without xylitol were repeated for the formation of XS S. mutans. Both XS and XR were cultured in different concentrations of xylitol (0%, 0.1% and 1%) then, cell growth, acid production and mRNA expression of gtf genes were analyzed. Xylitol reduced the cell growth of XS S. mutans in dose-dependent manner, but not reduced that of XR. Xylitol inhibited acid production of XS in dose-dependent manner, but not inhibited that of XR. Xylitol reduced the gtfB and gtfD mRNA expression of XS S. mutans which genes synthesized soluble and insoluble extracellular polysaccharides, but not reduced that of XR. These results indicate that the virulence of XR S. mutans is different characters of XS strains, which suggests XR strains may have different cariogenicity of XS strains. Further study is needed to explain the mechanism related to extracellular polysaccharide in the XR strains.

• Weed & Turfgrass Science
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• v.6 no.2
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• pp.124-129
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• 2017

The Experiments were conducted by moderate season culture of each of early, medium and late maturing varieties which were considered to be of strong salt tolerance in low and high salty reclaimed areas (0.2% at the May). This study was carried out to investigate the proper nitrogen fertilizer level and seeding rates at reclaimed saline land in Korea. The proper seeding rates were $40kg\;ha^{-1}$ in 0.2% saline land. The dry matter production of barnyard millet was possibly estimated by exponential functions of $Y=0.0098X^2+0.7030X+2.6267$. Effects of nitrogen rate on agronomic characteristics, forage yield, and chemical composition of barnyard millet to reclaimed tidal land are summarized as follows: The proper nitrogen fertilizer level was $200kg\;ha^{-1}$ in 0.2% saline land. N was absorbed actively before the emergence of the barnyard millet but showed relative decrease thereafter. The early growth of the barnyard millet was inhibited, resulting in the favorable late growth, increased panicle weight and ratio of matured grain. These results suggest that barnyard millet is the most forage crops for cultivation on reclaimed tideland in view of the good emergence and forage production.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.1
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• pp.28-33
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• 1996

This experiment was carried out at National Crop Experiment Station in 1994 to obtain basic information of growth characters and yield of rice under various seeding methods in direct seeding on dry paddy. Hwaseongbyeo sown on April 27 by flat drill seeding, high ridged drill seeding and hill seeding under different seed conditions, soil convering after seeding and irrigation methods. Nitrogen applied 150kg /ha by 3 times split application at rate of 40:30:30％ (basal: 5th leaf stage:panicle initiation stage). Seedling stands were higher in flushed irrigation water after seeding than in irrigation at 3rd leaf stage, and it also was higher in high ridged drill seedings than in flat drill seedings. Days for seedling stand, heading date were shorten 6~10 days, 2~3 days by flushed irrigation water after seeding, respectively. Number of tiller was more in high ridged drill seedings than conventional seedling method(Flat drill seeding ＋ intact seed ＋ soil covering after seeding ＋ irrigation at 3rd leaf stage after seedling stand) at early growth stage, but the most tiller number was highest in developed seeding method(Flat drill seeding ＋ soaked seed ＋ non soil covering after seeding ＋ fulshed irrigation water after seeding) at heading stage among used seeding methods. Lodging index was slightly high in high ridged drill seeding and conventional seeding. Field lodging was degree 1 in high ridged drill seedings and developed seeding, Milled rice yield in developed seeding was increased 7％ compaired with conventional seeding(5.35t /ha).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.314-320
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• 1984

Effects of phosphorous fertilizer on the growth habit and yield of monoculm and branch types of two leading sesame varieties was investigated. The photosynthetic rate of at each growing stage was high at the flowering stage. The photosynthetic rate of monoculm sesame variety, Pungnyeon was high prior to flowering stage, while the Kwangsan variety, branch type was high after the flowering stage. The level of phosphate were most effective in increasing photosynthesis when standard level of fertilizer was applied in both varieties. Kwangsan variety showed higher photosynthetic rate per unit area, higher NAR, and CGR and higher LAR and RGR at the maximum flowering stage than the Pungnyoeon variety. Those characters attained maximum level when standard levels of phosphorous fertilizer were applied. The protein and oil content of seeds were higher in Kwangsan variety compared with Pungnyeon. However, the carbohydrate of seeds was high for Pungnyeon variety. The highest protein content was attained when standard level of fertilizer were applied. The oil content appeared to increase as the level of applied fertilizer increased. The results suggest that the vegetative growth and seed yields of sesame may be enough with present level of fertilizers. However, higher amount of phosphorous fertilizer may be required to increase the oil content of sesame seeds.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.3
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• pp.308-313
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• 1995

In relation to shortening generation by using embryo culture of barley immature seed, it is important to find out profitable embryo age for embryo culture and to understand the relationship among embryo and other characters. Two varieties(Olbori and Dusan #12) were cultivated under two growth conditions(15/10 and 25/15$^{\circ}C$). The embryos were aseptically excised when immature seeds were collected 9, 13, 17, 21, 25 and 29 days after heading and cultured on $B_5$ medium. On the 21st day after heading, the length of embryos from top or middle part of spike was longer than that from bottom part. Embryos from bottom part under low temperature condition had the shortest length. Shoot length, root length and root number after embryo culture were little difference among three parts of spike under high temperature condition. Under low temperature, seedlings from bottom part of spike were inferior to those from top or middle part. Length of 29-day-old embryos under low temperature condition was similar to that of 17-day-old ones under high. Under high temperature condition, the length of 17-day-old embryo had positive correlation with kernel width, shoot length, root length and root number, but that of 21-day-old one didn't have. Seventeen-day-old embryos obtained from 25/15$^{\circ}C$ growth condition seem to be efficient to shortening generation by using embryo culture.

• Korean Journal of Medicinal Crop Science
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• v.7 no.1
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• pp.31-36
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• 1999

This study was carried out to investigate the effect of sulfuric fertilizers on allylisothiocyanate(allylNCS) content of upland Wasabia japonica Matsum cultivated in heating condition in the winter season. The rhizome's growth characters following soil application of sulfur dust were not significantly different compared to control, though its soil acidity and available sulfur content was higher than other treatments. Total sulfur content of plant was increased by soil application as compared to foliar application and allylNCS content of rhizome increased up to 22.8% in the sulfur dust treatment. The result showed that soil application was effective for supplying $SO_4^{-2}$ in upland Wasabia japonica Matsum when cultivated in heating condition. In the analysis of correlation coefficients between growth and quality characteristics, allylNCS content of rhizome showed the significantly positive correlation with total sulfur content of shoot, rhizome and allylNCS content of shoot.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.346-351
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• 2011

This research was done to identify the mass propagation method in winter daphne (Daphne odora Thunb) using its softwood cuttings and to investigate its plant characters established at different light and soil conditions as an indoor plant. Cuttings from winter daphne were taken and grown in different treatment consisted of rooting media (perlite, vermiculite, perlite + vermiculite (1 : 1) and commercial horticulture media soil), indole butyric acid (IBA) hormone concentrations (0, 100, 500, 1000 ppm and Rootone) and date of cutting. Transplants were grown at different light intensities (100, 1000, 2500 lux and control) and growing media. Results showed that cuttings grown in perlite + vermiculite (1 : 1) gave higher percentage (100%) rooting. Cuttings treated with Rootone and IBA 100 ppm showed good rooting growth and cutting taken in June, 25 gave the highest rooting (96.7%). The best plant growth obtained at 1000 lux (56~60 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) followed by 2500 lux (125~130 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and scoria mixed with commercial horticulture media soil showed better growth of transplants.

• Korean Journal of Plant Resources
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• v.20 no.5
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• pp.466-470
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• 2007

Nowadays burcucumber(Sicyos angulatus L.) has been widely used as a rootstock of Cucurbitaceae. The study was done to examine the effects of shading with different colored fabrics(white, red and aluminum-coated) on growth and cotyledon chlorophyll content of its seedling. Shading with the white colored fabric lengthened seedling height and hypocotyl length, but shading with the red colored fabric enlarged true leaf area. Total dry weight of each seedling was decreased in the order of no shading, white, red and aluminum, in which resulted from reductions of cotyledon dry weight in white colored fabric, cotyledon and true leaf dry weight in red colored fabric, and dry weight of cotyledon, true leaf and root in aluminum colored fabric. Cotyledon chlorophyll content was reduced by shading treatments although the 3 shading treatments showed nearly same content.

• Journal of Korean Society of Forest Science
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• v.78 no.3
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• pp.287-301
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• 1989

A tree of Ailanthus altissima Swingle was fastened with a plastic band, 19mm wide, around the stem 180cm above ground level and was left to grow under this condition for one year, By removal of this band the tumorous tissue gradually developed and the tree bearing distinct tumorous tissue, an overgrowth surrounding the stem, was harvested two years after the band removal. For the investigation of this tumorous part and its comparison with adjacent normal parts in the anatomical features of individual elements, the tumorous part and parts directly and 40cm above and below the tumorous part were obtained from the tree. The tumor wood having remarkably wider growth increment occurred in the 3rd growth ring the first year after removal of the fastened band, and the barrier zone which delimited the discolored wood from the normal-colored wood inwards appeared u1 the intra-2nd growth ring produced during the fastened period in the tumorous part and the false ring-like zones equivalent to barrier Zone were shown in the normal-colored 2nd growth rings of the parts directly and 40cm above and below the tumorous part, as well. The tumor wood, the 3rd growth ring, and proportion of the 2nd growth ring formed after barrier zone in the tumorous part shared common characteristics in the irregular growth ring boundary, misshapen and shorter individual fibers and vessel elements, and large ray widths and heights. The springwood pores were smaller in diameter in the tumor wood, and the larger radial and smaller tangential diameters of summerwood solitary pores and individual pores consisting of pore multiples in proportion of the 2nd growth ring formed after the barrier zone were transformed into near-isodiametric in the tumor wood, the 3rd growth ring, in the tumorous part. Only in proportion of the 2nd growth ring formed after the barrier zone were transformed into near-isodiametric in the tumor wood, the 3rd growth ring, in the tumorous part, ray densities greatly increased. And the massive tumor wood was caused not by cell size but by cell number because the radial and tangential diameters of fibers in the tumor wood, the 3rd growth ring, in the tumorous part were not sufficiently different from those in the same aged growth rings of the directly and 40cm above and below the tumorous part.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.4
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• pp.271-276
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• 2017

Waterlogging strongly affects maize (Zea mays L.) growth. It is necessary to find the screening method of waterlogging tolerant maize lines. This study was to investigate the growth characters at V3 stage of maize, when is very sensitive to waterlogging. Six Korean maize inbred lines were subjected to waterlogging at V3 stage for 30 days. The 30 days waterlogging treatment significantly reduced plant height, number of expanded leaves, and SPAD value, compared with the control plants. SPAD values were significantly different among the six inbred lines, KS140 was the highest. The dry matter accumulation of aerial and root part were significantly decreased by 30 days waterlogging. KS140 was the weightiest among inbred lines. The dry matter of adventitious root showed same trend. Waterlogging treatment significantly reduced to ear length and thickness, grains filling length, grain number per ear, and maize grain. Plant height, SPAD value, and number of fully-expanded leave showed high correlation with maize grain yield, but number of senescent leaves, dry matter of adventitious root and TR ratio did not, suggesting that the former three traits may be good indicator for evaluating 30-day waterlogging tolerance of maize inbred lines. KS164 was the highest yield by increasing of grains filling length and grain number per ear of among waterlogging inbred lines. According to the results, evaluation of maize waterlogging should be consider both early growth characteristics and resilience in the later growth stages.