• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.89-99
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• 2007

To develop durable and stable breeding strategies far the control of rice bacterial blight (BB) disease, the near-isogenic lines (NILs) with diverse resistance genes to BB isolates were evaluated in plant at three different growth stages using four Korean ($K_1,\;K_2,\;K_3,\;K_{3a}$) and three Japanese isolates (I, II, III). The resistance of the NILs to seven BB isolates tended to increase with plant aging. At the seedling stage, the NILs with single resistance genes were mostly resistant to $K_1$ race but they showed partial or no resistance to other isolates. A NILs (IRBB5) possessing xa5 had full resistance to the four Korean isolates, illustrating that it is a useful source to give enhancement to Korean breeding program. At the maximum tillering stage, resistance of NILs to $K_2,\;K_3$, I and II isolates considerably increased while resistance to $K_1,\;K_{3a}$ and III were similar to those of seedling stage. NILs with resistance gene of Xa4, xa5 and Xa7 proved to be the most stable to BB isolates at the maximum tillering stage. At the heading stage, most resistance genes of NILs were effective against BB isolates, and xa5 showed the consistent resistance to all the BB isolates including $K_{3a}$ and III isolates, demonstrating that resistance genes of Xa4, xa5 and Xa7 can be used either alone or combined to enhance resistance to BB disease in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.4
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• pp.424-429
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• 2012

This study was carried out to investigate the influence of different planting time on the synthesis of isoflavone in black soybean, Three varieties used in this experiment were lpumgeomjeongkong, Cheongjakong and Heugcheongkong which had different ecotypes, repectively. Seeds were sown at different time, May 15th, May 30th and June 15th with planting density of $60{\times}15cm$. In order to analyze the content of isoflavone, we collected sample every 5 days from 30 days after flowering to harvest and analyzed them with UPLC. As sowing was delayed, the content of isoflavone increased in all of three varieties. The content of genistein was greater than daidzein and glycitein. Increase of Glycitein was not distinct from 55 days after flowering(DAF) and it was stable against temperature change during the seed developing period. Although the content of genistein in Ilpumgeomjeongkong from 50 to 55 DAF, in Cheongjakong from 40 to 55 DAF and in Heugcheongkong from 60 to 65 DAF was lower than the content of daidzein, it was higher than that of daidzein afterward. In the statistical analysis on the relationship between average temperature and the content of aglycone isoflavone at 5-day intervals from 30 DAF during the grain filling period, genistein in Ilpumgeomjeongkong showed meaningful correlation as y=-15.28x+407.9 ($R^2=0.505^*$), diadzein in Cheongjakong showed meaningful correlation as y=-6.188x-164.5($R^2=0.454^*$), and genistein showed significantly high correlation as y=-11.59x+297.6 ($R^2=0.545^{**}$). Taking all the above results into consideration, it was suggested that the regions suitable for high content of isoflavone in black soybean be the northern area of Gyeonggi-do and Gangwon-do, Chungcheongbuk-do and inland area of Gyeongsangbuk-do, where are relatively low average temperature from flowering stage($R_2$) during the grain filling period.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.4
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• pp.397-406
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• 2009

This study was carried out to investigate the microclimate (photosynthetically active radiation and temperature) response to different shading materials(shade plate, and polyethylene net) on Korean ginseng(Panax ginseng C.A. Meyer) bed. Photosynthetically active radiation(PAR) under polyethylene net was approximately 24 ~ 30% higher than that under shade plate on sunny day. Also, PAR was remarkably decreased from the front to the rear rows of ginseng beds. Temperature under polyethylene net was higher than that of shade plate. Internal temperature under polyethylene net was 1.9 ~ 3.1% higher than that under shade plate at the different rows of ginseng bed. Mean of total daily temperature under polyethylene net was higher at the rear rows than at the front rows, while that under shade plate was higher at the front rows than at the rear row of ginseng bed. Mean of total daily temperature on sunny days(April 15 and May 17) was 7.3% lower under shade plate than above outside but, polyethylene net was 0.7% high, while that on cloudy days(April 11 and May 15) was 1.6% higher under polyethylene net than above outside, but shade plate was 0.7% low. Also, overall mean of total daily temperature under polyethylene net was 7.0, 7.8, and 8.8 % on sunny day(April 15 and May 17), and 1.7, 1.6, and 3.5% on cloudy day(April 11 and May 15) higher than that under shade plate, respectively. The SPAD values of 6 years old ginseng at two point(front, center) in bed under shade plate showed the highest value, and the lowest under polyethylene net. The SPAD of 6 years old ginseng at rear in bed was not statistically significant under two shading materials.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.4
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• pp.357-365
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• 2009

On the purpose to improve the milling efficiency as well as head-rice percentage after milling, an experiment to improve the removal ability of immature kernels in the immature brown rice separator (IBRS) was performed focused on varietal characteristics. The removal ability of immature grains by the IBRS was absolutely depending on kernel thickness of brown rice. The kernel thickness of the tested rice varieties distributed from 1.79 mm in Nonganbyeo to 2.16 mm in Daeribbyeo 1. Although there were some variation among rice varieties, it was roughly suggested that the suitable sieve-slit widths for good separation of the immature kernels were 1.9 mm for the varieties thicker than 2.08 mm in thickness, 1.8 mm for the varieties with 2.00-2.08 mm thickness, 1.7 mm for the varieties with 1.90-2.00 mm thickness, and 1.60-1.65 mm for the varieties thinner than 1.7 mm. It was found out that the higher the proportions of immature kernels in brown rice, the more conspicuous the improvement of milling efficiency as well as head rice rates by their removals. With increasing the sieve slit-widths beyond an optimum range, the losses of mature grains increased sharply. For effective separation of immature kernels, it was suggested that the optimum sieve-slit width should be set up depending on both of the kernel thickness and the critical loss limit of mature kernel.

• Horticultural Science & Technology
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• v.34 no.5
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• pp.727-735
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• 2016

This research was conducted to investigate the influence of various pre-planting $NO_3:NH_4$ ratios in the coir dust+peatmoss+perlite (3.5:3.5:3, v/v/v) medium on the growth of tomato plug seedlings (cv. Dotaerang Dia), changes in chemical properties of root media, and tissue nutrient contents. With the fixation of N concentration to $300mg{\cdot}L^{-1}$, the $NO_3:NH_4$ ratios were adjusted to 100:0, 73:27, 50:50, 27:73, 0:100. Then, root media containing various $NO_3:NH_4$ ratios and equal concentration of other essential nutrients were filled into 50-cell plug trays and the seeds of 'Dotaerang Die' tomato were sown. The investigation of seedling growth and tissue analysis for mineral nutrient contents based on the dry weight of above-ground tissue were conducted 6 weeks after sowing. As seedlings grew, the EC decreased quickly and pH increased gradually in the all treatment media. The plant height, fresh weight and dry weight of seedlings in the treatment of 50:50 ($NO_3:NH_4$) were 29.0 cm, 13.7 g, and 1.21 g, respectively, which were the highest among treatments tested. However, the seedlings in the treatment of 0:100 ($NO_3:NH_4$) had 26.5 cm, 11.2 g, and 0.92 g in plant height, fresh weight and dry weight, respectively. These were the poorest among the treatments tested. The tissue contents of N were 2.77 to 3.22% in all the treatments. The treatment of 27:73 ($NO_3:NH_4$) had the highest contents of Fe, Mn and Zn and that of 0:100 ($NO_3:NH_4$) had the lowest contents of Mg, Na, Cu, Mn and Zn among the treatments tested. The results indicate that $NH_4$ ratio should be lower than 50% in the coir dust+peatmoss+perlite (3.5:3.5:3, v/v/v) medium for seedling growth of tomato and the optimum ratio will be used to draw up guide lines for plug seedling production.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.616-625
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• 2016

This research was conducted to investigate the optimum level of nitrogen incorporated during formulation of root media as pre-plant fertilizer on the growth of plug seedlings of 'Bool-am No.3' Chinese cabbage. A root medium was formulated by blending peatmoss:coir dust:perlite at a ratio of 3.5:3.5:3.0 (v/v/v). The nitrogen was incorporated in the seven treatments at a rate of 0, 100, 250, 500, 750, 1,000, and $1,500mg{\cdot}L^{-1}$ during the root medium formulation. The concentrations of other essential nutrients except nitrogen were controlled to equal in all treatments. Then, the root medium was packed into 72-cell plug trays and seeds were sown. The growth measurements as well as tissue and soil solution analysis for nutrients were conducted 2 and 4 weeks after seed sowing. As seedlings grew, the pH in the extracted solution of all treatments tended to decrease. The decreases in the treatments of high N concentrations were more severe than those with low N, but the differences among treatments were not statistically significant. The differences of EC in extracted solution of root media among treatments were sizable until week 3, but the differences began to lessen and the EC decreased in all treatments after week 4. Growth of the aerial parts of plug seedlings at 2 weeks after sowing were highest in the $100mg{\cdot}L^{-1}$ and lowest in the $1,500mg{\cdot}L^{-1}$ treatments, but those at 4 weeks after sowing were highest in the $500mg{\cdot}L^{-1}$ and lowest in the $0mg{\cdot}L^{-1}$ treatments among all treatments tested. The tissue N content was highest and lowest in the treatments of 250 and $1,000mg{\cdot}L^{-1}$, respectively, when tissues were harvested at 4 weeks after sowing and analysed based on the dry weight of above-ground tissue. The contents of micronutrients were the highest in the 1,000 and $1,500mg{\cdot}L^{-1}$ treatments among all treatments. The results shown above indicate that the $250mg{\cdot}L^{-1}$ of pre-plant N and elevation of post-plant N concentration to above $100mg{\cdot}L^{-1}$ are suitable for raising plug seedlings of Chinese cabbage using inert media.

• Horticultural Science & Technology
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• v.34 no.5
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• pp.736-745
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• 2016

This research was conducted to evaluate the impact of various pre-planting $NH_4{^+}:NO_3{^-}$ ratios on the growth of plug seedlings of 'Bool-am No.3' Chinese cabbage. With fixation of the pre-planting N concentrations to $300mg{\cdot}kg^{-1}$ in a peatmoss+coir dust+perlite (3.5:3.5:3, v/v/v) medium, the $NH_4{^+}:NO_3{^-}$ ratios were varied to 0:100, 27:73, 50:50, 73:27, 100:0. Then, the each of root media containing various ratios of $NH_4{^+}:NO_3{^-}$ as well as equal concentrations of other essential nutrients was packed into 72-cell plug trays. After seeds of 'Bool-am No.3' Chinese cabbage were sown, the seedling growths were measured 2 and 4 weeks after sowing. The weekly analysis of root media and end-crop tissue analysis for mineral nutrients 4 weeks after seed sowing were also conducted. As the seedlings grew up, the pH of the root media increased, however ECs in all treatments of $NH_4{^+}:NO_3{^-}$ ratios decreased. The concentrations of K, Ca and Mg in root media were higher in the treatments of $NH_4{^+}:NO_3{^-}$ (100:0) and $NH_4{^+}:NO_3{^-}$ (73:27) than those of $NH_4{^+}:NO_3{^-}$ (0:100) and $NH_4{^+}:NO_3{^-}$ (27:73) 2 weeks after seed sowing. But the concentrations of K, Ca, Mg and Zn were get lowered in all treatments and the differences among treatments were not significant 4 weeks after sowing. The highest $NH_4{^+}$ and lowest $NO_3{^-}$ concentrations of the root media were observed in the $NH_4{^+}:NO_3{^-}$ (100:0) among all treatments. Contrary to these, the treatment of $NH_4{^+}:NO_3{^-}$ (0:100) had the lowest $NH_4{^+}$ and highest $NO_3{^-}$ concentrations. The seedling growth in terms of fresh and dry weights of aerial part were the highest in the treatment of $NH_4{^+}:NO_3{^-}$ (23:73) at 2 weeks after sowing and those of $NH_4{^+}:NO_3{^-}$ (50:50) at 4 weeks after sowing. The survival rate of seedlings in $NH_4{^+}:NO_3{^-}$ (100:0) treatment were 19% and the growth of aerial part 4 weeks after sowing was the poorest among all treatments tested. The results mentioned above indicate that the pre-planting $NH_4{^+}$ ratio in inert media should not exceed 25% in plug stage 1 through 3 (until 2 true leaf development) and 50% in plug stage 4 (after 2 true leaves to transplant).

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.272-278
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• 2013

To evaluate the effect of surface contaminated with Escherichia coli O157:H7 (E. coli O157:H7) on the microbiological safety of lettuce, this study was conducted to investigate the attachment, biofilm producing, survival, and cross-contamination of E. coli O157:H7 on stainless steel and polyvinyl chloride (PVC). The attachment rate of E. coli O157:H7 on PVC was 10 times higher than that on stainless steel after exposure 1 h in cell suspension. However, there was not a difference between two types of surface after exposure for 6 h and 24h. The biofilm producing of E. coli O157:H7 was TSB > 10% lettuce extracts > 1% lettuce extracts > phosphate buffer. When two kinds of materials were stored at various conditions ($20^{\circ}C$ and $30^{\circ}C$, relative humidity (RH) 43%, 69%, and 100%), the numbers of E. coli O157:H7 at $30^{\circ}C$, RH 43% or RH 69% were reduced by 5.0 log CFU/coupon within 12 h regardless of material type. Conversely, the survival of E. coli O157:H7 at RH 100% was lasted more than 5 days. In addition, the reduction rate of E. coli O157:H7 was decreased in the presence of organic matter. The transfer efficiency of E. coli O157:H7 from the contaminated surface to lettuce was dependent upon the water amount of the surface of lettuce. Especially, the transfer rate of E. coli O157:H7 was increased by 10 times in the presence of water on the lettuce surface. From this study, the retention of E. coli O157:H7 on produce contact surfaces increase the risk cross-contamination of this pathogen to produce. Thus, it is important that the surface in post harvest facility is properly washed and sanitized after working for prevention of cross-contamination from surface.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.57-64
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• 1997

The research was investigated to determine the effect of organic acids or packaging methods (PA) either alone or in combination on the quality of Aster scaber during storages. The Aster scaber was treated with organic acids and PA, and stored at different temperature $(1\;and\;5^{\circ}C)$. Total plate counts, weight loss, color change, and sensory evaluation were evaluated. Both organic acid treatments, PA, and combined treatment had little effect on the inhibition of total plate counts compared to the control (non-treatment). Organic acid treatments showed less weight reduction compared to the control and nitrogen treated package had the least weight reduction, but the combined treatments showed less weight reduction than organic acid treatments or packaging method alone. Organic acid treatments were little different from the control on color change, but nitrogen packages had the least color change, whereas combined treatments were a little reduced, but little different compared to the control or nitrogen packages. The nitrogen packages showed better effects on the sensory evaluation compared to other treatments and the results of sensory evaluation were consistent with that of weight reduction and color change, but not in total counts. All these results showed better effects in $5^{\circ}C$ rather than $1^{\circ}C$.

• Korean Journal of Environmental Agriculture
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• v.4 no.1
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• pp.18-24
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• 1985

A pot experiment was conducted to study the influence of potassium and cesium carrier on the uptake of radionuclide $Cs^{137}$ which is an element released usually from nuclear facilities, by paddy rice upon prolonged cropping of contaminated soils. The results are summarized as follows: 1) Visual toxic symptoms on the growth of rice plant due to treatment of radioactive cesium were not observed up to $20 {\mu}Ci/10Kg$ soil in a pot. 2) The yield and potassium content in rice plant were increased with potassium application, while the reverse was true for the calcium and magnesium. The addition of potassium to the soil markedly reduced $Cs^{137}$ uptake by rice plant but the addition of Cs carrier increased $Cs^{137}$ uptake. 3) Potassium and $Cs^{137}$ showed uniform distribution in all parts of plant and the contents of these two elements were high in the stems and leaves, and low in the heads. The ratio of $Cs^{137}$ to K was, however, not uniform in all parts of a plant. It was shown that this ratio was higher in the seed part, that is, chaff and hulled grain than in the leaves and stems. 4) $Cs^{137}$ absorption rate in rice plant was remarkably reduced with increase of potassium application and it was ranged from $0.02{\sim}0.47%$ in potassium non-treated plot to 0.01∼0.04% in plot treated with a concentration of 16Kg/10a. 5) The amount of $Cs^{137}$ and potassium uptake of rice plant depended on soil type. Uptake of $Cs^{137}$ by rice plant was higher in the soil with low pH and potassium content. The $Cs^{137}$ uptake by rice plant decreased as the potassium content and pH of soil was increased, but $Cs^{137}$ uptake increased when CEC and clay content in soil was high.