• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.219-225
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• 2012

Seed size has been considered as an effective criteria for selection of the most vigorous seeds in sorghum [(Sorghum bicolor (L) Moench]. The smaller seeds were inferior to the larger sizes in emergence and grain yield. This study was conducted to determine germination rate, field emergence and vigor of sorghum for selection of high quality seed by different seed size. Sorghum cultivar of two (Hwanggeumchal and Tojong) were separated into five seed size proportion (<2.36, 2.80, 3.15, 3.35 and >3.55 mm diam.) according to seed size. The larger seed was more higher 1,000 seeds weight, seed density, carbohydrates and protein content. Total seed germination performing varied 92% at the largest size (>3.55 mm diam.) frequently inferior to slightly 67% at smaller seed (2.36 to 2.80 mm diam.) in the standard germination test. Seed size did have a significant effect on mean emergence time (MET) and maximum emergence rate index (ERI) and percentage of emergence. It should be noted that the results refer to MET of sorghum seeds ranging from 4.26 to 4.74 days. The relationship of seed size was not only to stand establishment but to grain yield. Yield was most affected by seed size and large seeds were superior to the smaller seed in 25~37% of the cases. Especially, yield was significant under 3.15 mm the beginning.

• Korean journal of applied entomology
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• v.47 no.4
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• pp.407-411
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• 2008

This study was conducted to estimate the economic injury level (EIL) and economic threshold (ET) of the green peach aphid, Myzus persicae, on Chinese cabbage (Brassica campestris var). The changes of biomass of Chinese cabbage and M. persicae density were investigated after introduction of M. persicae at different density (0, 2, 5, 10, 15, and 20 per plant; inoculated at 10d after planting). The densities of M. persicae largely increased from the above initial densities to 0, 92.3, 177.4, 406.9, 440.4, and 471.3 aphids per plant at 18d after the initial inoculation, respectively. The biomass of Chinese cabbage significantly decreased with increasing the initial inoculated density of M. persicae: 602.0, 264.2, 262.0, 109.3, 151.0, and 67.3 g in above plots with different initial densities, respectively. The relationship between cumulative aphid days (CAD) and yield loss (%) of Chinese cabbage was well described by a nonlinear logistic equation. Using the estimated equation, EIL of M. persicae on Chinese cabbage was estimated 25 CAD per plant based on the yield loss 13%, which take into account of an empirical gain threshold 5% and marketable rate 92% of spring Chinese cabbage. Also, ET was calculated at 80% of EIL: 20 aphids per plant. Until a more elaborate EIL-model is developed, the present result may be useful for M. persicae management at early growth stage of Chinese cabbage.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.4
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• pp.245-251
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• 1973

Effects of lime and inoculation on dry matter yield and nutrient contents of three alfalfa varieties (Medicago sativa L. var. Moapa, Washoe and Lahontan) were investigated with pot culture using Red-yellow sandy loam soil (pH 4.9, from Ryogi hill) 1. In no lime plot germination was poor and harvest was nil, but Moapa was stronger than others. 2. Dry matter yield in uninoculation plot was Moapa>Washoe>Lahontan and effect of inoculation was reverse but nodule development was not clear by inoculation. 3. Dry matter yield in uninoculated plot tends to increase with cutting but effect of inoculation to decrease and the same in nitrogen content in herbage. 4. Moapa was higher in the content of N, Ca, Mg and lower in P, K than Washoe and Lahontan. 5. Washoe was higer in K and Mg and lower in P and Ca than Lahontan. 6. The content of microelements (Fe, Mn and Zn) tends to increase by inoculation and the content of P and K decreased with cutting. 7. High yielding capacity of Moapa seems to be attributable to strong absorption power of N, Ca, Mg and low requirement of P,K.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.3
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• pp.219-227
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• 1993

Broadcast-seeded rice in submerged paddy frequently lodge in the field. In general, the causes of lodging in rice cultivation differ with different cultural methods. This study was conducted to investigate the causes of lodging in broadcast-seeded rice (BSR) and hand-transplanted rice (HTR) under four nitrogen (N) levels. Lodging in BSR was mainly a root lodging due to shallow root distribution, while that in HTR showed a bending type owing to deep rooting system. At the upper soil layer (0-5cm from the surface of ground) the root distribution of BSR (65.2%) was much larger than that of HTR (51.6%), whereas at the 5-10cm soil layer the root distribution of BSR (18.5%) was much smaller than that of HTR (28.0%). The depth of buried culm base was much shallower in BSR (1.2cm) than in HTR (4.0cm). The plant height, fresh weight, lodging index, culm diameter and thickness in HTR were much greater than those in BSR, and the breaking strength of lower internode was similar in the two cultivation methods indicating that HTR would have more lodging causes than BSR. In spite of . the more advantages to lodging resistance in BSR it severely lodged in the field. The main lodging-inducing factors of BSR were the shallow root distribution and shallow depth of buried culm base. Besides these, the higher ratio of gravity center of culm was an important factor. This result suggested that for the fundamental prevention of lodging in BSR, an ideotype of rice plant with ' a deep-rooted behavior ' should be developed.

• Korean Journal of Medicinal Crop Science
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• v.6 no.1
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• pp.38-43
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• 1998

This experiment was carried out to gather basic information for improvement of peeling methods in peony (Paeonia lactiflora) roots which have been used for medicinal resources in Korea. Drying time required was shortened in thin root. Optimum drying time after machine peeling appeared to be 20 hrs in 5 to 10mm of root diameter, 39 hrs in 10 to 15mm, 48 hrs in 15 to 20mm, 56 hrs in more than 20mm, but those of unpeeled roots took 11 hrs in 5mm of root diameter and 4 hrs in exposed parent material. Paeoniflorin content in dried roots after peeling was lower than that of unpeeled root. Paeoniflorin content in root below 5mm in diameter was highest (6.15 %) and that was decreased in the increased root diameter up to 20mm, but it was slightly increased in root greater than 20mm in diameter.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.383-388
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• 2012

This study was conducted to assess damage to the welsh onion by Acrolepiopsis sapporensis Mastumura (Lepidoptera: Acrolepiidae) during the summer season, and to estimate the economic injury level (EIL) which results, providing basic data for pest management. The adult peaks of A. sapporensis in Suwon were observed in March, April, May, and September of 2009 and 2010 through the use of pheromone traps. The feeding of A. sapporensis results in white lines on the surface, and holes within welsh onions. During the entire larval period, one larva was able to damage 1.6 leaves and punch 11.9 holes, resulting in a total damaged leaf area of $1,321.6mm^2$. Through cage experiments and larval releases, a reduction of the mean number of leaves, increased percentage of leaf damage, and reduction in gross weight and marketable weight were observed. We could obtain a regression equation that showed a clear positive correlation between pest density and percentage of damaged leaf. Using this equation, the EIL of A. sapporensis on welsh onion was calculated to one larva per 10 plants based on 7% leaf damage observed for welsh onion.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.6
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• pp.495-500
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• 2007

Recently we are interest in organic farming of rice. The technology of paper mulching was practised without herbicide in machine transplanting cultivation of paddy. A field experiment was conducted in Gangseo series (coarse loamy, mixed, nonacid, mesic family of Aquic Fluventic Eutrochrepts) at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Republic of Korea in 2004. This experiment was carried out to evaluate soil redox potential, weed control and rice growth by the different organic matter in paper mulching transplanting. Compost, rice straw and soiling rye were incorporated as organic matter. The nitrogen amount of controlled-release fertilizer (CRF) plot was 80% compared with nitrogen amount ($110kg\;ha^{-1}$) of conventional fertilization. Mulching paper consisted of recycled paper which was coated with biodegradable plastics. There were no difference between conventional rice transplanting and paper mulching on missing hills after organic matter application. Weed control were the highest at added soiling rye plot. The redox potential of soil was the lowest in rice straw + CRF 80% plot at tillering stage. The $NH_4{^+}-N$ in soil was the highest at soiling rye + CRF 80% tillering stage. There was no difference in yield between soiling rye + CRF 80%, compost + CRF 80% and conventional fertilization plot.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.283-288
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• 1982

This experiment was carried out to improve the cultural practices of seedlings and to investigate the proper planting density in aromatic tobacco, Sohang. Two different cultural practices of seedling were employed; Temporary transplanting (TT; Conventional practices) and non temporary transplanting (N.T.). Vinyl pot sizes were $3.5cm{\times}3.5cm, \;4cm{\times}4cm$ and $5cm{\times}5cm$ Plants per hole were 1, 3, 5, 7 and 9. There were little difference among the vinyl pot sizes in all characters except the survival ratio. But it may be little problem on cultural practices by 7 plants per hole in $5cm\times$5cm vinyl pot. There were not significant in price per kg, yield per 10a and value per 10a between two cultural practices of seedlings and among three pot sizes. Mildness and filling power were increased by increasing the plants per hole. Combustibility of 5-9 plants were better than those of 1-3 plants per hole. The growing of 6 seedlings per hole in $5cm\times$5cm vinyl pot by non temporary transplanting resulted the best cultural practices for an aromatic tobacco, Sohyang.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.471-475
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• 2001

This experiment was conducted to evaluate the effect of slow-release fertilizer on warm type garlic cultivation in the Southwestern region of Korea. The slow-release fertilizers used were UF(Urea-Formaldehydes)70, 100, 130, CDU(Crotonylidene Diurea)100, and IBDU(Isobuty- lidene Diurea)100. The slow-release fertilizer treatment slightly increased plant height, leaf sheath diameter, and leaf number compare with conventional fertilizer treatment. Also, large bulb rate, nitrogen and pyruvic acid contents of garlic in slow-release fertilizer plot were higher than other treatments. Application of slow-release fertilizer increased the commercial yields.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.2
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• pp.59-65
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• 2000

The vertical distribution of pore water pressure in the highly saturated sand layer under the oscillating water pressure is studied theoretically and experimentally. By the experiments it is shown that the water pressure acting on the sand surface propagates into the sand layer with the damping in amplitude and the lag in phase, and that the liquefaction, the state that the effective stress becomes zero, occurs under certain conditions. These experimental results are explained fairly well by the same theoretical treatment as for the ground water problems in the elastic aquifer. The main characteristics of liquefaction clarified by the analysis are as follows: 1) The depth of the liquified layer increases with the increase of the amplitude and the frequency of the oscillating water pressure. 2) The increase of the volume of the water and the air in the layer increases the liquified depth. Especially the very small amount of the air affects the liquefaction significantly. 3) The liquified depth decrease rapidly with the increase of the compressibility coefficient of the sand. 4) In the range beyond a certain value of the permeability coefficient the liquified depth decrease with the increase of the coefficient.