• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.230-235
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• 1999

To study the effects of an urease inhibitor, N-(n-butyl)-thiophosphoric triamide (NBPT), and a nitrification inhibitor, dicyandiamide (DCD), on nitrogen losses and nitrogen use efficiency, urea fertilizer with or without inhibitors and slowrelease fertilizer (synthetic thermoplastic resins coated urea) were applied to direct-seeded flooded rice fields in 1998. In the urea and the urea+DCD treatments, NH$_4$$^{+}$ -N concentrations reached 50 mg N L$^{-1}$ after application. Urea+NBPT and urea+ NBPT+DCD treatments maintained NH$_4$$^{+}$ -N concentrations below 10 mg N L$^{-1}$ in the floodwater, while the slow-release fertilizer application maintained the lowest concentration of NH$_4$$^{+}$ -N in floodwater. The ammonia losses of urea+NBPT and urea+NBPT+DCD treatments were lower than those of urea and urea+DCD treatments during the 30 days after fertilizer application. It was found that N loss due to ammonia volatilization was minimized in the treatments of NBPT with urea and the slow-release fertilizer. The volatile loss of urea+DCD treatment was not significantly different from that of urea surface application. It was found that NBPT delayed urea hydrolysis and then decreased losses due to ammonia volatilization. DCD, a nitrification inhibitor, had no significant effect on ammonia loss under flooded conditions. The slow-release fertilizer application reduced ammonia volatilization loss most effectively. As N0$_3$$^{[-10]}$ -N concentrations in the soil water indicated that leaching losses of N were negligible, DCD was not effective in inhibiting nitrification in the flooded soil. The amount of N in plants was especially low in the slow-release fertilizer treatment during the early growth stage for 15 days after fertilization. The amount of N in the rice plants, however, was higher in the slow-release fertilizer treatment than in other treatments at harvest. Grain yields in the treatments of slow-release fertilizer, urea+NBPT+ DCD and urea+NBPT were significantly higher than those in the treatments of urea and urea+DCD. NBPT treatment with urea and the slow-release fertilizer application were effective in both reducing nitrogen losses and increasing grain yield by improving N use efficiency in direct-seeded flooded rice field.field.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.2
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• pp.137-144
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• 2004

The objective of this experiment was to suggest the optimum N fertilization level for turf type mixtures {Kentucky bluegrass(Newport) 40% + tall fescue(Rebell Jr.) 20%. + perennial ryegrass(Palmer II) 10% + redtop(Barricuda) 10% + red fescue(Salem) 10% + creeping bentgrass(Crenshaw) 10%}. The field trials were conducted from 1998 to 2000 at Chungnam National University in order to evaluate the dry matter yield and quality on the N levels(100, 150 and 200kg/ha). With increasing the N level, the average DM yields over 2-years of turf type mixtures significantly increased. The average total DM yields were obtained 6,551, 8,182 and 9,501kg/ha at N 100, 150 and 200kg/ha level(p<0.05), respectively. CP content and DMD were increased, whereas fibrous constituents was decreased(p<0.05), but CPDM and DDM yields were significantly increased with increasing the N levels over 2-year(p<0.05). Based on the results, considering the total DM yield and the quality of herbages which were incidentally produced from turf type mixtures, it can be suggested that the suitable N level was 200kg/ha. But increased N fertilizer usage for general purpose use and expenses on turf type mixtures should be considered in advance.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1994-1998
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• 2009

Nutrients were investigated for surface water and ground water of paddy field and upland in a rural watershed from May 2008 to January 2009. The cocentrations of TN and $NO_3-N$ in ground water higher than those in surface water due to fertilization on cabbage upland neighboring a river during May to September, but lower than those in surface water during October to January. However, the concentrations TP and $PO_4-P$ in ground water were lower than those in surface water. TP and $PO_4-P$ concentrations in ground water of paddy field were generally lower than those of upland.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.671-674
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• 2016

We cytogenetically analyzed a triploid King-Nupchi strain of the olive flounder Paralichthys olivaceus to define the simplest, most rapid, and most effective method of ploidy analysis in aquaculture farms. Female triploidy of the flounder King-Nupchi strain was induced by cold shock (3 min post-fertilization at 2-4℃ for 45 min). Triploid induction was confirmed by erythrocyte measurement (nuclear volume, 29.15±2.10 μm³); flow cytometry (2.14±0.03 pg/cell); chromosome count (3N=72); Ag-NOR banding; and silver staining. Silver staining of finned cells obtained using a solid tissue technique was the most effective method of ploidy verification.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.157-161
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• 2007

Nutrients were investigated for surface water, bottom sediment and ground water in a rural watershed from January 2006 to March 2007. The concentrations of TN and $NO_3-N$ in ground water were higher than those in surface water due to fertilization on cabbage upland neighboring a river during March to August, but lower than those in surface water during September to February. However, the concentrations TP and $PO_4-P$ in ground water were lower than those in surface water. The concentrations of TP and $PO_4-P$ in surface water was lower than those in bottom sediment. The TP concentration in the bottom greatly decreased during rainy season. due to flush sediment of bottom, and then gradually increased.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2001.06a
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• pp.179-180
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• 2001

1. 실험목적 : 벼 휴립건답직파재배시 절수재배에 알맞은 질소 수비량을 구명하고자 함. 2. 재료 및 방법 가. 공시품종 : 동진벼 나. 공시토양 : 전북통(미사질양토) 다. 물관리방법 : 3엽기부터 완전낙수기까지 5일 간격 고랑관개 라. 처리내용 -파종량(kg/ha) : 60, 100 -질소 수비량(kg/ha) : 24(50% 감비), 48(표준), 75(50% 증시), 96(100% 증시)(중략)

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.1
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• pp.2-11
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• 2020

Assisted reproductive technologies (ART) merely depend on improving the oocyte maturation and their developmental competence to produce good quality embryos. Oocyte maturation passes through long and complex molecular steps starts from the early embryonic life and ends with sperm fertilization. Oocyte developmental competence can be attained by improving the nuclear and cytoplasmic mechanisms together with some epigenetic maturation. In this review, we highlight the cornerstones of oocyte maturation on both nuclear and cytoplasmic levels. Interfering or supporting these molecular mechanisms would help in the development of novel regulating agents for reproductive performance of humans and livestock species.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.283-283
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• 2004

The eggs of most animal species are surrounded by an extracellular matrix known as chorion, egg envelope, egg coat, or zona pellucida. Development of fish embryo usually takes several days in an aquatic environment. During embryonic development, the chorion must protect embryo from physical damage and microbial infection in the exposed aquatic environment. (omitted)

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.31-36
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• 1993

A pot experiment was carried out to investigate the influence of application of nitrogen, phosphorus and calcium on the yield and uptake of Sr-90 by soybean plant. The results obtained were summarized as follows : 1. The application of N tended to decrease the dry matter yield of soybean. There was, however, difference in the effect on the yield between $NH_4-N$ and $NO_3-N$ ; the yield was higher in the former in the latter. On the other hand, the application of P and Ca increased the yield. 2. The uptake of Sr was decreased by the application of N, but such effect was greater in $NH_4-N$ than in $NO_3-N$. 3. The effect of N application in reducing the uptake of Sr. was enhanced by the application of P with N. 4. The combined application of P and lime showed significant effect of reducing the uptake of Sr by soybean plant. The uptake of Sr was lowest in the pot that received P, lime and $NH_4-N$ together.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.1
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• pp.37-43
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• 1981

This pot experiment was conducted to find out the optimal fertilization ratio of the cations(K: Ca: Mg) in various soil conditions. Soil samples were collected from uncultivated mountains and hills where development for grass lands is under consideration. The optimum ratios were computed by the Homes systematic variation technique. The results were summarized as follows : 1. The optimum fertilization ratios of the cations (K : Ca : Mg) for the high yields of grass-clover mixed sward at various areas were obtained (Table 4) 2. The relatively high optimum fertilization ratios of K in Daegu and Taegwalryong, Ca in Unbong, and Mg in Cheju district gave the high yields of clover in mixed sward. They were positively related to the low contents of the above cations in the soils or the relatively low content ratio comparing with other cations. 3. The yields of clover in mixed sward were seriously affected by the changes in both the fertilization ratio and total concentration of cations comparing to those of the grass yields. As a consequence, total yields, quality, and botanical composition of the mixed sward were also affected. 4. The antagonis among the cations K, Ca, and Mg was known from the point of mineral contents of grass and clover. 5. The equivalent ratio K/(Ca+Mg) or grass was greatly increased by the range of 2.4 and 3.3 in the K-group treatment, which was higher than the critical level 2.2 of grass tetany, otherwise that. of clover by the range of 0.9 and 1.2. Therfore, it may be concluded that if the botanical composition of grass/legume sward is optimum, the incidence of grass tetany can be eliminated.