• Journal of Embryo Transfer
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• v.11 no.3
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• pp.225-231
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• 1996

This study was conducted to investigate the effects of preincubation time, concentration and exposure time of sperm on in vitro fertilization of porcine follicular oocytes rnatured in in vitro. The results obtained are as follows ; 1. Effect of preincuhation time for porcine sperm capacitation on in vitro fertilization in medium with heparin was investigated. Normal fertilization rate was highest in 15 min(26.4%). However, there were no significant differences among preincuhation times of 5~90 min, 2. Normal fertilization rates of sperm concentrations were 17.0~26.5%, and normal fertilization rate from l$\times$ l05cell /ml concentration was also higher than those of other sperm concentration. 3. Normal fertilization rates of sperm exposure time of 4, 8, 12, 16 and 20 hours were 6.1, 20.8, 27.8, 25.0 and 26.7%, respectively. Normal fertilization rate from sperm exposure time of 12 hours was also higher than that of other sperm exposure times.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.372-381
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• 2013

The leaf growth and physiological characteristics of Forsythia saxatilis were investigated under different relative light intensities (RLI) and fertilization levels in order to find out the optimum environmental conditions for in-situ restoration. RLI and fertilization were four levels (30%, 43%, 63% of full sun and full sun) and three levels (non-fertilization, 2 times and 3 times of average forest soil in Korea), respectively. According to the increase of fertilization level under all RLI, leaf area increased and leaf dry weight and the ratio of leaf dry weight to leaf area decreased. As the fertilization level increased, photosynthetic pigment contents such as chlorophyll a, b and carotenoid under all RLI decreased. And pigment contents were the highest under full sun in the same fertilization level. Foliar nitrogen content under fertilization was higher than that under non-fertilization, and chlorophyll/nitrogen ratio decreased with the increase of fertilization level under all RLI. The increase of photosynthetic rate was observed with the increase of fertilization level at 63% of RLI and full sun, and dark respiration rate under fertilization was lower than under non-fertilization. Apparent quantum yield was lower at non-fertilization than that of fertilization, and it was highest at 63% of RLI under the same fertilization level. In conclusion, leaf growth and physiological characteristics of F. saxatilis could be improved under higher light conditions and fertilization.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.3
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• pp.97-106
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• 2006

The pollutant concentrations at experimental paddy plots with three (excessive, standard, reduced) different fertilization rates were investigated during 2001-2002 irrigation seasons. Mean concentrations of pollutants in ponded water were not significantly different among three experimental plots, but the T-N concentrations in percolated water significantly depended on fertilization rates. The T-N, T-P and $COD_{Cr}$, concentrations in ponded water during early irrigation season (late May to mid-June) were much higher than those during later irrigation season likely due to fertilization and low uptake by young rice crops. The T-N concentrations decreased but the concentrations of T-P and $COD_{Cr}$, increased three days after tillering fertilization. The removal rates of T-N by paddy plots were $0.13-0.16g/m^2{\cdot}d$ for an excessive fertilization plot, $0.08-0.25g/m^2{\cdot}d$ for a standard fertilization plot, and $0.03-0.34g/m^2{\cdot}d$ for a reduced fertilization plot three days after tillering fertilization. On the other hand, T-P and $COD_{Cr}$, were released three days after tillering fertilization.

• Journal of Korean Society of Forest Science
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• v.98 no.5
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• pp.558-562
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• 2009

The growth, carbon and nitrogen status of container grown black pine (Pinus thunbergii) seedlings were examined at various levels of foliar fertilization (control, 0.1%, 0.2%, 0.3%). Root collar diameter, height and dry weight of black pine seedlings increased significantly with increasing levels of foliar fertilization (P<0.05). Carbon concentration in needle of black pine seedlings was significantly higher in the foliar fertilization than in the control treatments (P<0.05), while other seedling components such as stem and roots were not significantly different (P>0.05) between the foliar fertilization and the control treatments. Nitrogen concentration and content were significantly greater in the foliar fertilization than in the control treatments (P<0.05). Shoot/root ratio of black pine seedlings (needle+stem dry weight/root dry weight) was greater in the foliar fertilization (2.40-2.89) than in the control treatments (1.87). However, nitrogen use efficiency was significantly lower (P<0.05) in the foliar fertilization (28-46) than in the control (111) treatments. The results indicate that morphological characteristics and nutritional status on container grown black pine seedlings were enhanced by various levels of foliar fertilization.

• Clinical and Experimental Reproductive Medicine
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• v.48 no.4
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• pp.362-367
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• 2021

Objective: The impact of early mechanical removal of cumulus cells on fertilization and embryonic development is not yet precisely known. This study aimed to investigate the effects of early and late cumulus cell removal on fertilization, polyspermy, embryonic development potential, blastocyst development, and clinical outcomes. Methods: A prospective study was conducted of patients who underwent in vitro fertilization between September 2019 and October 2020. Sibling oocytes were randomly allocated after insemination to early cumulus cell removal at 6 hours (group I) and late cumulus cell removal at 16-18 hours (group II). If total fertilization failure (TFF) was determined to have occurred at early cumulus cell removal, rescue intracytoplasmic sperm injection (ICSI) was performed. Fertilization, embryonic development, and pregnancy outcomes were compared. Results: A total of 912 oocytes were assigned to group I (458 oocytes) and group II (454 oocytes). Fertilization, polyspermy, embryo quality, and pregnancy outcomes were not significantly different between both groups. Rescue ICSI enabled fertilization of 79.2% of the TFF oocytes. Conclusion: Early cumulus cell removal at 6 hours had no significant difference in fertilization, polyspermy, embryo development, or obstetric and perinatal outcomes compared to late removal. Early cumulus cell removal combined with early rescue ICSI may have the potential to help couples with TFF.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.106-106
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• 2022

An appropriate amount of nitrogen fertilizer input during rice cultivation is essential for rice growth, quality control, and reduction of greenhouse gases in paddy fields. Therefore, it is necessary to develop a technology that can check whether an appropriate amount of fertilizer is applied in paddy fields. In this study, we tried to derive a method for diagnosing nitrogen fertilization level using spectroscopic diagnosis, physiological analysis, and molecular indicator genes. Nitrogen fertilization treatment was performed in a greenhouse by dividing into five treatment conditions: no fertilization (N0), low fertilization (N0.5), standard fertilization (N1.0), excessive fertilization (N1.5), and double fertilization (N2.0), respectively. Growth characteristics analysis was investigated by nitrogen fertilization conditions and growth stages, and the height of the canopy was analyzed using a laser scanner. Physiological and spectroscopic analyses were performed by analyzing chlorophyll and sugar contents and measuring SPAD and leaf spectrometer on rice leaves. In addition, real-time PCR experiment was performed to check the relative expression levels of several known nitrogen metabolism related genes. These results suggest that spectroscopic techniques can be helpful in diagnosing the level of nitrogen fertilization in rice paddy fields.

• Korean Journal of Plant Resources
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• v.11 no.2
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• pp.142-145
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• 1998

The experiment was conducted to elucidate the optimum planting data and fertilization level of Aruncus dioicus var. kamtscacus HARA. Plant height was increased as the seeding date was delayed. There was no transparent difference on plant height indifferent fertilization level. Nuber of stems was remarkably increased in the fertilization 14-14-12kg. Fresh leaf yield in the fertilization of 24-18-15kg was incresed about 31% comparing in the fertilization of 14-14-12kg. As a result, the optimum planing date and fertilization level was Jan. 15 and 24-18-15kg per 10a, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.388-392
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• 2016

The objectives of fertilizer recommendation are to prevent the application of excessive fertilization and to produce target yields. Also, optimal fertilization is important because crop quality can be influenced by fertilization. In this study, yields and fertilizer use efficiency of Taro (Colocasia esculenta Schott) were evaluated in different level of NPK fertilization. N, P and K fertilizer application rates were 5 levels (0, 50, 100, 150, 200%) by practical fertilization ($N-P_2O_5-K_2O=180-100-150kg\;ha^{-1}$), respectively. In the N treatment, the yields of Taro tuber were about $33Mg\;ha^{-1}$ from 90 to $360kg\;ha^{-1}$ N fertilization. However, the ratio of tuber to total biomass decreased with increasing N fertilization rate. In the P and K treatments, yields of Taro tuber were the highest at $150kg\;ha^{-1}$ fertilization. Fertilizer use efficiency was decreased by increase of N and K fertilization. Crude protein of Taro tuber was the highest at practical fertilization. Sucrose content of tuber was influenced by phosphate application.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.487-493
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• 2013

The effects of long-term fertilization on soil biological properties and microbial community structure in the plough layer in a rice paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK + Compost) for last 40 years. No fertilization plot (Control) was installed for comparison. Though fertilization significantly improved rice productivity over control, the long-term fertilization of NPK and compost combination was more effective on increasing rice productivity and soil nutrient status than single application of compost or chemical fertilizer. All fertilization treatments had shown significant improvement in soil microbial properties, however, continuous compost fertilization markedly increased soil enzyme and microbial activities as compared to sole chemical fertilization. Results of microbial community structure, evaluated by EL-FAME (ester-linked fatty acid methyl esters) method, revealed big difference among Control, NPK, and Compost. However, both Compost and Compost+NPK treatments belonged to the same cluster after statistical analysis. The combined application of chemical fertilizer and organic amendments could be more rational strategy to improve soil nutrient status and promote soil microbial communities than the single chemical fertilizer or compost application.

• Journal of Ecology and Environment
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• v.33 no.4
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• pp.317-323
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• 2010

Nutrient availability is a critical component of agroecosystems, and is relevant to both above- and below- ground interactions. The principal objective of this study was to determine how the cessation of fertilization affects the communities of weeds and soil organisms in a corn/wheat field. Changes in dominant weed species, substrate-induced respiration, and the population density of nematodes and microarthropods were evaluated. Microbial substrate-induced respiration (SIR) and the population density of microarthropods decreased following the cessation of fertilization and were partly correlated with the aboveground weed biomass. The cessation of organic fertilizer application but continuing application of inorganic fertilizer reduced the population density of nematodes. In response to the cessation of fertilization, weed communities were dominated by species with little dependency on fertilization. Amaranthus retroflexus was identified as the most dominant species in the corn field; however, it was replaced by Digitaria ciliaris after the cessation of fertilization. In the wheat field, the cessation of fertilization led to a rapid reduction in the biomass of most weeds, except for Vicia angustifolia, supposedly as the result of symbiotic nitrogen fixation. Additionally, the fact that weed biomass was partially correlated with SIR or the population density of microarthropods may reflect a mutual feedback between soil organisms and weeds. The results indicate that the cessation of fertilization alters communities of weeds and soil organisms through changes in weed biomass and interactions with symbiotic microorganisms.