• Korean journal of applied entomology
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• v.53 no.4
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• pp.415-425
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• 2014

This study investigated population fluctuations in two mite species in apple orchards over 20-year period. The occurrence of two major mite pests infesting apple trees, two-spotted spider mite Tetranychus urticae and European red mite Panonychus ulmi (Acari: Tetranychidae), was investigated from 1992 to 2011 in major apple-producing districts, including four to eight cities, in the southern part of the Republic of Korea. The 20-year trend revealed that more orchards were infested by T. urticae from 1992 to 1999, but thereafter P. ulmi became dominant. The observed mean density of P. ulmi was consistent, whereas that of T. urticae fluctuated during this period. The analysis of occurrence in four time periods reveals that the density of T. urticae decreased after 2002. The monthly sampling, revealed that the density of P. ulmi was higher in April, whereas the density of T. urticae was higher from May to August. This change may be due to a change in the frequency of pesticide spraying, ground vegetation management, a decrease in nitrogen fertilization, and the overall orchard management practices. However, this projection should be examined in more detail. On the basis of the findings of this study, it can be concluded that cultural practices, including fertilization, and environmental changes, such as pesticide spray frequency and integrated pest management practices, affect species dominance and population densities of the two mite species in apple orchards.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.4
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• pp.307-315
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• 1994

The object of this experiment was to suggest the suitahle N-P-K fertilization level for orchardgrass(0G)-red clover(RC) mixtures under the intensive system of short-term pasture utilization. The fields trials were conducted over 3-year period(1991-1993) to evaluate dry matter yield. botanical composition, chemical composition and CP, DDM yield on the N-P-K levels (0-0-0. 50-100-100. 100-150-150, 150-2OO-200. 200-250-250 and 300-350- 350kg/ha). With increasing level of N-P-K, the DM yield of OG in the OG-RC mixture were significantly increased(P< 0.05), however, that of RC was remarkably decrcawd(P

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.419-432
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• 1999

Objective: To establish the evaluation system of the quality of oocytes on the basis of the incidence of cumulus cells apoptosis, to investigate the relationships beween the incidence of cumulus cells and the outcomes of IVF-ET. Method: Thirth-four cycles undergoing controlled ovarian hyperstimulation for IVF-ET with tubal infertility (23 cycles) or unexplained infertility (11 cycles) were included in this study. Cumulus cell masses surrounding mature oocyte and co-culture of embryos with autologous cumulus cells during IVF-ET process. The incidence of apoptosis in cumulus cells was assessed by apoptosis detection kit fluorescein. The effect of co-culture using cumulus cells and the incidence of cumulus cells apoptosis. Results: The results were as follows: 1. The incidence of apoptosis in cumulus cells markedly increased in patients aged 40 or over, while the fertilization rate was greatly decreased in those age group. 2. Apoptosis in cumulus cells was found in both the fertilized oocytes and unfertilized oocytes, but the incidence of apoptosis was higher in unfertilized oocytes. 3. There is no clear correlation between apoptosis in cumulus cells and the number of oocytes retrieved. However, the incidence of apoptosis was increased when the number of oocytes retrieved was 5 and fewer in comparison with $6{\sim}10$. 4. Embryo grade was significantly affected by the incidence of apoptosis in cumulus cells. 5. Pregnancy rate of IVF-ET per cycle was 29.4%, and the pregnant group had the higher fertilization rate and a significantly lower incidence of apoptosis in cumulus cells compared with the nonpregnant group. 6. When cumulus cells were used as helper cells in the co-culture of the embryo, in vitro activity of cumulus cells based on morphological change and proliferation did not influence the quality of embryo, but was closely associated with the implantation rate and pregnancy rate, which was enhanced when morphological changes and proliferation of cumulus cells was more active. 7. This difference in the outcome of IVF-ET according to in vitro activity of cumulus cells used for co-cultue was not associated with the incidence of apoptosis in cumulus cells; but rather had likely relations with the different secretion pattern of protein, which may be an embryo trophic factor by cumulus cells. Conclusion: These results suggest that the incidence of apoptosis in cumulus cells can be used in predicting oocyte qualities and the outcomes of IVF-ET. And the effect of co-culture largely depends on the in vitro activity of cumulus cells as well.

• Journal of Aquaculture
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• v.10 no.4
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• pp.463-472
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• 1997

Floating and hatching rates, size and survival activity index(SAI) of spawned eggs of red spotted grouper, Epinephelus akaara were studied to understand egg qualities during the spawning periods in 1992, 1993 and 1995. The fish spawned from mid-July to mid-August when temperature ranged 23~$28^\circC$. Floating, fertilization and hatching rates were higher in the eggs from early to middle than those from late during the spawning period. SAI ranged 1.8~9.6, and it was closely related to survival rate until mouth operning time (SMOT). Egg diameter decreased gradually with the time of spawning, while diameter of oil globule was constant during the spawning periods. Induced spawnings were carried out with one injection of HCG over 5, 000 IU/kg body weight. Floating, fertilization and hatching rates of the induced spawning eggs were higher than those of untreated ones. Thus, induced spawning method with HCG was recommended for collecting fertilized eggs in bulk. Optimal time for the collection of high quality eggs was supposed to be from early to middle during the spawning periods. Considering that egg qualities were vulnerable within the period, hatchability, incidence of malformed larvae, SMOT and SAI were factors to be considered together to get good quality of eggs.

• Clinical and Experimental Reproductive Medicine
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• v.45 no.3
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• pp.122-128
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• 2018

Objective: To determine whether fragment removal on in vitro fertilization (IVF) day 2 improved the subsequent development and pregnancy outcomes of fragmented embryos compared to similar-grade embryos without fragment removal. Methods: This study was a retrospective analysis involving 191 IVF cycles in which all embryos had over 10% fragmentation (grade 3 or 4) on day 2 of the IVF-embryo transfer cycle from March 2015 to December 2017. IVF cycles were divided into the fragment removal group (n = 87) and the no fragment removal group (n = 104) as a control cohort. Before fragment removal, embryos with fragmentation on day 2 were incubated in $Ca^{2+}$- and $Mg^{2+}$-free biopsy medium under paraffin oil for 30 minutes. Microsurgical fragment removal was performed with later-assisted hatching and a handmade suction micropipette that had an outer diameter of $30{\mu}m$. Results: There were no significant differences in the characteristics of the patients between the control and the fragment removal groups. After fragment removal and subsequent in vitro culture for 24 hours, the number of blastomeres ($7.1{\pm}1.7$ vs. $6.9{\pm}1.6$) was comparable between the transferred embryos in the two groups, but the morphological grade of the embryos in the fragment removal group ($1.9{\pm}0.7$) was significantly higher than that of the control group ($3.1{\pm}0.5$, p< 0.01). The clinical pregnancy (43.7%) and implantation rates (25.8%) in the fragment removal group were significantly higher than those in the control group (28.8% and 14.0%, respectively; p< 0.05). Conclusion: Early fragment removal on day 2 significantly improved the subsequent development and pregnancy outcomes of fragmented embryos.

• Journal of Embryo Transfer
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• v.25 no.4
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• pp.263-266
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• 2010

Prediction of semen's fertilizing ability used in artificial insemination (AI) is one of very important factors on pig reproductive performance. In vitro fertilization (IVF) has been used for indirect evaluation of sperm's fertilizing ability and it has been showed as highly correlated index. In swine industry, increasing interest in preservation of boar semen raises questions on the sperm motility from semen used in commercial AI centers. Mitochondria in sperm mid-piece generate the energy to support motility and could be an explanation of impaired fertility. Objective of this study was to suggest usable sperm motility to farms in measuring the effect of sperm motility and sperm abnormality on in vitro production of embryo in which sperm's fertilizing ability can be determined indirectly. Semen samples were provided from local AI center and used within 3 days after collection. Semen samples were divided by 4 different motile groups (>70%; 61~70%; 51~60%; <50%) using CASA (computer-assisted sperm analysis) on the days of IVF. Developmental rate to the blastocyst stage from over 61% motile sperm group showed significantly higher rate than below 60% motile sperm group ($16.5{\pm}0.7{\sim}18.4{\pm}0.8%$ vs $6.3{\pm}0.8{\sim}11.5{\pm}0.7%$, p<0.05). In experiment to determine the relationship between sperm motility and viability and abnormality, over 61% motile sperm groups showed significantly higher viability rate compared to below 60% motile sperm groups ($84.8{\pm}4.0{\sim}88.1{\pm}4.0%$ vs $69.1{\pm}4.0{\sim}74.2{\pm}4.0%$, p<0.05). On the other hand, morphological sperm abnormality showed significantly higher in over 70% motile sperm group ($10.2{\pm}2.2$ vs $16.0{\pm}2.2{\sim}21.0{\pm}2.2%$, p<0.05). In experiment to find the correlation between sperm motility of 4 different motile groups and amount of mitochondria, lower motility group also showed lower level of mitochondria (p<0.05). The mitochondria parameter used in this study showed another possibility to differentiate the sperm motility. Taken together, because below 60% motile semen used in AI reduce the fertility, AI centers should provide the over 60% motile sperm to the farms at the time of AI.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.3
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• pp.159-163
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• 2011

Objective: To compare the IVF outcomes of mild ovarian stimulation with conventional ovarian stimulation in poor responders. Methods: From 2004 to 2009, 389 IVF cycles in 285 women showed poor responses (defined as either a basal FSH level ${\geq}$12 mIU/mL, or the number of retrieved oocytes ${\leq}$3, or serum $E_2$ level on hCG day <500 pg/mL) were analyzed, retrospectively. In total, 119 cycles with mild ovarian stimulation (m-IVF) and 270 cycles with conventional ovarian stimulation (c-IVF) were included. Both groups were divided based on their age, into groups over and under 37 years old. Results: The m-IVF group was lower than the c-IVF group in the duration of stimulation, total doses of gonadotropins used, serum $E_2$ level on hCG day, the number of retrieved oocytes, and the number of mature oocytes. However, there was no significant difference in the number of good embryos, the number of transferred embryos, the cancellation rate, or the clinical pregnancy rate. In the m-IVF group over 37 years old, the clinical pregnancy rate and live birth rate were higher when compared with the c-IVF group, but this result was not statistically significant. Conclusion: In poor responder groups, mild ovarian stimulation is more cost effective and patient friendly than conventional IVF. Therefore, we suggest that mild ovarian stimulation could be considered for poor responders over 37 years old.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.155-163
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• 1999

Nutrient balance during rice cultivation in the paddy of a local area under the environmental protection for drinking water supply was investigated. To compare nutrient balance in the paddy soil applied with different types of fertilization, 7 treatments were selected as followings : Recommended level of chemical fertilizers(R), Conventional fertilization(CF), Fresh cow manure(FCM), Cow manure compost(CMC), Straw compost+reduced chemical fertilizer(SCF), Fresh straw+recommended level of fertilizers(FSC), and no fertilization as control(C). Here, FCM, CMC and SCF were applied at the same level of total nitrogen as recommended in R. Rice yield was the highest in the recommendation(R) and fresh cow manure (FCM) treatments with $6,730kg\;ha^{-1}$(index 100), and followed by SCF (index 98), FSC (index 98), CMC(index 94), and CF(index 94). But statistically significant difference was not recognized among treatments except the control. Nitrogen infiltration loss was high in the simple chemical fertilizer treatments with $63kg\;ha^{-1}$ in CF and $58kg\;ha^{-1}$ in R during rice cultivation, respectively. Nitrogen infiltration loss was decreased below half level of chemical fertilizer treatments with cow manure treatments ($23kg\;ha^{-1}$ in FCM and $27kg\;ha^{-1}$ in CMC) and with reducing chemical fertilizer treatment by adding straw compost ($25kg\;ha^{-1}$). Phosphate was not leached during rice cultivation in paddy soil of a fluvial deposit type, in which oxidation horizon was developed broadly under around 15 cm depth of surface soil. Phosphate balance (A-B) was closed to 0 in all treatments except cow manure treatment (CMC), in which it was $+30kg\;ha^{-1}$ and show the possibility of over accumulation of phosphate by continuously replicated application of cow manure compost. Potassium balance was negative value in all but straw recycling treatment (FSC). It means that potassium was continuously supplied from soil minerals, uptaken by plants or eluted out of soil. In conclusion, by substituting inorganic fertilizer for organic fertilizer or reducing application rate of chemical fertilizer through mixing organic fertilizer, it would be possible to achieve the same rice yield as in the recommendation treatment and to decrease nutrient leaching below half level in rice paddy soil.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.52-61
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• 1984

Pot and laboratory tests were undertaken to investigate the influence of silicate fertilization on butachlor phytotoxicity to rice. Growth of rice seedlings at 150 ppm of $SiO_2$ was stimulated, while adverse effect was observed over 300 ppm of $SiO_2$ and growth reduction was enhanced with combination of butachlor and $SiO_2$ Rice growth in pot trial at 150kg/10a of silicate fertilization was not influenced by recommended amounts of butachlor and nitrofen, however, the growth of Seokwang byeo at 300kg/10a of silicate was markedly retarded by butachlor in the initial stage of growth. Growth reduction of Seokwang byeo caused by combined application of silicate and butachlor was recovered 50 days after herbicide application. Growth reduction from butachlor was not influenced by pH level and also degradation behaviors of butachlor in submerged soil was not altered by silicate fertilization. Adsorbed amount of butachlor on rice root was increased with addition of $SiO_2$ and its amount in Seokwang byeo was higher than that of Jinju byeo. Butachlor absorption by Seokwang byeo was accelerated by 150 ppm of $SiO_2$ applied simultaneously, but those effect was not encountered in Jinju byeo. Butachlor absorption of rice seedlings was also increased by 150 ppm of $K_2O$, while CaO hindered the absorption and $Na_2O$ had no effect on the absorption. Residual level of butachlor in Seokwang byeo treated with combined solution of butachlor and $SiO_2$ was continued higher than that with butachlor alone during 10 days after transplantation to culture solution.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.744-748
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• 2012

This study was carried out to investigate the incorporation effect of green manure crops (GMC) such as the hairy vetch on improvement of soil environment in reclaimed land during sorghum${\times}$sudangrass hybrid (SSH) cultivation over the past three years from 2009 to 2011. Plots consisted of conventional fertilization (CF) and incorporation of GMC were divided by rates of additional nitrogen fertilizer ($100kg\;ha^{-1}$) and decreased percentage of 30 50 70 100 fertilization in addition to non nitrogen fertilization (NNF). Soil physico-chemical properties, growth and yield potential were examined. The results were as follows. The testing soil was showed strong alkaline saline soil with low organic matter contents and less available phosphate while exchangeable sodium and magnesium were higher. Soil salinity was increased during cultivation of summer crop. However, SSH was not affected by salt content. The fresh weight of GMC at incorporation time was $18,345kg\;ha^{-1}$. Content of total nitrogen at incorporation time was 3.09% and the C/N ratio was 12.8. Fresh and dry matter yield of SSH were higher in the order of 30%, CF, N50%, N70%d, N100%, and NNF. Fresh and dry matter yield of SSH increased in the order of CF ($55,050kg\;ha^{-1}$, $16,250kg\;ha^{-1}$), N contents from 30% to 9%. Soil physical properties, such as bulk density were decrease with incoporation of GMC, while porosity was increased. Soil chemical properties, such as pH was decreased while content of exchangeable calcium, available phosphate, and organic matter were increased. Also contents of exchangeable sodium and potassium were decreased with incorporation of GMC than those before experiment. Thus, we assumed that incorporation of hairy vetch was more effective that can lead to reduce chemical nitrogen fertilizer and to improve soil environment in cultivating SSH on Saemangeum reclaimed land.