• Korean Journal of Weed Science
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• v.15 no.4
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• pp.289-297
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• 1995

Field experiments were conducted to evaluate the competitive characteristics of weeds with direct-seeded rice. In both dry- and water-seeded rice a weeds) started to grow over the plant height of rice from 45 days after seeding, and there was a great difference in plant height between rice and weeds from 75 days after seeding. Dry weights of weeds drastically increased from 30 days after seeding in both dry- and water-seeded rice, and the increase of dry weight was faster in dry-seeded rice than in water-seeded rice with time. Although weeds competed with rice at earlier growth stages, they did not reduce rice yields and its components until competition period of 75 days after seeding. Required period of weed free at the beginning of the season was 30 to 45 days from seeding in order to avoid any yield loss. The numbers of panicle per plant, spikelets per panicle, grain weight and yield of rice in dry-seeded rice had highly negative correlations with the growth ratios of Echinochloa crus-galli, Ludwigia prostrata, Cyperus difformis, Bidens frondosa, and Cyperus serotinus. In water-seeded rice, the number of plants, panicle per plant, spikelets per panicle and yield had highly negative correlations with growth rate of Echinochloa crus-galli, but the percentage of filled spikelet had negative correlation with Cyperus difformis. Research indicated that in direct-seeded rice weed competition with rice started from 30 days after seeding and significant yield loss by weed competition occurred from 75 days after seeding.

• Korean Journal of Organic Agriculture
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• v.27 no.4
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• pp.479-499
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• 2019

This study was conducted to investigate the responses of soil properties and microbial communities to different agricultural management and soil types, including organic management in Andisols (Org-A), organic management in Non-andisols (Org-NA), conventional management in Andisols (Con-A) and conventional management in Non-andisols (Con-NA) by using a pyrosequencing approach of 16S rRNA gene amplicon in Radish farms of volcanic ash soil in Jeju island. The results showed that agricultural management systems had a little influence on the soil chemical properties but had significant influence on microbial communities. In addition, soil types had significant influences on both the soil chemical properties and microbial communities. Organic farming increased the microbial density of bacteria and biomass C compared to conventional farming, regardless of soil types. Additionally, Org-NA had the highest dehydrogenase activity among treatments, whereas no difference was found between Org-A, Con-A and Con-NA and had the highest species richness (Chao 1) and diversity (Phyrogenetic diversity). Particularly, Chao 1 and Phyrogenetic diversity were increased in organic plots by 12% and 20%, compared with conventional plots, respectively. Also, regardless of agricultural management and soil types, Proteobacteria was the most abundant bacterial phylum, accounting for 21.9-25.9% of the bacterial 16S rRNAs. The relative abundance of putative copiotroph such as Firmicutes was highest in Org-NA plot by 21.0%, as follows Con-NA (13.1%), Con-A (6.7%) and Org-A (5.1%.), respectively and those of putative oligotrophs such as Acidobacteria and Planctomycetes were higher in Con-A than those in the other plots. Furthermore, LEfSe indicated that organic system enhanced the abundance of Fumicutes, while conventional system increased the abundance of Acidobacteria, especially in Non-andisols. Correlation analysis showed that total organic carbon (TOC) and nutrient levels (e.g. available P and exchangeable K) were significantly correlated to the structure of the microbial community and microbial activity. Overall, our results showed that the continuous organic farming systems without chemical materials, as well as the soil types made by long-term environmental factors might influence on soil properties and increase microbial abundances and diversity.

• Journal of Animal Science and Technology
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• v.47 no.5
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• pp.877-890
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• 2005

This study was carried out to determine the effect of different growing stages of winter cereal crops on the quality of silage materials and silages. Silages were made from the silage materials harvested at four growing stages(boot, heading, flowering, and yellow ripe) of barley, rye, oat, and wheat. Approximately 1 kg of silage materials harvested from each growing stage stored in vinyl bags with vacuum packing method and fermented at room temperature for 40 days. As the growing stages progressed, the moisture and crude protein contents of the silage materials decreased, and fiber contents(NDF, ADF and hemicellulose) increased. All the silage materials showed significantly higher contents of water soluble carbohydrate in the boot stages than in the flowering and yellow ripe stages. There was no tendency in acetic acid contents of silage materials cut at different growing stages. The overall pH of silage materials were in the range of 5.91-6.01, and there was no significant difference among growing stages. Buffering capacity of silage materials were in the range of 26.23-29.47meq/100g DM, and showed a tendency to decline as the growing stages proceeded. The moisture and crude protein contents of silages decreased significantly in all species as the growing stages proceeded, and the fiber contents vice versa. As the growing stages proceeded, the pH of the silages tended to increase, and the acetic, butyric, and lactic acid contents tended to decrease. The buffering capacity of silages had a tendency to decrease as the growing stages of winter cereal crops proceeded. Therefore, these features described above should be taken into consideration in order to make silages from winter crops economically.

• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.7-17
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• 2001

Growth optima and tolerance ranges of marine algae species nay vary greatly during the developmental stage. The establishment stage is clearly of great importance for each generation, affecting the performance of the adult population. The present study was aimed to determine the effect of various concentrations of inorganic nutrients and heavy metals on germination and germlings of Ulva pertusa Kjellman (Chlorophyta). Percent germination increased rapidly as irradiance level increased, reaching the maximum at 100 ${\mu}$mol m$\^$-2/s$\^$-1/ in both east and west seawater. Percent germination in the east seawater was higher than that in the west seawater at irradiances lower than 30 ${\mu}$mol m$\^$-2/s$\^$-1/, and there was no difference in percent germination between the two different seawaters at irradiances higher than 60 ${\mu}$mol m$\^$-2/s$\^$-1/. Germling growth increased in the both cases with increasing irradiances but no growth was found in the dark. Overall germling area was larger in the east seawater than in the west seawater. Number of cell increased with increasing irradiance and became light-saturated at 100 ${\mu}$mol m$\^$-2/s$\^$-1/ in the both cases. Germlings grown in the east seawater had more cells than those cultivated in the west seawater at irradiances lower than 60 ${\mu}$mol m$\^$-2/s$\^$-1/. In various combinations of nitrate and phosphate, percent germination increased with increasing nitrate concentrations irrespective of phosphate concentrations. At 3 days after inoculation, nitrate concentration of 2.5 ppm with all phosphate concentrations promoted germination. Area and number of cell of germlings increased with increasing nitrate concentrations in all phosphate concentrations. In various combinations of copper and lead, germination was delayed as copper concentrations increased in all lead concentrations. Percent germination was severely reduced at 1 ppm Cu$\^$2+/. Area and number of cell of germlings decreased with increasing copper concentrations in all lead concentrations. The highest copper concentration (1 ppm) clearly suppressed the germling growth in U. pertusa.

• Korean Journal of Environmental Biology
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• v.32 no.3
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• pp.168-175
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• 2014

In order to understand the phytoplankton community structure based on their cell size duringlow water temperature periods, we studied 10 stations in the East Sea, Korea on March, 2012. The minimum standing crops of total phytoplankton were $3.4{\times}10^6cells\;L^{-1}$ at the station 5. The maximum values were $7.6{\times}10^6cells\;L^{-1}$ at the station 8, which is two times the amount of the minimum. The carbon mass at the station 4 ($6.3{\times}10^8pg\;L^{-1}$) was more than forty times higher compared with station 5 ($0.08{\times}10^8pg\;L^{-1}$). From these results, we found a significant difference between standing crops and carbon mass which might have caused due to their differences in community structure and cell size. Therefore, we considered the types of plankton biomass to estimate the primary product in the specific location and/or time. The phytoplankton communities were classified in 3 types: microplankton (> $20{\mu}m$), nanoplankton (< $20{\mu}m$) and picoplankton (< $2{\mu}m$). In the case of picoplankton, various morphological types were observed during the study period. These various picoplankton species were further classified as S (spherical), SF (spherical&flagella), O (oval), OF (oval&flagella) or R (rod) type, and we analyzed their community structure based on these categories. The picoplankton was found to be the most dominant type at 8 stations and S type as the most popular. The picoplankton seems to be the significant organism in the marine ecology during low water temperature periods in the coastal waters of East Sea. Therefore, picoplankton \;-with scientific surveys can be considered as the database for their identification. In conclusion, we suggest that cell size of the phytoplankton would be the best criteria to accurately analyze their community structure and to reveal groups having more ecological influence.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.3
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• pp.92-98
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• 1988

With a purpose of finding out the effects of magnesium and boron enriched organic-compound fertilizer application on the dry matter yield, yield components and changes in the botanical composition on the hilly pasture, a field experiment was arranged with five different treatments as a randomized block design and lasted from September, 1984 to the end of growing season in 1986. The results obtained are summarized as follows : 1. As a early plant growth and development, winter hardiness, growth vigour and coverage of grasses at the plots with organic-compound fertilizer application were better comparing to single dressing. 2. Average dry matter yields for two years were shown significantly high due to increasing amount of fertilizer. This trend was same both single and organic-compound fertilizer. And dry matter yields with organic-compound fertilizer application of low (8, 693.1 kg/ha) and conventional level (12, 758.7 kg/ha) were appeared to increase by 10 and 15% than those of single dressing of Low (7, 930.6 kg/ha) and conventional level (11, 122.6 kg/ha), respectively. But it was not significant difference. 3. Dry matter yield of grasses was significantly gained by increasing amount of fertilizer. The yield of legumes at the plot without fertilization was significant higher comparing to fertilizing plots, but it was not different between low and conventional dressing levels. However, at the plots with organic-compound fertilizer application the yields of grasses were a little more increased by 8-14%, and legumes were much more gained by 26-29% than those of the same species groups with single dressing, but it was not significant between the different kinds of fertilizer in the same fertilizing level. 4. At the grassland management, the rate of legumes tended to dominate at the plot without fertilization gradually. On the other hand, the botanical compositions and the rates of grasses were much better maintained at the plots with fertilization. But the rates of legumes with organic-compound fertilizer application tended to increase a little more than those of single dressing gradually.

• Journal of Embryo Transfer
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• v.20 no.2
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• pp.105-112
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• 2005

The present study was conducted to examine some factors affecting in vitro development of oocytes from somatic cell nuclear transfer (SCNT) in Korean native goats. Recipient oocytes were surgically collected after superovulation by using CIDR and FSH, PMSG, hCG and estrous synchronization in Korean Native goats. For nuclear transfer, the fibroblasts from caprine ear cells and fetal fibroblasts were surgically harvested and were cultured in vitro until cell confluency in serum-starvation condition (TCM-199 + $0.5\%$ FBS) for 3 to 5 days. The zona pellucidae of matured oocytes were partially drilled by laser irradiation. A single somatic cell was individually transferred into each enucleated oocyte. The reconstructed oocytes were then electrically fused and activated. Activated NT embryos were cultured in mSOF medium supplemented with $0.8\%\;BSA\;6\~7\;day\;at\;39^{\circ}C,\;5\%\;CO_2,\;5\%\;O_2,\;90\%\;N_2$ in air. There were no significant difference in the number of embryos cleaved and 4-cell development between the fibroblast nuclei from mature ear cells and fetal cells, but the rate of 8-cell development was higher (P<0.05) in ear cells $(40.5\%)$ than in fetal cells $(55.5\%)$. However, the embryo development to morula or blastocyst was not significantly different between both the groups$(6.7\%\;vs\;16.0\%)$, respectively. The number of embryo cleaved $(79.0\%)$ were higher (P<0.05) in the oocytes activated with ionomycin+6-DMAP than in the oocytes activated electrically $(9.5\%)$. The development of fused embryos to morula or blastocyst was found $15.6\%$ in ionomycin+6-DMAP, but no morula or blastocysts were developed in electrical stimulation. The development rate of SCNT embryos to morula or blastocyst was love. (P<0.05) in SCNT embryos $(19.0\%\;vs\;0.0\%)$ than that in parthenotes $(66.1\%\;vs\;59.1\%)$. In the parthenotes, the cleavage rate and development to morula or blastocyst were significantly higher (P<0.05) as $86.8\%\;and\;50.0\%$ in ovulated oocytes than in follicular oocytes $(69.0\%\;vs\;23.6\%)$, respectively. These results suggest that some factors Including superovulation treatment, oocyte source, maturation of follicular oocytes, activation method and culture condition may affect in vitro developmental capability of embryos produced by somatic cell nuclear transfer in Korean Native goats, and the fusion rate be greatly low compared with other species.

• Journal of Embryo Transfer
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• v.21 no.3
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• pp.263-271
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• 2006

The purpose of this study was undertaken to compare ability of frozen-thawed sperm characteristics between two strains (miniature pig and Duroc). The semen was collected by gloved-hand method into a pre-warmed ($37^{\circ}C$) thermos bottle. The semen was diluted with same volume extender and added to LEY solution for freezing. The diluted semen was placed in 0.5 ml straws, and freezing was initiated by exposing the straws to liquid nitrogen ($LN_2$) vapours for 10 min before placing them into $LN_2$ for cryopreservation. The frozen-semen straw were thawed at 20, 37 and $50^{\circ}C$ for 1 min, 45 sec and 10 sec within water-bath. The semen sample were evaluated at 0, 3, 6, 9, and 12 h after incubation at $37^{\circ}C$ for analysis of sperm ability. Abnormality of spermatozoa in miniature pig was significantly (p<0.05) higher than that in Duroc at 0, 9 and 12 h of post-thawing incubation after frozen-thawing. The percentage of F-patterned spermatozoa in miniature pig was significantly (p<0.05) lower, while the percentage of AR (acrosome reacted spermatozoa) pattern was higher in the miniature than in the Duroc. On the other hand, there was no significant difference in the viability of spermatozoa thawed at different temperature ($20^{\circ}C\;and\;37^{\circ}C$) between two species, but the viability in miniature pig was higher (p<0.05) than in Duroc when sperm was thawed at $50^{\circ}C$. In conclusion, this study suggest that suitable freezing method for miniature pig semen is required for increasing post-thawing viability and fertilization capacity.

• The Korean Journal of Pharmacology
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• v.10 no.1 s.15
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• pp.31-40
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• 1974

1. The authors investigated the effects of $PGE_1$ on the action of sympathomimetics in the vas deferens of guinea-pig, comparing with those in the rat vas deferens, and also the action of $PGE_1$ on the motility of nerve-free smooth muscle of chick amnion. 2. In the isolated guinea-pig vas deferens, the actions of phenylephrine and norepinephrine were much potentiated by pretreatment with $PGE_1$. Futher, in the isolated hypogastric nerve-vas deferens preparation of guinea-pig, effects of phenylephrine, norepinephrine and tyramine on the contractile response of vas to the hypogastric nerve stimulation and to the transmural stimulation were also augumented especially in tension by $PGE_1$-pretreatment. 3. In the isolated hypogastric nerve-vas preparation of rat, both contractile responses to hypogastric nerve and transmural stimulation were slowly reduced by treatment with $PGE_1$ and the potentiated effect of phenylephrine or norepinephrine was not observed in spite of pretreatment with $PGE_1$. 4. The actions of phenylephrine and norepinephrine on the denervated vas deferens of guinea-pig were also enhanced by $PGE_1$ as it were in the intact vas deferens, but there was no significant effect by $PGE_1$ on the action of norepinephrine in the denervated rat vas deferens. 5. $PGE_1$ in low concentration $(10^{-8}g/ml)$ did not affect the spontaneous motility of nerve-free smooth muscle of chick amnion ($9{\sim}11$ th day incubated chick), but in large concentration $(5{\times}10^{-8}g/ml)$ it caused irregular and slightly inhibitory movement. Pretreatment with $PGE_1$ on chick amnion did not exert any change on the action of phenylephrine applied. However, the stimulatory action of physostigmine on the chick amnion was a little antagonized by the low concentration of $PGE_1$. 6. It might be summarized that there is species difference between the actions of $PGE_1$ on the vas deferens of guinea-pig and that of rat, and the action of $PGE_1$ on the guinea-pig vas deferens might be mediated by the other mechanism rather than by direct action on the vas musculature.

• Korean Journal of Food Science and Technology
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• v.18 no.1
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• pp.42-47
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• 1986

The fatty acid composition of lipids extracted from 18 kinds of salted and fermented sea foods which have been consumed in Korea were examined. The lipid contents of salted and fermented sea foods showed wide difference (0.8-11.9%) depending on species and portions of raw materials. In fatty acid composition of salted and fermented sea foods prepared with whole fishes, the saturated fatty acid was the most predominant component, and the major fatty acids were 16:0, 18:1, 22:6, 16:1 and 20:5. In case of salted and fermented products prepared with gills, roe or intestines, the polyenoic fatty acid was the main component, the major fatty acids were 18:1, 16:0, 22:6, 20:5, 16:1 and 18:3. In these products the composition ratios of 20:5 and 18:3 were higher, and that of 16:0 and 16:1 were slightly lower as compared with salted and fermented whole fish products. And in case of salted and fermented crustacea and mollusk, the polyenoic fatty acids such a 22:6 and 20:5 were the most predominant component, the abundant fatty acids were 22:6, 16:0, 20:5, 18:1 and 16:1. Judging from results, salted and fermented sea foods were abundant of the highly unsaturated fatty acids such as 20:5, 22:6 inspite of the long fermentation periods.