• Journal of Korean Society of Forest Science
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• v.96 no.6
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• pp.693-698
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• 2007

We have only one type of forest fertilizer involved a composition ratio of 12:16:4% (N:P:K). It is required to develop new fertilization ratios which are suitable to soil environmental conditions and seedling growth characteristics. This study was carried out to determine change of seedlings growth on different fertilizer composition ratios. Two coniferous seedlings (2-year old Pinus densiflora Sieb. et Zucc., 2-year old Larix leptolepis Gordon) and two deciduous seedlings (2-year old Quercus acutissima Carruth., 1-year old Betula platyphylla var. japonica Hara) were planted in pots (about 30 l) and the seedling growth responses after composition ratio treatments (N:P:K, 2:2:1, 3:4:1, 3:8:1, 6:4:1, 3:4:2, control) with 30g fertilizer were measured for three-year study period. Growth of height and root collar diameter of two coniferous seedlings was highest in 3:8:1 ratio compared with other fertilizer composition treatments or control, while there was not significantly different among fertilizer composition ratios except for 2:2:1 and 3:4:1 ratios. Height growth of two deciduous seedlings was highest in 3:8:1 ratio compared with other fertilizer composition treatments or control, while growth of root collar diameter showed the highest values in 6:4:1 ratio. The results indicated that the growth of four tree seedling types were better in 3:8:1 or 6:4:1 ratios than in 2:2:1 or 3:4:1 ratios.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.424-429
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• 2010

To solve the problems with excessive accumulation of soil inorganic N and resulting saline soils from overuse of nitrogen fertilizer, the effect of sucrose application on decrease of soil inorganic N content and electrical conductivity (EC) was studied. Sucrose treatment greatly reduced ${NH_4}^+$-N content in soil. The amount of reduction was greater as the amount of sucrose treatment was increased. When ${NH_4}^+$-N content was reached the lowest point (about 10 mg $kg^{-1}$or lower), the C/N ratio, which determines the amount of sucrose treatment, was around 10 regardless of initial ${NH_4}^+$-N content. For the rate of ${NH_4}^+$-N reduction 15~36 hours was required to reduce the initial ${NH_4}^+$-N content to half, and 36~69 hours to lower ${NH_4}^+$-N content to the lowest point (about 10 mg $kg^{-1}$or lower). In addition, sucrose treatment greatly lowered ${NO_3}^-$-N content. In case of C/N ratio above 10, initial ${NO_3}^-$-N content of 348 mg $kg^{-1}$ was reduced to the lowest of 14~21 mg $kg^{-1}$. As for the rate of ${NO_3}^-$-N reduction by sucrose treatment, it took 36~60 hours for ${NO_3}^-$-N content to reach the lowest point for C/N ratio of 10 or higher, and it took 3 weeks, comparably longer time, for C/N ratio of 5. Lowering soil EC from sucrose treatment showed the same trend as ${NO_3}^-$-N content. As an important energy and carbon source for humankind, sugar should not be wasted and must be carefully applied to soil. In principle, the best way of preventing salt accumulation in soil is to optimize the fertilizer input. However, when over-fertilization should be dealt with, the sucrose treatment would be a possible and effective counter-measure to reduce overdosed nitrogen sources in soil.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.2
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• pp.80-85
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• 2003

This study was conducted to find out the effect of a lime stabilized slaughterhouse waste(LSW) on the growth of chinese cabbage and soil pH. Two levels of the lime stabilized slaughterhouse waste treatment, 169 and $338kg\;10a^{-1}$, with N-P-K fertilization were tested, and treatments of N-P-K and N-P-K with slaked lime were included in the experiment as a control. Fresh weight of chinese cabbage at harvest was not significantly different among the treatments. However, in the LSW treatment of $169kg\;10a^{-1}$, fresh weight of chinese cabbage was 5% higher comparing to the N-P-K treatment. Contents of N, P, and K in chinese cabbage were higher in the LSW treatments in comparison to the control treatments. Competitive inhibition of Mg uptake by Ca in the treatments of LSW and lime was apparent. Soil pH was increased by the application of LSW, and the increase in the LSW treatment of $169kg\;10a^{-1}$ was nearly the same as the soil pH increase in the slaked lime treatment. The lime stabilized slaughterhouse waste can be considered as a potential soil amendment for amelioration of soil acidity and supply of organic matter as well.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.397-404
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• 2015

This study was conducted to find out the optimum nitrogen fertilization for production of good quality and high yield zoysiagrass (Zoysia japonica Steud.), the changes in chemical properties of soil in pot and field experiments treated with different levels of nitrogen fertilizer. In pot experiment, the fresh and dry weights of shoots and stolons and the number of shoots increased as nitrogen levels increased, and showed no significant between 24 and $48kg\;N\;10\;a^{-1}$. In field experiment, the shoot length, fresh and dry weights of shoots, roots and stolons, the number of shoots and total stolons length linearly increased as affected by increased nitrogen application, and were not significantly different between 24 and $32kg\;N\;10\;a^{-1}$. In both experiments, pH and exchangeable cations ($Ca^{2+}$ and $Mg^{2+}$) in soil decreased as the rate of nitrogen application increased. As a results, chemical properties of soil were more deteriorated in the plots of higher nitrogen fertilizer rate. Thus, these results demonstrated that the nitrogen fertilizer rate for maximum growth of zoysiagrass was $24kg\;N\;10\;a^{-1}$ in consideration of growth and soil condition.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.101-108
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• 2017

Egg development and early life history of the Korean natural monument fish Hemibarbus mylodon (Pisces: Cyprinidae) were investigated to provide basic data on biological characteristics and ecological recovery. Adult fish were collected from nature and transferred to the laboratory. For the first time, artificial maturation of females and males succeeded after 15 months of indoor culture. Mature eggs and sperm were obtained using Ovaprim injections (0.5 mL/kg) and then the eggs were fertilized using the dry method in the laboratory. The mature eggs were adhesive, turbid, and greyish; they averaged $2.21{\pm}0.06mm$ (n=30) in diameter. The embryos began to hatch about 78 h after fertilization at a water temperature $20{\pm}1^{\circ}C$, and the newly-hatched larvae were $6.6{\pm}0.75mm$ in total length (TL). At 14 days after hatching, the post-larval individuals were $13.5{\pm}0.23mm$ (TL), and their yolk sacs were completely absorbed. Twenty one days after hatching, they entered the juvenile stage and reached $13.5{\pm}0.23mm$ (TL). At 100 days after hatching, their band patterns, external form, and a pair of barbels were similar to those of adults, and they averaged $33.0{\pm}4.25mm$ (TL). The breeding technology and characteristics of early life history obtained in this study will be very helpful for conservation of H. mylodon in nature.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.201-207
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• 2017

To increase the productivity of in vitro development, the antioxidants have been used for culture system of bovine oocytes and embryos. However, comparative studies on these molecules are rare and direct beneficial effects on blastocyst production cannot be discriminated for best results. The study was conducted to determine the influence of N-acetyl-L-cysteine (NAC), N-acetyl-L-cysteine amide (NACA), glutathione (GSH) and cysteamime (CYS) on maturation competence of COCs from GV to MII stage and productivity of blastocyst formation during in vitro fertilization and culture. There was no difference among maturation rates of oocytes to metaphase II with polar body with antioxidants for any of the treatment groups (p>0.05). However, the significant improvement on the rate of blastocysts ($32.3{\pm}5.0%$) was found in 0.1 mM CYS treatment than 0.3 mM NAC, 0.2 mM NACA or 0.5mM GSH (p<0.05). The addition of NAC ($18.8{\pm}3.7%$) or NACA ($21.2{\pm}3.9%$) did not improve development competence to morula and blastocysts than control ($24.4{\pm}4.1%$) and GSH ($26.5{\pm}5.0%$) (p>0.05). Our study showed that medium supplementation with CYS during IVM and IVC improved the rate of bovine embryo development but not with NAC, NACA and GSH addition.

• Korean Journal of Ichthyology
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• v.34 no.2
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• pp.86-95
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• 2022

Egg development and morphological change of larvae and juvenile of the Roughscale sole, Clidoderma asperrimum, were investigated in the present study. Adult fishes were collected on the East Sea, Korea, from 2017 to 2018 and reared in a circular water tank (Ø 6×1 m) at water temperature of 12.8±1.9℃. Fertilized eggs ranged from 1.42 to 1.59 mm (mean 1.51±0.04 mm, n=50) in diameter. The eggs were spherical in shape, transparent, floating and colorless. The egg yolk was separated from the egg membrane 60 mins post-fertilization (PF), and an embryo was formed in 62 hrs PF. More than 50% of the eggs hatched within 144 hrs PF in the range of 10.2~11℃(mean 10.8℃). The size of the newly hatched larvae were 4.22~4.64 mm (mean 4.53±0.16 mm) in total length (TL), their mouth and anus were not open yet. At 10 days after hatching, the preflexion larvae reached 5.88~6.62 mm (mean 6.31±0.33 mm) in TL, and the yolk absorption was completed and the mouth began to open. At 55 days after hatching the larvae reached to flexion larvae stage and they were 10.4~13.3 mm (mean 12.7±1.3 mm) in TL, and the tip of notochord was bent upward. At 120 days after hatching the larvae reached to juvenile stage and they were 35.3~40.5 mm (mean 39.5±2.4 mm) in TL. Their all fins had completed set of the fin-rays (D. 79~94: A. 63~75) and the juveniles adopted a benthic life.

• Korean Journal of Ichthyology
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• v.33 no.4
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• pp.262-272
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• 2021

The egg development and early life history of Tribolodon hakonensis that collected from the Seomjin River were studied. The fertilized eggs of the T. hakonensis were slightly adhesive and separated with a yellow yolk and no oil globule. The size of the eggs was an average of 2.89 mm (2.79~2.96) in diameter. Fifty percents of the embryos were hatched in about 63 hrs after fertilization at water temperature of 20℃. The newly hatched larvae showed average 6.92 mm (6.09~7.60) in total length. At 8 days after hatching, they were 13.75±0.67 mm (n=10) in total length and their yolk sacs were completely absorbed, opening mouth and anus (postflexion larvae stage). At 40 days after hatching, they became juvenile and reached 26.99±1.82 mm (n=10) in total length and all their fin rays were formed. At 137 days after hatching, the young fish were 72.63±10.7 mm (n=10) in total length and their body shape, color and behavior were similar to those of adult fish. The size of eggs and the larva after hatching significantly affected the initial growth among groups of genus Tribolodon, and the hatching time of fertilized eggs and the growth rate of the early life history according to the water temperate were different.

• Development and Reproduction
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• v.12 no.3
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• pp.283-288
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• 2008

The Pseudogobio esocinus were caught at Wyuleo-ri, Gyeombaek-myeon, Boseong-gun, Jeollanamdo from April to May 2003. The fishes were incubated in transparent aquarium located at the laboratory of Chonnam National University, and their embryonic and larval development were observed. The fertilized eggs were spherical, semitransparent, and adhesive, and were $1.98{\pm}0.19mm$ (n=50) in diameter. The embryo, including 31$\sim$32 myotomes, hatched through egg membrane at 164 hrs after fertilization. The newly-hatched larvae were $4.61{\pm}0.83mm$ (n=10) in total length (TL). At that moment, yolk was not absorbed, and mouth and anus were not open. Star and spot shaped melanophores were distributed on the lens, and dorsal, ventral, and caudal parts. At 42 days after hatching, larva was $16.22{\pm}0.65mm$ (n=10) in TL. Melanophores were scaterred at head, back, and side parts. Morphological features of the embryo were transferred to juvenile stage showing similar features with those of the adult fish.