• Korean Journal of Weed Science
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• v.31 no.4
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• pp.401-404
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• 2011

Bromobutide, a paddy field herbicide, can effectively control annual and perennial weeds. It has an excellent weeding effect especially against Monochoria vaginalis and Scirpus juncoides etc. When it is mixed with other herbicides controlling weed spectrum and application timing can be broaden. Bromobutide has stable weeding effects regardless of field and weather conditions, and there is almost no phyototoxic effects to rice.

• Development and Reproduction
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• v.6 no.2
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• pp.77-82
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• 2002

In ascidians, a primitive chordate, maternal cytoplasmic factors and inductive interactions are involved in the specification of cell fates in early embryos. The larval structure of ascidians is relatively simple, and the major mesodermal tissues of the tadpole larva are notochord, muscle, and mesenchyme. Formation of muscle cells is a cell-autonomous process, and localized maternal macho-l mRNA specify muscle fate in the posterior marginal zone of the early embryo. In contrast, inductive influence from endoderm precursors plays important roles in the specification of notochord and mesenchyme fates. FGF-Ras-MAPK signaling is involved In the induction of both tissues. The difference in responsiveness of the posterior mesenchyme and anterior notochord precursors to FGF signaling is caused by the presence or absence of intrinsic factors that inherited from the posterior-vegetal egg cytoplasm, respectively. In these inductions, directed signal polarizes the induced cells and promotes asymmetric cell divisions to produce two daughter cells with distinct fates.

• Korean Journal of Ecology and Environment
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• v.51 no.2
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• pp.174-183
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• 2018

In the Sumeunmulbaengdui Wetland Protected Area of Jeju Island, there exists a unique pond, a so-called 'Ohmi', which is likely to be an oasis supporting the wildlife and escaped-livestock. We exquisitely described the diversity and distribution of plant community of the Ohmi. Despite its small area, six syntaxa were identified: Sphagnum community of peat bog type, Nymphoides coreana community of the floating-leaf limnetic vegetation, Scirpus triangulatus community and Schoenoplectus hotarui community of the littoral zone vegetation, and Deinostema violacea-Eleocharis congesta community and Eriocaulon atrum-miquelianum community of the ephemeral vegetation. A zonal distribution of plant communities along the water depth was recognized. The Sphagnum islets regarded as a typical component of peat bog, in Korea were first described at the center of the Ohmi. We conclude that the Ohmi is a primeval keystone habitat of the Sumeunmulbaengdui intermediate moor with a less oligotrophic ombrotrophic environment.

• Journal of Wetlands Research
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• v.10 no.2
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• pp.15-22
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• 2008

The role and distribution of fresh water algae was surveyed at Wangdeungjae Wetland of Mt. Jiri, a high mountain swampy land. Mean environmental factors were as follows; temperature was $17.6^{\circ}C$, pH was 6.3, conductivity was $24.6{\mu}S/cm$, TN was 0.6 mg/L, TP was 0.09 mg/L, and Chl-a was $11.9{\mu}g/L$, respectively. Algae were appeared 159 species(Chlorophyta 87, Bacillariophyta 56, Euglenophyta 11, and Cyanophyta 5). Desmid of Chlorophyta was 56 species, and dominant species was Aulacoseira distans of Bacillariophyta. To analyze food chain of the water ecosystem, we performed analysis of tadpole's stomach captured in the wetland. Tadpoles ingested mainly algae, and Aulacoseira distans was found in most quantity. Based on this study, algae take role of the primary producer as well as the prey of higher level predators(e.g. tadpoles) in the water ecosystem of Wangdeungjae Wetland.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.157-162
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• 1997

This study was conducted to investigate the change of weed community on paddy-upland rotation in 1996. In paddy-upland rotation, dominant weed species in paddy condition were Cyperous amuricus, Echinochloa crus-galli, Rotara indica and Lindernia procumbens. They were E. crusgalli, Digitaria sanguinalis and C. amuricus in upland condition. The number of weed occurrence on paddy and upland rotation reduced about 74-78% as compared with continuous paddy and upland condition. Similarity coefficient and Simpson index on paddy and upland rotation was 8-64, 0.34-0.35, respectively.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.72-78
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• 1985

A total of 220 tadpoles was captured in 6 areas and total 117 frogs, Rana nigromacuzata, were collected in 11 areas in Korea. They were examined for their infection status by the metacercariae of Fibricola seoulensis by peptic digestion technique and by histological observation with hematoBylineosin staining. This study was carried out from August, 1983 to September, 1984. Followings are the results. 1. The tadpoles of R. nigromaculata were positive for the metacercariae from 3.3% to 100% by area. The number of metacercariae per infected tadpole ranged from 1 to 584, and the mean number Per tadpole ranged from 7.6 to 221 by area. 2. The metacercariae from 16 tadpoles were counted by the body portion. A great majority of the metacercariae was collected from abdominal cavity, 98.3% of 484 counted larvae. And 6(1.2%) larvae were from proximal tail and 2(0.4%) from trunk. 3. Histological sections of tadpoles showed many metacercariae in abdominal cavity but none in other parts. The larvae were free in the spaces among intestinal loops or around primitive liver. A few larvae were in duct-like tissues near trunk wall. There was little infiltration of inaammatory cells. 4. The metacercarial infection rates of frogs ranged from 0% to 100% by area. The larval burden was 1 to 470 by infected frogs, and mean number ranged from 1 to 175.6 by area. By above results, it is suggested that the cercariae of F. seoulensis may infect R. nigromaculata already in the stage of tadpole. Almost all of the metacercariae were concentrated in abdominal cavity of tadpoles. According to the infection status of frogs, this nuke is prevalent almost nationwidely in rice paddies in Korea.

• The Korean Journal of Pesticide Science
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• v.7 no.4
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• pp.310-313
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• 2003

New series of 9-(5-Isoxazolemethoxyphenyl)imino-8-thia-l,6-diazabicyclo[4.3.0]nonan-7-one which are the cyclic imide type compounds were designed and synthesized. The herbicidal activities of main dominant weeds to these compounds were evaluated under rice field condition. There is the possibility for a new herbicide since the most of compounds were excellent to main dominant weeds occurring in rice field without the serious rice injury.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.378-384
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• 2007

Some of ecological factors and the early life history of endangered freshwater fish, Pseusobagrus brevicorpus, were investigated to proliferate artificially and to restore the population by release seedlings. The density of population in restricted area by small scale dam was 1.25 ind. $m^{-2}$, and the low capacity for reproduction having 200$\sim$250 eggs ind$^{-1}$. were thought to be a reason of this endangered situation. From the result of induction of natural spawning in aquarium after hormone injection it was considered that the spawning substrate would be aquatic plants with slender branches. The hatching was observed after 50 hrs after fertilization and the larvae showed aggressive behavior. Yolk was almost absorbed 3 days after hatching, and the larvae shaped tad-pole grew up to fry after 30 days. We discussed on the strategies for conservation of this species according to those results from investigation on ecology and early life history.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.308-312
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• 2011

A new paddy field herbicide, metazosulfuron granule is an herbicide for controlling annual and perennial weeds occurring in machinery transplanting paddy field. It is recommended to apply $30kg\;ha^{-1}$ 15 days after transplanting. As a result of preliminary tests, it could control seven annual species such as Echinochloa crus-galli, Bidens tripartita, Ludwigia prostrata, Monochoria vaginalis var. plantaginea, etc. and four perennial species including Cyperus serotinus, Sagittaria trifolia, Eleocharis kuroguwai, and Scirpus juncoides. Monochoria vaginalis var. plantaginea, S. trifolia and S. juncoides resistant to sulfonylurea- herbicides were also controlled. Because application timing of the herbicide is wide, it is very efficient to control the spraying timing by users. Phytotoxicity of rice cultivars was not observed, and the impact on the environment is very limited.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.305-312
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• 1995

Weed communities in the dry-direct seeded rice(Oryza sativa L.), soybean(Glycine max(L.) Merr.), and dry-direct seeded rice-soybean rotation system from the transplanted rice field were investigated in order to identify a change in weed species by paddy-upland rotation. Echinochloa species was the most dominant species in the dry-direct seeded rice and their great increase was observed in the continued practices of dry-direct seeded rice. Echinochloa spp., Chenopodium ficifolium, and Digitaria spp. were identified as the major weeds in soybean cultivation in paddy field. Practice of soybean rotation in the dry-seeded rice reduced weed occurrence, particularly at the soybean after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr soybean compared to the continued cultures of rice or soybean. In addition, cultivation of dry-direct seeded rice or soybean culture in the paddy rice field seemed to be helpful for suppression of perennial weeds(Eleocharis kuroguwai, Cyperus serotinus, Scirpus juncoides) and aquatic weeds(Monochoria vaginalis, Sagittaria spp. Potamogeton distinctus).