• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.1
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• pp.7-12
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• 2009

Mungbean should be harvested several times according to its physiological characteristics and weather conditions of cultivation region. In Korea, mungbean is usually sown in June and harvested three or four times, and the cultivated area is being rapidly reduced. Therefore, the author developed cultivation techniques of mechanical harvesting suitable for the weather conditions of the southern part of the Korean peninsula. The optimum sowing time of mungbean for mechanical harvesting in southern part of Korea is around July 20. When sown around July 15, mungbean should be harvested twice and then the mechanical harvesting of mungbean was not possible. Meanwhile, when sown after July 25, the mechanical harvesting was possible but the maturing period was longer and the seed yield was decreased. Therefore, it is safe to say that in Korea the mechanical harvesting of mungbean is possible for the middle part of Korea when the plant is sown before July 20 and for the southern coastal region of Korea when sown after July 20 (if July 20 is set up as the baseline for the southern part of Korea). Out of Keumseong and Owool, which are popularized cultivars in Korea most, Owool is determined to be most appropriate for mechanical harvesting. Owool is favorable for mechanical harvesting because, when compared to Keumseong, it is higher both in plant height and in pod height, and also the seed yield is better.

• Korean Journal of Plant Taxonomy
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• v.45 no.4
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• pp.353-361
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• 2015

Spatio-temporal variation in fruit set in orchids would affect long-term population viability and will influence genetic diversity over many generations. The aim of this study was to examine the breeding system of the nectariferous terrestrial orchid Epipactis thunbergii, to specifically determine levels of fruit set in terms of time and space under natural conditions. We examined pollination under natural conditions and conducted hand pollination experiments during a 2-year survey in four populations located along 1.5 km of coastal line in Jinguiri (rual village) [Jeollanam-do (province), southern Korea]. We found that, over a 2-year period, levels of percentage of fruit set were similar within patches of the four populations. By contrast, we detected significant differences in the percentage of fruit set among patches. We also found that plants with larger inflorescence size produced significantly more fruits than plants with fewer flowers. Over a 2-year period, the percentage of fruit set for E. thunbergii was similar but low (14.1%) compared to that averaged for eighty-four rewarding species (37.1%). However, an increase in fruit set was achieved by hand-pollinations: artificial self-pollination (90.5-95.2%), artificial geitonogamy (94.7-95.0%), and cross-pollination (artificial xenogamy, 91.3-91.4%). No emasculated flowers produced fruits and no automatic pollination was found in E. thunbergii. Our findings suggest that E. thunbergii is a self-compatible terrestrial orchid that depends on pollinators (insects) to achieve fruit set in natural habitats, and that local environmental conditions were similar over a period of 2 years in the study area. Our results also highlight the cryptic variation of fruit production in time, but more pronounced variability in space.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.490-494
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• 2011

Rice stripe virus (RSV) has been the main viral disease of rice plant in western coastal region of Korea since 2000. The control of the vector insect, small brown planthopper (Laodelphax striatellus), is the most effective management method of the persistently-transmitted viral disease. Thus, ecological study between RSV and the vector insect was needed and investigated in order to make effective control plan, especially about study on the feeding and transmission of the virus by the vector insect. Each larval stage of vector insect differed in vector competence; larvae over 4th stage were shown as higher transmission after feeding on RSV-infected rice plant. These 4th and 5th larvae had higher transmission rates, 69.2% and 67.9% respectively, than 44.8% of the adult stage. The vector competence, however, was changed according to temperature; the highest transmission rate was 93.3% on $30^{\circ}C$ in comparison to 70.6% on $25^{\circ}C$ and 43.8% on $20^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.522-527
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• 1997

To find out the optimum seeding rate in corrugated water seeded rice, field experiment was carried out at Yeongdeog Substation of the National Yeongnam Agricultural Experiment Station for two years, 1994 and 1995. A rice cultivar Donghaebyeo, was seeded on May 15 with five seeding rate from 3kg /10a to 7kg /10a. The number of seedling stand per unit area was curvilinearly increased with seeding rate. In characteristics of rice plant associated with lodging, the plant height, fresh weight per tiller, Culm wall thickness and ratio of gravity center were not significantly different among seeding rates, but the breaking strength of 4th internode was slightly decreased with increasing seeding rate and thus, lodging index was generally greater at higher seeding rate than lower seeding rate. Field lodging was observed at 1~3 degree in seeding rate of 5~7kg /10a. Panicle number per unit area was generally increase with increase of seeding rate, while ratio of ripened grain was decreased with increase of spikelet number. Milled rice yield was curvilinearly increased with seeding rate. The optimum seeding rate in the highest rice yield was 4.8kg /10a in 1994, and 4.3kg /a in 1995, respectively.

• 한국지구물리탐사학회:학술대회논문집
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• 2000.09a
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• pp.54-69
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• 2000

There are groundwater trouble by high-salinity yield inducing sea-water intrusion in Cheju Island. It is used groundwater-GIS(Well-lnfo) in the maintenance and management of groundwater in Cheju Island to grasp groundwater trouble area and cause of high-salinity yield. For 16 wells certain to yield high-salinity, we logged specific electrical conductivity(EC) and tried to get hold of freshwater and saltwater relationship. As result of distribution of $Cl^-$ by depth, it is showed up groundwater trouble by high-salinity yield in the east coastal area and the partly north coastal area. The reason of high-salinity groundwater yield are low-groundwater level by the structure of geology and low-hydraulic gradient etc. There is necessity for management to development and use of groundwater in the high-salinity area, special management area.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.1
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• pp.55-66
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• 2018

The cactus habitat in Jeju Island has a phytogeographically specific distribution in the East Asian region, and forms a unique landscape as the only native cactus (Opuntia ficus-indica (L.) Mill.) habitat in Korea. However, there has been no detailed investigation on the distribution of cacti in the habitat and no investigation on the diversity of the mixed composition of plants in the habitats and their correlation with the distribution of cactus populations. This study attempted to investigate the diversity of vascular plants in the Wollyeong-ri cactus habitat and record the actual distribution and trends of cactus distribution. In addition to the distribution characteristics of cacti, we also discuss the characteristics of species reflecting the characteristics of the habitat among the mixed population of plant species, as well as the biological and environmental factors that threaten the maintenance of cactus populations or require management for preservation of cacti. Considering the phenological character, we conducted the field surveys for flora identification six times between June 2015 and September 2017. The Engler classification system was used for the arrangement sequence and names of plants, and the Korean Plant Names Index was adopted for the Korean name of the species. The study results showed that the Wolryung-ri cactus habitat in Jeju Island has the characteristic physiognomy of an area dominated by cactus. For the vascular plants, a total of 125 taxa were identified, including 53 families, 104 genera, 109 species, 15 varieties and 1 forma. Endangered plants specified by the Ministry of Environment were not found. Two species, Cyrtomium falcatum and Asplenium incisum, were identified as the ferns, and no gymnosperms were found. In addition, 123 taxa of angiosperms, 91 taxa of dicotyledones and 32 taxa of monocotyledons were identified. The distributions of cacti were confirmed in 289 meshes corresponding to 59.3% of the total 487 meshes in the cactus protected area, which showed various coverage distributions ranging from 5% to 95%. Most of the meshes where no cacti were found are coastal areas with exposed basalt rocks where the soil depth has not developed or extremely restricted due to repeated waves, or areas where artificial facilities, grasslands, and observation paths have been constructed. On the other hand, there were 71 lattice points in 14.5% of the total area where the cactus showed 70% or higher dominance. Cacti are randomly distributed in these areas. They have adapted to the microhabitat environment and are found to be opportunistically distributed along the growable locations. Considering that the reproduction of cacti in the habitat is mostly dependent on parthenogenesis, the present distribution seems to reflect the potentially distributable regions of cacti in the habitat. Based on the results of field surveys, a management plan for conservation and protection of the protected areas has been proposed.

• Korean Journal of Plant Resources
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• v.30 no.4
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• pp.364-371
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• 2017

Limonium tetragonum is a halophyte grown naturally in the coastal region in South Korea. This study was conducted to investigate the effects of salt concentrations on seed germination, seedling growth, and antioxidant capacity of L. tetragonum. Seeds were collected from naturally grown plants of L. tetragonum and those at full maturity were used in this experiment. All experiments were performed at 0%, 0.5%, 1.0%, or 2.0% of salt concentrations. Seed germination rate was highest as 86% at $20^{\circ}C$ and followed as higher in order of $25^{\circ}C$, $30^{\circ}C$ and $15^{\circ}C$. The germination rate was about 80% at 0% or 0.5% of salt concentration, but it was very low at the salt concentrations higher than 1%. Growth of L. tetragonum seedlings showed no difference in Hoagland solution containing NaCl in the range of 0% to 1.0% and seedlings survived at 2.0% of NaCl concentration. As the salt concentration increased, the content of $Na^+$ in the shoot increased, but that of $K^+$, $Ca^{{+}{+}}$, or $Mg^{{+}{+}}$ decreased. The antioxidant activity and the content of total polyphenol and total flavonoid in the shoot were similar at 0% and 0.5% of NaCl and were highest at 2.0% of NaCl concentration. In conclusion, performance of seed germination and plant growth of L. tetragonum was highest at 0% and 0.5% of NaCl concentration, and showed no difference in antioxidant activity, total polyphenol contents, and total flavonoid contents at the same salt concentrations.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.426-436
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• 2012

This study was carried out to investigate actual vegetation, the structure of plant community, and ecological succession sere of coastal forest ecosystem in warm temperate climate zone, Taejongdae, Busan City, Korea to provide the basic data for planning of the forest management. As a result of analysis of actual vegetation, vegetation types divided into 35 types, and the area of survey site was $1,750,461m^2$. The ratio of vegetation type dominated by Pinus thunbergii was 80.7%, dominated by Quercus spp. was just 5.0%, and dominated by Carpinus tschonoskii was just 0.4%. Eighteen plots(size is $20m{\times}20m$) were set up and the results analyzed by DCA which is one of the ordination technique showed that the plant communities were divided into four groups which are community I(P. thunbergii community), community II(P. thunbergii-Quercus serrata community), community III(Q. serrata-P. thunbergii community), and community IV(Carpinus tschonoskii-P. thunbergii community). The age of community I was from 38 to 59 years old, that of community II was from 35 to 71 years old, that of community III was from 37 to 53 years old, that of community IV was from 50 to 72 years old, thus we supposed that the age of the study site is about from 38 to 72 years old. We supposed that the successional sere of the study site is in the early stage of ecological succession in the warm temperate climate zone. The dominant species will be changed from P. thunbergii to Q. serrata or Carpinus tschonoskii in the canopy layer, on the other hand, Eurya japonica will be dominant species in the understory layer, and E. japonica and Trachelospermum asiaticum var. intermediumwill be dominant species in the shrub layer for a while. According to the index of Shnnon's diversity(unit: $400m^2$), community I ranged from 0.8640 to 1.3986, community II was from 0.1731 to 1.1885, community III was from 0.8250 to 1.0042, and community IV was from 0.3436 to 0.6986.

• Korean Journal of Organic Agriculture
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• v.24 no.3
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• pp.465-484
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• 2016

This study evaluated the antifungal activity of varying concentrations of water-soluble extracts from native plants (Vitex rotundifolia, Tetragonia tetragonoides, Artemisia capillaris, Hibiscus hamabo and Ficus carica) against Stemphylium vesicarium, Penicillium italicum, Sclerotinia sclerotiorum, Pythium ultimum, Botrytis cinerea, Rhizoctonia solani and Colletotrichum gloeosporioides. Mycelium growth of pathogenic bacteria generally decreased in a concentration-dependent manner following treatment with the water extracts from donor plants. Closer analyses indicate varying inhibitory capacities depending on the type of donor plant and pathogenic bacteria. Specifically, mycelium growth of S. vesicarium varied depending on the concentration of the water extracts from T. tetragonoides (r = -0.857, p<0.01) and A. capillarys (r = -0.868, p<0.01). Also, P. italicum and V. rotundifolia (r = -0.833, p<0.01), S. sclerotiorum and V. rotundifolia (r = -0.862, p<0.01), A. capillaris (r = -0.902, p<0.01), B. cinerea and T. tetragonoides (r = -0.896, p<0.01) showed an inverse relationship. The rate of mycelial growth inhibition of pathogenic bacteria analysed are as follows: P. ultimum 94%, B. cinerea 50%, C. gloeosporioides 80% in 100% treatment of T. teragonoides. A. capillaris inhibited S. vesicarium by 43%, P. ultimum by 90%; H. hamabo inhibited P. italicum by 50%, S. sclerotiorum by 26%, and F. carica inhibited R. solani by 74%. Total phenol content with antifungal activities are as follows: A. capillaris 16.15 mg/g, F. carica 7.81 mg/g, V. rotundifolia 6.18 mg/g, H. hamabo 5.25 mg/g, T. tetragonoides 4.41 mg/g, and total flavonoid content is as follows: A. capillaris 27.57 mg/g, V. rotundifolia 12.49 mg/g, F. carica 11.45 mg/g, H. hamabo 5.77 mg/g, T. tetragonoides 5.08 mg/g.

• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.206-216
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• 2018

We analyzed the effects of spatio-temporal variation in the leaf production of oaks on the density and species richness of herbivores, as well as the consumption by herbivores in the east coastal region of Korea, which is an area that has been damaged by forest fires. The main herbivore that feeds on oak leaves was moth larvae. In mid-August the insect larvae showed the highest density and species richness. Approximately 60.5% of total plant-eating insect larvae were present from August to September 2011. Oak leaf production was at its peak from July to August, and the peak damage caused by herbivores was from August to September. Depending on the investigation timing and site of the survey, oak leaf production, larval densities, and species richness showed large variations. The average production of oak leaves between July and August was estimated to be $0.96ton\;ha^{-1}$. The production of oak leaves during this period also showed spatial variations ranging from 0.34 to $1.89ton\;ha^{-1}$. In August, the consumption of oak leaves by the herbivores showed spatial variations ranging from 0.15 to $1.51ton\;ha^{-1}$. Where oak leaves had a higher yield, they tended to increase in density and species richness of the herbivores. As the production of oak leaves increased, so did the overall consumption and consumption rate by the herbivores. This means that the production of oak leaves is highly related to time and space, and there is a concentration response in which the new individuals gather. Research into the spatio-temporal heterogeneity of the food sources and their effects on the higher levels of the food web can help us quantitatively understand and evaluate the structure and functions of the burnt ecosystem that is caused by forest fires.