• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.130-135
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• 1997

Tomatoes are flooded differently 0, 5, 10 and 15cm, according to the developing stages such as flowering stage under the condition of greenhouse. Along with this, they are treated according to the time condition such as 6, 12, 24, 48 and 120 hours. The results obtained are summarized as follows. Plant height decreased in the depth of $0{\sim}10cm$ for over 48 hours, in the depth of 15cm for over 24 hours. Number of leaves was the same as in control, and it decreased over. Number of flowers and fruit setting of individuals decreased conspicuously according as the depth and the hours got greater and longer. Adventitious root occurred remarkably in the depth of $0{\sim}10cm$, for over 24 hours and in the depth of 15cm, 12 hours. Epinastic curvature increased greatly as the depth and the hours got greater and longer. Diffusion resistance of stomata cell increased as the depth and the hours got greater and longer. Diseases occurred conspicuously as the hours of flooding got longer rather than as the depth greater. The preventing of diseases caused by insecticide was observed, but it was not greater than in the seedling and transplanting stage. Fertilization was effective in the case of increasing the weight of shoot. Number of fruits per plant did not decrease in the depth of 0cm up to 24 hours, but decreased on the deeper level of flooding and increased as the hours got longer. Moreover with the exception of 120 hours per respective depth of the treatment, average weight of a fruit got greater as the depth and the hours got greater and longer. In the case of epinastic curvature and diffusion resistance, there was negative correlation between all the other investigated characters and positive correlation between weight of a fruits and average weight of a fruit.

• Applied Biological Chemistry
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• v.48 no.1
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• pp.1-15
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• 2005

Pathogens, insects and weeds have significantly reduced agricultural productivity. Thus, to increase the productivity, synthetic agricultural chemicals have been overused. However, these synthetic compounds that are different from natural products cannot be broken down easily in natural systems, causing the destruction of soil quality and agricultural environments and the gradually difficulty in continuous agriculture. Now agriculture is faced with the various problems of minimizing the damage in agricultural environments, securing the safety of human health, while simultaneously increasing agricultural productivity. Meanwhile, plants produce secondary metabolites to protect themselves from external invaders and to secure their region for survival. Plants infected with pathogens produce antibiotics phytoalexin; monocotyledonous plants produce flavonoids and diterpenoids phytoalexins, and dicotylodoneous plant, despite of infected pathogens, produce family-specific phytoalexin such as flavonoids in Leguminosae, indole derivatives in Cruciferae, sesquitepenoids in Solanaceae, coumarins in Umbelliferae, making the plant resistant to specific pathogen. Growth inhibitor or antifeedant substances to insects are terpenoids pyrethrin, azadirachtin, limonin, cedrelanoid, toosendanin and fraxinellone/dictamnine, and terpenoid-alkaloid mixed compounds sesquiterpene pyridine and norditerpenoids, and azepine-, amide-, loline-, stemofoline-, pyrrolizidine-alkaloids and so on. Also plants produces the substances to inhibit other plant growths to secure the regions for plant itself, which is including terpenoids essential oil and sesquiterpene lactone, and additionally, benzoxazinoids, glucosinolate, quassinoid, cyanogenic glycoside, saponin, sorgolennone, juglone and lots of other different of secondary metabolites. Hence, phytoalexin, an antibiotic compound produced by plants infected with pathogens, can be employed for pathogen control. Terpenoids and alkaloids inhibiting insect growth can be utilized for insect control. Allelochemicals, a compound released from a certain plant to hinder the growth of other plants for their survival, can be also used directly as a herbicides for weed control as well. Therefore, the use of the natural secondary metabolites for pest control might be one of the alternatives for environmentally friendly agriculture. However, the natural substances are destroyed easily causing low the pest-control efficacy, and also there is the limitation to producing the substances using plant cell. In the future, effects should be made to try to find the secondary metabolites with good pest-control effect and no harmful to human health. Also the biosynthetic pathways of secondary metabolites have to be elucidated continuously, and the metabolic engineering should be applied to improve transgenics having the resistance to specific pest.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.543-553
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• 2023

The current status of domestic a agalmatolite mines in South Korea was investigated with a view to establishing a stable supply of agalmatolite and managing its demand. Most mined agalmatolite deposits were formed through hydrothermal alteration of Mesozoic volcanic rocks. The physical characteristics of pyrophyllite, the main constituent mineral of agalmatolite, are as follows: specific gravity 2.65~2.90, hardness 1~2, density 1.60~1.80 g/cm³, refractoriness ≥29, and color white, gray, grayish white, grayish green, yellow, or yellowish green. Among the chemical components of domestic agalmatolite, SiO₂ and Al₂O₃ contents are respectively 58.2~67.2 and 23.1~28.8 wt.% for pyrophyllite, 49.2~72.6 and 16.5~31.0 wt.% for pyrophyllite + dickite, 45.1 and 23.3 wt.% for pyrophyllite + illite, 43.1~82.3 and 11.4~35.8 wt.% for illite, and 37.6~69.0 and 19.6~35.3 wt.% for dickite. Domestic agalmatolite mines are concentrated mainly in the southwest and southeast of the Korean Peninsula, with some occurring in the northeast. Twenty-one mines currently produce agalmatolite in South Korea, with reserves in the order of Jeonnam (45.6%) > Chungbuk (30.8%) > Gyeongnam (13.0%) > Gangwon (4.8%), and Gyeongbuk (4.8%). The top 10 agalmatolite-producing mines are in the order of the Central Resources Mine (37.9%) > Wando Mine (25.6%) > Naju Ceramic Mine (13.4%) > Cheongseok-Sajiwon Mine (5.4%) > Gyeongju Mine (5.0%) > Baekam Mine (5.0%) > Minkyung-Nohwado Mine (3.3%) > Bugok Mine (2.3%) > Jinhae Pylphin Mine (2.2%) > Bohae Mine. Agalmatolite has low thermal conductivity, thermal expansion, thermal deformation, and expansion coefficients, low bulk density, high heat and corrosion resistance, and high sterilization and insecticidal efficiency. Accordingly, it is used in fields such as refractory, ceramic, cement additive, sterilization, and insecticide manufacturing and in filling materials. Its scope of use is expanding to high-tech industries, such as water treatment ceramic membranes, diesel exhaust gas-reduction ceramic filters, glass fibers, and LCD panels.