• Journal of Korean Society of Forest Science
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• v.17 no.1
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• pp.1-15
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• 1973

In an effort to improve the major tree species in Korea, the seed of Robinia pseudoacacia, Pinus rigida, Pinus densiflora, Pinus thunbergii and Larix leptolepis were treated with X-ray and thermal neutron at the Brookhaven National Laboratory, and germination rate of the seed and some characteristics of the seedlings from irradiated seed were investigated and the results were summarized as follows. 1. The germination rate of the irradiated seed of Robinia pseudoacacia, Pinus densiflora, Pinus thunbergii and Pinus rigida was decreased, when the irradiation time of thermal neutron increased from 3 hours to 9 hours. The seed of Larix leptolepis was completely died out in all range of irradiation time. 2. The seed of Pinus densiflora, Robinia pseudoacacia and Pinus rigida showed low germination rate, when the dosage of radiation increased in the range of 10,000r-30,000r X-ray. This dosage of radiation was almost lethal to the seed of Pinus thunbergii and Larix leptolepis. 3. The growth rate of radiated Robinia pseudoacacia has been decreased when the dosage of X-ray and thermal neutron increased. However, the trees treated with thermal neutron for 3 hours showed 14.9 percent-increase in seedling height and some thornless individuals appeared in this treatment. 4. Individuals with variegated leaf, rugose leaf and albino were appeared in X-ray and thermal neutron treatment. 5. Abnormal mitosis of somatic cell, cell with two nucleoli, cell with two nuclei and chromosome clump in mitosis of somatic cell were observed in Robinia pseudoacacia irradiated with thermal neutron. 6. Resistanty against pawdery mildew was decreased in Robinia pseudoacacia radiated with X-ray and thermal neutron. 7. Length of stomata did not show any difference however number of stomata per unit area decreased in Robinia pseudoacacia radiated with thermal neutron. The leaves of Robinia pseudoacacia radiated with thermal neutron were thicker than those of non-treated one, but width of palisade tissue was decreased. The most sensitive one among those species to the thermal neutron treatment was Larix leptolepis, followed by Pinus densiflora, Robinia pseudoacacia, Pinus thunbergii and Pinus rigida in the order. In X-ray treatment, the most sensitive one was Larix leptolepis, followed by Pinus densiflora, Pinus thunbergii, Pinus rigida and Robinia pseudoacacia in the order. Morphological, cytological variation of the radiated Robinia pseudoacacia seemed to indicate some possibility to be used for tree improvement.

• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.230-238
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• 1998

This study was conducted to compare the regeneration of the seedlings under different vegetation types and to identify the presence of allelopathy in Abies koreana(Ak) natural forest in Banyabong Peak(elevation, 1715m), of Mt. Chiri. Twenty quadrats($10m{\times}10m$) were placed in May, 1996 to classify vegetation structure using TWINSPAN. Water-soluble extracts from leaves and soil humus of different vegetation types were collected to test their effects on both seed germination of Ak and mycelial growth of ectomycorrhizal fungi. Phenolic compounds from soil humus were quantified using HPLC. Among the four vegetation types, Sasa borealis(Sb) was found in both Ak-Quercus mongolica(Qm) and Ak-Rhododendron schlippenbachii(Rs) communities. Natural seeding of Ak was $230,000{\pm}90,000seeds/ha$ in 1995 and their germination rate was 25% in an ideal laboratory condition. Density of Ak seedlings less than 5cm in height was 52,000/ha in 1996, while that of seedlings taller than 5cm in height was only 4,000/ha. In the case of Ak-Qm community, density of Ak seedlings with Sb understory was only 7% of the density of seedlings with Rs understary, suggesting the inhibitory effect of Sb. The germination rate of Ak seeds was significantly reduced by leaf extracts of Sb, and Rhododendron mucronulatum var. ciliatum(Rm) and Ak. Soil humus extract of Ak-Qm-Sb subcommunity reduced germination of Ak seeds by 81% and also reduced by 19% the respiration of mycelia of ectomycorrhizal fumgus, Lactarius sp. Among the seven phenolic compounds identified from the soil humus, extract, Ak-Qm-Sb subcommunity contained significantly high content of p-hydroxybenzoic acid, vanillic acid, and syringic acid. Particularly, p-hydroxybenzoic acid was present at 4.2ppm in the Sb roots and at 16.5ppm in the Sb humus, suggesting that it could be the primary allelopathic compound in Abies koreana forests with Sasa borealis understory.

• Journal of Korean Society of Forest Science
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• v.82 no.4
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• pp.366-380
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• 1993

Quercus acutissima ectomycorrhizae were classified as apical type, linear type, clavate type, diffuse type, pyramidal type, coralloid type, and nodular type. The surface texture of the fungal mantle at the initial stage of mycorrhizal formation was velvety. The surface texture of Pisolithus tinctorius(Pt) mycorrhizae at 30 September was well-developed felty mantle, Yellowish white. Except Pt all mycorrhizae formed by ectomycorrhizal fungi used to experiment were white with felty mantle. Mycorrhizae at the initial stage of mycorrhizae formation were creamy or creamy brown and swelled with thin mantle. Transverse and longitudinal sections showed radially-elongated cortical cell layers and epidermal cell with Hartig net. The transversal wideth of radially-elongated cortical and epidermal cells in the mycorrhizae with thick mantle on 30 September did not different with the mycorrhizae with thin mantle on the initial stage. Pt #250 formed coralloid mycorrizae but Pt KJ-1 did not although they are same species. On the mean length of linear type ectomycorrhizae of Pt KJ-1(2.21mm) was 1.5 times longer than that of Pt #250(1.32mm). The total dry weight of seedlings inoculated with Pt KJ-1, Pt #250, Lycoperdon pedicellatum, Scleroderma verrucosum were significantly heavier than those of suillus granulatus, Laccaria laccata.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.1
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• pp.9-16
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• 2016

To investigate the effect of soluble silicate zeolite dressing of the rice against bakanae disease, field trial in reclaimed land and in vitro were carried out. The coated rice seeds (SCS) which were dressed with the mixture of 25% silicic acids (binder), and the zeolite (coating powder). In wet direct seeding, uniform scattering of rice seeds on the soil surface and the better seedling establishment were shown in SCS treatment plots. The incidence of bakanae disease began from the mid tillering stage toward the heading stage. Around heading stage, the ratio of infected tillers reached its highest point by 9.9% in non-SCS treatment plots. While, in SCS treatment plots, the ratio of infected tillers was no more than 0.01%. The vitality of the pathogenic fungi of bakanae disease in the SCS and non-SCS samples were assessed. Samples were incubated for one week keeping proper humidity at $30^{\circ}C$ after inoculated with panicles of infected rice plants from experimental field plots. In non-SCS treatment, pinkish colonies were formed on the grain surface of panicle of infected plants, and mycelium, macro-conidia and micro-conidia were developed actively inside part of infected grain inoculated. While in SCS treatment, micro-conidia and mycelium were not survived and the growth of macro-conidia, mycelia were greatly inhibited and withered. Based on the results, it is concluded that the environmental friendly control of bakanae disease by use of SCS is possible and soluble silicate can be applied as agents for replacement of seed disinfection.

• Journal of fish pathology
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• v.18 no.1
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• pp.19-28
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• 2005

Scuticociliatosis has badly settled one of most damaging diseases during the seedling production process of olive flounder. Paralichthys olivaceus in Korea. We isolated a new type of Scuticociliate from flounder. The parasite metamorphoses to ciliate and cyst phases with each other by environmental changes and survive for a relatively long span. The ciliate was measured average 41.8 ${\mu}m$ in length and 21.0 ${\mu}m$ in width, and cyst was 17.0 ${\mu}m$ and 13.5 ${\mu}m$, respectively. Nutritional condition was determined as a major parameter of metamorphosing between ciliate and cyst stages. The ciliate transforms to a cyst stage because of food shortage, and the cyst returns to a ciliate stage with a favorite environmental condition and shows active growth and reproduction. The ciliate multiplied at the maximal density of $2.9 {\times} 10^5 {m\ell}^{-1}$cells in vitro cultivation at $15 ^{\circ}C$temperature using MS BHI medium and bacterial food sources. The ciliate could be proliferated at a 2.5 to $30 ^ \circ}C$ temperature range, pH 6 to 9, and 1 to 55 ppt salinity. Particularly, it survived over one week at $0 ^{\circ}C$temperature showing a high resistance against unfavorable environmental conditions. And the cyst survived for 320 days in the condition of $5 ^{\circ}C$with no feeding, but its survival period was markedly shortened in higher temperature conditions. The chemotherapeutants (formalin and hydrogen peroxide) were clarified as effective chemicals against the ciliate during in vitro trials, but the effect of therapeutants differed in proportion, depending upon the density and the bathing time of chemical compounds.

• Horticultural Science & Technology
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• v.30 no.4
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• pp.426-431
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• 2012

This study was conducted to establish an efficient screening method for resistant tomato to Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL). The resistance degrees of the six commercial cultivars of tomato to the pathogen were evaluated by dipping roots of the seedlings in spore suspension of five FOL isolates. On the basis of the results, two cultivars (Dotaerangmaster, resistant cultivar to FOL race 1; Supersunload, resistant cultivar to FOL race 2) and two isolates (KACC40043, FOL race 2; TF104, FOL race 3) were selected for system establishment. The disease development of the FOL isolates on the cultivars according to several conditions including root wounding, incubation temperature, inoculum concentration and dipping period of roots in spore suspension was investigated. The resistance of each cultivar to the disease was a race-specific response and hardly affected by the tested conditions except for incubation temperature of $20^{\circ}C$. The optimum temperature for disease development caused by FOL was 25 to $30^{\circ}C$. On the basis of the results, we suggest that an efficient screening method for resistant tomato cultivars to Fusarium wilt is to dip the non-cut roots of tomato seedlings at two-leaf stage in spore suspension of $1{\times}10^7\;conidia{\cdot}mL^{-1}$ for 0.5 hours and transplant the seedling to plastic pot with horticulture nursery media, and then to cultivate the plants in a growth room at $25^{\circ}C$ for 3 weeks with 12 hours light a day.

• Horticultural Science & Technology
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• v.28 no.5
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• pp.871-876
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• 2010

Seven native and four introduced herbs namely $Thymus$ $quinquecostatus$, $Chrysanthemum$ $zawadskii$ var. $latilobum$, $Rosmarinus$ $officinalis$, etc. were selected for analysis of the DPPH radical scavenging and anti-microbial activity of their extracts. These perennial herbs are classified as $Labiatae$ and $Compositae$ except for $Saururus$ $chinensis$ and can be propagated through seedling and cuttage. These edible herbs are used as medicinal as well as ornamental plants. Their extract has electron donating ability which ranges from 69.7 to 78.7% for native herbs and 67.4 to 75.4% for introduced herbs. Native herbs have higher (3.54%) average DPPH radical scavenging than introduced herbs. In native herbs, maximum DPPH radical scavenging activity was observed in $Agastache$ $rugosa$ (78.7%) followed by $Saururus$ $chinensis$ while $Chamaemelum$ $nobile$ showed highest activity among the introduced herbs. Many herbs viz. $Saururus$ $chinensis$, $Chrysanthemum$ $zawadskii$ var. $latilobum$ and $Solidago$ $virga-aurea$ var. $gigantean$ showed excellent anti-microbial activity against gram positive $Enterococcus$ $faecalis$, maximum (80.0%) by $Saururus$ $chinensis$. Other herbs viz. $Solidago$ $virga-aurea$ var. $gigantea$, $Chrysanthemum$ $zawadskii$ var. $latilobum$, $Salvia$Salvia $plebeia$, $Chrysanthemum$ $indicum$, $Rosmarinus$ $officinalis$, $Chamaemelum$ $nobile$ and $Lavandula$ $stoechas$ showed anti-microbial activity against gram negative $Citrobacter$ $freundii$. Especially, the inhibition of colony growth of $Citrobacter$ $freundii$ was highest in the extract of $Chrysanthemum$ $zawadskii$ var. $latilobum$, and $Chamaemelum$ $nobile$.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.2
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• pp.127-134
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• 1999

This study was performed to obtain the basic data to present rational silvicultural tending plan. It makes these widely distributed pine-oak mixed stand and each of pure stand in middle province on object of this study and do comparative analysis of light condition about stand parameter and natural regeneration according to each slope(north, west and south) conditions of location in central part of South Korea. Sample plots for pine-oak mixed stand and pine and oak pure stand were established on each of southern, northern and western slopes based upon site and growth conditions of the slope. Sample plot was a circle of 0.05ha with a diameter of 25.24 m. A sample plot has between 30 and 40 tree in it. Total 23 sample plots were established; 9 pure pine stands, 8 pine-oak mixed stands. and 6 pure oak stands across lower, middle, upper parts of slopes. Relative light intensity within a stand was' measured by crown- photo(fish-eye lens; 180$^{\circ}$) system through fish-eye lens and by comparing each plot with the denuded through PAR-sensor. The crown closure ratio of pure pine stand (75%) shows much lower than that of mixed stand (90.9%) and pure oak stand (93%). The relative light intensity within a stand showed an opposite result. The crown closure of mixed stands tended to become gradually low as the slope moves from the north to the south, but the relative light Intensity within the stand tended to rise. By analyzing the relationship between the relative light intensity within a stand and stand parameter, light intensity within a stand tended to decrease as the diameter and N/ha increase. Number of oak seedlings and light intensity within a stand is in a straight-line regression relation. In particular, the number of oak seedlings was the highest in mixed stands on the southern slope. But no single pine seedling was found. The unfavorable conditions of l0cm thick litter layer and low relative light intensity in a stand (ranging between 4% and 8%) is considered to prevent pine seeds from germinating.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.25-25
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• 2014

Three species of Fusarium, F. fujikuroi, F. verticillioides and F. proliferatum, are known to be associated with bakanae disease of rice [1, 2]. F. fujikuroi infects rice flowers and survive in endosperm and embryo of the seeds. Infected seed is an important source of primary inoculum of pathogens [3]. Seeds of rice (Oryza sativa cv. Boramchan) collected from bakanae-infected field were found to be 96% infected with Fusarium sp., 52% with F. fujikuroi, 42% with F. verticillioides, and 12% with F. proliferatum as determined by incubation method and species-specific PCR assays. F. fujikuroi was detected at lemma/palea, endosperm and embryo whereas F. verticillioides and F. proliferatum were recovered only from lemma/palea by means of component plating test. Seed disinfection methods have been developed to control bakanae disease and prochloraz has been most widely used for rice seeds. Two chemicals formulated with prochloraz (PC 1) and prochloraz + hexaconazole (PC 2) that inhibit biosynthesis of ergosterol strongly reduced the incidence of Fusarium spp. on selective media to 4.7% and 2.0%, respectively. Disease symptoms of rice seedlings in nursery soil were alleviated by chemical treatment; seedlings with elongated leaves or wide angle between leaf and stem were strikingly reduced from 15.6 to 3.2% (PC 1) and 0 (PC 2), stem rots were reduced from 56.9 to 26.2% (PC 1) and 32.1% (PC 2), and normal seedling increased from 0.4 to 13.3% (PC 2). Prochloraz has some disadvantages and risks such as the occurrence of tolerant pathogens [4] and effects on the sterol synthesis in animals and humans [5]. For these reasons, it is necessary to develop new disinfection method that do not induce fungal tolerance and are safe to humans and animals. Chlorine dioxide ($ClO_2$), that is less toxic, produces no harmful byproducts, and has high oxidizing power, has been reported to be effective at disinfection of several phytopathogenic fungi including Colletotrichum spp. and Alternaria spp. [6]. Gaseous $ClO_2$ applied to rice seeds at a concentration of 20 ppm strongly suppressed mycelial growth of Fusarium fujikuroi, F. verticillioides and F. proliferatum. The incidence of Fusarium spp. in dry seed with 8.7% seed moisture content (SMC) tended to decrease as the concentration of $ClO_2$ increased from 20 to 40 ppm. Applying 40 ppm $ClO_2$ at 90% relative humidity, incidence was reduced to 5.3% and resulted in significant reduction of disease symptoms on MS media. In nursery soil, stem rot was reduced from 56.9 to 15.4% and the number of normal seedlings increased from 0.4 to 25.5%. With water-soaked seeds (33.1% SMC) holding moisture in the endosperm and embryo, the effectiveness of disinfection using $ClO_2$ increased, even when treated with only 20 ppm for four hours. This suggests that moisture was a key element for action of $ClO_2$. Removal of the palea and lemma from seeds significantly decreased the incidence of Fusarium spp. to 3.0%. Seed germination appeared to decrease slightly by water-soaking at $30^{\circ}C$ because of increased SMC and by physical damage of embryos from hulling. These results indicate that the use of gaseous $ClO_2$ was effective as a means to disinfect rice seeds infected with Fusarium spp. and that moisture around the pathogens in the seed was an important factor for the action of $ClO_2$. Further investigations should be conducted to ascertain the best conditions for complete disinfection of Fusarium spp. that infect deep site of rice seeds.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.3
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• pp.108-118
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• 2012

To investigate the responses of yellow poplar (Liriodendron tulipifera L.) seedlings to the interactive effects of the elevated atmospheric $CO_2$ level and nitrogen addition, we measured biomass, photosynthetic pigments, photosynthesis, and the contents of nitrogen (N) and carbon (C) from the seedlings after 16 weeks of the treatments. Yellow poplar seedlings were grown under the ambient ($400{\mu}mol\;mol^{-1}$) and the elevated (560 and $720{\mu}mol\;mol^{-1}$) CO2 concentratoins with three different N addition levels (1.2, 2.4, and $3.6g\;kg^{-1}$) in the Open Top Chambers (OTC). The dry weight of the seedlings enhanced with the increased N levels under the elevated $CO_2$ concentrations and the increment of the dry weight differed among the different N levels. Photosynthetic pigment content of the yellow poplar leaves also increased with the increase of the $CO_2$ concentration levels. The effects of the N levels on the photosynthetic pigment content, however, were significantly different among the $CO_2$ levels. Photosynthetic rates were affected by the levels of $CO_2$ and N concentrations. Stomatal conductance and transpiration rates increased with increasing $CO_2$ concentration. The carboxylation efficiency of the seedlings without N addition increased under the higher $CO_2$ concentrations whereas that with N addition decreased under the elevated $CO_2$ concentrations. Nitrogen and carbon uptake in leaf, stem, and root increased with the elevated $CO_2$ concentration level and N addition. In conclusion, under the elevated $CO_2$ concentrations, physiological characteristics and carbon uptake of the yellow poplar seedling were improved and increased with N addition.