• Research in Plant Disease
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• v.19 no.4
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• pp.254-258
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• 2013

Fusaric acid (FA) is a mycotoxin produced by Fusarium species. Its toxicity is relatively low but often associated with other mycotoxins, thus enhancing total toxicity. To date, biosynthetic genes or enzymes for FA have not been identified in F. oxysporum. In order to explore the genetic element(s) for FA biosynthesis, restriction enzyme mediated integration (REMI) procedure as an insertional mutagenesis was employed using FA producing-F. oxysporum strains. Genetic transformation of two F. oxysporum strains by REMI yielded more than 7,100 transformants with efficiency of average 3.2 transformants/${\mu}g$ DNA. To develop a screening system using phytotoxicity of FA, eleven various grains and vegetable seeds were tested for germination in cultures containing FA: Kimchi cabbage seed was selected as the most sensitive host. Screening for FA non-producer of F. oxysporum was done by growing each fungal REMI transformant in Czapek-Dox broth for 3 weeks at $25^{\circ}C$ then observing if the Kimchi cabbage seeds germinated in the culture filtrate. Of more than 5,000 REMI transformants screened, fifty-three made the seeds germinated, indicating that they produced little or fewer FA. Among them, twenty-six were analyzed for FA production by HPLC and two turned out to produce less than 1% of FA produced by a wild type strain. Sequencing of genomic DNA regions (252 bp) flanking the vector insertion site revealed an uncharacterized genomic region homologous (93%) to the F. fujikuroi genome. Further study is necessary to determine if the vector insertion sites in FA-deficient mutants are associated with FA production.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.1
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• pp.8-17
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• 2018

Pre-harvest sprouting (PHS) refers to seed germination during ripening, due to loss of dormancy before harvest. As PHS in rice causes decrease in grain yield and quality, tolerance to PHS is an important trait of Japonica cultivars in Korea. It is important to investigate the related genes and environmental factors, because PHS is a quantitative trait. In this study, we examined PHS rates at three different times according to the cumulative daily mean temperature after heading (CTAH) for 5 rice cultivars released in Korea for 5 years from 2013 to 2017 to determine the effect of environmental factors on PHS. ABA content in ripening spikelets was analyzed to understand how it was related to PHS tolerance. PHS rate increased as CTAH increased from $800^{\circ}C$ to $1200^{\circ}C$. PHS rate was significantly different (p < 0.001) among the cultivars, showing Dasanbyeo, Jounbyeo, and Nampyeongbyeo to be PHS-tolerant, and Jopyeongbyeo and Gopumbyeo to be susceptible at all the CTAH of 800, 1000, and $1200^{\circ}C$. In 2015 and 2016, PHS rates were relatively higher, because of high temperature and frequent rainfall during the ripening period. In each cultivar, ABA content decreased as CTAH increased from $800^{\circ}C$ to $1200^{\circ}C$. However, there was no significant correlation between ABA content and PHS tolerance among the cultivars.

• The Journal of Natural Sciences
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• v.5 no.2
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• pp.49-62
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• 1992

This study was carried out to investigate the emergence, growth and yield components in rice inassoccation with Several cultivation methods direct sowing flooded paddy field(DSF), direct sowing by airplane(DSA), direct sowing in dry paddy field(DSD), 8days seedling planting(8DS), and 35days seedlingplanting(35DS). Also this study was attempeted to know the effects of calcium peroxide on germinationand early growth of rice under different soil conditions, seeding depth, application of organic matter,indirect sowing flooded paddy field.1. Rate of emergence was 73% in DSF, 70% in DSA, 62% in DSD, respectively, under the different cultivation method of rice in reclaimed paddy field.2. Degree of lodging in relation to cultivation was 5 at both DSF and DSA, 3 at DSD, 2 at both 8DS and 35DS respectively.3. Maximum tiller number was 568 per m2 at DSF and 527 at DSA. Heating was delayed for 4 days at DSF, 8 days at DSD and 2 days at 8DS as comparison with that at 35DS.4. Yield was higher 1% to 3% at DSF than that at DSA and DSD while decreased by 12% as compared with that of seedling planting.5. Total dry weight of seedling was decreased by 57% at 8DS, 60% at DSF 63% at DSD, respectively, under 0.3% of salinity. Ratio of decreasing in dry weight was higher with high salinity.6. The amount of O2 released was recorded highest to 2 to 3days after irrigatition, thereafter remaining constant to 10 days after irrigatition.7. The optimum coating amount of calcium peroxide for germination was a half of rice seed weight with 1 cm sowing depth and one-fold with 2-cm sowing depth when rice straw was not applied. With rice straw applied, on the other hand, the amount of peroxide was one-fold with 1-cm sowing depth. It was found that, under the condition of applied 600kg/10a, of 2-cm soil depth with rice straw calcium peroxide coating had no effect on emergence of rice seedling.8. In reclaimed paddy field, lodging degree was 7 with direct sowing by machine and 9 with direct sowing by hand.9. Yield was increased by 5% by applying rice straw with direct sowing by machine.

• Korean Journal of Environmental Biology
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• v.18 no.3
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• pp.331-336
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• 2000

In order to examine the effect of SO$_2$, which is the major component of acid rain, on the peroxidase activity, rice (Oryza sativa) seedlings were grown on the media containing various concentrations of Na$_2$SO$_3$. Na$_2$SO$_3$ concentrations needed for the 50% inhibition of rice seed germination were determined to be 300$\mu\textrm{g}$/ml at pH 7, 8$\mu\textrm{g}$/ml at pH 5 and 2$\mu\textrm{g}$/ml at pH 3. Notably, about 8 fold and 4 fold increase of the specific activity of the enzyme were observed with the seedlings treated with 8$\mu\textrm{g}$/ml Na$_2$SO$_3$ at pH 5 and 2$\mu\textrm{g}$/ml Na$_2$SO$_3$ at pH 3, respectively. The effects of Cd and Pb on the peroxidase activities and chlorophyll contents were also examined. About 3.9 fold higher peroxidase activities were found at 0.03mM Cd, and the chlorophyll contents were reduced to 63% of the control seedlings. At 0.04mM Pb, 2.5 fold higher enzyme activities were found and the chlorophyll contents were reduced to 72%. Therefore, the increases of rice peroxidase activities might be involved in the defense mechanism of the cell against various environmental stresses such as Na$_2$SO$_3$, Cd and Pb. The effects of Cu and Fe, which are the inducers of oxidative stresses by the generations of reactive oxygen species, on the peroxidase activities were also investigated. About 57% and 65% activity losses were found at 0.5mM CuSO$_4$ and 0.5mM FeSO$_4$, respectively, and radical scavenger ethanol almost completely protected both inactivations. However, dimethyl sulfoxide, mannitol, thiourea and histidine showed different radical scavenging effects one another against Cu and Fe inactivation.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.309-316
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• 1988

Several experiments were conducted to investigate the achene viability and growth characteristics of Eclipta prostrata (L.) L. No dormancy and no after-ripening requirement were found for E. prostrata achenes. When achenes were stored at room temperature, germination did not decrease with up to 5 months storage. Large differences in loss of viability of E. prostrata achenes occurred when different dehydration methods were used. Immediate dehydration resulted in high viability, but slow dehydration resulted in severe loss of viability. Achene viability at shallow burial depths (5 and 10 cm deep) was lower under upland soil conditions than under lowland soil conditions. Seedling growth was greatly reduced when flooding to a depth of 10 cm occurred at or before the 4-leaf stage. Flooding after the 4-leaf stage stimulated stem elongation. Branching started from the second week and usually terminated at the tenth week. Leaf size was determined by the branch which are related to the assimilate supply. Flowering of E. prostrata started during the fifth week after emergence, and mature achenes were produced from the sixth week. Ten to 14 days were needed for the achenes to mature. About 14,000 achenes were produced on each plant. Achene production per week increased from the sixth week to the tenth week and thereafter it declined. The average number of achenes per inflorescence decreased with delay in flowering.

• Research in Plant Disease
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• v.14 no.3
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• pp.143-152
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• 2008

Mixed-planting of two rice cultivars, HP ('Hopyeongbyeo') and NP ('Nampyeongbyeo'), having a dissimilar susceptibility to rice blast was practiced for chemical-free control of rice blast in the field. The HP/NP combination was selected for applying under mechanized agricultural conditions. Because they have similar genetic characteristics such as seed germination and heading time, culm length, rice quality and size of rice grains except susceptibility to blast. Incidence of panicle blast was reduced 50.4 % compare with supposed blast incidence by HP/NP mixed-planting when the seeds of two cultivars were combined 1 to 1 as weight. Supposed blast incidence was estimated from reduction of rice blast caused by addition of a resistant cultivar NP. Race diversity of Magnaporthe oryzae was examined for correlation with control effect of HP/NP mixed-planting on rice blast. The population of dominant race KJ-101 was diminished and replaced with various co-existing races and eleven new races were appeared in mixed-planting plot. Total number of race isolated from mixed-planting plot was not largely different from mono-culture. However, detection frequency of the new race was increased and variation of the population size of each race was decreased in mixed-planting plots. It was shown that a biased community with a dominant race (KJ-101 or KI-181) was altered to a balanced one of coexisting races. From these results, it was supposed that the balanced diversity among co-existing races within a community might be correlated to control effect by HP/NP mixed-planting on rice blast. Further more, it should be studied that genetic characteristics of the individual race including a virulence on cv. HP and NP was examined for verifying a correlation of mixed-planting effect and race diversity.

• Research in Plant Disease
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• v.14 no.3
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• pp.193-200
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• 2008

Blending of eggshell powder into soil as ratio of 1:5, 1:10, 1:15, 1:20, and 1:25 did not affect seed germination rates of several crops including Chinese cabbage. The blending increased pH of distilled water and decreased the viability of resting spores of Plasmodiophora hrassicae. The ratio of non-viable resting spores in eggshell-blending water was over five times higher than in distilled water of the same pH. Chinese cabbage (cv. 'Norangbom') grew more in eggshell-blended soil than in non-treated soil, but other crops grew less. Leaf numbers and above ground growth of Norangbom increased to around 150% and 470%, respectively, in soil blended with $1:20{\sim}1:15$ of eggshell powder. Even though the optimum sizes of eggshell powder were $0.8{\sim}2.0mm$ for growth and smaller than 0.4 mm for inhibition of clubroot disease of Chinese cabbage, there was no statistical difference among the sizes. Soil pH was above 8.0 in all eggshell treatments without any statistical difference among them. Eggshell powder blending to 1:20 showed lower control efficacy, 58.5%, than registered fungicide 'Hokanna (flusulfamide)', 78.5%. However, Chinese cabbage of that blending ratio recorded the highest growth among the treatments. Therefore, blending of eggshell powder into clubroot-contaminated soil may make culture of Chinese cabbage possible by growth-increasing, even though eggshell powder could not inhibit clubroot disease entirely.

• Korean Journal of Agricultural Science
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• v.14 no.1
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• pp.26-37
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• 1987

This studies were conducted to investigate pathgenicity and host range of Colletotrichum dematium isolated from anthracnose of pepper, and phytoxicity of its culture filtrate and the partially purified toxin. The results obtained were as follows. 1. Investigation on the host range of C. dematium has revealed that pepper as well as soybean, tomato, spinach, and beet were highly susceptible, egg plant and water melon were moderately susceptible and stone leek was slightly suceptible, but no symptoms were produced on carrot, tabacco, cucumber and melon. 2. The culture filtrates of C. dematium in Czapeck dox liquid media were toxic to leaves of pepper and caused necrosis and wilting of the plant. The toxicity of culture filtrates was most active at 15 days after fungal growth in Czapeck dox liquid media and the toxin productivity in still culture was higher than that in shaking culture. 3. The partially purified toxic substance was isolated from the culture filtrates by the acetone precipitation method. When cuttings of various pepper cultivars were placed in the toxin solutions, suceptible cultivars and resistant cultivars were equally toxic and showed necrosis and wilting of the leaves. 4. Several other plants such as soybean, tomato and carrot were also affected with the toxin solution by shoot cutting bioassay and showed veinal necrosis, leaf spots and wilting of the shoots. 5. The acetone precipitation toxin affected seed germination of pepper, cucumber, sesame and egg plant and inhibited the growth of root and hypocotyl of the seedlings.

• Journal of Korean Society of Forest Science
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• v.100 no.1
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• pp.95-104
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• 2011

Distribution types of native conifers (Juniperus chinensis, Pinus parviflora, Tusga sieboldii and Taxus cuspidata var. latifolia) were studied by phytosociological investigation and ZM method in Ulleung Island, South Korea. Two main types were divided maritime vegetation (Juniperus chinensis forest) and mountain vegetation (Taxus cuspidata var. latifolia forest and Pinus parviflora-Tusga sieboldii forest). The former was divided into sea cliff distribution (J-SC) and sea ridge distribution (J-SR) type. The latter was classified 7 distribution types; Taxus cuspidata var. latifolia forest was rock distribution (Ta-R) and mountain slope distribution (Ta-MS) type, and Pinus parviflora-Tusga sieboldii forest was rock distribution (P T-R), upper and ridge distribution (P T-UR, 3 units sub-types:1sub, 2sub, 3sub), and Mountain slope distribution (P T-MS) type. It was considered that J-SC, Ta- R, and P T-R were maintained by topographic climax, but J-SR, Ta-MS, P T-UR and P T-MS were the process of vegetation succession. Distribution types of topographic climax are entrusted to process of vegetation succession. Types in the process of vegetation succession will be needed tending of forest to promote saplings growth and seedlings germination. Especially in order to restore Tsuga sieboldii forest should be afforest and make forest gap because It is mid shade tolerant tree and purity percentage of its seed is 1~2%. It was considered that the composition of group mixture forest constituted Pinus parviflora, Tsuga sieboldii, Taxus cuspidata, Camellia japonica, Machilus thunbergii and Acer okamotoanum, etc. will be able to restore native vegetation, after take the form of forest gap by strong thinning and pruning of Pinus thunbergii forest.

• Korean Journal of Plant Resources
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• v.35 no.4
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• pp.435-444
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• 2022

Hibiscus hamabo Sieb. et Zucc. (yellow hibiscus) is a deciduous semi-shrub plant and mainly growing in Jeju Island. This is known the unique wild hibiscus genus and classified as an 2nd grade of endangered plant for Korean Red List. In previous studies, properties of germination, ecological, genetical and salt resistance have been reported. In this study, we investigated mass-proliferated adventitious root using bioreactor, antioxidant and whitening effects to conduct functional ingredients. Yellow hibiscus were collected from Gujwa, Jeju by prior permission and they were introduced by explant type and various medium composition after surface sterilization. As a result, seed response rates were evaluated at range of 51.17~51.83%, in terms of comprehensive efficiency of shoot and root formation. In the case of adventitious root propagation condition was confirmed in half strength Murashige and Skoog medium salts, 30 mg/L sucrose, and 2 mg/L indole-3-butyric acid for 8 weeks in 5,000 mL bioreactor. We also compared between relationship with biomass and secondary metabolites accumulation by total phenolics content, the flavonoid content, DPPH free radical scavenging activity and melanin content. The results indicated that adventitious root mass proliferation, antioxidant and whitening effect could develop value of the high-quality cosmeceutical ingredient and further metabolite studies.