• Korean Journal of Weed Science
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• v.14 no.2
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• pp.101-106
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• 1994

Factors affecting phytotoxicity of dithiopyr in rice such as transplanting depth, seedling age, soil texure were examined and mechanism of phytotoxicity in rice was also determined by absorption study of $^{14}C$-dithiopyr in rice seedlings under above conditions. Rice injury was occurred in shallow transplanting depth, young rice seedlings and sandy soil conditions. Higher amount of dithiopyr was absorbed in rice at shallow transplanting depth and sandy soil conditions which may related to phytotoxicity of dithiopyr.

• Weed & Turfgrass Science
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• v.6 no.4
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• pp.322-332
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• 2017

Microbial fertilizer has been used to prompt turfgrass growth and quality and to prevent turfgrass diseases in turfgrass management of golf courses. This study was conducted to evaluate effects of microbial fertilizer containing Lactobacillus fermentum (MFcL) on changes of turfgrass quality and growth by investigating turf color index, chlorophyll index, clipping yield, and nutrient content in the turfgrass tissue. Treatments were designed as follows; non-fertilizer (NF), control fertilizer (CF), MFcL treatments [CF+$1.0g\;m^{-2}$(MFL), CF+$2.0g\;m^{-2}$ (2MFL)], and only MFcL treatment (OMF; $1.0g\;m^{-2}$ MFL). Chemical properties of soil by application of MFcL was unaffected. Turf color index, chlorophyll index, clipping yield and nutrient content and uptake of MFcL treatments were similar to CF. Furthermore, turfgrass shoot density of MFL was increased by 20% than that of CF, and that of OMF by 22% than NF. These results show that the application of microbial fertilizer containing L. fermentum increased turfgrass shoot density, which is not attributed to nutrient uptake in this study, but needs to be further investigated with other mechanisms such as biostimulant induction or phytohormone production.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.408-412
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• 2013

Dollar spot caused by Sclerotinia homoeocarpa F.T. Benn. is a common and economically important turfgrass disease in South Korea. Fungicides mixture (propiconazole 25% + boscalid 47%) treatments, showing synergistic interaction, with three application rates (low: 50.3 ml $10a^{-1}$ and 97.5 g $10a^{-1}$, intermediate: 67.0 ml $10a^{-1}$ and 130.0 g $10a^{-1}$, and high: 100.5 ml $10a^{-1}$ and 195.0 g $10a^{-1}$) and two application intervals (10 and 15 days) were evaluated for control of dollar spot in creeping bentgrass golf course putting green. In both nontreated plots of field A and B, the disease has severed as 48.3 and 60.0% after the pathogen inoculation. Two fungicide mixture treatments showed significantly higher the disease control effect than a single fungicide treatment (propiconazole). Field A which showed more the disease severity but the fungicide still showed acceptable level of the disease efficacy (89.0%), significant differences in control value were not detected among treatments. The results suggest that the lower application rate of two fungicides mixture treatments may reduce the dollar spot disease severity in creeping bentgrass golf course putting green.

• Korean Journal of Weed Science
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• v.10 no.3
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• pp.214-220
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• 1990

To establish a greening assay for screening, and physiological and biochemical studies of the compounds affecting biosynthesis of plant pigments, were conducted on environmental factors, and on ways of incubation and illumination which affect plant greening. Greening was good when both cucumber and barley were grown for 5 to 6 days at $25^{\circ}C$ in darkness, when adaxial sides of cucumber cotyledons were contacted with the solution, and when barley leaf fragments were taken 0.5 to 2.0cm from the leaf tip. Potassium phosphate buffer(pH 6.0) at 10mM was most desirable for plant greening. The speed of greening during illumination was increased as the temperature increased from $15^{\circ}C$ to $35^{\circ}C$. The responses were sensitive more in cucumber than in barley, and in chlorophyll biosynthesis than in carotenoid biosythesis. The content of chlorophyll was greatest at the light intensity of 5000 and 1000 lux for cucumber and barley, respectively, but the biosynthesis of carotenoids were greatest at the light intensity higher than for chlorophyll. In use of solvents for dissolving chemicals, acetone, ethyl alcohol and DMSO at 10, 0.1 and 2.5% or less, respectively, did not affect the biosynthesis of plant pigments. $pI_{50}$ values were calculated for chemicals affecting pigment biosynthesis.

• Korean Journal of Weed Science
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• v.14 no.4
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• pp.239-244
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• 1994

As a fundamental study to control Alopeuclus aequalis Sobol. var. amurensis(Kom.) Ohwi., on dominant weed in barley and dry seeded rice cultivation on paddy fields, several factors which would have closer relations to its germination and emergence, were examined. The results are as follows. The dormancy of seeds were broken at dry-heat treatment of $30^{\circ}C$. The germination rate of the seeds was high in order of 15>10>20> $5^{\circ}C$ and was very low at more than $25^{\circ}C$. The emergence of A. aequalis was influenced little for the light, but had a tendency to be good on the dark condition. The seeds dried on room temperature germinated few but them treated on $30^{\circ}C$ for 24 hours were germinated over 80%. The A. aequalis occured few in the saline soil of salt concentration of more than 0.25% and the germination rate of seeds was very low on the over 0.5% solution of NaCl. On the solution of pH 6.0~12.0, the germination was not effected for pH but was very few on pH 2.0. At the paddy-lowland which have cultivated the soybean for three years A. aequalis emerged a few.

• Korean Journal of Weed Science
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• v.12 no.4
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• pp.374-379
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• 1992

Response of medicinal plants(58 species in 28 families) cultivated or naturally grown in Korea on paraquat (1,1'-dimethyl-4,4'-bipyridinium ion) was determined. All the plants, except for Jiwhang(Rehmannia glutinosa Liboch.) were killed by paraquat at 0. 8kg $ha^{-1}$. Jiwhang showed a great resistance to paraquat. The phytotoxic effect did not occur in Jiwhang with paraquat applied at 3.2kg $ha^{-1}$. Only 10% growth inhibition of Jiwhang was obtained at 4.8kg $ha^{-1}$. Normal growth of Jiwhang also occurred when at 0.8kg $ha^{-1}$ of paraquat different application dates from 2 leaf stage(LS) to 8 LS and/or five-repeated applications at 20-day intervals starting from 3 LS were employed. However, Jiwhang was completely killed by glyphosate[N-(phosphonomethyl) glycine], 2,4-D[2,4-dichlorophenoxy) acetic acid], and dicamba[3,6-dichloro-2-methoxy benzoic acid]+2, 4-D at the respective recommended rates.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.595-597
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• 2015

LMC X-4 is an eclipsing high-mass X-ray binary exhibiting a superorbital modulation with a period of ~ 30:5 days. We present a detailed study of the variations of the superorbital modulation period with a time baseline of ~ 18 years. The period determined in the light curve collected by the Monitor of All-sky X-ray Image (MAXI) significantly deviates from that observed by the All Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE). Using the data collected by RXTE/ASM, MAXI, and the Burst Alert Telescope (BAT) onboard Swift, we found a significant period derivative, $\dot{P}=(2.08{\pm}0.12){\times}10^{-5}$. Furthermore, the O{C residual shows complex short-term variations indicating that the superorbital modulation of LMC X-4 exhibits complicated unstable behaviors. In addition, we used archive data collected by the Proportional Counter Array (PCA) on RXTE to estimate the orbital and spin parameters. The detected pulse frequencies obtained in small time segments were fitted with a circular orbital Doppler shift model. In addition to orbital parameters and spin frequency for each observation, we found a spin frequency derivative of $\dot{v}=(6.482{\pm}0.011){\times}10^{-13}Hz{\cdot}s^{-1}$. More precise orbital and spin parameters will be evaluated by the pulse arrival time delay technique in the future.

• Korean Journal of Weed Science
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• v.11 no.1
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• pp.68-73
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• 1991

This study was conducted to determine the appropriate culture conditions for developing photoautotrophic cells from tobacco using plant growth regulators, sucrose and light condition in LS medium. The greatest callus induction was observed in the LS medium supplemented with $10^{-5}$ M NAA and $10^{-4}$ M BA, showing 3.08 g of callus fresh weight determined at 30 days after incubation. The highest chlorophyll content of callus was obtained in the LS medium supplemented with $10^{-5}$M NAA and $10^{-6}$ M BA, showing 28.42${\mu}g/g$. In both light and dark conditions, callus induction increased as the concentration of sucrose increased from 0.5%to 3.0%. In particular, in the light condition, the greatest callus induction was made in the LS medium supplemented with 2% sucrose. On the other hand, the heighest chlorophyll content was observed at 0.5% sucrose and chlorophyll wasn't induced in dark condition. The chlorophyll content of callus cultured in LS medium containing 0.75% sucrose was similar to 1% sucrose, as far as the chlorophyll content of callus was concerned.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.94-102
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• 2010

Field and pot experiments were conducted to investigate seedling emergence and early growth of Eleocharis kuroguwai panted on different dates. Non-linear regression analyses of observed data against effective accumulated temperature (EAT) with the Gompertz model showed that the Gompertz model works well in describing seedling emergence and early growth of E. kuroguwai regardless of planting date and soil burial depth. EATs required for 50% of the maximum seedling emergence of E. kuroguwai planted at 1, 3 and 5 cm soil burial depth in the pot experiment were estimated to be 54.5, 84.0 and $118.0^{\circ}C$, respectively, and $56.7^{\circ}C$ when planted at 1 cm in the field experiment. EATs required for 50% of the maximum leaf number of E. kuroguwai planted at 1, 3 and 5 cm soil burial depth in the pot experiment were estimated to be 213.3, 249.0 and $291.6^{\circ}C$, respectively, and $239.5^{\circ}C$ when planted at 1 cm in the field experiment. Therefore, models developed in this study thus predicted that if rotary tillage with water is made on 27 May under $+2^{\circ}C$ elevated temperature condition, dates for 50% of the maximum seedling emergence, 5 leaf stage and 5 cm plant height of E. kuroguwai buried at 3 cm soil depth were predicted to be 2 June, 10 June and 12 June. These dates are 1 day earlier for the seedling emergence and 3 days earlier for the early growth as compared with current temperature condition, suggesting that earlier application of herbicides is required for effective control of E. kuroguwai.

• Korean Journal of Weed Science
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• v.31 no.2
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• pp.146-151
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• 2011

Essential oil was extracted from cones of metasequoia (Metasequoia glyptostroboides) by steam distillation, fragrance was determined by sensorial analysis and chemical compositions were analyzed by gas chromatography-mass spectrometry with solid-phase microextraction apparatus. Metasequia contained 0.40% of essential oil in the cone. Major impact fragrances of the essential oil were woody, coniferous and herbal, and minor impact fragrances were minty, spicy and oily. There were nine constituents in the essential oil : 8 hydrocarbons and 1 oxide. Constituents were limonene (66.18%), ${\delta}$-3-carene (11.11%), ${\beta}$-caryophyllene (6.66%), ${\beta}$-myrcene (5.92%), ${\beta}$-pinene (4.14%), caryophyllene oxide (2.39%), camphene (2.32%), ${\alpha}$-caryophyllene (0.85%), and tricyclene (0.43%). Herbal and minty frangrances could be due to limonene and ${\delta}$-3-carene, spicy frangrance to caryophyllene, woody and coniferous frangrances to ${\alpha}$-pinene and ${\beta}$-pinene, and oily fragrance to camphene.