• Korean Journal of Weed Science
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• v.16 no.4
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• pp.301-308
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• 1996

In this study, a propagation characteristics of green kyllinga(Kyllinga brevifolia var. leiolepsis H.) was investigated. Two to three rhizomes(1st rhizome) arised from the basal part of main shoot at 4th leaf stage and were grown to extend on the soil surface. Then new shoots(lst tillers) emerged from every node of the 1st rhizome. Second rhizomes also arised from the basal part of lst tiller at the time of 4th leaf openning. With such a regularity, 5th rhizomes and about 688 shoots were produced from one plant during one year-cultivation without competition under the natural condition. The degree of vegetative growth and seed formation was 3 times and 2.5 times higher in rhizomeoriginated plant than in that from seed, respectively. The amount of seed formation and the 1000 seeds weight was highest in one planted on June 1 and Aug. 1, respectively. Short-day treatment of less than 14hr appeared to be necessary for the induction of flowering and it was effective as treated not during germination but since at least 2 leaf stage of green kyllinga. Each shoot individually responded to short-day. When plants were exposed to short-day (9hr, day / 15hr, night) treatment at the stage of 2-3 leaves, more than 7 cycles were required for flowering induction. Bolting in main shoot occurred after emergence of 4 leaves under the short-day condition. Exogenous $GA_3$ slightly accelerated the velocity of bolting only in short-day condition.

• Korean Journal of Weed Science
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• v.15 no.1
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• pp.46-53
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• 1995

The herbicidal activity of thiocarbamate herbicides and its effect on cell division and elongation were determined. The herbicides studied were molinate(S-ethyl-N,N-hexamethylenethiocarbamate), dimepiperate [S-(${\alpha}$,${\alpha}$-di methylbenzyle)piperidine-1-carbothioate], esprocarb [S-benzyl-N-ethyl-N-(1,2-dimethylpropyl) thiocarbamate], and thiobencarb [S-(4-chlorobenzyl)-N, N-diethylthiocarbamate]. The herbicides applied at the rates ranged from $10^{-6}$ to $10^{-5}M$ did not affect germination and post-germination root growth of rice(Oryza sativa L.) and barnyardgrass [Echinochloa crus-galli(L.) P. Beauv.], but inhibited the post-germination shoot growth. There was no inhibition of gibberellin-induced ${\alpha}$-amylase biosynthesis in de-embryonated rice seeds by the herbicides at $10^{-5}M$, but about 50-60% inhibition occurred at $10^{-4}M$. When the herbicides were applied 7 days after seeding, the rates required to 50% growth inhibition of barnyardgrass were 146g, 91g, 96g, and 102g ai/10a for molinate, dimepiperate, esprocarb, and thiobencarb, respectively. No effect of the herbicides on cell division was found at $10^{-4}M$, but about 31 to 47% inhibition as compared with the untreated check was obtained by treatment of the herbicides at $10^{-3}M$. However, about 33 to 38% inhibition of cell elongation occurred at $10^{-5}M$ of the herbicides. They also inhibited IAA-induced cell elongation.

• Korean Journal of Weed Science
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• v.15 no.3
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• pp.214-223
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• 1995

Tolerant corn cultivars to bentazon were selected and tolerance mechanism of corn cultivars to bentazon was studied by determining bentazon 6-hydroxylase(B6H) activity which was known to detoxify bentazon to 6-hydroxy bentazon at induced enzyme conditions with treatments of 1,8-naphthalic anhydride, ethanol and phenobarbital. Tolerant cultivars to bentazon were selected by growth response of corn by foliar application of bentazon to corn cultivars. Kwanganok, GA 209, IK 2, DB 544, and Suwon 19 were tolerant to bentazon, but KSS 3, KSS 4, KS 5, and Danok 2 were susceptible. Pretreating corn seeds with 1,8-naphthalic anhydride increased B6H activity at all cultivars, but the tendencies were more remarkable at Suwon 19 and GA 209, tolerant cultivars, than at Danok 2 and KS 5, susceptible cultivars. Treating corn shoots with ethanol increased B6H activity at Suwon 19 and GA 209. B6H activity was enhanced by treatments of ethanol at 1.0 or 2.5%, but decreased at ethanol 2.5 or 5.0% at Danok 2 and KS 5. Treating corn shoots with phenobarbital increased B6H activity at Suwon 19, GA 209, Danok 2, and KS 5 by treatments of phenobarbital at 2.0mM, but decreased at 4.0 or 8.0mM at all cultivars. Therefore, the tolerant mechanism of corn cultivars to bentazon may be explained partially by the activity of bentazon 6-hydroxylase which detoxifies bentazon to 6-hydroxy bentazon.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.118-123
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• 2015

Metagenomics is a powerful tool to isolate novel biocatalyst and biomolecules directly from the environmental DNA libraries. Since the metagenomics approach bypasses cultivation of microorganisms, un-cultured microorganisms that are majority of exists can be the richest reservoir for natural products discovery. To discover novel herbicidal substances from soil metagenome, we established three easy, simple and effective high throughput screening methods such as cucumber cotyledon leaf disc assay, microalgae assay and seed germination assay. Employing the methods, we isolated two active single clones (9-G1 and 9-G12) expressing herbicidal activity which whitened leaf discs, inhibited growth of microalgae and inhibited root growth of germinated Arabidopsis seeds. Spraying butanol fraction of the isolated active clones' culture broth led to growth retardation or desiccation of Digitalia sanguinalis (L) Scop. in vivo. These results represent that the screening methods established in this study are useful to screen herbicidal substances from metagenome libraries. Further identifying molecular structure of the herbicidal active substances and analyzing gene clusters encoding synthesis systems for the active substances are in progress.

• Korean Journal of Weed Science
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• v.5 no.1
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• pp.9-13
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• 1985

This study was conducted to evaluate herbicide resistant plant through tissue culture. Callus was induced from embryos of Echinochloa crusgalli Beauv. (var, oryzicola Ohwi, var. caudata Kitagawa and var, crusgalli). An optium medium for callus induction and succinate dehydrogenase activity in inducted callus were detected and callus growth of various varieties of Echinochloa crusgalli was assessed under the treatment of various rates of butachlor[N-(butoxymethyl)-2-chloro-N-(2,6-diethylphenyl)acetamide]. MS medium seemed to be the most appropriate to induce callus from the embryos of varieties of E. crusgalli by using 2,4-D about 5.5mg/l as a hormone source. The activity of succinate dehydrogenase in inducted callus showed positive reaction against to TTC(2,3,5-triphenyltetrazolium chloride) regardless of concentrations of butachlor and varieties of E. crusgalli, indicating that all the callus induced were alive. The callus growths derived from seeds of E, cnesgalli were greatly affected by various rates of butachlor and were completely inhibited at the highest concentration of butachlor, $10^{-3}M$, regardless of varieties of E. crasgalli. $10^{-6}M$ of butachlor inhibited 24.6% of the callus growth of E. crusgalli Beauv, var. oryzicola Ohwi, while E. crusgalli Beauv. var. crusgalli showed 42% of inhibition, showing that there was difference in response of varieties of E. crusgalli Beauv. to butachlor.

• Weed & Turfgrass Science
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• v.5 no.3
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• pp.111-125
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• 2016

Cordgrass (Spartina spp.) is recognized as a highly invasive plant in estuaries throughout the world because of remarkable versatility and resiliency, significant reproduction, strong adaptability, rapid spreading, and vigorous growth. In this review, therefore, to provide insights on the effective management practices, the previous research works were summarized and discussed. Spartina spp. is a perennial halophyte, warm-season (C4) grass that reproduces both sexually through seeds and asexually by rhizomes. Management strategies for cordgrass have included various physical, biological, and chemical controls. Herbicides are usually the most cost-effective means of control. Currently, glyphosate, imazapyr, fluazifop and haloxyfop have been practically used. To improve the control efficacy, a combination of two more than methods (example, mowing-spraying) is needed to be applied consistently every year for at least 3 to 4 years and to be sprayed with enough dry time (>4-6 hr) at an early growth stage (before flowering). Consistently repeated application of same herbicide have to be avoided to prevent an unexpected emergence of herbicide-resistant lines. On the other hand, Spartina spp. have many positive functions for agricultural and eco-engineering purposes. Thus, we have to give more intensive research for effectively managing advantages and disadvantages of Spartina plantations.

• Korean Journal of Weed Science
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• v.31 no.1
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• pp.84-88
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• 2011

This study was established to investigate the effects of seeding depth and seeding time on the emergence, growth, and N production of Vicia tetrasperma and V. hirsuta in 2007 and 2008. All seeds of both species were gathered from Dangjin, Chungnam in late June of 2005 and stored for two year at room temperature. Both V. species began to germinate at the end of June, passed the winter with the seedling stage, rapidly increased their height in April and May, were in full bloom in May, and then withered after entering mid-June. V. hirsuta had higher emergence rate and growth compared to those of V. tetrasperma. The optimum seeding time and seeding depth for a cover cropping was from late August to early September and from 1 to 5 cm, respectively. V. tetrasperma and V. hirsuta had a satisfactory growth and provided 43.8 and $55.4kg\;ha^{-1}$of N, respectively.

• Korean Journal of Weed Science
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• v.31 no.1
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• pp.78-83
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• 2011

This study was conducted to evaluate germination rate of Vicia tetrasperma and V. hirsuta as affected by storage duration, temperature, and light. All seeds of both species were gathered from Dangjin, Chungnam in the late June of 2004 and 2005, stored for a certain period of time, and then exposed for 20 days to the alternating temperatures ($15/^{\circ}C,\;20/10^{\circ}C,\;25/15^{\circ}C$, and $30/20^{\circ}C$) for evaluating the germination rate. Both 2004 and 2005, two species stored at room temperature for 3 months had germination rates less then 30% with applying various alternating temperatures for 20 days although the highest germination rate was obtained with $25/15^{\circ}C$ treatment. V. tetrasperma at 12 month storage after seed gathering in 2005 had 82% of germination rate with $25/15^{\circ}C$ treatment and showed the increased rate as time passed. V. hirsuta at 6, 9, and 12 month storage after seed gathering in 2005 ranged, however, from 33 to 53% of the germination rate at alternating temperature treatments for 20 days and did not seem to be affected by the elapsed time of the storage. Storage at room temperature was more effective for increasing germination rate of both species compared to those of the storage at low temperature. The germination rate of both species was not significantly affected by either exposure of light or short period of high temperature.

• Korean Journal Plant Pathology
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• v.13 no.3
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• pp.191-193
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• 1997

A new disease of arrowhead (Sagittaria trifolia L.)caused by Plectosporium tabacinum was observed at Yusung area in Korea. Infection occurred on the petioles, leaves, and seeds of young and old arrowhead plants. Small and brown spots developed on the infected areas initially, which later coalesced to form large dead areas resulting in the complete blight of the host plant. Inoculation of arrowhead seedlings by conidial suspension induced typical disease symptoms found in naturally infected plants. The new name for the disease 'arrowhead blight' is suggested. The pathogenic fungus was identified as Plectosporium tabacinum and its morphological and cultural characteristics are described.

• The Plant Pathology Journal
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• v.36 no.5
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• pp.476-490
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• 2020

The parasitic weed, Orobanche crenata, is one of the most devastating constraint for faba bean production in Mediterranean regions. Plant host defense induction was reported as one of the most appropriate control methods in many crops. The aim of this study was to elucidate the effect of salicylic acid (SA) and indole acetic acid (IAA) on the induction of faba bean resistance to O. crenata under the field and controlled experimental conditions. Both hormones were tested on two contrasting faba bean genotypes: Giza 843 (partially resistant to O. crenata) and Lobab (susceptible) at three different application methods (seed soaking, foliar spray, and the combination of both seed soaking and foliar spray). Soaking seeds in SA or IAA provided the highest protection levels reaching ~75% compared to the untreated control plants. Both elicitors limited the chlorophyll content decrease caused by O. crenata infestation and increased phenolic compound production in host plants. Phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase activities were stimulated in the host plant roots especially in the susceptible genotype Lobab. The magnitude of induction was more obvious in infested than in non-infested plants. Histological study revealed that both SA and IAA decreased the number of attached O. crenata spikes which could be related to specific defense responses in the host plant roots.