• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.264-268
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• 1997

Microbial metabolites from rhizosphere soil samples mainly inhabitated by Streptomyces are selectively uptaken into plants. The culture broth of a Streptomyces strain K9301 showed a major metabolite which disappeared in the medium 24hrs after planting of seedlings. This metabolite was selectively uptaken in the rice plants as well as the wheat plants. We identified the targeted metabolite showing a strong UV-absorbing spot at Rf 0.6 on TLC to be 2-aminobenzamide.

• The Korean Journal of Ecology
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• v.20 no.2
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• pp.103-109
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• 1997

Eleven phenolic compounds including caffeic acid were identified through analyzing the aqueous extracts of Pinus rigida by HPLC. Among them, protocatechuic acid was the maximum amount of 6.84 ppm. Seed germination of Cassia mimosoides var. nomame was significantly stimulated by the extract of P. rigida leaves in the proportion ot concentration. However, root growth was elevalted at a threshold concentration below 25%, but it was inhibited at high concentrations. In 50% extract of P. rigida, upward root tip of C. mimosoides var. nomame showed negageotropism which the root end showed necrosis. New isozyme bands were induced indicating concentration activity of peroxidase from the extract of C. mimosoides var. nomame, especially in the cathodic region. Although it reduced the mumber of isozyme bands of esterase, esterase activities were stimulated in the anodic region of C. mimosoides var. nomame. The activity of amylase was not remarkably different between control and treatment.

• Journal of Life Science
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• v.26 no.4
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• pp.484-489
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• 2016

Living organisms can maintain or extend their territories by producing allelochemicals that influence the growth, survival, and reproduction of other organisms. To identify natural biostimulants of positive allelochemicals, we screened 18 common seaweed extracts for enhancement of rhizoid and blade production in a convenient Porphyra suborbiculata monospore assay. By addition of methanolic extract from the most potent green seaweed, Codium fragile, 100% and 50% enhancement doses reflecting the amount of C. fragile extract required to enhance rhizoid formation (in terms of number of spores with rhizoids per total spores tested) were approximately 100 and 50 μg/ml, respectively, in the P. suborbiculata monospore culture. The C. fragile extract quickly enhanced rhizoid formation, rhizoid numbers per rhizoid-holding spore, rhizoid length, blade formation (in number of spores with blade per total spores tested), and blade length from most monospores at early culture days. The extract enhanced rhizoid formation after 2 days of culture significantly, rhizoid numbers per rhizoid-holding spore after 3 days, rhizoid length after 3 days, blade formation after 2 days, and blade length after 1 day, respectively, from most monospores. The allelochemicals that enhanced favorite seaweed species may be efficacious for new seaweed management technologies, including the development of biostimulant agents based on natural products.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.412-420
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• 2010

Weeds are known to cause enormous losses due to their interference in agro ecosystems. Because of environmental and human health concerns, worldwide efforts are being made to reduce the heavy reliance on synthetic herbicides that are used to control weeds. In this regard phytotoxicity of allelochemical sorgoleone, which is a major component of the hydrophobic root exudates of Sorghum bicolor was evaluated in different weed species and also its crop selectivity in greenhouse and field conditions. Sorgoleone strongly inhibited the growth of different weeds by pre-emergence and post-emergence applications both in greenhouse and field conditions. Post-emergence application of sorgoleone on 21-day-old weed seedlings had a greater inhibitory effect than the pre-emergence application. Again, broadleaf weed species were more susceptible than grass species to the application of sorgoleone at both stages of growth. Growth of broadleaf weed species was suppressed by greater than 80% for most of the weed species except a few species and among them the species Rumex japonicus and Galium spurium were completely suppressed at $200{\mu}g\;ml^{-1}$ sorgoleone. Like greenhouse trial, sorgoleone was more effective for broadleaf weed species followed by sedge and grass weed species in the field condition. The growth inhibition of weeds was slightly lower in field condition compared to greenhouse condition. The crop species like rice, barley, wheat, corn, perilla, tomato, soybean and Chinese cabbage were tolerant to sorgoleone while lettuce and cucumber were slightly susceptible to sorgoleone. Consequently, sorgoleone may be applied to control weeds in organic farms without affecting the growth of crop.

• Korean journal of applied entomology
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• v.54 no.2
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• pp.137-144
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• 2015

Plants can affect adversely the interaction among herbivores by inducing insect resistance chemicals and change of attack behavior of natural enemies. Also, plants may induce favorable effects to herbivores by production of allelochemicals, nutritional variation, or morphological changes. In this review, we examined the effects of the interaction among herbivores mediated by plants and plant-response induced by insect attack, or the life history strategies of insects on the community structure of herbivore insects, and discussed its ecological significance in community level.

• The Korean Journal of Ecology
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• v.13 no.2
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• pp.75-82
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• 1990

Toxic effert of water extract from leaves of Pinus rigida and some phenolic compounds on the seeds germination of Raphanus sativus var. hortensis for. acanthiformis Makino has been studied. There was little difference of germination percentage among the pH value of leaf extract (pH3~9). The germination percentage drastically with increased concentration level of leaf extract at about 60 percent. Seeds gemination of Raphanus sativus var. hortensis for. acanthiformis Makino inhibited severely by caffeic acid, ferulic acid and p-coumaric acid at M, but the germination percentage was higher than that of the control group in vanillic acid. In electrophoresis, there was no differences at earlier seedling stage of protein band between allelochemical treated and non-treated group, but in late stage, two protein band near 58kd and 27kd did not appeared in the toxic affected group. In case of caffeic acid treatment, two protein band near 58kd and 27kd did not found at late stage too.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.437-444
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• 2010

This study was conducted to determine the herbicidal activity of allelochemicals and identify herbicidal compounds in bulbs of Lycoris chinensis var. sinuolata. Methanol extract was purified by a series of silica gel flash column chromatography and HPLC. The final HPLC gave two active fractions and an herbicidal compound was obtained. By GC/MS analysis, the herbicidal compound was identified as montanine ($O^2$-methyl pancracine), an isoquinoline alkaloid. Montanine showed 100% of growth inhibition on the shoot and root of barnyardgrass (Echinochloa crus-galli) seedlings at $50\;{\mu}g\;mL^{-1}$ as compared with the control.

• Korean Journal of Weed Science
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• v.14 no.1
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• pp.42-48
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• 1994

The toxic compounds of sorghum stem extracts were isolated by different organic solvents and pH, and characterized and quantified in terms of their inhibition of seed germination and seedling growth in Echinochloa colona(L.) Link and radish(Raphanus sativus L.). Sequential partitioning of stem extract with various organic solvents with increasing polarity showed that all fractions of hexane, ethyl ether, methylene chloride, ethyl acetate, and the aqueous remainder inhibited germination and seedling growth in E. colona. Of the five fractions, the ethyl ether fraction had the greatest inhibitory effect on E. colona. Further separation of the ethyl ether fraction at different pH(pH 2-11) showed that phytotoxic compounds were acidic. The result indicates that the phytotoxin present in the stem extract may be nonpolar and acidic.

• Korean Journal of Weed Science
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• v.14 no.2
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• pp.156-162
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• 1994

To better understand the exact nature of the major toxic compound responsible for phytotoxicity of sorghum stem, the most toxic compound from the stem extract was isolated by rapid chromatography and subsequently purified by thin-layer chromatography(TLC) and high pressure liquid chromatography(HPLC). Of the eight fractions isolated by rapid chromatography, the fraction with solvent combinations of butanol (8) : acetic acid (1) : water (1) had the highest toxicity. Further separation of the fraction by TLC in a solvent mixture of butanol (24) : acetic acid (16.4) : water (7) : propanol (1) showed that the spot with an $R_f$ 0.71 had one major peak with retention time of 20.40 minutes. Upon subjecting gas chromatography and the HPLC fraction to the mass spectrometry, the toxic compound is probably one of the four compounds ; 1-methyl-1-(2-propynyl)-hydrazine, 1-aziridineethanol, 5-chloro-2-pentanone, and 2-(methylseleno)-ethanamine.

• Journal of Life Science
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• v.15 no.6 s.73
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• pp.871-878
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• 2005

This experiment was performed to examine the allelopathy effect of allelochemical substance on the crop plants. According to the experiment of the allelochemical substances in Hypochaeris radicata by HPLC, there are the differences at each part of plants. However, it is ascertained that there are 14 kinds of phenolic compounds ingredients that are $\rho$-hydroxybenzoic acid, chlorogenic acid, catechin, caffeic acid, syringic acid, salicylic acid, $\rho$-coumaric acid, ferulic acid, naringin, hesperidin, myricetin, trans-cinnamic acid, quercetin and naringenin. The chemicals like caffeic acid, ferulic acid, and naringenin are commonly included. The result of the chemical experiment shows that there are the differences at each season and part of plants. The leaves in May and blossoms and roots in July contain lots of phenolic acids. It is very high contents such as salicylic acid 2085.6 ${\mu}g/g$ and quercetin 1522.0 ${\mu}g/g$, especially in roots of plants. The result on the growth of crop plants treated by the aqueous extract of Hypochaeris radicata shows that the value of the control group and the test group are same in some cases. However, because the treat value of test group is towel'than that of control group in all items of the experiment, it is cofirmed that the growth of crop plants was inhibited and that the inhibitory effect was increased as its density of treatment was increased. The result of change in quantity shows that there are the differences at each kind of crop plants, but the inhibitory effect was increased as its concentration of treatment was increase with entire. As results, it is confirmed that H. radicata has the allelopathy effect to the crop plants. Especially the inhibitory effect on growth is high in gramineous crop, italian ryegrass and leguminous crop. purple alfalfa.