• Korean Journal of Weed Science
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• v.7 no.2
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• pp.144-155
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• 1987

Water extracts of polygonum hydropiper and Polygonum aviculare completely inhibited the germination of lettuce seeds. Methanol extracts from these two species also inhibited the seed germination of lettuce (Lactuca sativa) and Oenothera odorata. Fifteen phenolic acids in total were identified by GLC from P. hydropiper and eighteen from P. aviculare. The most common phenolic acids identified from P. hydropiper were sinapic, salicylic+vanillic and ferulic acid presented in all the fractions. In addition, salicylic+vanillic, tannic+gallic, sinapic, ferulic and p-coumaric acid seemed to be important phenolic compounds in terms of quantity. However, salicylic+vanillic acids were the unique phenolic acids occurred in all the fractions of P. aviculare. The others such as tannic+gallic, sinapic, ferulic, p-coumaric acid, p-cresol and catechol present in large amount appeared also the important phenolic substances influencing allelopathic effects of P. aviculare. Linolenic acid and oxalic acid were the major fatty and organic acids in both plant species, presented in 2.38mg/g and 20.588mg/g in P. hydropiper, 3.70mg/g and 14.288mg/g in P. aviculare, respectively, which seem to be exhibiting allelopathic effects of these plants. Total alkaloids were presented in low amount such as 0.20% in P. hydropiper arid 0.22% in P. aviculare which may not be important elements. Pet. ether extracts were 2.42% in P. hydropiper and 1.65% in P. aviculare, which exhibit another potential for allelopathic effects that need further investigation. Various authentic phenolic compounds at different concentrations inhibited the germination of lettuce seed, indicating that the phenolic substances identified here may be directly related to biologically active substance.

• Korean Journal of Organic Agriculture
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• v.22 no.1
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• pp.129-145
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• 2014

To evaluate the potential of Hypochoeris radicata L. for the development of environment-friendly organic materials, its growth characteristics, allelopathic effects and antifungal activity was investigated. The growth characteristics of H. radicata L. was investigated by measuring comparative number of shoot and flower, and the diameters of clones in mowing areas and non-mowing areas, respectively. As a result, the number of shoot and flower, and diameters of clones of H. radicata L. grown in mowing areas were much higher than those grown in non-mowing areas. Water extracts of H. radicata L. inhibited seed germination, and shoot, root and root hair growth of 14 test plants including Trifolium pratense, Festuca myuros, Bidens bipinnata and finally reduced heir biomass remarkably. The inhibitory effect of the extract was different depending on the kind and the part of tested plants. The extracts showed high antifungal activity against Pythium spp. and Phytophthora However, it showed comparably less antifungal activity against Rhizoctonia solani than Pythium spp. and Phytophthora. In conclusion, cutting H. radicata L. resulted increase of its vegetative and seed propagation and helped it to form large colony. Also it had an effect on growth of microbes and germination and growth of other plants. Therefore H. radicata L. holds the competitive dominant position in plant ecosystem in Jeju Island and it can be used as candidate of environment-friendly organic materials.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.371-379
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• 2010

Crimson clover (Trifolium incarnatum), hairy vetch (Vicia villosa) and rye (Secale cereale) are common leguminous cover crops. Because they contain water-soluble allelopathic substances that show a variable level in tissue depending on growth stage of the plants, the weed inhibition effects are dependent on the growth stage of cover crops. This study investigated the allelopathic effects of crimson clover, hairy vetch and rye on soybean, radish, oilseed rape and lettuce seeds germination and seedling growth. We used extract that were prepared from the shoots of crimson clover, hairy vetch and rye at different growth stages, vegetative growth stage, flowering stage, and fruiting stage. Applications of aqueous extracts from three growth stage of cover crops strongly affected to oilseed rape and lettuce seeds germination but the treatment resulted in a slight inhibition of the germination in soybean and radish. Radical length was more sensitive to aqueous extracts than seed germination rate. Especially, three cover crops extracts at vegetative growth stage highly inhibited seedling root growth of oilseed rape and lettuce by over 80% and 90% respectively. Furthermore, the $GR_{50}$ values were lowest in the treatment of extracts from vegetative growth stage and the level of phenolics was decreased by the order of vegetative growth stage, flowering stage and fruiting stage.

• The Korean Journal of Ecology
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• v.24 no.3
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• pp.125-130
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• 2001

The allelopathic effects of aqueous extracts from Trifolium repens were studied. Aqueous extracts of leaves, stems, roots and flowers of T. repens strongly inhibited the seed germination and seedling growth of Zoysia japonica. In general, the higher concentration of the extracts showed the more great inhibition effect. The phenolic compounds extracted from T repens were analysed and identified using gas chromatography. 14 phenolic compounds were isolated from the leaves, stems, roots and flowers: caffeic acid, p-hydroxy benzoic acid, ferulic acid, gallic acid, p-coumaric acid, vanillic acid, trans-cinnamic acid, 2,5 dihydroxy benzoic acid, syringic acid, 2-hydroxy cinnamic acid, benzoic acid, salicylic acid, phloroglucinol and phanylacetic acid. The seed germination and relative growth ratio of Z. japonica by 14 phenolic compounds were inhibited in whole treatment. Stronger growth inhibitor were benzoic acid, salicylic acid and trans-cinnamic acid. From these results it is suggested that the phenolic compounds from T. repens seemed to be responsible for the allelopathic potential.

• Korean Journal of Weed Science
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• v.14 no.1
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• pp.34-41
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• 1994

To better understand the allelopathic effect of sorghum(Sorghum vulgare L.), the inhibitory activities of water extracts of the stem, leaf and root, and of residues of the stem to major crops and weeds associated with them were evaluated. The allelopathic activity of sorghum plants was species specific, and depended on source and concentration. Germination, and shoot and root length of all test species were inhibited by the different concentrations of the stem extract. Among the crop species, radish showed the most inhibition, followed by wheat and rice. Maize was the least sensitive species. Of the weed species, Ipomoea triloba was most inhibited, followed by Echinochloa colona and Rottboellia cochinchinensis. The water extracts of leaves, stems, and roots significantly inhibited germination and seedling growth in E. colona and radish. The stem extract gave the greatest inhibitory effect on E. colona while all three extracts produced similar response in radish. In the greenhouse trial, sorghum stem residue placed on the soil surface as mulch significantly inhibited seedling growth in E. colona and radish, but not that in rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.652-665
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• 1997

Allelopathic effects on some crops(rice, barley, wheat, Chinese cabbage, leaf mustard, onion, welsh onion, tobacco, red pepper) for extracts of Phytolacca americana and Armoracia rusticana were investigated in MS solid medium. Germination percentage, radicle length, hypocotyl length, plant height, fresh weight, dry weight, and seedling vigor were rapidly inhibited by methanol extract from Phytolacca americana according to increase of the concentration in test plants. Autotoxicity of Phytolacca americana began to appear at concentrations greater than 50$\mu$l methanol extracts per 20ml medium. The fresh weight and dry weight of Phytolacca americana were also decreased by its own methanol extract according to increase of the concentration. Initial amounts of growth of all crops were also inhibited by methanol extracts from Armoracia rusticana, but the inhibitory effects were lowered than those of methanol extracts of Phytolacca americana. Of four fractions, ethyl acetate, petroleum ether, $1^{st}H_2O, 2^{nd}H_2O$, reextracted from methanol extracts of Phytolacca americana, the ethyl acetate fraction showed the highest allelopathic effects on germination percentage and initial amounts of growth. Chlorophyll contents of rice, barley and Chinese cabbage were more inhibited in the ethyl acetate fraction than in the other fractions. Free proline content of Chinese cabbage was increased 31.2 times in the 100$\mu l$ ethyl acetate fraction, and the contents of rice and barley were also increased according to concentration levels in the ethyl acetate fraction.

• Korean Journal of Weed Science
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• v.7 no.2
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• pp.156-164
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• 1987

Allelopathic activity of dominant upland weed species was determined using aqueous and methanol extracts and dried residues of the weeds. Germination and seedling growth of radish (Raphanus sativus L.) and sesame (Sesamum indicum L.) were greatly inhibited by 2% (w/v) aqueous extracts of Artemisia asiatica Nakai and Portulaca oleracea L., respectively. Great phytotoxicity on both indicator plants occurred by 2% (w/v) aqueous extracts of Capsel/a bursa-pastoris (L.) Medik. A complete inhibition in germination and seedling growth of radish was caused by 2% (w/v) methanol extract of A. asiatica. There was about 90% inhibition in germination and seedling growth of sesame due to 2% (w/v) methanol extracts of A. asiatica, P. oleracea and Trifolium repens L. Phytotoxic effects varied with extract solution, weed species and indicator plants employed, indicating that the weed species contained different contents and kinds of allelopathic chemicals. Water potential and pH adjusted to those of the extracts did not affect germination and seedling growth of the indicator plants. Phytotoxicity increased with increasing concentration of the extracts obtained from four suspected alleopathic weeds. Soil-incorporated plant residues of A. asiatica and P. oleracea caused greater phytotoxicity on radish than those of C. bursa-pastoris and T. repens.

• Korean Journal of Organic Agriculture
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• v.23 no.3
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• pp.481-495
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• 2015

The study researched germination of the plants and growth of Fungus according to concentration of aqueous extracts in order to provide basic data for developing natural agricultural resources by using Persicaria longiseta. The seed germination of Amaranthus spinosus was inhibited at 25% P. longiseta extract, while Agrostis stolonifera ssp. palustris was not affected at all concentrations tested. Especially, the seed germination rate and fresh weight of Trifolium incarnatum at 20% P. blumei extract were higher than those of control plot. The early growth of most receptor plant seedlings was promoted at 25% and 50% of P. blumei extracts, but the radicle growth of all receptor plants was significantly inhibited at > 25% of P. longiseta extract. The response of receptor plants to P. longiseta extract was different according to the plant species and the plant parts. The growth of plant pathogenic fungus in PDA medium showed an increasing inhibition tendency with increasing concentrations of P. longiseta extract. Especially, P. longiseta extract showed the greatest antimicrobial activity against Phytophthora infestans, Phythium graminicola, and Pythium venterpoolii. The content of total phenolic compound in P. longiseta was higher in leaves (1082.3 mg/L) but lower in roots (228.6 mg/L) and stems (207.8 mg/L), which is an allelopathic chemical. As these results are summarized, P. longiseta have competitive advantage because they release phenolic compounds with allelopathic effect and affect on germination, growth and fungi growth on underground flora compared to native plants and they have eligibility for natural herbicide and germicide.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.228-235
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• 1997

This experiments were conducted to determine the effect of allelopathy and autotoxicity in alfalfa. Among several alfalfa cultivars, the substances exudated from seven cultivars including Medicago sativa, c.v. Luna, Sparta, Magnum, Husky, Milkmaker, Challenger and Anchor inhibited the germination and seedling growth of radish, ranging from 60 to 80％. When allelopathic substances were exudated from the soil of the alfalfa-cultivated field, the increased levels of substance retarded the germination rate and seedling growth of radish and alfalfa. The inhibition rate was about 80％, compared with that of control. Thus, this study indicates that the allelopathy and autotoxicity substances of alfalfa influenced the germination and seedling growth in alfalfa itself and radish. When allelopathic substances were analysed by using gas chromatograph, several kinds of phenol compounds were detected as follows; Salicylic acid, hydroxybenzoic acid, vanillic acid, syringic acid, coumaric acid, and ferulic acid.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.04a
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• pp.174-175
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• 2005