• The Korean Journal of Ecology
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• v.24 no.1
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• pp.67-73
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• 2001

The allelochemicals from aqueous extracts of A. artemisiifolia var. elatior leaves and roots were analyzed and 60 compounds in the leaf and 53 compounds in the roots were inspected. The main compounds were acids,. especially phenolic acids and some non-acids. The total amount of compounds in the aqueous extracts of A. artemisiifolia var. elatior leaves was higher than in the roots. The aqueous extracts had much high inhibiting effects on the germination and seedling elongation of selected plants. In both cases, the inhibiting effects were very different with different selected plants and increased significantly as the concentration of aqueous extracts increased. Capsicum annum, Achyranthes japonica, and Oenothera odorta plants were suffered more significant inhibition effects than Raphnus sativus, Cucumis sativus, Brassica camperstris plants. Aqueous extracts from leaves had slightly higher inhibition effects than the aqueous extracts from the roots.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.271-278
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• 2011

The allelopathic effects of Lantana camara L. (Family:Verbenaceae) on germination and seedling establishment of some agricultural crops and weed species have been identified. Aqueous extracts of dry leaves and contaminated soil where L. camara is grown were used to verify allelopathic effect on seed germination of five bioassay species; Raphanus sativas, Capsicum annum, Lycopersicum esculantem, Crotalaria juncia and Chromoleana odorata. Fifty seeds from each bioassay species were placed in a petri dish containing leaf extracts or contaminated soil, and seed germination were examined after 3 days. The plant house experiments were carried out to evaluate the impact of L. camara contaminated soil and leaf debris using L. esculantem as the indicator plant. Seed germination of L. esculentem, C. junica and Capsicum annum was significantly inhibited by L. camara contaminated soil. However, the degree of inhibition varied among the bioassay species. The aqueous extract of dry leaves of L. camara was highly phytotoxic and it significantly reduced seed germination of all bioassay species. There was a decline in plant height, leaf area and shoot dry weight of tomato only in early growth stages when grown in L. camara contaminated soils. However, incorporation of leaf debris into soil affected the vegetative growth of tomato in early stages when the leaf debris concentration was increased. Growth recovered at the latter part of the life cycle. On the basis of these results it can be concluded that the allelochemicals in L. camara contaminated soils are harmful to the seed germination of crop species. The adverse effect was present only during the early growth stages and it did not suppress the latter part of the plant growth. These responses are attributed to allelopathic effects which need confirmation under field conditions.

• Korean Journal of Medicinal Crop Science
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• v.25 no.4
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• pp.244-251
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• 2017

Background: The application of crop rotation systems may reduce the occurrence of soil-borne diseases by releasing allelochemicals and by subsequent microbial decomposition. Methods and Results: For reduction of ginseng root rot by the crop rotation system, after harvesting 6-year-old ginseng, fresh ginseng was grown along with continuous cultivation of sweet potato, peanut, and bellflower. Growth of 2-year-old ginseng was significantly inhibited in the continuous cultivation than in the first cultivation. Sweet potato, peanut and bellflower cultivations assisted in obtaining normal yields of ginseng in the first year after the harvest of 6-year-old ginseng. Salt concentration, potassium and sodium contents were gradually decreased, and, organic matter was gradually increased through cirp rotation. Phosphate, calcium and magnesium contents were not altered. The density of the root rot fungus was gradually decreased by the increase in crop rotation; however it was decreased distinctly in the first year compared to the second and third year. The severity of root rot disease tended to decrease gradually by the increase of crop rotation. Conclusions: Short-term crop rotation for three years promoted the growth of ginseng, however root rot infection was not inhibited significantly, although it was somewhat effective in lowering the density of the root rot pathogen.

• Korean Journal of Medicinal Crop Science
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• v.24 no.4
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• pp.294-302
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• 2016

Background: Crop rotation plays an important role in improving soil chemical properties, minimizing the presence of disease pathogens, and assists in neutralizing autotoxic effects associated with allelochemicals. Methods and Results: Five rotation crops of sudan grass, soybean, peanut, sweet potato, and perilla were cultivated for one year with an aim to reduce yield losses caused by repeated cropping of ginseng. In 2-year-old ginseng grown in the same soil as a previous ginseng crop, stem length and leaf area were reduced by 30%, and root weight per plant was reduced by 56%. Crop rotation resulted in a significant decrease in electrical conductivity, $NO_3$, and $P_2O_5$ content of the soil, whereas organic matter, Ca, Mg, Fe, Cu, and Zn content remained-unchanged. Soil K content was increased following crop rotation with sudan grass and peanut only. Rotation with all alternate crops increased subsequent ginseng aerial plant biomass, whereas root weight per plant significantly increased following crop rotation with perilla only. A significant positive correlation was observed between root rot ration and soil K content, and a significant negative correlation was observed between ginseng root yield and the abundance of actinomycetes. Crop rotation affected the soil microbial community by increasing gram negative microbes, the ratio of aerobic microbes, and total microbial biomass whereas decreases were observed in actinomycetes and the ration of saturated fatty acids. Conclusions: In soil exhibiting crop failure following replanting, crop rotation for one year promoted both soil microbial activity and subsequent ginseng aerial plant biomass, but did not ameliorate the occurrence of root rot disease.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.133-141
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• 1995

The effects of allelochemicals from medicinal plants have been studied as photo-synthetic inhibitor for photoautotrophic(PA) cultured cells. The extracts from 9 plant species were used for measuring the physiological effects on the liverwort cultured cell in following areas; germination inhibition, chlorophyll contents, hill activity, cell viability, photosynthetic oxygen evolution,and protein pattern changes on SDS PAGE. Germination inhibitions were detected in all plant after treating with 10% extract. Especially, treatment with 10% extract from Pulsatilla koreana and Aconitum carmichael inhibited germinations completely. Chlorophyll fornation was inhibited completely by treating PA cells with extract of Pulsatilla koreana, whose effect was similar to that of DCMU 10-3M, inhibitor for photosynthetic electron trans-fer. The treatment with extract from Pulsatilla koreana on PA cell showed the highest hill activity and the lowest cell viability among extracts studied. Oxygen releasing has been decreased down to 14-77% after treating with extracts from Pinellia ternata, Araliacont inentaila, Pulsatilla koreana and Vitex rotundifolia. Especially, 60$\mu$l of Pulsatilla koreana extract into 2ml mixture of PA cell inhibit-ed oxygen release up to 50%. Protein bands on SDS-PAGE, 14kD, 31kD, 41kD, 53kD, and 73kD, were not detected after treating Pulsatilla koreana extract on PA cells.

• Korean Journal of Environmental Agriculture
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• v.24 no.4
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• pp.391-397
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• 2005

This study was carried out to examine the allelopathic effect of the aqueous extract of Hypochaeris radicata L. on growth of three gramineous forage crops, tall fescue, perennial ryegrass and italian ryegrass. The result on relative elongation ration (RER) of gramineous forage crops treated with the aqueous extract of Hypochaeris radicata L. and the change of quantity generally indicated the inhibitory effect. The inhibitory effect was increased as its concentration was increased. As a result, it is ascertained that the aqueous extract of Hypochaeris radicata L. has allelopathy effect. According to the chemical experiment of the allelochemical substances in Hypochaeris radicata L. by HPLC, there are the differences at each part of plants. However, it is ascertained that there are eleven phenolic compounds, ${\rho}-hydroxybenzoic$ acid, chlorogenic acid, catechin, caffeic acid, syringic acid, salicylic acid, ${\rho}-coumaric$ acid, ferulic acid, hesperidin, trans-cinnamic acid and naringenin. Especially three phenolic acids such as caffeic acid, ferulic acid and naringenin were detected from all part of the plant.

• The Korean Journal of Ecology
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• v.28 no.3
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• pp.135-139
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• 2005

This study was carried out to find the allelopathic effect of volatile materials released from Eupatorium rugosum. The GC method was employed for analysis of volatile materials from E. rugosum and 49 chemical substances were identified such as $\beta$-caryophyllene, $\alpha$-terpinenol, chamazulene, bornyl acetate, $\alpha$-pinene, etc. including unidentified three chemicals. Germination test in Phaseolus radiatus was done to find the inhibition effect of volatile materials using some chemicals which were proved to be important component or much amounts ones in E. rugosum. It was strongly inhibited by linalool and terpinen-4-ol. Seedling elongation and radicle growth of that were proportionally inhibited by the concentration of the essential oil, especially $\alpha$-pinene and bornyl acetate. Biomass of receptor plant was slightly decreased more than 58 ${\mu}l$ of the extract in case of $\alpha$-pinene, while it was decreased more than 19 ${\mu}l$ of that in bornyl acetate but it was shown non-significant. From the above results, it was found that volatile materials from E. rugosum showed a allelopathic effect and also $\alpha$-pinene, bornyl acetate, linalool and terpinen-4-ol used in bioassay were some of major allelochemicals in germination inhibition and especially linalool and terpinen-4-ol are prominent effect on growth inhibition of other plant.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.285-294
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• 1994

Dried top and root extracts of seven different weed species, fresh top and root extracts, and various concentrations of extract (0, 5, 10 and 15%, W/V) and residue rate (0.0, 0.25. 0.5, 0.75 and 1.0%) of velvetleaf (Abutilon theophrasti Medic.) were used to study their allelopathic effects on alfalfa in the laboratory and greenhouse. Top and root aqueous extracts of common lambsquarter (Chenopodium album L.), giant foxtail (Setaria faberii Herrm), redroot pig-weed (Amaranthus retroflexus L), velvetleaf, large crabgrass (Digitaria sanguinalis L), canada thistle (Cirsium arvense L.) and prostrate knotweed (Polygonium aviculare L.) significantly inhibited germination, seedling length, weight, and vigor in alfalfa. Top growth extracts of weeds exhibited greater allelopathic effects than root extracts. Alfalfa test species, WL-320, responded significantly different to the various weed species extracts in terms of allelopathic effect. The regression slopes of various top extracts showed significant variation with respect to germination percentage. Velvetleaf (b=3.69) extracts were the most inhibitory, while large crabgrass (b=2.39) extracts had the least allelopathic effect on alfalfa. When compared the activity of fresh velvetleaf extract to that of dry velvetleaf extract, dry extract was more inhibitory to alfalfa germination and seedling growth. Germination, seedling length and weight of alfalfa were inversely proportional to the concentration of dried velvetleaf extracts. Seedling emergence and survival percentage was inhibited by velvetleaf residue mixture treatment. Also, more of the toxic effects were observed from the dried top extracts, as compared to extracts from fresh top and root. These results demonstrate the allelopathic activity of different weed species extracts and suggest that weeds may affect crop growth and development due to the inhibitory effects of allelochemicals present in weed tissue.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.295-305
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• 1994

Greenhouse and laboratory studies were conducted to investigate the allelopathic potential of alfalfa and vetch residues on soybean and corn using various extract concentrations (0, 5, 10, 15 and 20%, w/v) and residue rates (0, 0.25, 0.5, 0.75 and 1%, w/w). Aqueous extracts of alfalfa (Medicago sativa L.) and vetch (Vicia spp.) exhibited an allelopathic effect on soybean and corn seed germination, seedling length and weight. The degree of inhibition significantly increased as the aqueous extract concentration increased. Alfalfa and vetch 20% extracts reduced soybean seed germination, seedling length and weight by 35%, 57%, 32% and 15%, 42%, 25% respectively, when compared to control. Corn germination, seedling length and weight was inhibited by 20%, 23%, 38% by alfalfa and 19%, 18%, 35% by 20% vetch extracts. Alfalfa and vetch extracts inhibited secondary root formation and branching as the extract concentration increased. Alfalfa and vetch 20% extracts inhibited by 41% and 32% secondary root numbers, respectively as compared to control. It was found that the aqueous extract of alfalfa resulted in greater reduction in germination, seedling length and weight of soybean than that of vetch. Alfalfa and vetch 1% residue rate inhibited soybean plant height by 30% and 10%, leaf area by 31% and 23%, and dry weight by 18% and 1%, nodule number by 27% and 20% also. Alfalfa and vetch residue significantly enhanced plant height, leaf area and dry weight of corn. The maximum stimulation occurred with 0.25% and 1% of alfalfa and vetch residue rates, respectively. Plant height, leaf area, and dry weight increased by 23%, 59%, 58% and 17%, 52%, 94% with alfalfa and vetch residues of 0.25% and 1%, respectively. This study demonstrates that there is an allelopathic potential resulting from alfalfa and vetch residues on soybean growth and yield. It also suggests that these residues may affect crop growth and development due to the inhibitory or stimulatory effects of allelochemicals existing in the residue.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.221-231
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• 2010

A simple extraction method was applied to control four selected cyanobacteria, solitary (SMA) and colonial Microcystis aeruginosa (CMA), and green algae, Scenedesmus quadricauda and Chlorella vulgaris using a domestic plant and mineral. Three kinds of concentrations (1, 5, and 10 mg $L^{-1}$) of three fresh plants Camellia sinensis, Quercus acutissima, and Castanea crenata, three minerals loess, quartz porphyry, and natural zeolite, and plant-mineral composite, totally seven materials were prepared with the simple extraction processes: drying and grinding of material, water-extraction by high temperature-sonication and filtering. Cyanobacteria SMA and CMA (over 60% of control) were effectively inhibited with the low concentration (1 mg $L^{-1}$) of plants Q. acutissima and C. crenata and natural zeolite, while green alga S. quadricauda (below 50% of control) also retarded in growth. Low concentrations (1 mg $L^{-1}$) of C. sinensis effectively increased the growth of C. vulgaris, while loess also induced the algal growth of S. quadricauda. Therefore, our results indicate that crude extract of domestic plants, Q. acutissima and C. crenata can be also useful to control the cyanobacterial bloom in eutrophic lake, whereas C. sinensis and loess may be a good growth factor or useful media for the algal mass culture.