• Korean Journal of Soil Science and Fertilizer
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• v.31 no.1
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• pp.46-50
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• 1998

This study was conducted with pot experiment to find out the effect of ginkgo leaf wastes application produced from the pharmaceutical process on the growth and yield of red pepper. Four kinds of ginkgo leaf wastes, the natural dried leaves, the leaves produced from the pharmaceutical process, the dried leaves to remove methanol after the pharmaceutical process, and the leaves washed with water to removal methanol and some activated materials after pharmaceutical process, were treated with two levels of application rates. The growth responses and yield were measured throughout the experimented period. Shoot growth of red pepper was inhibited by all treatment of ginkgo leaf wastes compared to the treatment of NPK and NPK+compost. Red pepper yields were also significantly reduced by treatment of the ginkgo leaf wastes except for the treatment of the water washed ginkgo leaf wastes, 1,000 kg/10a, which showed similar yield to NPK treatment. The major reseon to reduce the growth and yield seemed to be originated from the allelopathic substances of the ginkgo leaves. The organic matter contents of the soil after experiment were slightly increased with the treatment of the ginkgo leaf wastes and compost than that of NPK treatment. Based on these results, this study for using the ginkgo leaf wastes should be done more to utilize the wastes of the pharmaceutical process as a organic fertilizer.

• Korean Journal of Plant Resources
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• v.19 no.3
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• pp.405-410
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• 2006

A series of aqueous or methanol extracts from four different Korean salad plants were assayed to determine their allelopathy and antioxidant activity. The extracts applied on filter paper in a Petri-dish bioassay significantly inhibited root growth of against alfalfa (Medicago sativa) seedlings. Leaf extracts from 40 g dry tissue $L^{-1}$ of Aster yomena was most phytotoxic to alfalfa root growth, and followed by that of Cirsium japonicum, Taraxacum officinale, and Ixeris dentate. Methanol extracts of plants dose-dependently increased DPPH free radical scavenging activity in vitro. Antioxidant activity of methanol extracts from the same plant species was investigated, and the result showed high DPPH free radical scavenging activity in Cirsium japonicum, Aster yomena, and Ixeris dentate, however, in Taraxacum officinale was least activity. By means of HPLC analysis, chlorogenic acid, p-coumaric acid, and total phenolics with 7.68, 17.47 and 18.64 mg, $100g^{-1}$, respectively, showed the highest amounts in methanol extracts from Cirsium japonicum leaves. These results suggest that Compositae salad plants contain water-soluble substances with allelopathic potential as well as antioxidant activity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.101-106
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• 2006

Common thistle contains water-soluble substances that are phytotoxic to neighboring plant species. A series of aqueous extracts from leaves, stems, roots and flowers of common thistle (Cirsium pendulum Fisch.) were assayed against alfalfa (Medicago sativa) seedlings to determine their allelopathy, and the results showed highest inhibition in the extracts from flowers and leaves, and followed by stems, and roots. The extracts at 40 g dry tissue $L^{-1}(g\;L^{-1})$ applied on filter paper in a Petri-dish significantly inhibited root growth of test plant by 87%. Methanol extracts at 100 g $L^{-1}$ from leaves inhibited root growth of alfalfa and barnyardgrass (Echinochloa crus-galli) by 89 and 98%, respectively. Hexane and ethylacetate fractions of common thistle reduced alfalfa root growth more than did butanol and water fractions. Incorporation into soil with the leaf residues at $100g\;kg^{-1}$ inhibited shoot fresh weights of barnyardgrass and eclipta (Eclipta prostrate) by 88 and 58%, respectively, showing higher sensitivity in grass species. These results suggest that common thistle plants had allelopathic potential for eco-friendly vegetation management, and that especially their activities were differently exhibited depending on plant part.

• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.189-196
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• 1993

Allelopathic inhibition by substance(s) originated from sicklepod(Cassia tora L.) seed on germination of other plant seeds, was confirmed and used to elucidate general mechanism of allelopathy which was occurred widly in natural and/or agricultural ecosystems. The mechanism was deduced from changes in water contents, ${\alpha}$-amylase activities, protease activities, concentrations of abscisic acid and total phenolic compounds during germination of rice and radish seeds treated with water-soluble extracts of sicklepod seeds. The results obtained were summarized as follows. 1. The % germinations of radish, rice, lettuce, barley seeds were decreased by substances originated from crushed sicklepod seeds. 2. By the treatment of water-soluble extracts of sicklepod seeds, the inhibition of germination of radish seeds was occured with the sequential phenomena of increase of protease activity(synthesis), decrease of water content and increase of total phenolic compounds content. 3. In rice, the inhibition of seed germination by the water-slouble extracts of sicklepod seeds was related to increase of abscisic acid concentration and then decrease of ${\alpha}$-amylase activity(synthesis).

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.131-140
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• 1995

This experiment was conducted to test the effect on germination and seedling growth of major industrial crops and weed control potential using alfalfa plant. When dried alfalfa residues were mixed into vermiculite, germination, length of shoot and root of crops, such as Perilla frutescens, Sorghum nevosum, Platycodon grandiflorum and weeds, Digitaria saguinalis, Setaria viridis, Siegesbechia pubescens, Ammaranthus lividus, and Solanum nigrum, were significantly inhibited as the dried residue concentration increased. More than 10% concentration of the dired residue caused 80% germination and growth inhibition. The fresh alfalfa exudation also inhibited the germination and seedling growth of crop, barley, rye, alfalfa, and sesame, and weeds, Echinochloa crus-galli, Siegesbechia viridis, and Portulaca oleracea. The degree of inhibition showed the different response according to the fresh exudation concentration, types of crops and weeds. Generally, as the exudation concentration increased, the germination and seedling growth of crops and weeds inhibited. The exudation of dried residue also exhibited the strong inhibition effect on germination and seedling growth of crops, alfalfa, Platycodon grandiflorum, barley, sesame, rye and weeds, D. sanguinalis, S. pubescens, S. viridis, P. oleracea, E. crus-galli, At the 10% concentrations, S. pubescens, and P. oleracea were not germinated and showed only 15% germination in the S. viridis. From this study, would conclude that alfalfa plant contained water soluble phytotoxic substances which were inhibitory to weeds and crops. This results suggest that alfalfa had some possibility to control some weed species using toxic compounds like natural herbicide.

• 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.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.169-175
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• 1988

This experiment was conducted to determine the presence of allelopathic substance in Portulaca oleracea L. Water and methanol extract from P. oleracea markedly inhibited the germination of lettuce, rice, raddish etc., indicating the presence of biological substances. The biochemical substances such as ferulic, p-coumaric, salicylic, vanillic, p-hydroxybenzoic acid etc., belonging to phenolic compounds were detected in a large amount, which may be responsible for exhibiting inhibitory effects. Various phenolic compounds were detected from different samples such as freshly, dried plants, seeds and callus. The highest amount of tannic and gallic acids were detected in dried samples of P. oleracea, the highest grantity of salicylic and vanillic acids in fresh samples, the largest amount of ferulic acid in seed sample, the highest amount of p-hydroxybenzoic and p-chlorobenzoic acids in callus. Linolenic acid was presented in amount of 9.203 mg/g in dried plant of P. oleracea as one of the major fatty acids and oxalic acid presented 27.941 mg/g as one of the major organic acids. These compounds seemed to be related to inhibitory effect of P. oleracea which needs further study.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.2
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• pp.160-167
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• 1992

The growth of weeds and some other plants has been considered to be inhibited by sicklepod(Cassia tora L.) sharing the habitat. The study was conducted, for the first time, to propose that this phenomenon is not only due to competition for physical and nutritional conditions but also due to allelopathy. In addition, autotoxicity of sicklepod was examined. The results are summarized as follows. 1. Rice sheath length reduced progressively from 18 % to 36 % with increasing the concentration of treating aqueous extracts of sickle pod seeds, but rice germination was not affected. In contrast, radish hypocotyl length was not reduced by the aqueous extract treatment but radish germination was significantly reduced by 66 % at 1 : 10 and 1 : 5 treatment. 2. Total chlorophyll contents in rice seedling decreased from 50 % to 65 % by treatment of seed aqueous extracts diluted from 1 : 50 to 1 : 5 ratio. 3. Aqueous extracts of sicklepod leaves significantly reduced hypocotyl length and fresh weight in radish and germination in rice, but mung bean was slightly affected by aqueous extracts only in fresh weight. 4. Volatiles from fresh, immature seeds with husk reduced the radish germination and seedling growth and radish root growth appeared to be more sensitive to the exposure to volatiles from fresh immature seeds than both germination and hypocotyl growth. 5. Volatiles from sickepod leaves inhibited germination and growth of radish, rice and mung bean, and seedling growth was more sensitive to volatiles from leaves than germination. 6. Volatiles from sicklepod leaves reduced germination and radicle length of sicklepod itself. 7. Collectively, it is concluded that there are water-soluble and volatile substances responsible for allelopathy in sicklepod.