• The Korean Journal of Ecology
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• v.24 no.1
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• pp.61-66
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• 2001

The total amount of monoterpenoids in A. artemisiifolia var. elatior leaves was increased continuously after Apr. and the highest amount was in Jul. The major monoterpenoids in A. artemisiifolia var. elatior leaves were consisted of 29 compounds and were dominated by No. 2, octene, α -pinene, β -myrcene ,1,3,6-octatrine, endo-borneol and (-)-bornyl acetate. The allelopathic effects of A. artemisiifolia var elatior leaves on the roots and shoots elongation of the selected plants were studied and there were significant allelopathic effects. The effects were much different between the selected plants and the effects signifcantly became higher with the quantity of leaves used in the experiment. The Lactuca sativa, Achyranthes japonica, and Oenothera odorta were suffered much higher effects than the other species. The allelopathic effects were also different with the leaves sampled in different seasons and the effects in july were found a little higher than in June and May.

• 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.30 no.1
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• pp.34-42
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• 2010

Competitive ability, allelopathy, made the common ragweed (Ambrosia artemisiifolia var. elatior ) one of the most dangerous weeds in Korea. The aim of this research was to evaluate the role of common ragweed as test species under laboratory bioassay and glasshouse conditions. Inhibition effect of the leaf extract was higher than that of stem and root parts extracts on germination and seedling growth of weeds. The 5% concentration of leaf extract of common ragweed inhibited the germination rate of Echinochloa crus-galli, Digitaria sanguinalis and Cyperus microiria by 68.3, 74.6 and 87.3%, respectively, as compared to the control. Generally, increasing incorporation concentration inhibited seedling growth of weeds. Incorporation of 5% common ragweed residue significantly reduced the plant length of E. crus-galli, D. sanguinalis and C. microiria by 48, 63 and 68%, respectively, as compared to the control. Also, the values of dry weight were 72, 78 and 71%, respectively. Contrarily, the emergence rate of soybean and corn was not affected by the incorporation of 5% concentration of common ragweed residue. However, the dry weight was inhibited by 37 and 28%, respectively. These results suggest that common ragweed had the ability to control some weed species using toxic compounds like natural herbicide.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.396-404
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• 2010

Phenolic compounds, which are products of secondary metabolism, have been demonstrated to be widespread growth substances in plants. The objectives of this study were to identify the phenolic compounds in common ragweed (Ambrosia artemisiifolia var. elatior) by HPLC and to evaluate their effects on germination and seedling growth of three weed species. Under controlled conditions in Petri dishes at $25^{\circ}C$, $10^{-3}$ and $10^{-4}$ M solutions of phenolic compounds were evaluated in seed germination tests. Four phenolic compounds (caffeic acid, O-coumaric acid, ${\rho}$-coumaric acid and ferulic acid) in common ragweed plant were identified and their concentration was increased from the stage before flowering through full flowering stage. Treatment of O- and ${\rho}$-coumaric acids delayed the seed germination of Digitalia ciliaris, while the treatment of caffeic acid delayed the seed germination of Echinochloa crus-galli. In time to 50% germination ($T_{50}$), phenolic compounds at $10^{-4}$ M promoted in Cyperus microiria and E. crus-galli but the level of $10^{-3}$ M delayed the $T_{50}$ of those weeds. The O-coumaric acid inhibited seed germination and seedling growth of the tested weeds and especially it perfectly inhibited the root growth of E. crus-galli.