• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2005.04a
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• pp.3-14
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• 2005

To investigate phytotoxic substances in some donor plants and their biological activities, seed germination and seedling growth of receptor plants were examined at different concentrations of aqueous extracts and essential oils of the donor plants. Germination of some receptor species was inhibited by the extracts, while seedling growth was decreased to a lesser degree than in the germination test. Germination, seedling growth and dry weight growth of Achyranthes japonica grown in pot were proportionally inhibited by the extracts. Volatile substances emitted some donor plants caused inhibitory effects in the germination and seedling growth of the receptor species. Essential oil of the plants extracted by Karlsruker's apparatus Inhibited growth of microorganisms, callus growth and root hair development of receptor plants. The cortical cells at the root tips of Latuca sativa treated with essential oils showed contraction of the cytoplasm, resulting in plasma membranes becoming detached from the cell walls and the cells metamorphosing irregularity. Accumulation of lipid granules Inside contracted cytoplasm and degeneration of mitochondrial cristae were also observed. The GC/MS method was employed for analysis and identification of allelochemicals from donor plants. Sixty-one chemical substances such as camphene, cineole etc. were identified from essential oils of Artemisia argyi.

• 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.

• The Korean Journal of Ecology
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• v.20 no.2
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• pp.111-123
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• 1997

Although the number of active workers in Australia is small the range of species associated with allelopathic activity is at least as large as that reported elsewhere in the world. In this paper, work on native and infroduced plants is discussed under the general heading of "conventional allelopathy", thiat is, interactions between plants which are chemically mediated. Work in which compounds associated with allelopathy, in the conventional sense, are biologically active in different contexts is included under "unconventional allelopathy", Examples which involve microorganisms, corals and other marie species, and mammals are discussed.mmals are discussed.

• Journal of Ecology and Environment
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• v.34 no.3
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• pp.279-286
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• 2011

The effect of allelochemicals on growth, root nodule nitrogen fixation activity, and ion patterns of soybeans were investigated. We prepared 50 g/L (T50), 100 g/L (T100), and 200 g/L (T200) extract concentrations by soaking fresh red pine needles in a nutrient solution. Adding needles to the nutrient solution increased the content of total phenolic acids, osmolality, and total ions. The total phenolic content in the T50, T100, and T200 extracts were $206{\pm}12.61$, $335{\pm}24.16$, and $603{\pm}12.30$ mg gallic acid equivalents, respectively. The $K^+$, $Mg^{2+}$, $Ca^{2+}$, and $PO_4^{3-}$ content increased by adding needles to the nutrient solutions, whereas $SO_4^{2-}$ content decreased. The growth inhibition of soybeans was proportional to the needle extract concentrations, and the T100 and T200 concentrations resulted in remarkable growth inhibition. On day 20 after treatment, dry weight and nitrogen fixation activity of the root nodules were reduced by the T100 and T200 treatments, whereas the T50 treatment was not difference from the control. After day 10, total ion content in all treatment groups was not different in comparison with the control. However, total ionic content in all treatment groups decreased significantly compared with that in the control after day 20. The lowest total ion value was found for the T200 concentration. The T200 treatment also resulted in significantly reduced $SO_4^{2-}$ content. The amounts of $Mg^{2+}$, $Ca^{2+}$, and $Mn^{2+}$ were higher than those of the control for the T50 treatment on day 10 and for T100 on day 20 after treatment. A significant increase in osmolality was observed in the T200 treatment on day 10 and in the T100 treatment on day 20. These results suggest that under severe allelochemical stress conditions, a remarkable reduction in nodule formation, nitrogen fixation activity, and ion uptake eventually resulted in a decrease in leaf production. Furthermore, increased $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Mn^{2+}$, and osmolality in soybeans exposed to lower concentrations of allelochemicals than the critical stress level helped overcome the stress.

• The Korean Journal of Ecology
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• v.17 no.1
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• pp.23-35
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• 1994

To investigate phytotoxic substances in Artemisia argyi, the donor plant, and their biological activities, seed germination and seedling growth of receptor plants such as Arundinella hirta, Echinochloa crus-galli, Rumex crispus and Lactuca sativa were examined at different concentrations of aqueous extracts of the donor plant. Germination of four receptor species was inhibited by the extracts, while seedling growth was decreased to a lesser degree than in the germintion test. Germination, seedling growth and dry weight growth of Achyranthes japonica grown in pot were proportionally inhibited by the extracts. Volatile substances emitted from A, argi plant caused slight inhibition in the germination and seedling growth of the receptor species. Essential oil of the plant extracted by Karlsruker's apparatus inhibited growth of microorganisms and callus growth of Pinellia ternata and Oryza sativa. The GC /MS method was employed for analysis and identification of allelochemicals from A. argyi leaves. Sixty-one chemical substances such as a-pinene, camphene, 1. 8-cineol, etc. were identified from essential oil of A. argyi. The results of this experiment on seed germination, seedling growth, microorganism culture and tissue culture indicated that naturally occurring chemical substances from A. argyi would be responsible for the growth inhibition of plants studied.

• Journal of Korea Foresty Energy
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• v.22 no.3
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• pp.11-19
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• 2003

Allelopathic effects of black locust(Robinia pseudoacacia L.) was evaluated through germination tests using 13 different species including R. pseudoacacia itself. The water extract from leaf or root of R. pseudoacacia was separately tested. Seed germination of several species was inhibited in the presence of leaf or root extract, although the level of germination was in a wide range depending on the species. Seed germination of R. pseudoacacia was suppressed by 30 % in its leaf extract. Among tested tree species, Hibiscus syriacus and Alnus frma showed significantly inhibited germination in the root extracts whereas Thuja orientalis exhibited germination inhibition in the leaf extract. HPLC was carried out to identify allelochemicals in extracts of leaf and root using eight authentic phenolic compounds that are known to be responsible for allelopathy. The major phenolic compounds occupying about 40 % of total phenolic acids were gentisic acid in leaves and vanillic acid and syringic acid in roots. The leaves contained 7 times more phenolic acids than the roots. Among 8 tested phenolic compounds vanillin was detected only in roots and coumaric acid in leaves. Consequently, 3 out of 13 species showed significantly inhibited germination due to leaf or root extract. This germination test indicates that the inhibitory allelopathic effect by R. pseudoacacia is caused by chemical interaction not by nutritional competition and that the allelochermicals of black locust act species-specifically. No specific influence of the total amount of phenolic compounds on the allelopathic inhibitory germination and the synergic effect by each phenolic compound may play a role for the allelopathic effect by R. pseudoacacia.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.114-114
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• 2022

There are 28 families and 166 species of exotic weeds on agricultural land and among these, 23 families and 80 species of exotic weeds occur on pastures. Among them, the Solidago altissima is a perennial weed belonging to the asteraceae family and it is an exotic weed that spreads to the surrounding area using methods such as high seed production, vegetative propagation using underground rhizomes and allelochemical. Accordingly, in 2009, the Ministry of Environment designated it as an ecosystem-disrupting species. This study was conducted to obtain basic data about the effects of S.altissima derived allelochemicals on forage crops. The root of S.altissima was separated, dried in the shade and then pulverized to prepare an root powder. Powder was repeatedly extracted with methanol for 3 days and concentrated under reduced pressure to obtain an root methanol extract. Dissolve the extract in distilled water, dispense it in a separate-funnel and proceed with liquid-liquid extraction by adding equal amounts of n-haxane (Hex), chloroform (CHCI₃), ethyl acetate (EtoAC), and butanol (BuOH) in order of increasing polarity. A seed-bioassay was performed using fractions for each solvent, followed by separation and purification by silica gel column chromatography. As a result of the fraction germination test for each solvent, the IC₅₀ values using the fresh weight of each fraction were 898.3 mg L^-1, 676.3 mg L^-1, 1160 mg L^-1 and 1360 mg L^-1. CA, CB, and CC fractions were obtained through primary silica gel column chromatography that used CHCI₃ fraction. As a result of seed-bioassay using each fraction, the IC₅₀ values for the fresh weight of each fraction was 537.3 mg L^-1, 1280 mg L^-1 and 1947 mg L^-1. Based on this, 5 fractions were obtained as a result of secondary silica gel column chromatography using the CA fraction. A seed-bioassay was performed, as a result, the lowest IC₅₀ value was calculated as 226.7 mg L^-1 in the CAE fraction. Based on this, the fraction was analyzed by GC-MS. The results of this study can be used as basic research data on the effects of weeds on forage crops and allelochemicals secreted from S. altissima.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.5
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• pp.402-406
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• 2003

Greenhouse and laboratory studies were conducted to determine the allelopathic potentials of extracts or residues from sweet potato (Ipomoea batatas L. (Lam). The extracts applied on filter paper in a Petri dish bioassay significantly inhibited root growth of alfalfa. Aqueous leachates at 40g dry tissue $\textrm{L}^{-1}$ (g $\textrm{L}^{-1}$) from leaves showed the highest inhibition against alfalfa, and followed by stems and roots. Alfalfa root growth was significantly inhibited by methanol extracts of the same plants as the concentration increased. The effect of residue incorporation into soil on seedling growth of com, soybean, barnyard grass and eclipta was examined in the greenhouse, and results showed that the leaf residues at 200g $\textrm{kg}^{-1}$ by plant parts inhibited shoot dry and root dry weights of test plants by 60-80%. By means of HPLC, causative allelopathic substances present in plant parts of sweet potato "Sinyulmi" were identified as coumarin, trans-cinnamic acid, o-coumaric acid, p-coumaric acid, and chlorogenic acid. Total content of these compounds for leaves extracts were detected as the greatest amount in EtOAc fraction, especially trans-cinnamic acid was the greatest component. These results suggest that sweet potato plants have herbicidal potentials, and that their activities exhibit differently depending on plant parts.ant parts.

• Plant Resources
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• v.7 no.1
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• pp.69-76
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• 2004

Lettuce (Lactuca sativa L.) is known to contain water-soluble substances that are biologically active. Aqueous or methanol extracts and residues from leaves of lettuce plants were assayed to determine their allelopathic effects, and the causative allelochemicals from fractions were quantified by means of HPLC analysis and bioassayed. Extracts from oven-dried leaf samples were more phytotoxic than those from freeze-dried samples. Leaf extracts of 40 g L$^{-1}$ were completely inhibitory on root growth of alfalfa (Medicago sativa L.), while root growths of barley (Hordeum vulgare L.) and soybean (Glycine max L.) were less sensitive. Early seedling growth of both alfalfa and barnyard grass (Echinochloa crus-galli) was significantly reduced by methanol leaf extracts. The major allelopathic substances analyzed by HPLC were coumarin, trans-cinnamic acid, o-coumaric acid, p-coumaric acid and chlorogenic acid. Of them p-coumaric acid was found as the greatest amount (8.9 mg 100 g$^{-1}$ ) in the EtOAc fraction; only coumarin was found in all the fractions. Hexane and EtOAc fractions of L. sativa reduced alfalfa root growth more than did BuOH and water fractions. These results suggest that lettuce had potent herbicidal activity, and that its activity differed depending on type and amount of causative compounds by fraction.