• Journal of Plant Biology
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• v.32 no.1
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• pp.41-49
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• 1989

Phenolic compounds such as gallic acid, ferulic acid, p-hydroxybenzoic acid, vanillic acid, salicylic acid, tannic acid, and hydroquinone were identified from the aqueous extracts and volatile substances of tomato plant by paper chromatography, high performance liquid chromatography and gas chromatography. The seed germination and seedling growth of the experimental species, lettuce and egg plant, were severely inhibited in 5$\times$10-3M of phenolic reagents identical to those identified from tomato plant. Germination and growth rate of test species in 5$\times$10-4M and 5$\times$10-5M were higher than that of 5$\times$10-3M. Therefore, 5$\times$10-3M of phenolic compounds would be assumed to be threshold concentration for allelopathic effects.

• 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.

• Journal of Ecology and Environment
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• v.32 no.1
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• pp.9-12
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• 2009

Artemisia capillaris and Artemisia iwayomogi are weeds used as medicinal plants in Korea under the name "Injin". I collected leaves of A. capillaris and A. iwayomogi, examined them for phytotoxic effects from volatile substances and determined the composition of monoterpenes in the leaves. The effects of volatile substances from each species on seed germination and radicle elongation in each of the two Artemisia species were assessed. The volatile substances of A. capillaris did not negatively affect the seed germination of A. capillaris, but they did inhibit radicle elongation. Rates of seed germination of A. iwayomogi decreased when the seeds were exposed to high concentration of A. capillaris volatile substances. The inhibition of seed germination and radicle elongation by volatile substances from both Artemisia species was stronger for A. iwayomogi than for A. capillaris. I identified the monoterpenoids from the leaves with a gas chromatograph-mass spectrometer (GC-MS). The main constituents of A. capillaris were acenaphthylene (37.91%), $\beta$-pinene (12.08%), 4-carene (10.61%) and $\gamma$-curcumene (9.92%), while those of A. iwayomogi were germacrene-$\delta$ (32.15%), borneol (21.24%), camphor (20.45%) and trans-caryophyllene (7.75%).

• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.354-361
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• 2021

Understanding the phytotoxic mechanism of methyl bromide (MB), an essential fumigant during the quarantine and pre-shipment process, is urgently needed to ensure its proper use and reduce international economic losses. In a previous study, two main MB-induced toxic mechanisms such as reactive oxygen species (ROS) and auxin distribution were selected by analyzing transcriptomic analysis. In the study, a 3-week-old A. thaliana was supplied with 1 mM ROS scavengers [N-acetyl-L-cysteine (NAC) or L-glutathione (GSH)] and 1µM indole-3-acetic acid(IAA) three times every 12 h, and visual and gene expression assessments were performed to evaluate the reduction in phytotoxicity by supplements. Phytotoxic effects on the MB-4h exposed group were decreased with GSH application compared to the other single supplements and a combination of supplements at 7 days post fumigation. Among these supplements, GSH at a concentration of 1, 2, and 5mM was suppled to A. thaliana with MB-fumigation. During a long-term observation of 2 weeks after the fumigation, 5 mM GSH application was the most effective in minimizing MB-induced phytotoxic effects with up-regulation of HSP70 expression and increase in main stem length. These results indicated that ROS was a main key factor of MB-induced phytotoxicity and that GSH can be used as a supplement to reduce the phytotoxicity of MB.

• Asian Journal of Atmospheric Environment
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• v.5 no.2
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• pp.65-78
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• 2011

Ozone ($O_3$) is a main component of photochemical oxidants, and a phytotoxic anthropogenic air pollutant. In North America and Europe, the current concentration of $O_3$ has been shown to have significant adverse effects on vegetation. In this review, we summarize the experimental studies on the effects of $O_3$ on the growth and photosynthetic activity of Japanese forest tree species to understand the present knowledge and provide sound basis for future research toward the assessment of $O_3$ impacts on Japanese forest ecosystem. Since the 1990s, several Japanese researchers have conducted the experimental studies on the effects of ambient levels of $O_3$ on growth and physiological functions such as net photosynthesis of Japanese forest tree species. Although the sensitivity to $O_3$ of whole-plant growth is quite different among the species, it was suggested that the current ambient levels of $O_3$ in Japan are high enough to adversely affect growth and photosynthetic activity of Japanese forest tree species classified into high $O_3$ sensitivity group such as Japanese beech. The N load to soil has been shown to reduce the sensitivity to $O_3$ of Japanese larch and increase that of Japanese beech. To establish the critical level of $O_3$ for protecting Japanese forest tree species, therefore, it is necessary to take into account the N deposition from the atmosphere. There is little information on the combined effects of $O_3$ and other environmental factors such as elevated $CO_2$ and drought on growth and physiological functions of Japanese forest tree species. Therefore, it is necessary to promote the experimental study and accumulate the information on the combined effects of $O_3$ and any other abiotic environmental factors on Japanese forest tree species.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.30-35
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• 2004

Compositae plants are known to contain biologically active substances that are allelopathic to agricultural crops as well as weed species. Aqueous extracts from leaves of Xanthium occidentale were assayed against alfalfa (Medicago sativa) to determine their allelopathic effects, and the result showed that the extracts applied onto filter paper significantly inhibited seed germination as well as root growth of alfalfa. Untreated seeds germinated in 60h, but extract concentrations greater than 30g $\textrm{L}^{-1}$ delayed seed germination. The extracts significantly inhibited seed germination of alfalfa, and $\beta$-amylase activity of alfalfa and barley seeds during 24-36 hours after treatment. Aqueous extracts of 40 g $\textrm{L}^{-1}$ from X. occidentale were completely inhibited the hypocotyl and root growth of alfalfa. Aqueous leaf extracts showed the highest inhibitory effect and followed by root and stem extracts. Early seedling growth of both alfalfa and barnyard grass (Echinochloa crus-galli) was significantly reduced by methanol extracts. By means of high-performance liquid chromatography, chlorogenic acid and trans-cinnamic acid were quantified as the highest amounts from water and EtOAc fractions, respectively. BuOH and EtOAc fractions of X. occidentale reduced alfalfa root growth more than did hexane and water fractions. The findings of the bioassays for aqueous or methanol extracts reflected that the inhibitory effect of extract was closely related to the level of responsible allelochemicals found in plant extracts.

• Journal of Plant Biotechnology
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• v.5 no.1
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• pp.19-23
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• 2003

The Ac (activator) which is one of the well-characterized transposable elements from maize was examined for its transposition possibility to the heterologous plant (P.nigra x maximowiczii) genome via Agrobacterium tumefacience (LBA4404) mediated transformation system. A number of transgenic plants were successfully recovered after 30 weeks by amount reduction from 50 to 15 g/$m\ell$ kanamycin for in vitro selection to minimize phytotoxic effects and to increase callus growth and regeneration efficiency. Among transgenic plants, 62 out of 106 transgenic poplars (58.5%) showed abnormal phenotypes such as severe serrated leaves and light leaf coloration. Indigo staining with X-gluc proved indirectly the restoration of Gus enzyme function and the presence of Ac in poplar genome by PCR. Southern analysis indicated the transposition and existence of Ac element in poplar genomes. In this research, an Agrobacterium-mediated transformation system in poplar species was developed and identified that Ac derived from maize can be excised and trans posed into other poplar genomes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.322-328
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• 2006

A series of methanol extracts from leaf and root parts in spring- and winter-barley plants were assayed to determine their allelopathy and antioxidant activity. The methanol extracts applied on filter paper in a Petri-dish significantly inhibited root growth of Chinese milkvetch (Astragalus sinicus L.) seedlings. Leaf extracts at 25 and 50 g $L^{-1}$ inhibited root growth of Chinese milkvetch seedlings more than root extracts. No difference in phytotoxic effects of spring- and winter-barley seedlings extracts on root growth of Chinese milkvetch was observed. Methanol extracts dose-dependently increased DPPH free radical scavenging activity in vitro. DPPH free radical scavenging activity was higher in the methanol extracts from winter-barley seedlings than in those from spring-barley seedlings, and from leaf extracts than from root extracts. The antioxidant potential of the individual fraction from the methanol extracts of spring-barley seedlings was in order of n-butanol>ethyl acetate>water>chloroform>n-hexane fraction. By means of HPLC analysis, spring-barley (200.62 mg $100g^{-1}$) had more amount of total phenol acid than winter-barley (114.08 mg $100g^{-1}$). Especially, ferulic acid was detected in spring-barley extract (183.46 mg $100g^{-1}$) as the greatest amount. These results suggest that early seedlings of barley plants had potent allelopathy and antioxidant activity, and their activities were differently exhibited depending on plant parts and growing condition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.1
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• pp.50-55
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• 2003

Herbicidal activity of $\delta$-aminolevulinic acid(ALA), an intermediate for the biosynthesis of tetrapyrroles such as chlorophyll, heme, bacteriochlorophyll, and vitamin $\textrm{B}_{12}$ analogues, was examined to determine the variation in phytotoxic potential against different plant species as affected by different application methods. Seed-soaking treatment, ALA at low concentrations did not affect shoot and root lengths of test plants while at highest concentration reduced them by 20 to 30%. Alfalfa showed the most tolerant response to ALA in both pre- and post-emergence application, and followed by rice. When applied with pre-emergence, cotyledons of Chinese cabbage were severely bleached with 0.5 mM of ALA at 24 hrs after application, and root growth of rice, barnyard grass, and alfalfa was significantly inhibited with increasing of concentration. With post-emergence application, ALA at 2 to 4 mM reduced shoot and root growths of Chinese cabbage and barnyard grass completely. Herbicidal effects of ALA were more enhanced in the treatment combined with 2,2-dipyridyl sthan single application in barnyard grass and Chinese cabbage. The results suggest that alfalfa was the most tolerant to ALA among the tested plants, and that post-emergence application of ALA exhibited greatest photodynamic activity against tested plants.

• 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.