Showing papers on "Allelopathy published in 1991"

Allyl isothiocyanate release and the allelopathic potential of Brassica napus (Brassicaceae)

Abstract: The allelopathic potential of Brassica species has been attributed to release of the mustard oil glycosides which they produce in large quantities. Upon hydrolysis, these glucosinolates yield isothiocyanates, compounds with strong antibiotic properties. The objective of this study was to assess whether Brassica napus, a common and widespread crop and weed crucifer, is capable of allelopathic interference, and if so, whether its glycoside derivative, allyl isothiocyanate (Al), is capable of producing this interference. Wild type and low glucosinolate-mutant B. napus were grown in low organic content soil under greenhouse conditions, and Al release into soil was monitored. Most plants released low levels of Al, though approximately 10% released much higher levels. Wild type plants released more Al than mutants. Growth of the target species, Medicago sativa, was not affected by additions of Al to soils at concentrations equal to the median and 95% quantile from the B. napus soils. In replacement series experiments, the two B. napus genotypes suppressed growth of M. sativa equally despite differences in Al release rate. In an intraspecific replacement series experiment, the two B. napus genotypes were equal competitors. Under our experimental conditions, B. napus showed no indication of being allelopathic, and Al concentrations typical of soils around B. napus plants did not inhibit target plants.

Difference in hydroxamic acid content in roots and root exudates of wheat (Triticum aestivum L.) and rye (Secale cereale L.): Possible role in allelopathy

Abstract: Hydroxamic acids (Hx) produced by some cereal crops have been associated with allelopathy However, the release of Hx to the soil by the producing plant-an essential condition for a compound to be involved in allelopathy-has not been shown GC and HPLC analysis of roots and root exudates of wheat (Triticum aestivum L) and rye (Secale cereale L) cultivars, with high Hx levels in their leaves, demonstrated the presence of these compounds in the roots of all cultivars analyzed and in root exudates of rye Moreover, bioassays employing root exudates collected from wheat and rye seedlings demonstrated that only rye exudates inhibited root growth of wild oats,Avena fatua L, a weed whose root growth is inhibited by Hx These results suggest that rye could potentially interfere with the growth ofAvena fatua in nature and that this interference could be due to the release of Hx to the soil by way of roots

2,2'-OXO-1,1'-azobenzene: Selective toxicity of rye (Secale cereale L.) allelochemicals to weed and crop species: II.

Abstract: Three allelochemicals from rye or its breakdown products were evaluated for activity on garden cress (Lepidum sativum L.), barnyardgrass [Echinochloa crus-galli (L.) Beauv.], cucumber (Cucumis sativus L.), and snap bean (Phaseolus vulgaris L.). 2,4-Dihydroxy-1,4(2H)-benzoxazin-3-one (DIBOA), 2(3H)-benzoxazolinone (BOA), and 2,2'-oxo-1,1'-azobenzene (AZOB) were all applied singly at 50, 100, and 200 ppm and in two- and three-way combinations each at 50 and 100 ppm. AZOB at 100 and 200 ppm produced 38-49% more inhibition than DIBOA, while combinations of BOA/ DIBOA, which contained AZOB at 100 ppm had 54-90% more inhibition when compared to DIBOA/BOA combinations. All combinations were slightly antagonistic to barnyardgrass, while several combinations caused a synergistic response to garden cress germination and growth. Cucumbers and snap beans exhibited both types of responses, depending on the allelochemical combination and application rate. The plant-produced benzoxazinones were more inhibitory to crops than weeds. Therefore, improved herbicidal selectivity would be expected if there were rapid transformation of the benzoxazinones to the microbially produced AZOB.

Generalized plant defense: effects on multiple species

Abstract: Two species of lepidopteran herbivores, Manduca sexta (Sphingidae) and Trichoplusia ni (Noctuidae), were reared on synthetic diet containing either the alkaloid nicotine or the flavonoid rutin. Survival and pupal weight of the specialist M. sexta did not differ when larvae were reared on diet containing nicotine or rutin. In contrast, the generalist T. ni did not survive on diet containing 0.125% nicotine or greater, whereas larvae survived on all concentrations of rutin. These data demonstrate that the alkaloid nicotine is inhibitory toward generalist, but not specialist herbivores, whereas the flavonoid rutin has no effect on specialist herbivores and limited effects on generalist herbivores. Five species of Pseudomonas bacterial pathogens: P. syringae, P. syringae pv. angulata, P. syringae pv. tabaci, P. fluorescens, and P. solanacearum were grown on nutrient agar containing nicotine or rutin at concentrations ranging from 0.0 to 1.0% wet weight in 0.1% intervals. No species of Pseudomonas grew at concentrations greater than 0.5% nicotine when 106 colony forming units (cfu) were used, but growth occurred at all concentrations of rutin when 102 cfu were used. These data indicate that nicotine was inhibitory to growth of both herbivores and pathogens, suggesting that certain plant secondary chemicals with high toxicity are of a generalized nature and affect multiple species. Differences in the sensitivity of organisms to allelochemicals such as generalist or specialist can make it appear that specific allelochemicals affect specific organisms, when in fact it is the tolerance of the organism to the plant chemical that is responsible. In four separate studies, the growth of M. sexta, T. ni and Helicoverpa zea was significantly lower on plants inoculated with P. solanacearum. Alteration in leaf quality by P. solanacearum was due to either reductions in leaf nutrients or increases in allelochemicals. We speculate that localized or systemic induction by both herbivores and pathogens can cause changes in leaf quality, effecting each other's subsequent colonization. The generalized nature of plant secondary compounds and potential reciprocal effects on induction by both species suggests that herbivores and pathogens may affect plant quality through induction and diffuse interactions of disparate species can alter the community of organisms colonizing a plant.

Interactions Among the Effects of Herbivory, Competition, and Resource Limitation on Chaparral Herbs

Abstract: Older chaparral stands are frequently characterized by gaps in the canopy and by a lack of herbaceous vegetation in these openings. Many causes for the lack of herb growth in gaps have been postulated, including lack of seeds in the soil, limited nutrients and water, competition with shrubs for resources, interference competition (i.e., allelopathy), and herbivory. An experiment was conducted to assess the individual and combined effects of four main factors (trenching to reduce root competition, caging to reduce herbivory, nutrient addition, and water addition) on herb germination, survival, and growth in chaparral dominated by chamise, Adenostoma fasciculatum. We found strong interactions among these treatments. Therefore, no single factor can be regarded as causing the absence of herbs in chaparral. Herb establishment was limited by herbivory and root competition with shrubs for limited nutrients and/or water. Survival was enhanced by trenching, caging, and water. Growth was enhanced by nutrient addition, but the magnitude of this nutrient effect became appreciable only within trenched, caged plots. The vegetative cover of annual herbs in gaps was limited by the combined effects of herbivory, competition with the roots of shrubs, inadequate nutrients, and inadequate water.

Survey of Japanese Medicinal Plants for the Detection of Allelopathic Properties

Abstract: 薬用植物, および香料植物の一部から, 他感作用候補植物を, レタスに対する発芽・生育試験とフザリウムに対する抗菌性試験 (胞子発芽と菌糸伸長試験) から検索した。その結果, 作物や一般雑草よりも高い頻度で, 活性の強い他感作用候補植物が得られた。植物発芽・生育阻害活性も抗菌性もともに最も強かったのは, キンポウゲ科のオキナグサとセンニンソウであった。これらは著名な毒草としてすでに知られており, とくにセンニンソウは牧草地に侵入する有害雑草として良く知られている。これに次ぐものとして, オオグルマ, フレンチタイム, アンミビスナーガ, ゲッケイジュがあった。ユリ科のニラとニンニクは, 水抽出液の抗菌性が, カンゾウとクスリウコンはメタノール抽出液の抗菌性が強かったが, 植物生育阻害作用は小さかった。逆にヨウシュヤマゴボウ, ニッケイ, ペパーミントは, 抗菌性は小さかったが, 植物の発芽・生育阻害が強かった。

Allelopathic dominance ofMiscanthus transmorrisonensis in an alpine grassland community in Taiwan

Abstract: A study site located at 2600 m elevation in Tartarchia Anpu, Nantou county, Taiwan, exhibits a unique grassland community composed of two principal species,Miscanthus transmorrisonensis andYushinia niitakayamensis, and 35 other species. The relative frequencies of the two species are 12% and 11%, while their relative coverages are 25% and 19.5%, respectively. The values for the remaining 35 species are lower than4% each, while species diversity of the community is −3.04839, indicating great diversity. To elucidate the mechanism of dominance ofM. transmorrisonensis, allelopathic evaluation of the plant was conducted. Aqueous extracts of M.Transmorrisonensis plant parts with two ecotypes were bioassayed. The extracts showed significant phytotoxic effects on seed germination and radicle growth of four tested plants: rye grass, lettuce, and two varieties of Chinese cabbage. In addition, rhizosphere soils underMiscanthus also exhibited significant phytotoxicity, indicating that allelopathic interaction was involved. Some responsible phytotoxic phenolics, namely, p-coumaric, ferulic, vanillic, protocatechuic, o-hydroxyphenylacetic, andm-hydroxyphenylacetic acids, and 4-hydroxycoumarin and phloridzin were identified. Allelopathy thus can play an important role in regulating plant diversity in the field.

Allelopathic impact of volatile components fromEucalyptus on crop plants

Abstract: The effect of crude volatile oils from the leaves ofEucalyptus globulus andE. citriodora and the pure terpenes - cineole and limonene from these oils, (in vapour form) was studied onPhaseolus aureus, Lens esculentum, Hordeum vulgare and Avena sativa. The parameters like germination of seeds, seedling growth, values of cell survival, and content of water and chlorophyll of the crops formed the system of bioefficacy study. The allelopathic impact of the oil vapours from the eucalypt tree becomes evident from the negative response of the parameters studied. The impact of the E. citriodora oil vapours compared to that ofE. globulus oil or the pure terpenes was seen to be relatively greater in almost all parameters under investigation. A strong reciprocal correlation that exist between the concentration and the seedling growth or the water content of the crops under study supports the dose linked allelopathic phenomenon. It is suggested that oil vapours ofEucalyptus exert their effect through impairing the respiratory as well as photosynthetic ability of the target plants.

Allelopathic Potential of Parthenium hysterophorus L.

Abstract: Allelopathic influences of aqueous extracts of congress grass (Parthenium hysterophorus L.) were investigated on germination and seedling vigour of cereals (rice and wheat) and pulses (black gram and chick pea). The observations on germinations of crop seeds were recorded daily while linear growth of plumules and radicles were measured 2, 4 and 6 days after initiation of study. Aqueous extract of this weed exhibited allelopathic effects on germination and seedling vigour of both cereals and pulses. With increase in concentrations of aqueous extract there was decline in percentage of germination in both cereals and pulses but germination of pulses were more adversely affected than cereals. It was also observed that aerial portion of plant part was found to be more potent than sub-aerial portion in reducing germination and length of roots and shoots of both cereals and pulses under test. The aqueous extract of 10 % concentration obtained from aerial/sub-aerial portion of plant brought about maximum reduction in length of roots and shoots.

Allelopathic Potentials of a Wild Rice, Oryza Perennis

Abstract: To learn about genotypic variations in allelopathic potential, 24 strains of a wild rice, Oryza perennis Moench, collected from tropical Asian and American countries, and two rice cultivars (O. sativa L.), were planted at Nankang, and water extracts from their leaves and stems taken at the booting stage were used for bioassay with Chinese cabbage and rice seeds. The extracts were also used for chromatographic analysis to determine the contents of nine phenolic acids. The strains tested markedly differed in root-growth suppression rates in bioassay and contents of phenolic acids, but the two kinds of measurements were largely uncorrelated. The root-growth suppression rate in Chinese cabbage was considered as representing the allelopathic potential better than that in rice. Stepwise regression analysis showed that a combination of several phenolic acids and their interactions could account for the root- growth suppression rate in Chinese cabbage. The result of bioassay clearly indicates the main direction of differentiation in O. perennis strains.

Biological activity and chemical isolation of root saponins of six cultivars of alfalfa (Medicago sativa L.)

Abstract: Wheat, cheat and Trichoderma viride bioassays were used to establish the relationship between the content of biologically active saponins in the roots and the degree of winter dormancy and/or time of six cultivars of alfalfa over the period January to August, 1988. Wheat and cheat bioassay results indicated no significant difforences among cultivars, whereas T. viride was inhibited most by extracts of roots collected during months with high rainfall and rapid growth. Cheast seedling roots were inhibited 8–10% more than those of wheat seedling roots indicating that alfalfa root saponins were more effective as allelopathic compounds in preventing growth of cheat than that of wheat alone. An average of 14 different saponins per cultivar were separated by thin-layer chromatograms. Saponins, and the aglycones produced by acid hydrolysis of the May samples, were separated by thin-layer chromatography. The conclusion is that the amount, structure, and type of saponins present in alfalfa roots vary with time.

Effect of phenolic compounds on asparagus mycorrhiza

Abstract: Asparagus (Aspurugus o@iic~nulis L.) produces several cinnamic acid derivatives known to be allelochemicals (Young. 1984: Young and Chou. 1985; Hartung ef ul.. 1990). It has been suggested that these allelochemicals may either be directly involved in asparagus decline by affecting plant vigor (Young. 1984; Young and Chou, 198s) or indirectly through chemical-mediated changes in the microbial community (iiartung and Stephens. lYX3). which in turn aflcct plant growth. Wacker CI cl/. (199Ob) have shown that ferulic acid, an allclochcmical found in asparagus roots, decreases root colonization by vesicular arbuscular mycorrhirae (VAM) and the growth ol’ mycorrhiznl asparagus. Wackcr (*I ul. (IYYOc) I‘ound a change in the composition of the VAM fungal community in asparagus fields with increasing age up IO 20 yr. Root colonization by VAM fungi and spore density in the soil also c Wackcr cr ul.. IYYOa) plant health may be adversely alTected if the nutritional contribution to asparagus by native VAM fungal species decreases with plant age. Because available P decreased with increasing number of years cropped in asparagus, soil P may not be the factor responsible for the reduction in root colonization by VAM fungi and the change in the composition of the VAM fungal community observed by Wacker (1990~). Accumulation of phcnolic allclochcmicals produced by asparagus could be a mechanism by which asparagus monocropping alters the species composition of the VAM fungal community. WC report the etfrcts of’ fcrulic. catTcic and methylencdioxycinnamic (MDC) acids and also those of soil extracts from an asparagus field soil and an adjacent non-cultivated soil on VAM formation and growth of asparagus. To examine the etTccts of three phenolic acids on VAM formation in asparagus. asparagus seeds (cv. “Mary Washington”) were surface-sterilized (Elmer and Stephens, 1988). germinated and sown into plastic cell-pack units (2 x 2) with 8Og of washed sand per cell. A 9.0cm dia Petri dish base was used under each J-cell unit to avoid chemical cross-contamination. A VAM fungus resembling G/r~nlus/ct.vcicu/urunr (Thaxtcr) Gerd. and Trappc emend. Walker and Koske was multiplied in pot cultures with sorghum (.Sorlral seedlings. Alier transplanting, plants were watcrcd weekly with IO ml of 0.1 strength

Allelopathic effects of alfalfa plant residues on emergence and growth of cucumber seedlings

Abstract: Growth chamber test demonstrated that alfalfa (Medicago sativa L.) residue is toxic to cuncumber (Cucumis sativus L.) seed germination and seedling growth. Ground alfalfa roots at 0.5% (w/w, dry weight) inhibited germination when added to the growing medium. Alfalfa roots at 0.5% were also toxic to pregerminated cucumber seed. However, cucumber seedlings grew normally if this same medium was watered and incubated for >1 day before planting. Alfalfa particle size in media influenced cucumber performance, with the intermediate size (1 to 2 mm) being lethal to cucumbers

Influence of light on plant allelochemicals: a synergistic defense in higher plants

Abstract: Plant phototoxins are broad-spectrum biocides which adversely affect an array of potential plant enemies, including among others disease-causing pathogens, nematodes, insect herbivores, and competing plant species. Thus far, plants which contain these broad-spectrum allelochemicals have been found to occur in open habitats (i.e., in full sunlight) where a defensive mechanism mediated by light would seem to operate most effectively. The levels of available light in shaded environments, although considerably lower than full sun (1–10% of full sun), are equivalent to the intensities of light used to kill phototoxin-treated insects in laboratory studies. This suggests that phototoxic reactions might mediate important organismal interactions in shaded environments as well. In this study, more than 230 Costa Rican rainforest plants were bioassayed for phototoxic metabolites in an effort to ascertain their prevalence among plants growing in moderate to extreme shade. Microbial bioassays, employing Bacillus cereus (a gram positive bacterium), Escherichia coli (a gram negative bacterium), and Saccharomyces cerevisiae (a yeast) were used to rapidly and sensitively indicate phototoxic action and potential for insecticidal action. Tissue extracts from 12 plant families tested positive for phototoxins. This is the first report of phototoxins occurring in eight of those families (Acanthaceae, Campanulaceae, Gesnariaceae, Loganiaceae, Malpigaceae, Phytolaccaceae, Piperaceae, and Sapotaceae). The presence of phototoxins in rainforest plants suggests that phototoxic plant allelochemicals may function as important defenses in low-light, as well as high-light, environments.

Evidence that sweet potato (Ipomoea batatas) is allelopathic to yellow nutsedge (Cyperus esculentus).

Abstract: In fi'eld studies, 'Regal' sweet potato greatly reduced yellow nutsedge growth when the two species were grown together using standard cultural practices. At the end of the growing season, yellow nutsedge shoot dry weight per m2 in plots where the two species were planted together was less than 10% of shoot weight in plots where nutsedge was grown alone. Presence of yellow nutsedge did not markedly affect sweet potato growth. When grown together in a greenhouse experiment designed to minimize the competitive effects of sweet potato on yellow nutsedge, yellow nutsedge growth was reduced more than 50% by sweet potato 8 and 12 weeks after planting. The most polar fraction of serially extracted sweet potato periderm tissue was highly inhibitory to yellow nutsedge root growth. These results indicate that sweet potato interference with yellow nutsedge under field conditions is partially due to allelopathy. Nomenclature: Yellow nut- sedge, Cyperus esculentus L. #3 CYPES, sweet potato, Ipomoea batatas L. (Lam.), 'Regal'. Additional index words. Root growth inhibition, interfer- ence, CYPES.

Allelopathic activity of decomposing straw of wheat and oat and associated soil on some crop species

Abstract: Allelopathic effects of decomposing straw of wheat ( Triticum aestivum L.) and oat ( Avena sativa L.) and associated soil were assessed on germination and early root growth of wheat, oat, and subterranean clover ( Trifolium brachycalycinum Katzn. & Morley). Although allelopathic activity was widespread during decomposition, only speed of germination and root length were affected with both inhibitory and stimulatory effects. Important differences in sensitivity were found among the target species, with mainly subterranean clover being stimulated, and the grasses mainly inhibited. Conversely, only minor differences in effectiveness were found between the source species. Soil treatments were less effective than straw treatments, with a generalised pattern of inhibitory cycles being evident. Results suggest that allelopathic activity might be of minor relevance in mulch tillage involving the investigated species. However, further research to characterise and identify the chemicals responsible for observed allelopathic effects is needed.

Effects of kinetin formulations on allelochemicals and agronomic traits of cotton

Abstract: Twelve candidate plant growth regulator formulations were applied twice at two levels to fruiting cotton (Gossypium hirsutum L.). Leaves and squares were collected for analysis of allelochemicals (gossypol, tannin, anthocyanin, flavonoids) at 3 and 5 weeks after the first treatment. The plots were machine harvested one time to determine yield. Seeds were delinted and analyzed for agronomic traits and gossypol. Leaf gossypol and square gossypol were the categories most frequently increased by the bioregulators (...)

Phytotoxic Effects of Naturally Occurring Chemicals from Pinus koraiensis on Experimental Species

Abstract: To find out allelopathic potential of naturally occurring substances emitted form pinus korairnsis, water extracts and volatile sudstances of the tree materials werw provided and used for tests such as seed germination and seedling growth test. In general, the more was the concentration of the extracts and essential oils, the worse was growth effects of the selected species. The germination an the growth were inversely proportional to the concentration of the extracts and the essential oils of p. koraiensis. in other words, the chemical substances had the biological toxic activity. gc and gc/ms methods were employed for analysis and identification of phytotoxic substances from the tree leaves. Sixteen chemical compounds were identified from water extracts and nineteen from essential oils of p. koraiensis leaves. Through the experiment on germination and seedling growth test, the chemical substances naturally occurring from p. koraiensis seemed to be responsible for the allelopathic potential in this study. p

Allelopathic Effects of Osmunda cinnamomea on Three Species of Dryopteris

Abstract: Plants can reduce competition for limited resources by chemically inhibiting the growth and development of other species (allelopathy). In moist environments, the inhibitory chemicals are leached from growing or senescent leaves by rainfall, are exuded from the roots, or result from decomposition of the plant (Rice, 1984). Most studies of allelopathy in pteridophytes have focused on the effect of fern species on angiosperms. For example, Gliessman & Muller (1978) found in southern California meadows that toxins from Pteridium aquilinum severely affected some species of herbs and annual grasses while not affecting or only slightly affecting others. Of the few investigations of allelopathy among fern species, even fewer have focused on species which are found in the same general habitat. Two studies involving species found in the same general habitat investigated chemical interactions at the gametophyte stage of the life cycle. Bell (1958) found that various extracts of prothalli from Dryopteris filix-mas inhibited germination or reduced growth in D. borreri gametophytes; Petersen & Fairbrothers (1980) found that gametophytes of Osmunda cinnamomea reduced growth in Dryopteris intermedia gametophytes and that D. intermedia gametophytes reduced growth in 0. cinnamomea gametophytes. Other studies of species found in the same general habitat looked at the effect of the sporophyte on the gametophyte stage of the life cycle. Bell & Klickoff (1979) discovered that sporophytes of Polystichum acrosticoides, Polypodium vulgare, and Onoclea sensibilis reduced gametophyte growth for all species but P. vulgare. Munther & Fairbrothers (1980) found autotoxic as well as allelopathic inhibition of spore germination from sporophytes of Osmunda cinnamomea, 0. claytonia (no allelopathic effects), and Dennstaedtia punctilobula. All of the species used in these studies, although found in the same general habitat, do not generally occur in close proximity. This paper reports on an experiment performed to determine the allelopathic effect of sporophytes of Osmunda cinnamomea on the number and growth rate of gametophytes of Dryopteris carthusiana, D. cristata, and D. goldiana. 0. cinnamomea grows in close proximity with D. carthusiana and D. cristata but not with D. goldiana. 0. cinnamomea is, however, found in the same general habitat as D. goldiana. Both of the experiments with 0. cinnamomea mentioned above showed allelopathic effects on Dryopteris and other species (Munther & Fairbrothers, 1980; Petersen & Fairbrothers, 1980). Cinnamic acid and benzoic acid derivatives, which have been implicated as allelopathic agents in a number of studies (Rice, 1984), have been found in 0. cinnamomea (Bohm & Tryon, 1967).

Allelopathic Effects of Growth Inhibitor from Artemisia princeps var. orientalis

Abstract: A number of laboratory experimentes have performed to elucidate water-soluble of volatile substances from wormwood plant(artemisia princeps var. orientalis) as growth inhibitor or phytotoxicant. in germination tests with aqueous extracts of leaves, stems and roots of the wormwood plants, most tested species showed that relative germination ratio was inversely proportional to comcentration of the extracats. and seedling elongation and dry weight of the species were heavily inhibited with the extracts, incubated leaves, volatile substances of the leaves and soil underneath wormwood plants. gas Chromatography was employed to find out possible phytotoxic substances or growth inhibitors of wormwood leaves. ten substantes have isolated, and most of them were identified as terpenoids.

Studies on the Allelopathic Effects of the Several Weeds

Abstract: The allelopathic potentials of several Korean weeds were inverstigated in the greenhouse and laboratory. Aqueouse extracts and plant litters of several weeds were tested at different dilutions for allelopathic effect on germination and Barley growth of crop species. Among the several species of weeds. Portulaca oleracea and Chenopodium album had the highest allelopathic effect to the four species to 30%, while the extract of Portulaca oleracea increased those to 4.7% on an average when compare with control plant. In greenhouse experiment Portulaca oleracea highly reduced the emergence rate indices of barley, soybean. radish and corn to 30, 49, 36 and 68% that of control plant, respectively. Plant height and dry weight of indicate plants were reduced by the residues of Portulaca oleracea and Chenopodium album.