Showing papers on "Allelopathy published in 1989"
TL;DR: In this paper, experimental plant populations were grown at varying densities and varying levels of phytotoxins in the soil to investigate the potential interacting influences of allelopathy and resource competition on plant response and yield-density relationships.
Abstract: (1) Experimental plant populations were grown at varying densities and varying levels of phytotoxins in the soil to investigate the potential interacting influences of allelopathy and resource competition on plant response and yield-density relationships. (2) Experiments were performed with (a) bahiagrass, Paspalum notatum, grown in soil treated with gallic acid and hydroquinone, putative inhibitors produced by Polygonella myriophylla and (b) tomato, Lycopersicon esculentum, grown in soils from under and around black walnut, Juglans nigra. (3) Phytotoxicity decreased as plant density increased. This was attributed to plant 'dilution' of phytotoxins, i.e. the sharing of the available phytotoxin among many plants at high densities such that each received a small sub-lethal dose. (4) Phytotoxins caused characteristic deviations from expected yield-density relationships. Low to moderate phytotoxin concentrations caused a decrease in the slope of the log yield-log density relationship. Contrary to the expected consequences of increased density and resource competition, the presence of high phytotoxin concentrations may cause a reversal in the slope of predicted log yield-log density relationships at low plant densities, such that maximum individual plant weight occurs at an intermediate density. (5) Demonstration of either decreasing phytotoxicity with increasing plant density or a reversal in slope of the predicted log yield-log density relationship is proposed as an indication of the presence of toxic substances in soil. (6) The ecological implications of these results are discussed.
194 citations
TL;DR: Sudex tissue collected at 7 days of age possessed a greater percentage of these phytoinhibitors on a per gram basis than did older sudex tissue, while the percentage ofp-hydroxybenzaldehyde in ether extracts of tissue also increased, while that of the acid and aldehyde decreased.
Abstract: Experiments were conducted under controlled conditions to investigate the apparent allelopathic effects of sudex [Sorghum bicolor (L.) Moench ×Sorghum Sudanese (P.) Stapf, cv. FFR 201] on weed and vegetable species. Allelopathic potential, as measured by radicle elongation of herbaceous indicator species, decreased with increasing sudex age. Greatest potential allelopathic activity of sudex shoot tissue was observed when sudex was collected at 7 days of age. Small-seeded broadleaf species were more inhibited in the presence of sudex shoot tissue than were grass species. Two major phytoinhibitors were isolated from aqueous extracts of sudex shoot material by partitioning with diethyl ether, followed by thin-layer and liquid column chromatography. Phytoinhibitors were identified asp-hydroxybenzoic acid andp-hydroxybenzaldehyde, potentially the enzymatic breakdown products of the cyanogenic glycoside dhurrin. The I50 values of these compounds using a cress (Lepidium sativum L.) seed bioassay were 140 and 113 μg/ml for the acid and aldehyde, respectively. Sudex tissue collected at 7 days of age possessed a greater percentage of these phytoinhibitors on a per gram basis than did older sudex tissue. As sudex tissue age increased, the percentage ofp-hydroxybenzaldehyde in ether extracts of tissue also increased, while the percentage ofp-hydroxybenzoic acid decreased.
127 citations
TL;DR: It is argued that such communication is part of the similarities in plant and animal responses to stress and may contribute to plant defense.
Abstract: Allelopathy is identified particularly with chemical activity between plants; entomologists refer to allelochemicals in a broader context. Recent work shows that several groups of compounds associated with allelopathy also play a part in communication between plants and other organisms. It is argued that such communication is part of the similarities in plant and animal responses to stress and may contribute to plant defense.
71 citations
TL;DR: Results indicated that decomposed alfalfa roots and their associated soil produced a 51–56% reduction in bladygrass seed germination and root and shoot length of blady Grass seedlings were reduced by an average of 88%.
Abstract: Greenhouse and laboratory experiments were conducted at the Agricultural and Water Resources Research Center Station, Baghdad, in 1985 and 1986 to investigate the possible allelopathic potential of alfalfa (Medicago saliva L.) and its decomposed residues on bladygrass (Imperata cylin-drica L. Beauv.), a noxious weed in Iraq, and to isolate, characterize, and quantify possible allelopathic agents in alfalfa residues and root exudates. Results indicated that decomposed alfalfa roots and their associated soil produced a 51–56% reduction in bladygrass seed germination. Root and shoot length of bladygrass seedlings were reduced by an average of 88%. Decayed and undecayed mixtures of alfalfa roots and soil at 0.015∶1 (w/w) inhibited bladygrass seedlings reproduced from rhizomes by 30 and 42%. It was found that root exudates of alfalfa seedlings caused significant reduction in shoot and root dry weights of bladygrass seedlings when alfalfa and bladygrass were grown together in nutrient culture. Caffeic, chlorogenic, isochloro-genic,p-coumaric,p-OH-benzoic, and ferulic acids were detected in alfalfa root exudates and residues. The highest amount (126 fig phenolic acids/g soil) of these compounds was found in alfalfa root residues after six months of decomposition in soil.
54 citations
TL;DR: This paper concludes with a discussion of some frontier areas of research in allelopathy, including interaction between the unicorn plant and cotton and structure-function of flavonols serving as allelochemicals in chloroplast-mediated electron transport and phosphorylation.
Abstract: Allelopathic interactions between plants and other organisms have been recognized by scientists worldwide because they offer alternative uses in agriculture, such as decreasing our reliance on synthetic herbicides, insecticides, and nematicides for disease and insect control. The recognition of the role that allelopathy can have in producing optimum crop yields is of fundamental importance. Despite much optimism and some progress in unravelling the complexities of biochemical interactions between species, a firm foundation for the scientific rationale of the existence and function of the allelopathic phenomenon has not been developed. Allelopathic chemicals are primarily secondary products of plant metabolism which have been an enigma to plant scientists; however, they undergo a variety of reactions with plant, insect and animal species that inhibit or stimulate their growth and development. Examples of some allelochemicals and their basis of molecular and biological action are shown: interaction between the unicorn plant (Proboscidea louisianica L.) and cotton (Gossypium hirsutum L.); diterpenoid alkaloids (fromDelphinium ajacis L.) as allelochemicals; substances that occur in wheat (Tritcum aestivum) and wheat soil that cause autotoxic effects; alfalfa (Medicago sativa L.) root saponins as allelochemicals; humic acids from wheat soil as allelochemicals; and structure-function of flavonols serving as allelochemicals in chloroplast-mediated electron transport and phosphorylation. This paper concludes with a discussion of some frontier areas of research in allelopathy.
45 citations
TL;DR: A potential exists for bitter sneezeweed interference with developing alfalfa and Italian ryegrass seedlings following fall interseeding into pastures infested with bitter sneezeeweed.
Abstract: Research was conducted to determine the poten- tial for allelopathy to occur in pastures infested with bitter sneezeweed. Aqueous extracts of bitter sneezeweed leaves reduced alfalfa and Italian ryegrass seedling growth as much as 50% at concentrations of 0.5% (w/v). Leaf extracts were more phytotoxic than either stem or root extracts and seedling growth was reduced more than seed germination. Bitter sneezeweed tissue mixed in potting soil at concentrations as low as 0.3% w/w reduced alfalfa seedling numbers by 43%, plant height by 26%, and foliage dry matter production by 54% compared to plants cultured in soil without bitter sneezeweed leaf tissue. The potential concentration of bitter sneezeweed leaf material in soil in the pasture ecosystem was determined to be 0.5% w/v in the liquid phase and 0.2% w/w in the solid phase. Alfalfa seedling growth was reduced by 70% when germinating seed were placed under a bell jar with a potted mature bitter sneezeweed plant compared to control seedlings. A potential exists for bitter sneezeweed interference with developing alfalfa and Italian ryegrass seedlings following fall interseeding into pastures infested with bitter sneezeweed. Nomenclature: Bitter sneezeweed, Helenium amarum (Raf.) H. Rock #3 HENAM; alfalfa, Medicago sativa L., Italian ryegrass, Lolium multiflorum Lam. Additional index words.Weed interference, bioassays, pas- ture interseeding, allelopathy, alfalfa, Italian ryegrass,
41 citations
Journal Article•
39 citations
TL;DR: Leaf extracts and leaf leachates ofProsopis juliflora and Prosopis cineraria showed the allelopathic compounds to be phenolic in nature in both the species, suggesting accumulation of toxic substances in soil layers, inhibiting growth of other species.
Abstract: The allelopathic effects ofProsopis juliflora were studied both in the laboratory and in nature and compared with that ofProsopis cineraria to understand the chemical nature of allelochemics. Both species occupy the same habitats butP. cineraria does not appear to have any toxic effect on other plants under its canopy.P. juliflora is highly allelopathic and does not allow the growth of any other species. Leaf extracts and leaf leachates ofP. juliflora were inhibitory. Decaying leaves were also inhibitory at early stages of decomposition. Live roots were not found to be inhibitory in cogermination and interplanting of seeds. Chemical investigation of the extracts showed the allelopathic compounds to be phenolic in nature in both the species. Slow decomposition and heavy accumulation of leaf litter belowP. juliflora may possibly result in accumulation of toxic substances in soil layers, inhibiting growth of other species.
37 citations
TL;DR: The breeding system, relatively tall growth habit and relatively large quantity of pollen produced all support the in vitro evidence of P. pratense as a pollen-allelopathic species.
Abstract: summary
Pollen extracts from live locally-common grassland species in eastern Ontario, Canada were tested for in vitro allelopathic effect on the pollen germination of 17 sympatric target species in 1987. The flowering phenologies of the test and target species were recorded to determine if any phenologically-divergent species showed evidence of in vitro pollen-allelopathic interactions. Phleum pratense L. demonstrated pollen-allelopathic effects on all targets except Linaria vulgaris Hill. P. pratense also exhibited significant phenological divergence with seven of the target species. Pollen extracts from Agrostis stolonifera L., Melilotus alba Desr., and Vicia cracca L. inhibited pollen germination in some of the target species, but the results suggest that these effects were pH-mediated. The pollen extract of Erigeron annuus (L.) Pers. did not cause inhibition of pollen germination in any of the target species. Further tests with pollen extract of P. pratense and another 23 sympatric target species were performed in 1988. Pollen germination was significantly inhibited in all but two of these species: A. stolonifera and P. pratense. Hence the pollen of P. pratense was not auto-allelopathic. The breeding system, relatively tall growth habit and relatively large quantity of pollen produced all support the in vitro evidence of P. pratense as a pollen-allelopathic species.
37 citations
TL;DR: Results indicate that nitrogenase activity (acetylene reduction) of alders growing in 2 × 10−3 M juglone was reduced relative to alder without added jugl one after one day, and in 2× 10−6 M jug lone after five days, suggesting that this soil can readily detoxify juglones.
Abstract: European black alder trees [Alnus glutinosa (L) Gaertn] fix nitrogen with nodular symbionts and are interplanted with valuable black walnut trees (Juglans nigra L) to increase soil nitrogen fertility However, on some soils interplanted alder can be killed by black walnut's allelochemical juglone In order to better understand the effects of juglone directly on the growth, nitrogen fixation, and root respiration of black alder, we grew nodulated alders hydroponically in a nitrogen-free nutrient solution at juglone levels of 2 × 10−6, 2 × 10−5, and 0 molar (M) Results indicate that nitrogenase activity (acetylene reduction) of alders growing in 2 × 10−3 M juglone was reduced relative to alders without added juglone after one day, and in 2 × 10−6 M juglone after five days Root respiration (CO2 evolution) and the relative increase of plant fresh weight were reduced in the 2 × 10−5 M juglone treatment In a related experiment, black alder germinants were grown in Flanagan silt loam soil dosed with 10−3, 10−4, and 0 M juglone The inhibitory effects of 10−3 M juglone on radicle elongation ceased 22–37 days after juglone treatments were started, suggesting that this soil can readily detoxify juglone
30 citations
TL;DR: A bioassay approach was utilized to characterize the specificity and chemical nature of phytotoxins in extracts of alfalfa soils as compared to fallow soil or soil where a cereal was the previous crop.
Abstract: Problems associated with continuously planting alfalfa (Medicago saliva L.) or seeding to thicken depleted alfalfa stands may be due to autotoxicity, an intraspecific form of allelopathy. A bioassay approach was utilized to characterize the specificity and chemical nature of phytotoxins in extracts of alfalfa soils as compared to fallow soil or soil where a cereal was the previous crop. In germination chamber experiments, water-soluble substances present in methanol extracts of soil cropped to alfalfa or barley (Hordeum vulgare L.) decreased seedling root length of alfalfa L-720, winter wheat (Triticum aestivum L. Nugaines) and radish (Raphanus sativa L. Crimson Giant). Five days after germination, seedling dry weights of alfalfa and radish in alfalfa soil extracts were lower compared to wheat or red clover (Trifolium pralense L. Kenland). Growth of red clover was not significantly reduced by soil extracts from cropped soil. Extracts of crop residue screened from soil cropped to alfalfa or barley significantly reduced seedling root length; extracts of alfalfa residue caused a greater inhibition of seedling dry weight than extracts of barely residue. A phytotoxic, unidentified substance present in extracts of crop residue screened from alfalfa soil, which inhibited seedling root length of alfalfa, was isolated by thin-layer chromatography (TLC). Residues from a soil cropped continuously to alfalfa for 10 years had the greatest phytotoxic activity.
TL;DR: Data indicated that bollworm larvae use the same enzymatic pathways to respond to plant allelochemicals and insecticides, and differences in responses may relate most closely to variations in the concentration of alleLochemicals in the diet.
Abstract: Cotton plant allelochemicals were fed to bollworm, Heliothis zea (Boddie), larvae and effects on responses to insecticides and levels of detoxifying enzymes were measured. Addition of 0.1 % gossypol or lyophilized cotton flower buds induced increased tolerance to the easily metabolized organophosphate insecticide methyl parathion. In contrast, feeding freshly excised flower buds to larvae decreased tolerance to methyl parathion. Neither type of diet affected toxicity of the pyrethroid insecticide permethrin. Aldrin epoxidation was induced in larvae fed flower bud diets. Data indicated that bollworm larvae use the same enzymatic pathways to respond to plant allelochemicals and insecticides. Differences in responses may relate most closely to variations in the concentration of allelochemicals in the diet.
TL;DR: The results of this study indicate that juglone is less toxic to algae than fish, and the potential of juglones for aquatic management purposes is limited.
Abstract: Allelopathic growth inhibition of various freshwater algal species was observed upon the addition of juglone to culture medium under laboratory conditions. Juglone is a phenolic chemical compound common to most parts of the black walnut (Juglans nigra L.). Growth inhibition of all species occurred at a juglone concentration of 10(-3) M. Three of the five species were inhibited by a concentration of 10(-4) M juglone, while no inhibition occurred at 10(-5) M juglone. The results of this study indicate that juglone is less toxic to algae than fish. Therefore, the potential of juglone for aquatic management purposes is limited. Algal biomass will increase at natural juglone concentrations from 10(-8) to(-10) M due to the elimination of secondary producers. Algal biomass will decrease at natural juglone concentrations between 10(-4) and 10(-3) M. Species richness will decrease at juglone concentrations of 10(-5) and higher.
TL;DR: Allelopathic effects of aqueous extract of three weeds, Ageratum conyzoides L., Imperata cylindrica (L.) Beauv and Commelina benghalensis L. of Nigerian savanna were investigated on the germination and seedling vigour of soybean (Glycine max [L.] Merr.) and maize (Zea mays L.)
Abstract: Allelopathic effects of aqueous extract of three weeds, Ageratum conyzoides L., Imperata cylindrica (L.) Beauv and Commelina benghalensis L. of Nigerian savanna were investigated on the germination and seedling vigour of soybean (Glycine max [L.] Merr.) and maize (Zea mays L.). Aqueous extracts of these weeds exhibited allelopathic phenomenon on seed germination and seedling vigour. Aqueous extracts of I. cylindrica and C. benghalensis at 1 % and 5 % concentration (w/v) had stimulatory effect on soybean germination as against inhibitory effect of 10 % aqueous extract of all weeds on the germination of both soybean and maize seeds. Seedling vigour-length of roots and shoots and fresh weight of seedlings were promoted by aqueous extract of A. conyzoides up to 5 % concentration in soybean whereas all concentrations of extract stimulated the seedling vigour of maize. Aqueous extract of I. cylindrica up to 5 % also caused stimulatory effect on the seedling vigour of both crops but such effects were lesser in magnitude than that observed in case of A. conyzoides. On the contrary, the aqueous extract of C. benghalensis at all concentrations resulted in deleterious effect on the seedling vigour of both soybean and maize.
TL;DR: The strong plant growth inhibitory activity, together with the occurrence in most parts of the tree at high levels, indicated that 3-hydroxyuridine may be involved in the allelopathy of the Tree.
TL;DR: Eleven common species of terra firme moist tropical forest trees from the western Brazilian Amazon were tested for allelopathy, and D. hirsuta was found to be ant-mediated, killing more than 50% of the lettuce seeds.
TL;DR: Allelopathy plays an appreciable role in natural vegetation and plantations in Taiwan and an aggressive kikuyu grass was planted in a deforested land where Chinese fir grew previously, to help in understanding the mechanism of biological interactions between plants.
Abstract: Allelopathic compounds, including fatty acids, phenolics, flavonoids, terpenoids, and alkaloids, have been found in various plants and soils of different habitats in Taiwan since 1972. For example, in a monoculture of rice plants, phytotoxins were produced during the decomposition of rice residues in soil, suppressed the growth of rice seedlings, and reduced the numbers of tillers and panicles, leading to yield reduction. The allelopathic metabolites are also affected by environmental factors, such as oxygen, temperature, soil moisture, microbial activity, and levels of fertilizers in soil, and allelopathy was pronounced in areas where environmental stresses were severe. Substantial amounts of phytotoxic mimosine and phenolics were released into soil by plant parts of Leucaenaleucocephala, and these suppressed the growth of many understory species except that of L.leucocephala itself. A unique pattern of absence of understory plants was ubiquitous beneathPhyllostachys edulis, due primarily to an allelopathic effect. In a forest pasture intercropping, an aggressive kikuyu grass was planted in a deforested land where Chinese fir grew previously, to help in understanding the mechanism of biological interactions between plants. Aqueous soil leachate and extracts of the grass significantly, retarded the growth of local weeds but not that of the Chinese fir. Allelopathy thus plays an appreciable role in natural vegetation and plantations in Taiwan.
TL;DR: It appears that allelopathic compounds of plant and microbial origins build up in old citrus soil and may act as predisposal agents for the infection of citrus roots by soil pathogens.
Abstract: The interactive effects of citrus root residues and soil fungi on citrus replant problems were investigated. The results indicated that incorporation of citrus root residues in combination with the pathogenic fungiPhytophthora citrophthora, Pythium aphanidermatum andFusarium solani in soil caused more reduction to sour orange growth than did the root residues alone. Subsequent experiments showed that extracts of different parts of sour orange and leachates of some soil fungi increased the disease index of citrus roots grownin vitro. The citrus extracts did not affect growth of the test fungi.
TL;DR: The data suggest that ursolic acid and other natural detergents which are released from a source plant enhance the solubilization of allelopathic lipids via micellization and seem to play a significant role in the water transport of lipophilic phytotoxins to target seeds or seedlings.
Abstract: The hypothesis that allelochemicals released from members of the Florida scrub community deter the invasion of fire-prone sandhill grasses was investigated. Constituents of the endemic scrub members, Ceratiola ericoides, Conradina canescens and Calamintha ashei, were examined for their phytotoxic activity. Effects of the plant natural products on the germination and radicle growth of lettuce (Lactuca sativa), as well as little bluestem (Schizachyrium scoparium) and green sprangletop (Leptochloa dubia), two native grasses of the Florida sandhill community, were tested. The data suggest that ursolic acid and other natural detergents which are released from a source plant enhance the solubilization of allelopathic lipids via micellization. In general, natural surfactants seem to play a significant role in the water transport of lipophilic phytotoxins to target seeds or seedlings.
01 Oct 1989
TL;DR: Results suggest that Nymphaea odorata and Brasenia schreberi are both highly inhibitory and are therefore candidates for aquatic weed management and indicate that the simple lettuce seedling assay may be a reasonable first 'easy' assay for determining the allelopathic potential of aquatic plants.
Abstract: : Use of allelopathic terrestrial plants has received attention in agriculture as a weed management strategy. Putnam (1983) achieved success with annual rotation of allelopathic crops or companion plantings of allelopathic and perennial crops. He was able to suppress up to 95% of several important weeds. Allelopathic aquatic plants may provide a management system for undesirable aquatic vegetation. Replacement of an undesirable species by a desirable one as a long-term, site-specific method of aquatic plant management was suggested over 30 years ago. This report presents results of a literature search and feasibility study of the use of allelopathic aquatic plants for aquatic plant management. To establish a list of potential allelopathic plants, 16 aquatic macrophytes native to the southeastern United States were subjected to two bioassays -- one involving lettuce seedlings and one involving the aquatic plant Lemna minor as the target species. The results suggest that Nymphaea odorata and Brasenia schreberi are both highly inhibitory and are therefore candidates for aquatic weed management. The results also indicate that the simple lettuce seedling assay may be a reasonable first 'easy' assay for determining the allelopathic potential of aquatic plants. Keywords: Aquatic weed control; Allelopathy; Aquatic macrophytes; Bioassay; Biocontrol; Growth inhibition.
TL;DR: It is suggested that monitoring the status of manganese in planted spruce seedlings when using allelopathic cover straw mulches be used as a method for preventing the establishment of weed species.
Abstract: The potential allelopathic (phytotoxic or beneficial) effect of barley, oat, and wheat straw mulches was evaluated on growth, mineral nutrition, and mycorrhizal status of black spruce seedlings, un...
01 Jan 1989
TL;DR: It’s time to get used to the idea of having to pay for something you don’t really need.
Abstract: 培地に混和した植物葉のアレロパシーを調べるため, 雑草または作物葉粉末と石英砂を混和して, ポットまたはシードリングケースに詰め, 検定植物としてキュウリ (品種: 四葉) を播種し, その後の生長を比較した。得られた結果の概要は以下のとおりである。1. クズ葉を混和した場合にはキュウリの生長は促進され, ソバおよび陸稲を混和した場合には対照区と大差がなく, シロザ, シロバナチョウセンアサガオ, ヨモギおよびメヒシバを混和した場合には抑制された (Fig. 1, 2)。2. シロザおよびシロバナチョウセンアサガオ葉粉末の量を変えて石英砂と混和し, キュウリを播種したところ, これら粉末の混和量が多い場合ほどキュウリの生長は抑制された (Fig. 3, 4)。3. シロザ葉粉末, シロザ葉粉末のエタノール抽出物, 抽出残渣を石英砂と混和した培地におけるキュウリの生長は, いずれの場合も対照区より劣ったが, とくにシロザ葉粉末および抽出残渣を混和した場合に著しかった (Fig. 5)。4. シロザ葉粉末を混和した培地におけるキュウリの生長の抑制は, ポット内の液の浸透圧およびpHの上昇, およびシロザに含まれる生長抑制物質の作用の結果であろうと考察した。
TL;DR: In this paper, the authors present two main mechanisms of allelopathy: 1) direct transfer of metabolites between neighbouring plants during their life and 2) accumulation and transformation of bioactive substances in the environment with their subsequent influence on higher plants.
Abstract: There exist two main mechanisms of allelopathy: 1) direct transfer of metabolites between neighbouring plants during their life and 2) accumulation and transformation of bioactive substances in the environment with their subsequent influence on higher plants. The latter mechanism is similar to that causing soil sickness or soil toxicity. Allelochemicals affect all functions of the living system: photosynthesis, respiration, mineral nutrition, transpiration, immunity, and growth. The initial biochemical effect of allelochemicals seems to be on the synthesis of protein mediated by RNA/DNA. Knowledge of the mechanisms of concrete signals during realization of hereditary codes would serve as a powerful tool for the improvement of crop plant development and productivity.