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  • Digitale Medien  (14)
  • allelopathy  (13)
  • Sorghum bicolor  (4)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 10 (1984), S. 161-170 
    ISSN: 1573-1561
    Schlagwort(e): Ferulic acid ; allelopathy ; temperature stress ; sorghum ; soybean
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Experiments were conducted to test the hypothesis that alleiopathic effects of ferulic acid (FA) may be altered by the temperature conditions of the growth environment. Growth of grain sorghum and soybean seedlings over a 10-day treatment period showed that a significant interaction effect occurred between environmental temperatures and FA treatments. Sorghum grown with an average day temperature of 37 °C and soybeans grown at 34 °C had greater dry weight reductions caused by FA than when the respective environments were 8 °C and 11 °C lower. The threshold concentration for inhibition of sorghum growth was 0.2 mM FA under the hot conditions and 0.4 mM FA with the cooler conditions. Soybeans were more sensitive than sorghum, and these inhibition thresholds for the hot and cool environments were 0.1 and 0.25 mM FA. These results demonstrate that temperature stress enhances allelochemical inhibition and indicate that interactions with the environment are an important consideration for understanding allelopathy.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 14 (1988), S. 1829-1844 
    ISSN: 1573-1561
    Schlagwort(e): Allelochemicals ; allelopathy ; autotoxicity ; bioregulators ; crop production ; crop residue ; herbicides ; no-tillage ; phytotoxins ; weed control ; weed interference
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Strategies for utilizing allelopathy as an aid in crop production include both avoidance and application protocols. There are immediate opportunities for management of weed and crop residues, tillage practices, and crop sequences to minimize crop losses from allelopathy and also to use allelopathic crops for weed control. Varieties of grain and forage sorghums (Sorghum Spp.), sunflower (Helianthus annuus L.), oats (Avena sativa L.), wheat (Triticum sativum L.),rye (Secale cereale L.), and others may provide weed control and in some instances crop stimulation from their residues. Our four-year field study with cultivated sunflower resulted in no differences in weed biomass between plots with and without herbicide (EPTC) applications. Strip cropping that included sorghum showed that in the subsequent year weed density and biomass were significantly lower in the previous-year sorghum than in soybean strips. Possibilities exist for modification of crop plant metabolism to alter production of allelochemicals. Allelochemical-environmental interactions must be considered in efforts to benefit from allelopathy. Under greenhouse conditions, joint application of low levels of atrazine, trifluralin, alachlor, or cinmethylin with a phenolic allelochemical showed that these two categories of inhibitors acted in concert to reduce plant growth. Allelochemicals may also be adapted as yield stimulants or environmentally sound herbicides, such as cinmethylin and methoxyphenone. Isolation of bialophos, tentoxin, and others shows that bacteria and fungi are good sources of biologically active compounds.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 18 (1992), S. 197-207 
    ISSN: 1573-1561
    Schlagwort(e): Sorgoleone ; mitochondria ; inhibitor ; allelochemical ; allelopathy ; root exudate ; Sorghum bicolor ; electron transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The aim of this investigation was to determine if sorgoleone (SGL), a hydrophobic compound inSorghum bicolor (L.) Moench root exudate, interferes with mitochondrial functions. Tests were conducted on mitochondria isolated from etiolated soybean [Glycine max (L.) Merr.] and corn (Zea mays L.) seedlings. The data show SGL is a potent inhibitor of state 3 and state 4 respiration rates in both soybean and corn. Using either NADH, succinate, or malate as substrate, the I50 was about 0.5μM SGL for state 3 and 5.0μM for state 4 based on 0.3–0.5 mg mitochondrial protein. Absorption spectra indicate SGL blocks electron transport at theb-c 1 complex. These data show that disruption of mitochondrial function may be a mechanism of SGL-mediated growth inhibition previously reported and demonstrate a probable role of SGL inSorghum allelopathy.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 25 (1999), S. 1611-1621 
    ISSN: 1573-1561
    Schlagwort(e): Hydroquinone ; allelopathy ; plant water balance ; photosynthesis ; chlorophyll fluorescence ; 13C isotopes ; leafy spurge ; Euphorbia esula ; small everlasting ; Antennaria microphylla Rydb
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Field observations indicate leafy spurge (Euphorbia esula) is inhibited by the presence of Antennaria microphylla. Hydroquinone (HQ), one of several compounds isolated from A. microphylla has been shown to inhibit leafy spurge seed germination, root elongation, and callus culture growth. The present study was designed to analyze the effects of HQ on water relations and photosynthesis of leafy spurge. Plants grown in 0.25 mM HQ had consistently higher leaf diffusive resistance and lower transpiration rates than control plants (P 〈 0.05). Chlorophyll fluorescence was significantly lower than controls (P 〈 0.05) towards the end of the treatment period. At the end of the treatment, tissue from 0.25 mM HQ plants had higher levels of 13C, indicating there had been a sustained interference with stomatal function. These data suggest that a disruption of the plant water balance is one mechanism of leafy spurge inhibition by A. microphylla.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 26 (2000), S. 2095-2109 
    ISSN: 1573-1561
    Schlagwort(e): Caffeic acid ; allelopathy ; plant water balance ; photosynthesis ; chlorophyll fluorescence ; 13C carbon isotopes ; leafy spurge ; Euphorbia esula ; small everlasting ; Antennaria microphylla
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Leafy spurge (Euphorbia esula), a native perennial weed introduced from Eurasia around the turn of the century, disrupts natural and agroecosystems across much of the Northern Great Plains. While leafy spurge displaces many native plant species, it has been demonstrated that small everlasting (Antennaria microphylla), a native perennial, is allelopathic to leafy spurge. Caffeic acid (CA), one of three compounds isolated from small everlasting, inhibits leafy spurge seed germination, root elongation, and callus culture growth. This study investigated the mechanism of this interference at the whole-plant level. Results indicate that inhibition of growth in leafy spurge after exposure to CA is primarily due to a disruption of plant–water relations. Leafy spurge cuttings were propagated in 0.5 strength Hoagland's nutrient solution for 30 days. For treatments, six plants were transferred into nutrient medium amended with either 0.1 or 0.25 mM CA for a period of 30 days. To determine the effect of pH, two additional groups of six plants were grown in nutrient medium adjusted with HCl corresponding to pH levels of plants treated with CA (pH 5.5–5.8 for 0.1 mM CA and pH 4.5–4.8 for 0.25 mM CA). By day 12 of the treatment period, plants treated with both levels of CA had significantly higher leaf diffusive resistances than control plants. Plants grown at the corresponding pH levels experienced higher diffusive resistances later in the treatment period (day 21). Transpiration was similarly affected with treated plants showing relatively higher transpiration rates compared to controls. Chlorophyll fluorescence was significantly lower than controls in all treated plants by end of the treatment period. The stable carbon isotope ratio (13C:12C) in these plants was higher than controls. These data show that a disruption of plant water relations is the primary mechanism of plant growth inhibition.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 5 (1979), S. 815-824 
    ISSN: 1573-1561
    Schlagwort(e): Ferulic acid ; p-coumaric acid ; vanillic acid ; chlorophyll a ; chlorophyll b ; allelopathy ; inhibitors ; soybean ; sorghum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Experiments were designed to test the hypothesis that interference with chlorophyll metabolism may be one mechanism of inhibition of plant growth in allelopathic interactions. Effects of ferulic,p-coumaric, and vanillic acids on soybean and grain sorghum growth and chlorophyll content were quantified and compared after seedlings were treated with these compounds in a nutrient culture. Following a 6-day treatment cycle, dry weights of soybean seedlings were reduced by both 10−3 M and 5 × 10−4 M treatments of ferulic,p-coumaric and vanillic acids. Soybean weight reductions in each case were paralleled by a significant reduction in the concentration (μg Chl/mg dry wt) of chlorophylls a and b and total chlorophyll in the unifoliate leaves. Sorghum seedling growth was also reduced by each of the compounds at the 5 × 10−4 M level, but leaf chlorophyll concentration was not below that of control plants.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 4 (1978), S. 425-436 
    ISSN: 1573-1561
    Schlagwort(e): synergism ; vanillic acid ; p-hydroxybenzoic acid ; allelopathy ; inhibition ; sorghum ; radish
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Radish and grain sorghum germination and sorghum growth were inhibited in a synergistic manner by combinations of vanillic andp-hydroxybenzoic acids. At threshold inhibition levels, 2.5 × 10−3 M vanillic acid-treated radish seeds had 71 % of control germination after 24 hr and 2.5 × 10−3 Mp-hydroxybenzoic acid-treated radish yielded 95% germination. A mixture of 2.5 × 10−3 M of each of these two phytotoxins showed 52% germination after 24 hr. Equimolar mixtures of 5 × 10−3 M vanillic andp-hydroxybenzoic acids allowed sorghum germination of 60% of untreated seeds after 24 hr, whereas separate treatments of individual phenols had 93% and 96% of control seed germination. Sorghum root and shoot elongation and total seedling growth were more sensitive than germination to vanillic andp-hydroxybenzoic acid treatments, and synergistic effects also were apparent. A combination of 5 × 10−3 M vanillic with 5 × 10−3 Mp-hydroxybenzoic reduced root length more than either did individually, and a mixture of 5 × 10−4 M vanillic with 5 × 10−4 Mp-hydroxybenzoic acid reduced sorghum seedling growth to approximately that resulting from a 10−3 M concentration of either phenol alone. Phytotoxin levels inhibitory to sorghum growth caused small increases in lower leaf surface diffusive resistance, but did not close stomates, and this effect was not judged to be the cause of reduced sorghum growth.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 11 (1985), S. 65-72 
    ISSN: 1573-1561
    Schlagwort(e): Bioassay ; Lemna minor ; allelochemical ; allelopathy ; duckweed
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Investigations in allelopathy often require the use of a bioassay for evaluating limited quantities of potentially active growth regulators. A bioassay procedure was developed usingL. minor grown in 1.5-ml aliquots of nutrient medium with and without allelochemicals in wells of 24-well tissue culture cluster dishes with loose-fitting lids. Tests using six replications per treatment with several flavonoid compounds and derivatives of coumarin, benzoic acid, and cinnamic acid demonstrated that the bioassay was capable of measuring inhibition at levels of compound ranging from 50 to 1000 μmol. Strongly inhibitory treatments were visible after 1 or 2 days. After 7 days of growth, frond number, growth rate, and dry weight were used to evaluate effects. The bioassay system is relatively simple, very sensitive, reproducible, and can be used for testing small amounts and dilute concentrations of unknowns which have been separated by chromatography.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 15 (1989), S. 951-960 
    ISSN: 1573-1561
    Schlagwort(e): Allelopathy ; grain sorghum ; Sorghum bicolor ; weed inhibition ; weed management
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Three years of field data in northeastern Nebraska demonstrate that a grain sorghum crop reduces weediness in the following crop year. Weed growth was consistently lower in sorghum areas the year after strip-cropping fields with sequences of four-row bands of grain sorghum, soybeans, and corn. Percentage weed cover was significantly lower early in the year, and midsummer weed biomass was well below that found after corn and soybeans. Weed biomass in June and July following corn was two to four times that of grain sorghum strips. Inhibitory effects of grain sorghum were primarily on broadleaf weeds, often showing no action on grass weeds. No obvious differences were noted in the weed species present after the three crops. Allelopathy provides a logical explanation for the sorghum-mediated weed inhibition found in this study. The data have implications for weed management strategies in agriculture.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 18 (1992), S. 1-11 
    ISSN: 1573-1561
    Schlagwort(e): Sorgoleone ; phytotoxin ; allelochemical ; allelopathy ; root exudate ; Sorghum bicolor ; Sorghums ; weed inhibition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Root exudates ofSorghum bicolor consist primarily of a dihydroquinone that is quickly oxidized to ap-benzoquinone named sorgoleone. The aim of this investigation was to determine the potential activity of sorgoleone as an inhibitor of weed growth. Bioassays showed 125μM sorgoleone reduced radicle elongation ofEragrostis tef. In liquid culture, 50-μM sorgoleone treatments stunted the growth ofLemna minor. Over a 10-day treatment period, 10μM sorgoleone in the nutrient medium reduced the growth of all weed seedlings tested:Abutilon theophrasti, Datura stramonium, Amaranthus retroflexus, Setaria viridis, Digitaria sanguinalis, andEchinochloa crusgalli. These data show sorgoleone has biological activity at extremely low concentrations, suggesting a strong contribution toSorghum allelopathy.
    Materialart: Digitale Medien
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