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  • 1990-1994  (8)
  • 1985-1989  (5)
  • 1905-1909  (2)
  • Analytical Chemistry and Spectroscopy  (5)
  • allelochemical  (5)
  • Allelopathy  (3)
  • General Chemistry  (2)
Source
Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Use ofLemna minor L. as a bioassay in allelopathy (1985)
    Springer
    Journal of chemical ecology 11 (1985), S. 65-72 
    Details
    ISSN: 1573-1561
    Keywords: Bioassay ; Lemna minor ; allelochemical ; allelopathy ; duckweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987606
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Prior cropping with grain sorghum inhibits weeds (1989)
    Springer
    Journal of chemical ecology 15 (1989), S. 951-960 
    Details
    ISSN: 1573-1561
    Keywords: Allelopathy ; grain sorghum ; Sorghum bicolor ; weed inhibition ; weed management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01015190
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Sorgoleone from root exudate inhibits mitochondrial functions (1992)
    Springer
    Journal of chemical ecology 18 (1992), S. 197-207 
    Details
    ISSN: 1573-1561
    Keywords: Sorgoleone ; mitochondria ; inhibitor ; allelochemical ; allelopathy ; root exudate ; Sorghum bicolor ; electron transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00993753
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of juglone on growth, photosynthesis, and respiration (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 559-568 
    Details
    ISSN: 1573-1561
    Keywords: Juglone ; allelopathy ; allelochemical ; photosynthesis ; chioroplast ; mitochondria ; Lemna minor ; Glycine max
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The impacts of juglone on plant growth and several other physiological functions were evaluated in this study. Juglone inhibitedLemna minor growth, chlorophyll content, and net photosynthesis at treatments between 10 and 40μM. Soybean leaf disks vacuum infiltrated with as little as 10μM juglone had reduced photosynthesis. Oxygen evolution by chloroplasts isolated fromPisum sativum was inhibited by juglone with an I50 of 2μM. Micromolar treatments of juglone stimulated oxygen uptake in mitochondria isolated fromGlycine max. These data suggest perturbations of chloroplast and mitochondrial functions may contribute to plant growth reductions observed in juglone-mediated allelopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00994325
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  • 5
    Electronic Resource
    Electronic Resource
    Phytotoxicity of sorgoleone found in grain Sorghum root exudates (1992)
    Springer
    Journal of chemical ecology 18 (1992), S. 1-11 
    Details
    ISSN: 1573-1561
    Keywords: Sorgoleone ; phytotoxin ; allelochemical ; allelopathy ; root exudate ; Sorghum bicolor ; Sorghums ; weed inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00997160
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  • 6
    Electronic Resource
    Electronic Resource
    Bioassay of naturally occurring allelochemicals for phytotoxicity (1988)
    Springer
    Journal of chemical ecology 14 (1988), S. 1821-1828 
    Details
    ISSN: 1573-1561
    Keywords: Allelopathy ; bioassay ; mechanism of action ; seed germination ; radicle growth ; seedling growth ; Lemna bioassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The bioassay has been one of the most widely used tests to demonstrate allelopathic activity. Often, claims that a particular plant species inhibits the growth of another are based entirely on the seed germination response to solvent extracts of the suspected allelopathic plant; few of these tests are of value in demonstrating allelopathy under natural conditions. The veracity of the bioassay for evaluating naturally occurring compounds for phytotoxicity depends upon the physiological and biochemical response capacity of the bioassay organism and the mechanism(s) of action of the allelochemicals. The possibility that more than one allelochemical, acting in concert at very low concentrations, may be responsible for an observed allelopathic effect makes it imperative that bioassays be extremely sensitive to chemical growth perturbation agents. Among the many measures of phytotoxicity of allelochemicals, the inhibition (or stimulation) of seed germination, radicle elongation, and/or seedling growth have been the parameters of choice for most investigations. Few of these assays have been selected with the view towards the possible mechanism of the allelopathic effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01013479
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  • 7
    Electronic Resource
    Electronic Resource
    The effects of ferulic acid on the mineral nutrition of grain sorghum (1987)
    Springer
    Plant and soil 98 (1987), S. 99-109 
    Details
    ISSN: 1573-5036
    Keywords: Allelopathy ; Ferulic acid ; Magnesium ; Mineral content ; Phosphorus ; PotassiumSorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two week old sorghum seedlings (Sorghum bicolor L. Moench) were treated with ferulic acid added to the nutrient solution. Effects on tissue concentration of P, K, Mg, Ca, Fe, and Zn were evaluated after 3 and 6 days. Treatemnts of 0.25 mM ferulic acid approximated the growth inhibition threshold, and after 6 days 0.5 mM treated plants weighed less than controls. Both treatments reduced the P content of the roots and shoots at the 3- and 6-day harvests in three replicate experiments. Roots of treated plants at both harvests had a lower concentration of K and Mg. These reductions in P, K, and Mg were most extensive from the 0.5 mM ferulic acid regime. In some cases at both harvests, shoot K was lower and Mg was higher than control tissue. Ferulic acid effects at the 3-day harvest included an elevation of Ca and depression of Fe in shoots. Changes in nutrient content preceded measurable differences in plant weight. These data indicate that one mechanism of growth inhibition by this allelochemical may be an alteration of nutrient balance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02381731
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of root exudate sorgoleone on photosynthesis (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 369-375 
    Details
    ISSN: 1573-1561
    Keywords: Sorgoleone ; allelochemical ; allelopathy ; photosynthesis ; chloroplast ; root exudate ; Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The aim of this investigation was to determine if sorgoleone (SGL), ap-benzoquinone inSorghum bicolor root exudate, is a photosynthesis inhibitor. Assays usingGlycine max leaf disks showed concentrations as low as 10μM SGL inhibited oxygen evolution more than 50%. Tests conducted on chloroplasts isolated fromPisum sativum showed that SGL is a powerful inhibitor of CO2-dependent oxygen evolution. Using a chloroplast suspension equivalent to 80–100μg chlorophyll, the I50 was approximately 0.2μM SGL. These data indicate inhibition of photosynthesis is part of the explanation for growth reduction caused by this allelochemical.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00993702
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetic energy effects in an ion ensemble subjected to mass-selective isolation and resonance excitation: A simulation study (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 499-509 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simulation study is described of the behaviour of ions confined in a quadrupole ion trap during each of two separate operations of a tandem mass spectrometric experiment. The two operations are those of mass-selective ion isolation and mass-selective resonance excitation to the point of ion ejection from the ion trap. The method of mass-selective ion isolation simulated is that of consecutive ion isolation. Simulation data indicate that the collisional history of the ions prior to the isolation process can greatly influence the degree to which ions survive this process. Simulation data for mass-selective resonance ejection are compared with experimental data obtained with a Finnigan-MAT ion trap mass spectrometer. In each operation, the facility with which ions absorb energy from the field within the ion trap, whether this field is derived from the R.F. drive potential or a supplementary potential, can determine the extent to which ions are retained within the ion trap during the two mass-selective operations described.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280506
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of collisional cooling on boundary-activated decomposition in an ion-trap mass spectrometer (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 929-934 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: When the working point of a precursor ion confined within a quadrupole ion trap is moved to the vicinity of a boundary of the stability diagram, fragmentation of the precursor ion can be induced by virtue of energy gained from the radio-frequency trapping field. This behaviour is known as the ‘border effect’. When the isolated precursor ion is subjected to a cooling period of variable duration, in the presence of helium buffer gas and prior to experiencing the ‘border effect’, a high degree of control of the fragmentation pattern is achieved. The cooling period causes decreases in both ion kinetic energy and ion axial excursions. From this preliminary study, it is suggested that the deposition of internal energy during the ‘border effect’ can be varied by changing the duration of the cooling period. In addition to a degree of control of internal energy deposition, the amount of energy which can be deposited in this manner, though unknown, appears to exceed those energy levels achievable with resonance excitation and the ‘border effect’ without collisional cooling, in that an additional fragmentation channel is accessed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290071014
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