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  • 1
    ISSN: 1432-2048
    Keywords: Calcium ; Cation exchange ; Lycopersicon esculentum ; Rhythm ; diurnal Transport (calcium) ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tomato (Lycopersicon esculentum Mill. cv. Moneymaker) and maize (Zea mays L. cv. spec.) plants were supplied with 45Ca-labeled nutrient solutions for a period of 8 or 16 h in the dark, in the light, or in a light-dark régime. Plant parts were analyzed for 45Ca content. The partitioning of 45Ca between mature leaves and meristems was shown to be affected by the presence of light. The transport of 45Ca to meristems was higher in a dark period than in a comparable light period. Experiments with excised tomato shoots yielded similar distribution patterns of 45Ca over leaves and meristems, thus excluding root pressure as the main driving force for the enhanced import of 45Ca into the meristems in the dark. Results are discussed in terms of cation-exchange transport and competition between the various calcium sinks.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5036
    Keywords: Cadmium ; Cation exchange ; Copper ; Heavy metals ; Illite clay ; Nickel ; Organic matter ; Tetraethylenepentamine ; Tetren ; Transition metal complexes ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The ion exchange behavior of heavy metals (Cu, Zn, Ni, Cd) in soils is shown to be strongly influenced by complex formation with tetraethylenepentamine (tetren). In a heavy clay (illite) soil, the metal (complex) concentration in the equilibrium solution is lowered by some two orders of magnitude, as compared to the aqueous metal ions. In a sandy loam, in which the exchange properties are nearly exclusively due to organic matter, the addition of tetren leads to a significant increase of the metal (complex) in solution. These effects are interpreted in terms of the high adsorption selectivity of the metal complexes for clay particles (illite clay) and the competition of tetren with the chelating groups of the humic fraction (sandy loam). In this case the resulting tetren complexes remain in solution and can be immobilized by addition of small amounts of clay to such a soil.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5036
    Keywords: Cation exchange ; Copper ; Copper complex ; Copper-64 ; Corn ; Cyperus papyrus ; Papyrus ; Tetraethylenepentamine ; Tetren ; Transport ; Xylem ; Zea mays L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The consequences of complex formation with tetren (tetraethylenepentamine) for the uptake and mobility of copper in the plant is studied. Short term supply of double labelled Cu-tetren (64Cu,14C-tetren) in nutrient solution to corn plants (Zea mays L., cv. spec.) indicates a stoichiometric uptake of the 1-1 complex. This is reflected in the increased shoot/root ratio of the64Cu-content (two orders of magnitude) resulting from an enhanced mobility of the complexed Cu in the plant. Increasing Cu-concentrations reduce the uptake of tetren, and an interaction between the uptake of tetren and Cu-tetren is demonstrated. The changed mobility of the64Cu-tetren complex is shown in more detail using cut shoots of papyrus plants (Cyperus papyrus L. cv. spec.) andin vivo detection of the64Cu radiation during transport. Results are discussed in terms of the effect of complex formation on the cation exchange process during xylem transport.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5036
    Keywords: Copper ; Copper complex ; Corn ; Heavy metals ; Nutrient solutions ; Tetraethylenepentamine ; Tetren ; Zea mays L ; Zinc ; Zinc complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Complex formation of copper with tetraethylenepentamine (tetren) has some pronounced effects on the rate of uptake of the metal in corn, grown on nutrient solutions. At normal copper levels (0.02 ppm) in the medium, complex formation leads to a nearly hundredfold decrease in the rate of uptake, growth rate being slightly improved. Similar effects are observed at high copper levels (0.05 and 1 ppm) in which case the growth rate, severely affected in the absence of tetren, can be restored to normal values. High excess of tetren in the medium leads to copper-deficiency. Evidence is presented that the metal is taken up and translocated to the shoot as a metal complex and that its rate of translocation through the xylem is higher than for the aqueous ion. The effects in the case of zinc are similar although somewhat less marked.
    Type of Medium: Electronic Resource
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