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  • 1
    Electronic Resource
    Electronic Resource
    Development and replenishment of the P-depletion zone around the primary root of maize during the vegetation period (1987)
    Springer
    Plant and soil 101 (1987), S. 247-255 
    Details
    ISSN: 1573-5036
    Keywords: freeze-cutting ; dynamics ; depletion zone ; root longevity ; maize ; P-deficiency ; phosphate ; radioautography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the development and replenishment of P-depletion zones around the primary root of maize (Zea mays L. cv ‘Garbo’) was studied during a vegetation period (80 days) under greenhouse conditions in a loamy sand of low P-availability. A recently described freeze-cutting technique was used to determine radial diffusion of labelled phosphate to the primary root. The development of the depletion zone was biphasic. In the initial phase after two days of growth of the primary root in a soil layer labelled with33P a minimum of isotopically exchangeable P (EP) was observed which had decreased to about 30% of its original amount at the root surface. At that time the corresponding P-concentration in the soil solution was calculated to be as low as 5×10−7 M. The depletion zone had already spread 0.4 mm from the root surface. During the second phase, between the 10th and 20th day of plant growth the concentration of EP at the root surface increased slowly but did not change markedly. However, the depletion zone continued to spread and after the 20th day of growth reached its maximal diameter (1.07 mm from the root surface) but remained completely within the root hair cyclinder; the single root hairs never exceeded 1.14 mm in length. The biphasic growth of the depletion zone was probably caused by proton extrusion of the root tip. Acidification of the soil solution from pH 5.8 to about 3.9 results in an about 3-fold rise of the concentration of desorbed phosphate and might also have activated acidophilic P-translocators of the root during the initial phase. Anion over cation uptake normally prevailing during the later stage of root development might resulted in a rise of the soil pH within the root hair zone. Consequently P-availability, as well as P-uptake capacity declined, but P-uptake by the seminal root still continued until the 20th day. Subsequently, the P-concentration within the depletion zone increased again while simultaneously its extent was reduced until it was almost completely replenished after 60 days indicating a loss of P-uptake capacity of the primary root. Within the root tissue33P was accumulated to about twice the concentration of that in the undepleted soils. This accumulation corresponded to periods of high uptake due to the development of root laterals. In the root cortex a high P-content was observed during the first 30 days of growth. At the onset of the reproductive stage of the plant the P-content of the shoot and especially in the developing seeds rose considerably at the cost of phosphate stored in the root cortex. The accumulation of33P in the root tissue indicated that nutrient gain was mainly achieved during the early stages of plant development and that P was temporarily stored to some extent within the root system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02370652
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  • 2
    Electronic Resource
    Electronic Resource
    Reassessment of root competition for P of field-grown maize in pure and mixed cropping (1988)
    Springer
    Plant and soil 106 (1988), S. 299-301 
    Details
    ISSN: 1573-5036
    Keywords: lupin ; maize ; phosphate ; root competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root competition for phosphate (P) in the field was calculated with maize i) as singly grown plants, ii) in pure cropping and iii) in mixed cropping with lupin. The experimentally determined parameters used for this purpose were thein situ root-distance pattern as registered by autoradiography and the P-depletion cylinder around a maize root as determined autoradiographically under radial diffusional flow. The results do not indicate any competition for P between roots of adjacently grown plants in either pure or mixed cropping. On the other hand, the P-depletion cylinders of approximately one third of the roots of an individual maize plant were found to overlap. However, when allowance was made for the concentration gradients within a depletion cylinder, the actual competition for phosphate was less than 1%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371230
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and properties of a cellulose exchanger with the crown ether diaminodibenzo-17-crown-5 as anchor group (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 227 (1995), S. 101-110 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Cellulose- Austauscher wurde aus “o-Aminophenol-Cellulose” durch Diazotieren und Kuppeln mit Diaminodibenzo-17-krone-5 hergestellt. Die Verteilungskoeffizienten für Ca2+, Sr2+, Ba2+, Na+ und K+ wurden in Wasser/Methanol-Mischungen als Funktion des Wassergehaltes bestimmt. Die Trennung von Ca2+, Na+ und K+ und die Fraktionierung der Calciumisotope 48Ca und 40Ca wurde untersucht. Der Anreicherungsfaktor ε = 4.9 · 10-3 für 48Ca2+ ist merklich größer als der für Kationenaustauscher mit SO3H-Gruppen gefundene, aber niedriger als der in der Literatur für bestimmte Kryptanden angegebene Wert.
    Notes: A new cellulose exchanger was synthesized from “o-aminophenolcellulose” by diazotation and coupling with diaminodibenzo-17-crown-5. The distribution coefficients for Ca2+, Sr2+, Ba2+, Na+ and K+ were determined in water/methanol mixtures as a function of the water content. Separation of Ca2+, Na+ and K+ and fractionation of the calcium isotopes 48Ca and 40Ca were investigated. The enrichment factor ε = 4.9 · 10-3 for 48Ca2+ is appreciably higher than that found for cation exchange resins with —SO3H groups, but lower than that reported for certain cryptands.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052270110
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  • 4
    Electronic Resource
    Electronic Resource
    Eni naturwissenschaftliches Literaturkarussell. Biologie (1993)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 27 (1993), S. III 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19930270209
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  • 5
    Electronic Resource
    Electronic Resource
    Disproportionierung der Sulfinsäuren und die Struktur der Sulfinsäureanhydride (1958)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 70 (1958), S. 268-269 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19580700904
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