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  • 1975-1979  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Simultaneous uptake and translocation of magnesium and calcium in barley (Hordeum vulgare L.) roots (1976)
    Springer
    Planta 128 (1976), S. 267-269 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The patterns of uptake and translocation of magnesium in different regions of the root are very similar to those of calcium. Once the endodermis has become suberized translocation of either ion to the shoot is greatly reduced and it is concluded that magnesium, like calcium, appears to move across the root cortex largely in the free space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393239
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of phosphate-stress on phosphate absorption and translocation by various parts of the root system of Hordeum vulgare L. (barley) (1978)
    Springer
    Planta 139 (1978), S. 47-53 
    Details
    ISSN: 1432-2048
    Keywords: Hordeum ; Phosphate ; Root transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants of Hordeum vulgare (barley) were grown initially in a solution containing 150 μM phosphate and then transferred on day 6 to solutions with (+P) and without (-P) phosphate supplied. After various times plants from these treatments were supplied with labelled phosphate. Analysis of plant growth and rates of labelled phosphate uptake showed that a general enhancement of uptake and translocation was found, in plants which had been in the-P solution, several days before the rate of dry matter accumulation was affected. Subsequently a detailed analysis of phosphate uptake by segments of intact root axes showed that the enhancement of phosphate uptake by P-stress occurred first in the old and mature parts of the seminal root axis and last in the young zones 1 cm from the root apex. During this transition period there were profound changes in the pattern of P absorption along the length of the root. Most of the additional P absorbed in response to P-stress was translocated to the shoot, particularly in older zones of the axis. Enhancement of phosphate uptake in young zones of nodal axes occurred at an earlier stage than in seminal axes. The results are related to the P-status of shoots and root zones and discussed in relation to the general control by the shoot of phosphate transport in the root.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390809
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The influence of temperature on the exudation of xylem sap from detached root systems of rye (Secale cereale) and barley (Hordeum vulgare) (1976)
    Springer
    Planta 132 (1976), S. 297-304 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Roots of intact plants of rye and barley which had been growing at 20° were cooled for 12–72 h at 8–14° C while the shoots were kept at 20°. The roots were then excised and placed in solutions at temperatures ranging from 2.5–22.5° C. The rate of exudation of xylem sap and the chemical composition and osmotic potential of the sap were measured and compared with controls which had been kept at 20° C during the pretreatment period. Pre-cooling increased the fluxes of K+, Ca2+ and H2PO 4 - into the xylem sap of both species by factors of two to three; the total volume of exudate rose by larger factors. Thus the concentrations of these ions were lower in the sap exuding from cooled roots than in that from controls. Measurements of the osmotic potential of the sap from barley roots indicated that the osmotic driving force in cooled and control roots was similar even though flow in the former was much greater. The enhancement of exudation was shown to be dependent on the duration and the temperature experienced by the roots during pretreatment, and was lost rapidly when roots of intact plants were returned to 20°. Analysis of the temperature coefficients for exudation and Arrhenius plots revealed very distinct changes in the activation energy for exudation above and below a transition temperature. In control plants of barley and rye this temperature was around 10° C, but in cooled roots of rye there was a significant shift in the transition temperature to 5° C. Activation energies for exudation of control and cooled roots above or below the transition temperature were broadly similar, thus pre-cooling roots did not alter the temperature sensitivity of exudation but merely its rate at a given temperature. The results are discussed in relation to active ion transport, membrane fluidity and the resistance of the root to water flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399730
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Calcium-related disorders in plants — a possible explanation for the effect of weather (1978)
    Springer
    Plant and soil 50 (1978), S. 723-725 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Incidence in the field of crop disorders known to be due to localised calcium deficiency bears little relation to soil calcium status, and is more often associated with particular types of weather. We are suggesting that brief periods of soil partial anaerobiosis following wet weather, and other unfavourable soil physical conditions such as compaction, lead to a temporary reduction in the distal, undifferentiated region of roots from which the majority of the calcium taken up is transported to the shoot. This might lead to a transient calcium deficiency in rapidly growing shoot tissues, and thence to necrosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02107226
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Calcium-related disorders in plants — a possible explanation for the effect of weather (1978)
    Springer
    Plant and soil 50 (1978), S. 723-725 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Incidence in the field of crop disorders known to be due to localised calcium deficiency bears little relation to soil calcium status, and is more often associated with particular types of weather. We are suggesting that brief periods of soil partial anaerobiosis following wet weather, and other unfavourable soil physical conditions such as compaction, lead to a temporary reduction in the distal, undifferentiated region of roots from which the majority of the calcium taken up is transported to the shoot. This might lead to a transient calcium deficiency in rapidly growing shoot tissues, and thence to necrosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02107226
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Structure and permeability of the epidermal/hypodermal layers of the sand sedge (Carex arenaria, L.) (1979)
    Springer
    Protoplasma 101 (1979), S. 331-347 
    Details
    ISSN: 1615-6102
    Keywords: Carex arenaria ; Epidermis ; Hypodermis ; Permeability ; Roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During the normal course of development in the root of sand sedge (Carex arenaria), many of the cells in the central cortex degenerate to form an extensive aerenchyma. The epidermis and multi-layered hypodermis become heavily suberized and only remain attached to the stele by a few, thin, radial files of cortical cells that have not autolyzed. These changes make it possible for epidermal/hypodermal sleeves to be isolated so that their permeability can be determined. The coefficient of diffusive permeability for tritiated water is of the order of 20 nm s−1, while the permeability coefficient for self diffusion of labelled phosphate and calcium is approximately 5.0 and 4.0 nm s−1 respectively. These values are approximately 200 (water) and 500 (phosphate and calcium) times lower than similar determinations made on isolated sleeves of onion roots. The outer layers of the mature root ofC. arenaria are thus extremely impermeable: any significant absorptive function has been lost at the expense of a protective role provided by the modified cortex for the vascular stele.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276972
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    Paper (German National Licenses)
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