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  • Springer  (34)
  • Cambridge University Press  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Uptake and long-distance transport of phosphate, potassium and chloride in relation to internal ion concentrations in barley: evidence of non-allosteric regulation (1984)
    Springer
    Planta 160 (1984), S. 500-507 
    Details
    ISSN: 1432-2048
    Keywords: Chloride uptake (root) ; Hordeum (ion uptake) ; Ion uptake ; Nutrient deficiency ; Phosphate uptake (root) ; Potassium uptake (root)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The extent to which uptake and transport of either phosphate, potassium or chloride are controlled by the concentration of these ions within the root, perhaps through an allosteric mechanism, was investigated with young barley plants in nutrient solution culture. Plants were grown with their roots divided between two containers, such that a single seminal root was continuously supplied with all the required nutrient ions, while the remaining four or five seminal roots were either supplied with the same solution (controls) or, temporarily, a solution lacking a particular nutrient ion (nutrient-deficient treatment). Compared with controls, there was a marked stimulation of uptake and transport of labelled ions by the single root following 24 h or more of nutrient dificiency to the remainder of the root system. This stimulation, which comprised an increased transport to the shoot and, for all ions except Cl-, increased transport to the remainder of the root system, took place without appreciable change in the concentration of particular ions within the single root. However, nutrient deficiency quickly caused a lower concentration of ions in the shoot and the remaining roots. The results are discussed in relation to various mechanisms, proposed in the literature, by which the coordination of ion uptake and transport may be maintained within the plant. We suggest that under our conditions any putative allosteric control of uptake and transport by root cortical cells was masked by an alternative mechanism, in which ion influx appears to be regulated by ion efflux to the xylem, perhaps controlled by the concentration of particular ions recycled in the phloem to the root from the shoot.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411137
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  • 2
    Electronic Resource
    Electronic Resource
    Larger adenylate energy charge and ATP/ADP ratios in aerenchymatous roots of Zea mays in anaerobic media as a consequence of improved internal oxygen transport (1985)
    Springer
    Planta 165 (1985), S. 51-58 
    Details
    ISSN: 1432-2048
    Keywords: Adenine nucleotide ; Adenylate energy charge ; Acrenchyma ; Anaerobiosis ; Anoxia ; Gas space (root) ; Oxygen ; Root (O2 supply) ; Zea (root, oxygen)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Internal transport of O2 from the aerial tissues along the adventitious roots of intact maize plants was estimated by measuring the concentrations of adenine nucleotides in various zones along the root under an oxygen-free atmosphere. Young maize plants were grown in nutrient solution under conditions that either stimulated or prevented the formation of a lysigenous aerenchyma, and the roots (up to 210 mm long) were then exposed to an anaerobic (oxygen-free) nutrient solution. Aerenchymatous roots showed higher values than non-aerenchymatous ones for ATP content, adenylate energy charge and ATP/ADP ratios. We conclude that the lysigenous cortical gas spaces help maintain a high respiration rate in the tissues along the root, and in the apical zone, by improving internal transport of oxygen over distances of at least 210 mm. This contrasted sharply with the low energy status (poor O2 transport) in non-aerenchymatous roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392211
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  • 3
    Electronic Resource
    Electronic Resource
    Ethylene-promoted adventitious rooting and development of cortical air spaces (aerenchyma) in roots may be adaptive responses to flooding in Zea mays L (1979)
    Springer
    Planta 147 (1979), S. 83-88 
    Details
    ISSN: 1432-2048
    Keywords: Adventitious roots ; Air spaces (aerenchyma) ; Ethylene ; Oxygen ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The roots and stem base of intact, 10 day old maize (Zea mays L. cv. LG11) plants, grown in nutrient solution, were continuously aerated either with ethylene (5 μl l-1) in air or with air alone. Ethylene treatment hastened the emergence of adventitious (nodal) roots from the base of the shoot, but slowed their subsequent extension. Ethylene also promoted the collapse of cells in the cortex of these roots, with lysigenous development of prominent air spaces (aerenchyma). Non-aeration of the nutrient solution caused endogenously produced ethylene to accumulate in the roots, and stimulated both the emergence of adventitious roots and the formation of cortical air spaces in them. With non-aeration the concentration of oxygen did not fall below 1% in the equilibrium gas phase (air=20.8%). Complete deoxygenation of the nutrient solution, produced by passing oxygen-free nitrogen gas, prevented both air space formation and the evolution of ethylene by root segments. These results suggest that adventitious rooting and cortical air space formation in nodal roots in Zea mays may be stimulated by enhanced concentrations of endogenous ethylene arising either from entrapment of the gas by unstirred water layers around the roots and/or by increased biosynthesis. These responses are considered conducive to survival in waterlogged soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384595
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  • 4
    Electronic Resource
    Electronic Resource
    Electron microscopy of gas space (aerenchyma) formation in adventitious roots of Zea mays L. subjected to oxygen shortage (1983)
    Springer
    Planta 157 (1983), S. 350-357 
    Details
    ISSN: 1432-2048
    Keywords: Aerenchyma ; Gas space (roots) ; Oxygen shortage (roots) ; Zea (aerenchyma)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper examines the ultrastructure of cortical cells in maize root tips during the early stages in lysigenous aerenchyma formation, promoted by oxygen-deficient nutrient solution. The aim was to determine whether changes in fine structure were compatible with oxygen starvation as the primary cause of cell degeneration and death. There was an initial collapse of some cortical cells, indicating loss of turgor, and the cytoplasm became more electron dense. Mitochondria and endoplasmic reticulum appeared normal at this early stage though the tonoplast lost its integrity. Subsequently the cytoplasm became less electron dense than surrounding healthy cells, and underwent further degeneration while the plasmalemma retracted from the cell wall. Cell walls remained unaltered until this stage, but some then became thin and electron transparent. No cells of the stele were found to degenerate. These observations, which do not readily accord with the hypothesis that oxygen starvation was the cause of cell death, are compared with detailed studies of cell degeration in other cell types. An alternative mechanism for the stimulation of cortical cell lysis in poorly oxygenated roots involving the hormone ethylene, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397407
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  • 5
    Electronic Resource
    Electronic Resource
    Stimulation of ethylene production and gas-space (aerenchyma) formation in adventitious roots of Zea mays L. by small partial pressures of oxygen (1985)
    Springer
    Planta 165 (1985), S. 486-492 
    Details
    ISSN: 1432-2048
    Keywords: Adventitious root ; Aerenchyma ; Environmental stress ; Ethylene and O2 deficiency ; Oxygen deficiency ; Root (adventious) ; Zea (aerenchyma, ethylene)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adventitious roots of two to four-weekold intact plants of Zea mays L. (cv. LG11) were shorter but less dense after extending into stagnant, non-aerated nutrient solution than into solution continuously aerated with air. Dissolved oxygen in the non-aerated solutions decreased from 21 kPa to 3–9 kPa within 24 h. When oxygen partial pressures similar to those found in non-aerated solutions (3, 5 and 12 kPa) were applied for 7 d to root systems growing in vigorously bubbled solutions, the volume of gas-space in the cortex (aerenchyma) was increased several fold. This stimulation of aerenchyma was associated with faster ethylene production by 45-mm-long apical root segments. When ethylene production by roots exposed to 5 kPa oxygen was inhibited by aminoethoxyvinylglycine (AVG) dissolved in the nutrient solution, aerenchyma formation was also retarded. The effect of AVG was reversible by concomitant applications of 1-aminocyclopropane-1-carboxylic acid, an immediate precursor of ethylene. Addition of silver nitrate, an inhibitor of ethylene action, to the nutrient solution also prevented the development of aerenchyma in roots given 5 kPa oxygen. Treating roots with only 1 kPa oxygen stimulated ethylene production but failed to promote gas-space formation. These severely oxygen-deficient roots seemed insensitive to the ethylene produced since a supplement of exogeneous ethylene that promoted aerenchyma development in nutrient solution aerated with air (21 kPa oxygen) failed to do so in nutrient solution supplied with 1 kPa oxygen. Both ethylene production and aerenchyma formation were almost completely halted when roots were exposed to nutrient solutions devoid of oxygen. Thus both processes require oxygen and are stimulated by oxygen-deficient surroundings in the 3-to 12-kPa range of oxygen partial pressures when compared with rates observed in air (21 kPa oxygen).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398093
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in the kinetics of phosphate and potassium absorption in nutrient-deficient barley roots measured by a solution-depletion technique (1984)
    Springer
    Planta 160 (1984), S. 490-499 
    Details
    ISSN: 1432-2048
    Keywords: Hordeum (ion uptake) ; Ion uptake ; Nutrient deficiency ; Phosphate uptake (root) ; Potassium uptake (root)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From measurements of the rates of depletion of labelled ions from solution in the low concentration range, we described the phosphate and potassium uptake characteristics of the roots of intact barley plants in terms of the kinetic parameters, K m and I max (the maximum rate of uptake). In relatively young (13 d) and older (42 d) plants, cessation of phosphate supply for 4 d or more caused a marked increase in I max (up to four times), without concomitant change in K m, which remained between 5 and 7 μM. By contrast, 1 d of potassium starvation with 14-d plants caused a decline in the K m (i.e. an increased apparent affinity for potassium) from 53 μM to 11 μM, without alteration to I max. After longer periods of potassium starvation, I max increased (about two times) while the K m remained at the same low value. Growth of shoots and roots were unaffected by these treatments, so that concentrations of ions in the tissues declined after 1 d or more of nutrient starvation, but we could not identify a characteristic endogenous concentration for either nutrient at which changes in kinetic parameters were invariably induced. The possible mechanisms regulating carriermediated transport, and the importance of changes induced in kinetic parameters in ion uptake from solution and soil are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411136
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison of analytical methods for extraction of chloride from plant tissue using36Cl as tracer (1991)
    Springer
    Plant and soil 136 (1991), S. 265-268 
    Details
    ISSN: 1573-5036
    Keywords: chloride extraction ; 36Cl ; liquid scintillation ; radio isotopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eleven published and unpublished methods for extraction of chloride from plant tissue were compared, using a homogeneous sample of dried, ground maize leaves previously labelled with36Cl. The most effective method of extraction of Cl−, estimated by liquid scintillation counting of36Cl, was with hot water. However, six other methods, including either cold water extraction, or dry-ashing at 500°C of plant material previously treated to give an alkaline pH, gave36Cl values that were not statistically different from that obtained with hot water extraction. The lowest estimates of36Cl content were obtained either by wet digestion in nitric/acetic acid or by dry-ashing following Mg(NO3)2 treatment of the plant material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02150058
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  • 8
    Electronic Resource
    Electronic Resource
    The development of waterlogging damage in wheat seedlings (Triticum aestivum L.) (1980)
    Springer
    Plant and soil 54 (1980), S. 77-94 
    Details
    ISSN: 1573-5036
    Keywords: Nutrients ; Oxygen ; Roots ; Soil ; Toxins ; Waterlogging ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of waterlogging on concentrations of gases and various solutes dissolved in the soil water were investigated in the laboratory, to determine whether the early disruption to the growth of wheat was most closely associated with depletion of dissolved oxygen, accumulation of toxins, or changes in concentrations of nutrient ions in the soil water. Waterlogging slowed shoot fresh weight accumulation, leaf extension and nodal root growth; it also caused death of the seminal root system and early senescence of the lower leaves. However, the shoot dry weight initially increased above that of the non-waterlogged controls, and thus was not a reliable indicator of the early restriction to plant growth and development. The symptoms of damage to shoots and roots were attributed to the fall in soil oxygen concentrations, rather than to any decrease in concentration of inorganic nutrients in the soil water, or to the accumulation of any other measured solutes to toxic concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02182001
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of waterlogging on young wheat plants (Triticum aestivum L.) and on soil solutes at different soil temperatures (1982)
    Springer
    Plant and soil 69 (1982), S. 311-326 
    Details
    ISSN: 1573-5036
    Keywords: Aeration ; Calcium ; Carbon dioxide ; Ethylene ; Nitrate ; Nitrite ; Nitrous oxide ; Oxygen ; Potassium ; Roots ; Triticum aestivum ; Waterlogging ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We report a study of the mechanism by which the response of plants to waterlogging can be modified by soil temperature. Wheat was grown initially in well-aerated soil in a controlled environment room before the soil was flooded with aerated, deionized water. The soil temperature was maintained constant in the range 6–18°C while the air temperature was at 14°C. Waterlogging damage was greater in plants at the higher soil temperatures when the plants were compared at the same chronological age. However, when compared at the same growth stage, the response to soil temperature was little differenti.e. plants subjected to waterlogging for a long time at low soil temperatures exhibited a similar reduction in growth and other properties as those subjected briefly at higher temperatures. The concentration of dissolved oxygen in the soil solution declined rapidly at all temperatures, being almost zero after 36 h waterlogging. Temperature affected rates of change of the concentrations of dissolved carbon dioxide, ethylene, nitrous oxide, nitrite, nitrate, calcium and potassium. The importance of soil-and plant-determined properties in the waterlogging response of plants at different temperatures are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02372453
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  • 10
    Electronic Resource
    Electronic Resource
    The supply of nutrient ions by diffusion to plant roots in soil (1970)
    Springer
    Plant and soil 33 (1970), S. 545-563 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Measurements were made of the diffusion of P32-labelled phosphate to single roots of onion, leek and rye-grass growing in an Upper Greensand sandy loam (UGS) and a Coral Rag Clay (CRC) to which different amounts of phosphate had been added. Concentration-dependent diffusion coefficients for phosphate ions in the soils were calculated from phosphate desorption isotherms in calcium chloride. The experimental uptake by roots of known dimensions was compared with supply expected by diffusion to a cylindrical model root of the same dimensions. Allowance was made for absorption by the root hairs on rye-grass roots. Phosphate absorption by a cm length of intact root was found to continue for at least 16 days for onion, 10 days for leek and 5 days for rye-grass. Over a wide range of conditions (phosphate concentrations, soils, plant species), experimental uptake was close to the maximum calculated to be possible for the diffusion model except on one soil at a high level of phosphate. Although the concentration of phosphate in the soil solution at the root boundary appeared to be reduced to a small fraction of the initial concentration, because of the extreme non-linear form of the desorption isotherm less than 1/2 of the P32 exchangeable pool of P was considered to contribute to diffusion. Phosphate uptake by rye grass could only be accounted for if the root hairs were active. Although only a small fraction of the uptake is derived from inside the root hair cylinder, this increases the efficiency of the central root 2.3 fold by providing a zone close to the central root through which phosphate moves very readily.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378245
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