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  • 11
    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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  • 12
    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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  • 13
    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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  • 14
    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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  • 15
    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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  • 16
    Electronic Resource
    Electronic Resource
    Measurement and modelling of photosynthetic response of pearl millet to soil phosphorus addition (1996)
    Springer
    Plant and soil 184 (1996), S. 67-73 
    Details
    ISSN: 1573-5036
    Keywords: pearl millet ; Pennisetum glaucum (L.) R. Br. ; phosphorus ; photosynthesis ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract There have been no studies of the effects of soil P deficiency on pearl millet (Pennisetum glaucum (L.) R. Br.) photosynthesis, despite the fact that P deficiency is the major constraint to pearl millet production in most regions of West Africa. Because current photosynthesis-based crop simulation models do not explicitly take into account P deficiency effects on leaf photosynthesis, they cannot predict millet growth without extensive calibration. We studied the effects of soil addition on leaf P content, photosynthetic rate (A), and whole-plant dry matter production (DM) of non-water-stressed, 28 d pearl millet plants grown in pots containing 6.00 kg of a P-deficient soil. As soil P addition increased from 0 to 155.2 mg P kg−1 soil, leaf P content increased from 0.65 to 7.0 g kg−1. Both A and DM had maximal values near 51.7 mg P kg−1 soil, which corresponded to a leaf P content of 3.2 g kg−1. Within this range of soil P addition, the slope of A plotted against stomatal conductance (gs) tripled, and mean leaf internal CO2 concentration ([CO2]i) decreased from 260 to 92 μL L−1, thus indicating that P deficiency limited A through metabolic dysfunction rather than stomatal regulation. Light response curves of A, which changed markedly with P leaf content, were modelled as a single substrate, Michaelis-Menten reaction, using quantum flux as the substrate for each level of soil P addition. An Eadie-Hofstee plot of light response data revealed that both KM, which is mathematically equivalent to quantum efficiency, and Vmax, which is the light-saturated rate of photosynthesis, increased sharply from leaf P contents of 0.6 to 3 g kg−1, with peak values between 4 and 5 g P kg−1. Polynomial equations relating KM and Vmax, to leaf P content offered a simple and attractive way of modelling photosynthetic light response for plants of different P status, but this approach is somewhat complicated by the decrease of leaf P content with ontogeny.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029275
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  • 17
    Electronic Resource
    Electronic Resource
    Assessment of a rapid method, using soil cores, for estimating the amount and distribution of crop roots in the field (1980)
    Springer
    Plant and soil 55 (1980), S. 297-305 
    Details
    ISSN: 1573-5036
    Keywords: Barley ; Cereals ; Root distribution ; Root growth ; Soil ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A study was made of the relationship between the number of roots (Nr) observed on unit area of the freshly exposed, horizontal faces of soil cores, and the amounts of roots (per unit volume) present in the same cores. Soil cores, 7 cm diameter, were extracted to depths of 1 m from cereal crops in 1976 at three field sites located on clay soils. Sampling was either at the start of stem elongation, or at anthesis. Estimates of root length per unit soil volume (L) were derived from Nr by assuming random orientation of roots in the soil. Values of L were found to be highly correlated with the measured lengths of both the main roots (root axes) and the total roots (axes and laterals) washed from the soil at a given growth stage, for each of the soils. On average, L was 3.3 times the length of root axes washed from the soil, and was 0.42 times the length of total roots, but there was appreciable variation between different growth stages and field sites. Possible factors giving rise to differences between L and the measured lengths of roots are discussed. Estimates of root length from observation of soil cores may nonetheless provide a suitable basis for rapidly comparing therelative distribution of roots down the soil profile under field conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181809
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  • 18
    Electronic Resource
    Electronic Resource
    The supply of nutrient ions by diffusion to plant roots in soil (1969)
    Springer
    Plant and soil 30 (1969), S. 252-270 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A single-root technique is used to measure the rate of supply of potassium by diffusion to 1-cm portions of cylindrical roots of onion and leek plants growing in soils containing different levels of exchangeable potassium. The relation between uptake and characteristics of the plant and soil is interpreted on the basis of a diffusion supply model. Uptake is accounted for in terms of the geometry of the absorbing root surface, the physiologically controlled absorbing power of the root, and the diffusion through the soil. The different uptakes of potassium by roots of comparable absorbing power from different soils can be predicted with some success from calculations using the root dimensions and either diffusion coefficients of potassium in soil, derived from flux to a cation exchange resin paper, or the form of the potassium scorption isotherm relating the concentration of labile ions to those in the soil solution. It is calculated that diffusion through the soil has reduced potassium uptake by the roots to between 87 and 39 per cent of that expected for roots of the same absorbing power in a stirred culture solution at the same initial soil solution concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01349514
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  • 19
    Electronic Resource
    Electronic Resource
    The supply of nutrient ions by diffusion to plant roots in soil (1969)
    Springer
    Plant and soil 31 (1969), S. 407-424 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Observation of soil grown roots of rye-grass shows that an approximately cylindrical volume of soil, the root hair cylinder, is densely occupied by root hairs. Estimates are given of the concentration of labile and solution potassium within the root hair cylinder during experiments measuring potassium uptake from two soils by single roots. Calculations, using a diffusion model, suggest that labile potassium concentrations may be reduced to between 99.3 and 53 per cent of the initial, depending on the diffusion characteristics of the soil and nutrient demand by the root. Of the total potassium absorbed by a root in 4 days, the proportion which is supplied from within the root hair cylinder is small (0.8 to 6.3 per cent) indicating that diffusion to the root from the soil outside the root hair cylinder is of paramount importance. When root demand is high, diffusion appears to limit uptake to between 71 and 59 per cent of that which roots of comparable physiology would be expected to absorb from stirred solution of the same concentration. Nevertheless, the presence of root hairs is calculated to have enhanced uptake by up to 77 per cent compared with roots without hairs because they virtually increase the root diameter. Diffusion does not appear to be a limiting factor when root demand is low and hairs can then add little to the efficiency of the root system in potassium absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01373813
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  • 20
    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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