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  • Rheology  (1)
  • root sampling  (1)
  • 1
    ISSN: 1573-5036
    Keywords: Grevillea robusta ; maize ; root length ; root biomass ; root sampling ; sieves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The purpose of this study was to investigate the effects of different mesh sizes on the recovery of root length and biomass and to determine whether the degree of recovery was influenced by plant species and sample location. Sieves of 2.0, 1.0, 0.5 and 0.25 mm (4.0, 1.0, 0.25 and 0.06 mm2) mesh sizes were used to recover and measure the root length and biomass of Zea mays L. (maize) at 0–15 cm and 30–45 cm depths and of Grevillea robusta A. Cunn. ex R. Br. (grevillea) at the same depths 1.0 m and 4.5 m from a line of grevillea trees. At 0–15 cm, the coarser sieves (sum collected with 2.0 and 1.0 mm sieves) recovered approximately 80% of the total root biomass measured, but only 60% of the root length. The proportion of total maize root length and biomass recovered by the coarser sieves decreased with soil depth. The proportion of total grevillea root length recovered by the coarser sieves was similar at the two soil depths, but increased slightly with distance from the tree line. The ≥ 0.5 mm sieves recovered between 93 and 96% of grevillea and maize root biomass and between 73 and 98% of their root length, depending on the sample location. Roots passing through the 0.5 mm sieve, but recovered by the 0.25 mm sieve were about 20% of total maize root length and grevillea root length at 1.0 m from the tree line but 〈 5% of the total grevillea root length at 4.5 m from the tree. Roots passing through the 0.5 mm sieve but recovered by the 0.25 mm sieve contributed only slightly to root biomass. Although the ≥ 0.5 mm sieves provided adequate measurements of root biomass, the ≥ 0.25 mm sieves were required for accurate measurement of fine root length. There was no universal correction for root length and biomass underestimation when large sieve sizes were used because the proportions of length and biomass recovered depended on the plant species and on soil depth and distance from the plant.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 211 (1999), S. 87-91 
    ISSN: 1573-5036
    Keywords: Rheology ; root mucilage ; viscoelasticity ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root mucilage was collected from 3–4 day-old axenically-grown maize seedlings (Zea mays L. cv. Freya). The water potential of the hydrated mucilage was measured by thermocouple psychrometry and the rheology at low deformation rates was studied using an oscillating cone and plate rheometer which provides information on both the elastic and viscous components of its behaviour. Water potential decreased as mucilage solute concentration increased, reaching a value of −60kPa at 1.2 mg mL−1. At the lowest oscillation rate, the mucilage had a dynamic viscosity of 145 mPa s and behaved as a weak viscoelastic gel. After filtration to remove suspended root cap cells and other solid plant material, mucilage viscosity was reduced to 5–10 mPa s at low oscillation rates and the behaviour was that of a viscous liquid. The decrease in viscosity which occurs on filtration indicates that the root cap cells form an integral part of the gel system, either by interacting directly with each other or via the polysaccharide. Our observations provide further support for the idea that mucilage plays a major role in maintaining root-soil contact in the rhizosphere.
    Type of Medium: Electronic Resource
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