Root responses to soil physical conditions and the role of root-particle contact
type: CreativeWork
description: This thesis considers the elongation o f root and shoots in relation to matric potential and soil strength in contrasting species. The role of root-particle contact for root and shoot elongation in relation to particle/aggregate size and bulk density at various matric potentials is discussed. Root and shoot elongation o f maize and lupin in soil and vermiculite at matric potentials ranging from -0.03 MPa to -1.6 MPa were investigated. Both root and shoot elongation rate of maize and lupin were significantly slower in vermiculite than in soil (p <0.001). As vermiculite has very different particle size distribution and hydraulic properties from soil, the degree of contact between root and vermiculite was thought to provide a possible explanation for the slower elongation rates. A new method was developed to quantify root-particle contact using X-ray microtomography and verified using ‘phantoms’ (model systems o f known dimensions). Root-particle contact was approximately 25 % greater in soil than in vermiculite. The greater root-particle contact in soil was thought to provide better growth conditions than in vermiculite. Root and shoot elongation were examined when plants were place in humid air above an osmotic solution (KC1) to evaluate the degree to which root elongation could occur in the absence o f solution contact. No significant shoot elongation occurred and root elongation was more reduced than in vermiculite. Hairless maize and barley mutants and their wildtypes were used to investigate further the effects o f root-particle contact when water availability is limiting in both soil and vermiculite systems. Root elongation rates o f the hairless mutants were slower than those of the wildtypes, when the growth medium was wetter than -1.6 MPa. However the reduction in root elongation o f hairless maize may have been due to pleiotropic effects slowing the elongation (the elongation rate relative to the maximum elongation rate was not significantly different). The …
abstract: This thesis considers the elongation o f root and shoots in relation to matric potential and soil strength in contrasting species. The role of root-particle contact for root and shoot elongation in relation to particle/aggregate size and bulk density at various matric potentials is discussed. Root and shoot elongation o f maize and lupin in soil and vermiculite at matric potentials ranging from -0.03 MPa to -1.6 MPa were investigated. Both root and shoot elongation rate of maize and lupin were significantly slower in vermiculite than in soil (p <0.001). As vermiculite has very different particle size distribution and hydraulic properties from soil, the degree of contact between root and vermiculite was thought to provide a possible explanation for the slower elongation rates. A new method was developed to quantify root-particle contact using X-ray microtomography and verified using ‘phantoms’ (model systems o f known dimensions). Root-particle contact was approximately 25 % greater in soil than in vermiculite. The greater root-particle contact in soil was thought to provide better growth conditions than in vermiculite. Root and shoot elongation were examined when plants were place in humid air above an osmotic solution (KC1) to evaluate the degree to which root elongation could occur in the absence o f solution contact. No significant shoot elongation occurred and root elongation was more reduced than in vermiculite. Hairless maize and barley mutants and their wildtypes were used to investigate further the effects o f root-particle contact when water availability is limiting in both soil and vermiculite systems. Root elongation rates o f the hairless mutants were slower than those of the wildtypes, when the growth medium was wetter than -1.6 MPa. However the reduction in root elongation o f hairless maize may have been due to pleiotropic effects slowing the elongation (the elongation rate relative to the maximum elongation rate was not significantly different). The …
author: Schmidt, Sonja
language: eng
date published: 2011-1
date modified: 2026-07-24T00:50:10Z
provider: Abertay University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Abertay Dundee