MODELLING OF THE HYDRAULIC ARCHITECTURE OF ROOT SYSTEMS : AN INTEGRATED APPROACH TO WATER ABSORPTION : MODEL DESCRIPTION

A numerical model simulating water uptake by root systems is presented. This model can combine the locally measured root hydraulic conductances with data on the root system architecture to give a detailed description of water absorption, from the single root level to the entire root system. This is achieved by coupling a three-dimensional root system architecture model with laws describing water flow in roots. In addition to water absorption studies, the model has been developed so that it can be included in a soil water transfer simulator in order to analyse soil–plant interactions for water uptake. The use of the model in describing water absorption is illustrated for a specific case where the hydraulic conductances are considered uniform in the whole root system. In this way, analytical results of Landsberg and Fowkes (Annals of Botany42: 493–508, 1978) are extended from the single root to the root system level. The influence of the type of root system architecture, axial conductance between crowns of maize nodal roots, transpiration in the course of the day, and non-homogeneous soil water potential on fluxes and water potentials in the root system are examined. The dynamics of the total conductance of the maize root system with plant growth is also shown for this case of uniform conductance in the root system. Cases which consider other distributions of the conductance in the root system are presented in an accompanying paper.

[1]  Park S. Nobel,et al.  A Finite-element Model of Radial and Axial Conductivities for Individual Roots: Development and Validation for Two Desert Succulents , 1992 .

[2]  E. Steudle,et al.  Axial and Radial Hydraulic Resistance to Roots of Maize (Zea mays L.). , 1989, Plant physiology.

[3]  M. Canny,et al.  Rates of water uptake into the mature root system of maize plants , 1993 .

[4]  W. R. Gardner,et al.  Water Uptake by Plants: I. Divided Root Experiments , 1977 .

[5]  C. Osmond,et al.  Encyclopedia of plant physiology. New series. Volume 12B. Physiological plant ecology II. Water relations and carbon assimilation. , 2011 .

[6]  Z. Kabala,et al.  Water Transport in an Unsaturated Medium to Roots with Differing Local Geometries , 1992 .

[7]  F. Smedt,et al.  Solving three-dimensional hexahedral finite element groundwater models by preconditioned conjugate gradient methods , 1994 .

[8]  François Tardieu,et al.  Modeling Root Water Potential and Soil‐Root Water Transport: II. Field Comparisons , 1991 .

[9]  R. Aiken,et al.  DYNAMIC ROOT RESPONSES TO WATER DEFICITS , 1992 .

[10]  E. Schulze,et al.  Water and Plant Life , 1976, Ecological Studies.

[11]  J. Sanderson.  Water Uptake by Different Regions of the Barley Root. Pathways of Radial Flow in Relation to Development of the Endodermis , 1983 .

[12]  W. R. Gardner.  DYNAMIC ASPECTS OF WATER AVAILABILITY TO PLANTS , 1960 .

[13]  Bingru Huang,et al.  Root Hydraulic Conductivity and Its Components, with Emphasis on Desert Succulents , 1994 .

[14]  A. Eshel,et al.  Plant roots : the hidden half , 1991 .

[15]  T. Simonneau,et al.  Water uptake regulation in peach trees with split‐root systems , 1994 .

[16]  P. Nobel,et al.  Variations in root water potentials : influence of environmental factors for two succulent species , 1991 .

[17]  Joe Landsberg,et al.  Water Movement Through Plant Roots , 1978 .

[18]  J. Passioura.  The effect of root geometry on the yield of wheat growing on stored water , 1972 .

[19]  E. Fiscus.  The Interaction between Osmotic- and Pressure-induced Water Flow in Plant Roots. , 1975, Plant physiology.

[20]  François Tardieu,et al.  Modeling root water potential and soil-root water transport. I. Model presentation , 1991 .

[21]  S. Running,et al.  Water Uptake, Storage and Transpiration by Conifers: A Physiological Model , 1976 .

[22]  T. H. Honert,et al.  Water transport in plants as a catenary process , 1948 .

[23]  E. Newman.  PERMEABILITY TO WATER OF THE ROOTS OF FIVE HERBACEOUS SPECIES , 1973 .

[24]  P. Nobel,et al.  Hydraulic conductivity of concentric root tissues of Agave deserti Engelm. under wet and drying conditions , 1995 .

[25]  P. E. Weatherley.  Water Uptake and Flow in Roots , 1982 .

[26]  Fred J. Molz,et al.  Models of water transport in the soil‐plant system: A review , 1981 .