USDA-ARS, Great Plains Systems Research Unit
P.O. Box E, 301 S. Howes
Fort Collins, CO 80522
A two-dimensional model of corn root growth has been developed and linked to a two-dimensional model for water, heat and solute transport in soils. Th purpose of this model is to research how different management practices influence root growth and utilization of water and nitrogen from different parts of the root zone. This knowledge is then used to identify practices that help the most efficient use of water and nitrogen and minimize leaching below the root zone. The model may also be used by plant breeders to screen new varieties for their root growth.
Our intermpretation of photographs and line drawings of corn root systems during the growing season was that, as the root system develops, there is a change from a primarily horizontal growth direction early in the life cycle to a primarily vertical growth direction for later stages in the life cycle. We generalized these data to delineate a region to the legft and right, as viewed along the center of the plant row, and downward in which root growth and downward in which root growth may potentially occur. The size of the region is defined by the growth area is defined by the extension rate of the root system and the growth angle from the horizontal. The horizontal extension of the root region is assumed to progress by the extension rate times the cosine of the growth. The vertical extension of the root region is assumed to progress by the extension rate times the sine of the growth angle. The values of these coefficients are dependent upon the corn hybrid and the age of the plant. The increase of root density for a given position in the root zone follows a first-order dynamics; it is proportional to existing density. The decrease in root density due to root death is proportional to the square of the existing density. The net change of density is the difference between the two. The proportionality constants are a function of growth stage. Suboptimal environmental conditions of soil temperature, bulk density and water content influence root growth.
Source: Rootsim2D Home