Determination of total root surface area in soil core samples by image analysis

Abstract

A root analysis method is described that estimates total root surface area from soil core samples, employing image analysis. Digital greyscale images of stained root samples, cut into 1–2 cm lengths, were analysed to measure their total profile area, A b ( A b = 2 RL, where R is radius and L is length). Based on the cylindrical nature of the roots, and the equation for total surface area, A r = 2 πRL, the two-dimensional measurement ( A b ) can be converted into the three-dimensional estimation of a root cylinder's total surface area. The analysis is shown to be very precise and repeatable. It is automated to a large extent, and is rapid. This method can be employed by virtually any image analysis system currently available. The method can be applied as the sole source of quantification, or it can be used to complement root length estimates or other relevant parameters. Quantification of total root surface areas may be a better index to supplement correlative studies (e.g. root absorption potential) than a strictly linear root length, in that its values integrate the diverse range of diameters in a typical root sample.