Fig. 4

Vertical image of a hybrid maize root system. b Color image in (a) was processed into a binary black and white image. c The image in (b) was used for calculating the box dimension. The log–log graph relates box side length r to the number of boxes N needed to cover the root shown in (b). The slope of the “space filling box count” line is the box dimension of the root in image (b). d This plot shows the local box dimensions for image (b). This graph indicates that N and r are related by the power law \( N = r^{ - Dim} \) within the scale range of 1–256 pixels. All images and graphs were produced using the public Matlab program “boxcount.m”.