Figure 1.

X‐ray CT images/reconstruction of (a) a root system encountering a compacted layer and (b) a root growing through the compacted layer. (a) Cross‐sectional view of a soil column in the xy‐plane with a compacted layer in between less dense layers. Blue and yellow lines represent the projection of the different polylines on the xy‐plane. Colours: yellow—node 4 and blue—node 3. Scale bar at 5 cm. (b) A 3D reconstruction of a segmented root growing through the denser layer. The white arrows represent the sectioning positions along the root axis (1 cm before, within and after the compacted layer). Scale bar at 1 cm [Colour figure can be viewed at wileyonlinelibrary.com]