Fig. 1

Root system sampling equipment (a–c, e–g) and root box (d). Root system sampling equipment is composed of a urethane foam board (a), a nail board (b), a workbench with aluminum square pipes and guide bars (c), a clip (e), a stainless steel grid (f), and a pressing plate (g). Dotted circles in a and b indicate holes for the guide bars (dotted circles in c). The root box is placed on the workbench along the aluminum square pipes (brackets in c). Arrows in b indicate the holes for protrusions of the grid pressing plate (arrows in g). The protrusions on the pressing plate (arrows in g) push the intersections of the grid (arrows in f) to separate the whole root specimen sandwiched between sheets from the equipment