Table 1.

List of features extracted and selected for analysis of S. miltiorrhiza root images.

Software	Features extracted	Type	Description
RhizoVision/WinRHIZO	Total root length; average, median, and maximum diameter; volume; surface area; length; surface area; and volume histograms	Agronomic traits	The sum of the Euclidean distances between the connected skeletal pixels in the entire root topology
			The average, median, and maximum diameters that are computed across all root skeleton
			Volume and surface area are calculated as the sum of values from all skeletal pixels
			Length, surface area, and volume computed according to the diameter ranges
RootScan	Root cross-sectional area (RXSA)	Anatomical traits	All components of the cross-section
	Total cortical area (TCA)		All components inside RXSA but outside the stele
	Total stele area (TSA)		All areas of stele
	Xylem vessel area (VSA)		Total cross-sectional area of all metaxylem vessels
	Stele/cross-section		Proportion of cross-section occupied by stele
	Stele/cortex		Relative tissue allocation to stele and cortex
RootScape	Landmark placement defined by user	RSA	Defined landmarks that characterize the root system architecture