Table 1.

List of five categories 28 phenotypic traits of stem obtained by automated image processing pipeline

Phenotypic types	Description	Units
Intensity-based	Average intensity (AI)	Gray-level
Geometry-based (dimensional)	Width (W)	mm
	Height (H)	mm
	Main axis length (MAL)	mm
	Main axis width (MAW)	mm
	Circumcircle radius (CR)	mm
	Inscribed circle radius (ICR)	mm
	Area (A)	mm2
	Perimeter (P)	mm
	Convex hull area (CHA)	mm2
Geometry-based (dimensionless)	Rectangularity (RA), $\text{RA}=\frac{\text{A}}{\text{MAL}\times \text{MAW}}$	–
	Aspect ratio (AR), $\text{AR}=\frac{\mathit{MAW}}{\mathit{MAL}}$	–
	Circularity (CIR), $\text{CIR}=\frac{4\pi ·A}{P^2}$	–
	Eccentricity (ECC), $\text{ECC}=\frac{\sqrt{MA{L}^2-MA{W}^2}}{\mathit{MAL}}$	–
	Sphericity (SPH), $\text{SPH}=\frac{\text{ICR}}{\text{CR}}$	–
	Convexity (CV), $\text{CV}=\frac{A}{\mathit{CHA}}$	–
Distribution-based	Distance from vascular bundle to stem center (DC)	mm
Layer-based (equal-distance, equal-area)	Area of each layer (AEL)	mm2
	Number of vascular bundles in each layer (NVBEL)	–
	Area of vascular bundles in each layer (AVBEL)	mm2
	Voronoi area of vascular bundle in each layer (VAVBEL)	mm2
Growth-based (epidermis, periphery, inner)	Area of each function zone (AEFZ)	mm2
	Number of vascular bundles in periphery zone (NVBPZ)	–
	Number of vascular bundles in inner zone (NVBIZ)	–
	Area of vascular bundles in periphery zone (AVBPZ)	mm2
	Area of vascular bundles in inner zone (AVBIZ)	mm2
	Voronoi area of vascular bundle in periphery zone (VAVPZ)	mm2
	Voronoi area of vascular bundle in inner zone (VAVIZ)	mm2