Table 2.

Degree of leaves visibly wilted, plant growth index (PGI), relative chlorophyll content [Soil Plant Analysis Development (SPAD) value], water content of leaves and stems, stem water potential (ψ_stem), and leaf curling index of Shepherdia ×utahensis at eight substrate volumetric water content treatments (θ_t).

				Water contenty
θt (m3·m−3)	Leaves wilted (1–5 scale)z	PGIy	SPAD	Leaf (%)	Stem (%)	ψstem (MPa)	Leaf curling indexx
0.40	4.7 abv	33.4 a	58.9 a	59.2 a	62.7 a	−0.82 ab	0.04 bc
0.35	4.8 a	33.2 a	58.2 a	62.6 a	63.6 a	−0.65 a	0.05 bc
0.30	4.7 ab	36.7 a	58.3 a	59.7 a	60.4 a	−0.90 ab	0.02 c
0.25	3.7 bc	23.1 b	56.1 ab	58.1 a	58.5 ab	−1.95 bc	0.06 bc
0.20	3.4 cd	22.6 b	52.1 ab	57.1 a	58.7 ab	−1.45 b	0.03 bc
0.15	2.2 de	17.2 b	49.0 abc	51.1 a	49.9 b	−1.98 c	0.10 abc
0.10	1.9 e	18.3 b	43.4 bc	51.2 a	52.4 b	−1.97 bc	0.11 ab
0.05	1.0 e	17.6 b	34.9 c	23.3 b	36.8 c	−5.76w	0.17 a
Linear	**u	NS	NS	NS	NS	NS	NS
Quadratic	NS	NS	NS	***	***	NS	NS
Cubic	****	****	****	****	****	*	****

^z1 = over 65% of the leaves wilted; 2 = 35–65% of the leaves wilted; 3 = up to 35% of the leaves wilted; 4 = less than 10% of the leaves wilted; and 5 = plant was fully turgid (Zollinger et al., 2006).

^yPlant growth index = [(height + length + width)/3], while water content of leaves and stems was calculated using the equation: [fresh weight (FW) − dry weight (DW)/FW x 100% (Zhou et al., 2021).

^xLeaf curling index was determined using the equation: [distance between the margins of flattened leaf (D_max)-distance between the margins of curling leaf (D_i)]/D_max (Nilsen, 1987).

^WOnly two data were recorded due to high plant mortality.

^vMeans with same lowercase letters within a column are not significantly different among treatments by Tukey–Kramer method with a significance level specified at 0.05.

^uNS, *, **, ***, **** Nonsignificant, significant at p ≤ 0.05, 0.01, 0.001, or 0.0001, respectively.