Fig. 1

S. tonkinensis phenotypic responses to different irrigation treatments. Morphological traits of S. tonkinensis under three irrigation treatments: control treatment (CK), mild drought treatment (MDT), and severe drought treatment (SDT) (A). Bar = 20 mm. The effects of drought treatment on root fresh weight (g) and dry weight (g) in CK, MDT, and SDT (B). Effect of drought treatment on soluble sugar content (C), soluble protein content (D), MDA content (E), peroxidase activity (F), superoxide dismutase activity (G), and catalase activity (H). Each bar represents the mean ± standard error, n = 3. ** indicates a significant difference at p < 0.01 compared with CK using a two-tailed Student’s t-test. Different letters represent significant differences at p < 0.05 (LSD test)