Fig. 5

Effects of Si and NaCl treatment on palisade tissue thickness (a), spongy tissue thickness (b), the ratio of palisade to spongy (c), tissue structure compactness (d), tissue structure porosity (e), and leaf thickness (f) of two varieties of licorice. Results are mean for four replicates with different letters indicating differences at P < 0.05 by Duncan’s multiple comparison tests