Involvement of Hormone- and ROS-Signaling Pathways in the Beneficial Action of Humic Substances on Plants Growing under Normal and Stressing Conditions

Figure 7

Tonoplast aquaporin gene expression in rice plants subjected to treatments with HA under normal (b) and stress growth conditions (a). (a) (T1) − P–HA: no application of PEG-6000 or HA (control); (T2) + P–HA: PEG-6000 and no HA; (T3) + P + HA20: PEG-6000 and 20 mg (C) L⁻¹ HA; (T4) + P + HA40: PEG-6000 and 40 mg (C) L⁻¹ HA; (T5) + P + HA80: PEG-6000 and 80 mg (C) L⁻¹ HA. (b) HA20 (20 mg (C) L⁻¹), HA40 (40 mg (C) L⁻¹), and HA80 (80 mg (C) L⁻¹) (adapted from [16, 19]). Different letters represent significant differences between the average values of treatments, as determined by Tukey’s test; . The error bar represents the mean ± standard error (SE) of three replicates.

(a) HA application under stress conditions

(b) HA application under normal conditions