Fig. 2

Foliar application of different EBR compounds significantly enhances nicotine accumulation in the upper leaves of flue-cured tobacco during its developmental stages. CK2 means foliar spraying with 250 mL of water per plant; B1 indicates foliar spraying with 250 mL of 0.2 mg·L^− 1 EBR solution per plant; B2 indicates foliar spraying of 250 mL of a mixed solution containing 0.2 mg·L^− 1 EBR, 0.1 g·L^− 1 α-Cyclodextrin, 0.1 mg·L^− 1 Tween 80, 1 g·L^− 1 CaCl₂, 1.5 g·L^− 1 ZnSO₄·7H₂O, and 2 g·L^− 1 KH₂PO₄ per plant. B3 indicates foliar spraying of 250 mL of a mixed solution containing 0.2 mg·L^− 1 EBR, 0.1 g·L^− 1 α-Cyclodextrin, 0.1 mg·L^− 1 Tween 80, 2 g·L^− 1 CaCl₂, 3 g·L^− 1 ZnSO₄·7H₂O, and 4 g·L^− 1 KH₂PO₄. 10 d, 20 d, 30 d, 40 d and 50 d indicate the days after treatment with different EBR compounds. The data presented are the mean ± SD. Different letters indicate significant differences among the treatments based on Duncan’s test (P < 0.05)