Exogenous application of 4-FPA influences levels of PODs, H2O2, and flavonoids in rice. Mean levels (+SE, n = 5 to 6) of PODs (A); H2O2 (B); and flavonoids (C) in plants at 2 and/or 4 d post the following treatments: W-NP, 4-FPA-R, 4-FPA-R+W-NP, and control (Con). Details of treatments are described in Methods. LLD, lower limit of detection; e7g, eriodictyol 7-O-glucoside; a5g, apigenin 5-O-glucoside; l7g, luteolin 7-O-glucoside. Letters indicate significant differences among treatments (P < 0.05; Duncan’s multiple range test).