Interaction between background light intensity and local or FRw treatments. Relative angles of petiole and lamina and relative petiole elongation with a background light intensity of 40 (A to C), 80 (D to F), 140 (G to I), and 180 µmol m⁻² s⁻¹ PAR (J to L). Treatments consisted of supplemental local FRt, FRw, and WL control. 40 PAR WL n = 12, FRt n = 24, FRw n = 24; 80 PAR WL n = 11, FRt n = 22, FRw n = 27; 140 PAR WL n = 16, FRt n = 19, FRw n = 25; and 180 PAR WL n = 23, FRt n = 22, FRw n = 23. Measured for 24 h with treatment start time at ZT 2. Lines represent mean ± Sem. Letters indicate P < 0.05, calculated per every 2 h using 2-way ANOVA and Tukey post hoc test using the sample sizes indicated above. Shaded areas indicate night without light or FR exposure.