Oat coleoptile curvatures under uniform or blue-gradient SPFD irradiation. Uniform distribution of SPFD at λp = 405, 460, 630, 660, and 735 nm along the x-axis at y = 0 and z = 17.3 cm (A), curvature of oat coleoptiles (B) when irradiated for 23 h with the SPFD depicted in (A), and a photograph of vertically growing coleoptiles (C) at x = −11.3 cm are presented. Modified distribution of SPFD at λp = 460 nm (D), curvature of oat coleoptiles (solid circles in E) when irradiated with the SPFD depicted in (D), and a photograph of coleoptiles showing positive curvature (F) at x = +11.3 cm are presented. The SPFD gradient at λp = 460 nm along the x-axis at y = 0 and z = 17.3 cm is depicted as open circles in (E). No-bending vertical coleoptile growth is defined as 0 deg curvature. Coleoptile curvature to positive x is defined as positive curvature. Bars in (B) and (E) represent standard deviations.