Petiole explants were obtained from in vitro grown diploid (2x = 22) Echinacea purpurea plantlets. Shoots were regenerated by culturing the explants on MS basal medium containing 0.3 mg/L benzyladenine (BA), 0.01 mg/L naphthaleneacetic acid (NAA) and four concentrations (30, 60, 120, and 240 mg/L) of colchicine for 30 days, or 120 mg/L of colchicine for various durations (7, 14, 21, and 28 days...
