Abstract

Five plant growth regulators were applied to container-grown Photinia × fraseri as foliar sprays to determine their influences on plant size and lateral branching. Height, width, and lateral branch number were determined at three month intervals over one year. Treated plants generally were shorter than control plants in response to uniconazole, paclobutrazol, and benzylaminopurine (BA) and were taller than controls when BA was applied with gibberellins A_{4 + 7}. Each growth regulator altered one or more growth factors dependent on the time after application. Paclobutrazol and uniconazole reduced shoot width 3 months after application (MAA) and 3 to 6 MAA, respectively compared to the control plants. Higher rates of uniconazole and paclobutrazol were responsible for shoot width reductions 12 MAA. Lateral branching was increased 3 MAA by dikegulac-sodium and paclobutrazol at the highest rates only and was reduced by uniconazole 12 MAA. Uniconazole reduced shoot dry weight 12 MAA.