Four rates of seven plant growth regulators were foliar-applied to 11.4 liter containers of Photinia × fraseri after initial root establishment. Growth regulators studied were uniconazole, paclobutrazol, dikegulac-sodium, ancymidol, 6-BA, GA4+7 and, 6-BA + GA4+7. Six months after application, plant height, plant width, growth index, and number of lateral and terminal branches were recorded.
Applications of uniconazole (30 mg a.i./liter), 6-BA alone or in combination with GA4+7, and dikegulacsodium stimulated lateral branching. The number of lateral branches increased linearly as paclobutrazol rates increased from 60 to 180 mg a.i./liter. Growth index decreased with increasing application rates of uniconazole and paclobutrazol, while the growth index of photinia treated with other growth regulators wasn't affected by application rate. Plant height was increased in GA4+7 treated plants.