Effects of Gibberellic Acid on the Photoperiod-Controlled Growth of Woody plants

Abstract

Vegetative growth of Camellia is prevented on short-days; while on long-days the growth takes place in flushes. Periodic treatment with gibberellic acid results in flushes of growth on short-day conditions, apparently completely analagous to the effect of long-day treatment. On long-days the onset of growth is promoted by gibberellic acid treatment, but the amount of growth and the subsequent onset of dormancy are unaffected. Neither Pinus coulteri nor Pseudotsuga macrocarpa is affected by similar gibberellic acid treatments.