Flowering Response of the Olive (Olea Europaea L.) to Certain Growth Regulators Applied Under Inductive and Noninductive Environments

Olive trees grown in containers received outdoor winter chilling until February 27, 1969, then were moved to a greenhouse where several growth regulators were applied by dipping shoots into test solutions. Flowering was promoted by a growth retardant, B-9 (Alar-85) at 100 ppm, and was inhibited by either GA3 at 25 or 50 ppm or ABA at 10 or 50 ppm; in addition, ABA at 10 ppm stimulated lateral buds-normally flower buds-to grow vegetatively NAA at 50 ppm caused total inhibition of bud development. Cytokinin (6-benzylamino purine) at 50 or 250 ppm had no effect. Under noninductive conditions (trees held in a heated greenhouse throughout the winter months), repeated applications (twice a week for 10 weeks) of IAA, GA3, IAA + GA3, a mixture of GA4 and GA7, or ABA failed to substitute for the low-temperature requirement for flower induction, although GA3 strongly stimulated shoot growth.