Abstract

The phytohormone gibberellin is involved in the regulation of many physiological process including flower induction and shoot growth. In this study, gibberellic acid (GA3) was used in order to induce the reversion of olive tree vegetative buds towards a floral ones in vitro. For this, six varieties (Marsaline, Chemchali, Picholine, Chemlali, Zalmati and Oueslati ) was tested and explants, consisting of a single node segments, were grown in media containing three concentrations of GA3 (1, 2 and 10 mg/l). Results show that Marsaline seems  to be the most able variety in regenerating floral structures. For this variety, 5 cases of reversion were observed mainly on the medium containing 10 mg/l GA3. This same medium was also favorable for  this transformation for the other varieties (3 cases on Picholine, one each on Chemchali , Zalmati and Oueslati). The examination of the histological sections confirmed this transformation. In addition, this experiment showed that GA3 can be at the origin of an interesting growth rate of vegetative  buds,  which elongation depend on variety as well as GA3 concentration.

Key words: Olive tree, in vitro flowering , GA3, reversion.