Strategies to Improve Rooting and Acclimatization of Cork Oak

In this work the inclusion of 2 mg l-1 of indole-3-butyric acid (IBA) in the rooting medium produced 78% rooting. The rooting percentage was improved to 95% by basal immersion of shoots in 0.5 g l-1 IBA for 2 min. With this method high number of long and vigorous roots developed during the second week after IBA treatment. Differences in root morphology related with rooting induction method were observed. The roots formed by dipping were more branched than those resulting by auxin addition to the culture medium. Darkness during the first week of rooting resulted in a remarkable enhancement of the rooting percentage, number of roots developed per shoot and the length of the longest root. Well-rooted plantlets were transplanted into a mixture of peat and vermiculite and incubated in a growth chamber with high humidity. Hardening of plantlets under high humidity during four weeks was found to be essential for successful acclimatization. After two months, plants were transferred to the glasshouse and the percentage of surviving plantlets after six months ranged from 60% to 72%