Semi-Hardwood Cutting Propagation of Autochthonous Olive Varieties from Galicia: A First Evaluation of Rooting Ability.

Olive trees (Olea europaea L.) show propagation behaviour that is strongly dependent on genotype. A dozen previously unknown autochthonous olive varieties from Galicia (north-western Spain) have recently been identified through molecular and botanical characterisation techniques. However, their suitability for vegetative propagation remains unknown. Survival, callus formation and rooting were evaluated in semi-hardwood cuttings of 12 autochthonous Galician varieties and the control variety Cobrançosa in two trials carried out in winter-spring and summer--autumn 2025 (676 and 622 cuttings, respectively). Binary variables were analysed using generalised linear models (binomial distribution, logit link). The variety effect was highly significant for all three variables (p < 0.0001), while the cutting date was not significant as a main effect; the variety × date interaction was significant for survival and rooting but not for callus formation. Mean rooting increased from 19% in winter to 61% in summer, although some varieties showed the opposite pattern. A strong negative correlation was found between flowering on the mother plant and rooting, and no correlation was found between callus formation and rooting. These results provide a first quantitative reference on the vegetative propagation of autochthonous Galician olive varieties and supply baseline information for their multiplication and conservation.