AN EASY METHOD OF BREAKING OLIVE STONES TO REMOVE MECHANICAL DORMANCY

The low germination percentage of olive seeds is due to a physiological dormancy, but the hard endocarp represents a physical barrier preventing radicle emergence. As chemical scarification does not always work all right, endocarps of ‘Aberquina’, ‘Queslati’, ‘Galega’, ‘Picual’ and ‘Manzanilla’ having well developed seeds were broken by pressing them transversely or longitudinally in a bench vise. As endocarps do not prevent water imbibition by seeds and are better handled during stratification, breaking was done at three times: immediately after freeing them from the pulp, after being dried in the lab and after a month stratification at 15°C needed to overcome the physiological dormancy. Results showed that seeds were not damaged at all when dry, while very few did were when still humid right after removing the stones from the fruit, this applying to both ways of pressing the stones. However, the important swelling of the seed taking place during the stratification period makes it to further fill the space inside the stone, thus resulting in a high percentage of damaged seeds, but only when pressing the stones transversely. Thus, a simple and fast procedure is available for nurseries and breeders to propagate rootstocks or germinate the seeds of either planified or random crosses, respectively.