The effects of the stage of maturity and treatments with thidiazuron and ethephon on germination of olive seeds (Olea europea L.)

The effect of treatments with thidiazuron (TDZ) and ethephon on germination of olive seeds (Olea europaea L. cvs Canino and Moraiolo) were studied using fruits harvested at three different dates. In cv Moraiolo, both effects were also evaluated on isolated organs as embryos and endosperm. TDZ significantly improved germinability of Canino and Moraiolo seeds harvested in September and, also increased the germination percentage in Moraiolo seeds harvested on the first date of October. Ethylene released from ethephon significantly affected both germination parameters in Canino seeds harvested in September but only germination time in seeds of Moraiolo at the same harvesting date. Thidiazuron improved the development of embryos and endosperm and the growth of seedlings, ethylene affected only the development of endosperm. The response to treatments appeared linked to the stage of seed maturity, indicating differences in the hormonal control of dormancy between cultivars. In Moraiolo embryo germinability was always higher than seed germinability, suggesting a negative effect of the surrounding seed tissues on seed germination. Such dormancy, which gradually increased during maturation, resided mainly in the endosperm and partly within the embryo.