Induction, maturation and germination of holm oak (Quercus ilex L.) somatic embryos

Somatic embryo induction from immature zygotic embryos followed by embryo development and maturation has been achieved in holm oak ( Quercus ilex L.). Different types of explant have been assayed for the induction of somatic embryogenesis. Only immature zygotic embryos, collected in August, were successfully induced. Best results were obtained in Gamborg et al. ( 1968) medium supplemented with 10 muM BAP and 10 muM NAA. The reduction of the macronutrient concentration improved the rate of somatic embryo maturation and decreased that of secondary embryogenesis. Liquid medium provided a significantly higher fresh weight of somatic embryos and a higher rate of secondary embryogenesis than agar-solidified medium, while the latter was more adequate for embryo maturation. Secondary embryogenesis was controlled by culturing the maturing somatic embryos in medium with a high sucrose concentration in standard light conditions. Osmopriming on medium with 270 mM sucrose stimulated maturation, fresh and dry weight growth and germination potential.