Quercus suber L. Somatic Embryo Germination and Plant Conversion: Pretreatments and Germination Conditions

Osmoticum (high sucrose concentration) and chilling (4° C) treatments were assayed in order to promote germination (radicle elongation) and plant conversion of Quercus suber somatic embryos. Those treatments were applied before embryos were set to germinate on Murashige and Skoog (MS) liquid medium. Chilling for 2 mo. improved germination rate (best results close to 100%). On the other hand, that treatment increased plant conversion, especially when high sucrose concentration was used. The best results were obtained with$150 g l^{-1} sucrose$(75% of cultured embryos converted to plants). Incubation conditions during germination were also studied. Although there were no significant differences on final results, warmer temperatures and darkness increased germination rate. The influence of the different treatments on shoot morphology was also studied. The highest percentages of shoots with normal leaves obtained were close to 25%.