Quercus suber L. somatic embryo germination and plant conversion: Pretreatments and germination conditions

Osmoticum (high sucrose concentration) and chilling (4 degreesC) treatments were assayed in order to promote germination (radicle elongation) and plan t conversion of Quercus suber somatic embryos. Those treatments were applie d before embryos were set to germinate on Murashige and Skoog (MS) liquid m edium. Chilling for 2 mo. improved germination rate (best results close to 100%). On the other hand, that treatment increased plant conversion, especi ally when high sucrose concentration was used. The best results were obtain ed 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 d arkness increased germination rate. The influence of the different treatmen ts on shoot morphology was also studied. The highest percentages of shoots with normal leaves obtained were close to 25%.