<Emphasis Type="Italic">In vitro</Emphasis> germination of zygotic embryos excised from cryopreserved endocarps of queen palm (<Emphasis Type="Italic">Syagrus romanzoffiana</Emphasis> (Cham.) Glassman)

Queen palm (Syagrus romanzoffiana Cham.] Glassman) is a palm species best known as an ornamental tree for urban landscaping, but recently, it has been evaluated as a potential crop for biofuel production. The objective of the present work was to establish a cryopreservation technique for queen palm to ensure long-term conservation of this species. The cryopreservation protocol consisted of direct immersion in liquid nitrogen (LN) of whole endocarps with water contents ranging from 5.5 to 10.9%, followed by slow thawing at room temperature (25 ± 2°C) excision and in vitro culture of zygotic embryos. Viability of zygotic embryos isolated from endocarps with different water contents was evaluated before (control) and after freezing in LN using in vitro culture on Woody Plant Medium (WPM) medium. Germination percentages of zygotic embryos isolated from endocarps stored in LN varied from 84 to 93%, whereas those isolated from controls ranged from 55 to 71%. Germination rates were significantly higher for zygotic embryos excised from cryopreserved endocarps. The water content of control or frozen endocarps did not have a significant effect on germination percentages of zygotic embryos. Zygotic embryos excised from endocarps following cryopreservation in liquid nitrogen developed into normal plantlets after in vitro culture. The technique tested is simple, efficient, and can be used in plant gene banks as a routine approach for long-term conservation of queen palm germplasm.