Resumo

ABDELNOUR, Ana; AGUILAR, Mª Elena  e  VALVERDE, Lissette. Micropropagation of pilon (Hieronyma alchorneoides). Agron. Costarricense [online]. 2011, vol.35, n.2, pp.09-19. ISSN 0377-9424.

Pilon (Hieronyma alchorneoides) (Euphorbiaceae) is one of the native timberspecies of Costa Rica best adapted to conditions of open plantation. Due to its growth characteristics and variety of uses, the demand for planting material has increased. This species presents serious problems with seed reproduction; it is adioecious, the fruit production varies overtime and between trees, trees produce largequantities of fruit but are heavily predated by different birds. In recent years, the percentage of damaged fruit has increased due to wasps and the seeds lose their ability to germinate within days of harvest (recalcitrant). Thes factorsmake micropropagation an attractive option for masspropagation of the species. In the present study various stages of in vitro cultivation were evaluated. The aseptic establishment of theembryos was achieved by scarifying the seeds with  concentrated sulfuric acid for 10 min, followed by  incubation in 5.5% sodium hypochloride (NaClO)  for 30 min, then embryos were inoculated on the  culture medium described by  Murashige and  Skoog (MS) without growth regulators. When vegetative material was used as initial explant, the use of 0.095% mercuric chloride (HgCl2) during 5 min, allowed 50% of cuttings to develop shoots under aseptic conditions on a simple MS medium. It was observed that pilon does not require the addition of growth regulators during bud induction nor in the multiplication stages. During rooting, the addition of indole butyric acid (IBA) at concentrations of 0.1 mg.l-1 promoted the highest percentage of rooted shoots (80%), the largest number of roots per stem (5.0) and the best quality of the roots formed. Survival of in vitro plants after acclimation under greenhouse condition reached 70%

Palavras-chave : Micropropagation; in vitro culture; pilon; Hieronyma alchorneoides; cytokinins.

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