The babassu (Orbignya oleifera Burret) is a palm that contains oilseeds whose biomass can be used for biofuel production. Due to difficulties in germinating the species, in vitro cultivation techniques are sought as a viable alternative to expand studies on germination. The objective of this study was to evaluate different types of tube caps for in vitro growth of babassu seedlings. Thus, zygotic embryos were inoculated in tubes containing MS medium with a 50% salt concentration, which were sealed with diferent caps, a cotton plug, plastic cap, PVC film and plastic cap with PVC film. During the in vitro culture, the mean length of seedlings, the formation of the cotyledon petiole and root, as well as oxidation of the explants were evaluated. The cotton plug exhibited a positive effect on the initial steps of in vitro cultivation, which promoted more vigorous plants with greater mean lengths; however, its effect decreased as the cultivation time increased. The cotton plug is an alternative and eight-fold less expensive than a conventional plug, which favors early in vitro growth of O. oleifera Burret.
Key words: Babassu, Goiás Cerrado, tissue culture.