Oil palm (Elaeis guineensis) seeds are highly dormant immediately after harvest. In practical horticulture this
dormancy has been traditionally overcome by a dry-heat treatment and, more recently, through the application
of hydrogen cyanamide (HC). Initiation and release of dormancy have been related in other plant species to
changes in endogenous hormone concentrations. Therefore, the effect of the aforementioned dormancy release
treatments on germination and on endogenous concentration of indole-3-acetic acid (IAA), abscisic acid (ABA),
gibberellins GA1, GA3 and GA20 (GAs), zeatin/zeatin riboside and N6(Δ2-isopentenyl) adenine/N6(Δ2-isopentenyl)
adenosine was evaluated in oil palm seeds. Heat- and HC-treated seeds germinated above 90% after 37 d, while
germination of control seeds was below 4% at the same time. A sharp reduction in ABA concentration in
embryos and endosperm was the most notable outcome during the dry-heat and HC treatments, the latter one
in a lesser degree. HC treatment additionally caused an increase in IAA levels in embryos and endosperm
during the imbibition phase. Changes in concentration of other hormones (e.g., GAs and cytokinins) could not
be directly related to dormancy release in this species. Participation of additional factors, such as changes in
sensitivity to plant hormones, cannot be ruled out.