XVI International Botanical Congess

Major changes in indole-3-acetic acid (IAA) and cytokinin (CK) levels occur at different phenological phases of Tillandsia recurvata shoots. Young plants of T. recurvata have weak apical dominance, as early in development, side shoots appeared, and branch growth was correlated with a strong increase in the zeatin level. The flowering phase was characterized by a significant increase in free base cytokinins, zeatin and isopenteniladenine, in comparison to the levels found in adult vegetative shoots. In contrast, both free base CKs declined in the fruiting phenological phase while the IAA level increased dramatically. It was concluded that in the phases characterized by intense organ formation, such as in the juvenile and flowering stages, there was an enhancement of CK content, mainly due to zeatin, leading to a lower IAA/CK ratio. E-mail: hmercier@usp.br