Structural and cytological aspects of mango floral induction using paclobutrazol

•PBZ restricts cell expansion at the mango stem apex.•PBZ causes accumulation of phenolic and lipophilic compounds in the leaves.•Cell expansion and axillary bud formation indicate floral differentiation.•Floral differentiation involves ontogenesis of the inflorescence axes and flowers.•Flowering occurs under semiarid conditions in eight stages over 32 days. Mango flowering induction using the gibberellin synthesis repressor paclobutrazol (PBZ) allows off-season production and two annual harvests under semiarid growing conditions. Structural and cytological changes in the stem apex and leaves resulting from the application of the PBZ technique are unknown, however, as are the patterns of development of reproductive structures. We sought to investigate the morphological, histological, and cytological aspects of floral induction in 'Palmer' mangos using PBZ, and to characterize its flowering in a semiarid region of Brazil. Anatomical evaluations of stem apices were performed, and ultrastructural and micromorphometric evaluations were made of leaves at 30, 60 and 90 days after PBZ application, as well as under control conditions. The ontogenesis of the plant’s inflorescence was characterized and flowering was described under field conditions. PBZ caused restrictions of cell expansion and the accumulation of both cells and phenolic compounds in the stem apex related to the transition to the reproductive phase. Floral induction does not provoke significant changes in leaf micromorphometry, although phenolic compounds, calcium oxalate crystals, and lipophilic substances accumulate in the mesophyll. Cell expansion and the formation of axillary buds at the stem apex indicate floral differentiation and the triggering of ontogenesis of the inflorescence, with the development of inflorescence axes and flowers. Flowering occurs in eight stages over 32 days, and the descriptions presented here should be useful for enhancing floral induction and mango orchard management.