Exogenous Application of Gibberellic Acid Improves Flowering in Kalanchoë

Abstract

Kalanchoë is an economically important genus comprising numerous potted plants and recently is also emerging as cut flowers. However, the lack of information about flower-inducing factors limits the number of species that can be used in commercial production and breeding programs. Therefore, the aim of this study was to investigate the effects of exogenous application of gibberellic acid (GA3) on flower induction and flowering quality of Kalanchoë longiflora and Kalanchoë pinnata. The experiment was conducted under a short day (SD) photoperiod with a day temperature of 22 °C and a night temperature of 15 °C for 8 weeks. The treatments consisted of four applications of either 0.25 or 0.50 μg of GA3 per plant per week, providing a total of 100 μg or 200 μg/plant and 0 μg/plant for the control. The volume of 100 μL of GA3 solution containing 1% agarose was applied to the shoot apex using a pipette. For both species, flowering was enhanced by the GA3 treatments compared with the control plants. Gibberellin-treated plants flowered earlier, produced more inflorescences, and exhibited an increased number of flowers compared with the control plants. Moreover, the GA3 treatments in K. longiflora delayed the appearance of wilted flowers. Plant height increased in plants that received GA3, but the number of nodes did not differ from the control plants. Thus, we conclude that the application of GA3 improves flowering of Kalanchoë species and can be a useful tool for the production of cut flower cultivars.