Effect of cold night temperature on flowering of Kalanchoe species

Control of flower induction is one of the most important aims in the floriculture industry as it determines the usefulness of plants for cross-pollination and production of flowering plants. The Kalanchoë genus contains around 140 species and numerous interspecific hybrids with a broad range of morphological traits, which makes this genus one of the most cultivated potted plants in the world. Commercial cultivars are easily induced to flowering by short days photoperiod, however, the number of species used for breeding is limited due to the lack of knowledge of flower inducing factors. Many studies suggested that cold night temperature can positively affect flowering in some Kalanchoë species. This study aimed to evaluate flowering in K. prittwitzii, K. marmorata and K. longiflora exposed to different night temperatures (6°C, 12°C and 18°C) combined with short day photoperiod (8 h). K. prittwitzii exhibited 100% flowering in all treatments, and flowering was enhanced by low night temperatures. K. marmorata had minimal flowering response to the treatments and K. longiflora did not flower in any of the treatments. The results support a postulate that interaction between different stimuli is required for flower induction in Kalanchoë species and demonstrate that night temperature can modify the flowering response. Therefore, the interaction between different factors during the plant life cycle requires further investigation.