The flower development and photoperiodism of native Kalanchoe spp. in Taiwan

Flower initiation and development of Kalanchoe spp. were investigated in this study. The sequence of events in the differentiation process was divided into 8 stages: vegetative growth, flower initiation, bract primordium, sepal primordium, petal primordium, stamen primordium, pistil primordium, and visible floret stages. Under the short-day condition, Kalanchoe spathulata, Kalanchoe blossfeldiana ‘Tenorio’, and Kalanchoe garambiensis meristems initiated differentiation after 5, 10, and 15 days, respectively. K. spathulata, K. garambiensis, and K. blossfeldiana ‘Tenorio’ differentiated from the vegetative stage into the visible flower bud stage in 45, 50, and 55 days, respectively. The development from flower initiation to the visible flower bud stage was most rapid in K. spathulata, followed by K. garambiensis and K. blossfeldiana ‘Tenorio’. Kalanchoe gracilis differentiated from the vegetative growth stage into the visible flower bud stage in 105 days. Therefore, K. spathulata and K. garambiensis exhibited flower characteristics relatively early. The main differences in flowering between species/cultivars were initiation timing and the time for subsequent development. The sepal primordial stage was the most sensitive stage to the short-day condition during flower development in Kalanchoe spp. The minimum number of short-days needed for flowering of K. spathulata, K. garambiensis, K. blossfeldiana ‘Tenorio’, and K. gracilis were 15, 15, 25, and 56 days, respectively. Therefore, K. spathulata or K. garambiensis can be used to produce hybrids in relatively fewer short-days.

► Kalanchoe spathulata and Kalanchoe garambiensis exhibited early flower characteristic.
► Sepal primordial stage was the most sensitive stage to the short-day condition during Kalanchoe spp. flower development.
► The native species required relatively less time for flower initiation and development and show the short-day response.
► K. spathulata or K. garambiensis seem to be useful as potential parents in breeding programs that aim to develop new cultivars with a short-day requirement.