Photoperiodic Flower Induction of Several Kalanchoe Species and Ornamental Characteristics of the Flowering Species

Abstract

Our objectives in this study were to identify the flowering response of Kalanchoe spp. to photoperiodic treatments and characterize flowering and vegetative characteristics of flowering plants. Twenty vegetatively propagated Kalanchoe spp. were grown under one of four photoperiodic treatments: 1) short days (SD; 8-h photoperiod) for 16 weeks; 2) night interruption lighting (NI; 2000 to 0200 hr) for 16 weeks; 3) SD for 8 weeks then transferred to NI for 8 weeks; or 4) NI for 8 weeks then transferred to SD for 8 weeks. Kalanchoe beauvardii, K. behariensis, K. fedtschenkoi, K. longiflora, K. marmorata, K. marnieriana, K. streptantha, K. tomentosa, and K. vigueridoi did not flower under any treatment. Kalanchoe laetivirens and K. rosei had minimal flowering when exposed to NI followed by SD, whereas K. pumila had minimal flowering when exposed to SD followed by NI. Kalanchoe glaucescens, K. laciniata, K. manginii, K. nyikae, K. rotundifolia, K. uniflora, and K. velutina flowered when exposed to SD for 8 or 16 weeks, and node number below the inflorescence and days to first open flower for these species increased when NI preceded SD. Kalanchoe millotii flowered under a 16-week SD treatment only. No plants flowered when grown under only NI. We classified K. glaucescens, K. laciniata, K. manginii, K. millotii, K. nyikae, K. rotundifolia, K. uniflora, and K. velutina as obligate SD plants. Flower diameter, total flower number, total color index, shoot length, branch number, and leaf length and width varied among species. Based on these ornamental characteristics, we identified K. glaucescens, K. laciniata, K. manginii, K. nyikae, K. uniflora, and K. velutina as potential ornamental flowering potted plants.