The genus Kalanchoe includes 139 species indigenous to Madagascar, southern and eastern Africa, and, to a lesser extent, tropical Africa, the Arabian Peninsula, and southeastern Asia (Descoings, 2005; Gherig et al., 2001). One species, K. blossfeldiana von Poellnitz, is grown commercially as a flowering potted plant, whereas other species are grown as minor flowering or potted plants (Dole and Wilkins, 2005). Kalanchoe spp. are generally amenable to cultivation and propagate readily from stem and leaf cuttings or plantlets produced along leaf margins (Descoings, 2005). Additionally, Kalanchoe spp. can vary in flower color, size, number, and inflorescence structure as well as foliage size, shape, and color (C. Currey, personal observation).
Photoperiodic flower induction is a common mechanism for floral induction. Plants that flower when exposed to SD or long-days (LD) are classified as SD plants (SDP) or LD plants, respectively (Thomas and Vince-Prue, 1997). Dual-daylength plants must be exposed to a specific sequence of photoperiods. For example, long–SD plants (LSDP) must be exposed to LD followed by SD (Thomas and Vince-Prue, 1997). Kalanchoe spp. studied have been categorized into two different photoperiodic response groups with respect to flowering: SDP and LSDP. K. blossfeldiana and K. porphyrocalyx (Baker) Baillon were classified as SDP (Schwabe, 1985; Zimmer, 1985). Zeevaart (1985) classified four Kalanchoe spp. as LSDP: K. daigrimontiana Hamet & H. Perrier, K. laxiflora Baker, K. pinnata (Lamarck) Persoon, and K. prolifera (Bowie ex Hooker). To produce floriculture crops commercially, requirements for flower induction need to be identified to program flowering (Roh and Lawson, 1998). This study was undertaken to evaluate the potential of additional Kalanchoe spp. as new flowering ornamental plants.
Our objectives in this study were to: 1) identify the response of Kalanchoe spp. to photoperiodic treatments and classify them into photoperiodic response groups; and 2) characterize flowering and vegetative characteristics of flowering species to select species that have potential as new ornamental potted or garden plants.
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