Cacti have potential as new floriculture and landscape crops. Cacti can have ornamental spines, unique forms, and occasionally showy flowers and can often survive dry conditions. The epiphytic cacti Schlumbergera, Hatoria, and Rhipsalidopsis have been commercialized as flowering potted plants (Boyle, 1990, 1991; Meier, 1995; O’Leary and Boyle, 1999, 2000). Subsequent work on Schlumbergera and Hatoria showed BA spray application during flower initiation increased flower number (Boyle, 1995; Heins et al., 1981; Ho et al., 1985). In other work, Japanese and Korean scientists facilitated the development of a grafted cactus industry (primarily Gymnocalycium and Echinopsis grafted on Hylocereus) where plants are grown for colorful and/or uniquely shaped scions as potted plants (Kim and Kim, 2006). Erwin (1996) subsequently researched temperature and photoperiod effects on grafted cacti growth to decrease scion losses.
Little recent work has focused on desert cacti flowering physiology. Work by Runger on temperature and photoperiod effects on Mammillaria zeilmanniana (Runger, 1967), Mammillaria longicoma (Runger, 1968a), Notocactus tabularis (Runger, 1971), Rebutia marsoneri (Runger, 1968b), and Rebutia violaciflora flowering (Runger, 1973) showed cool temperature (5–17 °C) and photoperiod interacted to affect flowering, and species varied in temperature and photoperiod requirements for flower induction and development. Research here examined irradiance, photoperiod, and cool-temperature effects on flowering of the desert cactus hybrid Echinopsis ‘Rose Quartz’.
‘Rose Quartz’ is cross between Echinopsis silvestrii and another Echinopsis species (parent not reported, R. O’Connell) that is asexually propagated. Echinopsis silvestrii is indigenous to the Tucuman and Salta regions of northern Argentina where it is often solitary, with white, nonfragrant, 2–5 cm long flowers (Anderson, 2001; Hunt et al., 2006). Other Echinopsis species are indigenous to northern Argentina, northeastern Chile, and northwestern Brazil, and Bolivia, and have large white, yellow, red, or orange flowers that can be fragrant (Anderson, 2001; Hunt et al., 2006). ‘Rose Quartz’ has large red flowers, blooms repeatedly, is large stemmed, and branches readily (personal observation). The habit and prolific flowering of this cultivar make it a potential new ornamental crop. Research objectives here were to 1) determine whether photoperiod, irradiance, and/or a 5 °C exposure affected Echinopsis ‘Rose Quartz’ flowering, and to 2) determine whether BA spray application affected Echinopsis ‘Rose Quartz’ flowering.
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