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Flowering responses of Heliconia psittacorum L.f. × H. spathocircinata Aristeguieta `Golden Torch' to temperature and photosynthetic photon flux (PPF) were determined in controlled-environment conditions using a 2 × 2 factorial combination of temperature (32C day/20C night and 24C day/20C night) and PPF (475 and 710 μmol·m–2·s–1). Temperature had no significant effect on new shoot production, with an average of 9.3 shoots per plant being produced over the 248 days of treatment. More shoots, however, were produced at the higher PPF level (10.1 compared with 8.3 shoots). The proportion of shoots that initiated flowers (85%) was similar in all treatments. The duration from shoot until inflorescence emergence was significantly less at 32C day/20C night than at 24C day/20C night (140 and 146 days, respectively) and was unaffected by PPF. This duration also was significantly affected by the interacting effects of order of shoot appearance and the number of leaves subtending the inflorescence. The second shoots to emerge had the shortest duration from shoot emergence to inflorescence emergence. The number of leaves subtending the inflorescence increased at the higher temperature and decreased as shoot order increased but was unaffected by PPF. Temperature and PPF levels influenced total leaf area at flowering, with highest areas being achieved in the high temperature–low PPF combination. Acceptable flower quality with at least two, opened, well-formed, well-colored bracts was obtained in all treatments, although flower stems were taller and thicker at 32C day/20C night and these dimensions increased further with increasing order of shoot appearance. Stem diameters tended to be thinner at the lower PPF level. Overall, temperature was more dominant than light in influencing production and quality of flowers, but developmental factors associated with the order of shoot appearance also played a significant role. Flower production of `Golden Torch' should be feasible in temperature-controlled glasshouses in temperate regions where mean air temperatures can be maintained at ≈20C.
Tubers of Sandersonia aurantiaca Hook. were soaked in 1000 mg·L-1 GA3, 20 mg·L-1 uniconazole, 200 mg·L-1 benzyladenine, or water for 2 hours and then sprouted at 12, 18, or 24 °C. The effects of these treatments on flower stem quality were then determined at forcing temperatures of 18, 24, or 30 °C. Stem length increased with sprouting temperature only at a forcing temperature of 18 °C. Floret numbers increased with sprouting temperature at all forcing temperatures, but the effect was greatest at the 18 °C forcing temperature. The 12 °C sprouting treatment reduced floret numbers at all forcing temperatures. Soaking tubers in GA3 increased stem length but drastically reduced floret numbers, while soaking in uniconazole reduced stem length but had no significant effect on floret numbers. Soaking in BA strongly promoted branching, which resulted in large increases (>30%) in floret numbers per stem with little change in stem length. Of the three growth regulators, only BA was effective in improving cut flower stem quality. Chemical names used: gibberellic acid (GA3); (E)-(+)-(S)-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pent-1-ene-3 -ol (uniconazole); N 6-benzylamino purine (benzyladenine; BA).