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- Author or Editor: Lindsay J. Davies x
The effects of night temperature (NT) and photosynthetic photon flux (PPF) on time to flower and flower yield in `Bristol Fairy' and `Bridal Veil' Gypsophila paniculata L. (perennial baby's breath) were studied in controlled environments. Plants were grown with nights at 8, 12, 16, and 20C and 450 or 710 μmol·s-1·m-2 photosynthetic photon flux (PPF). Days were at 20C. In both cultivars, the times from the start of treatments to visible bud and from visible bud to anthesis were delayed at the lower PPF and at an NT <20C. The delays in `Bristol Fairy' were greater than those in `Bridal Veil'. Failure of `Bristol Fairy' plants to reach anthesis was common at SC NT and either 450 or 710 μmol·s-1·m-2 PPF; whereas in `Bridal Veil', nearly all plants flowered, regardless of environmental conditions. Flower yield (measured as fresh weight of inflorescences) decreased with NT in `Bristol Fairy' but was highest at 8 or 12C in `Bridal Veil'. In a second experiment using the same cultivars, the effect of curtailing long-day (LD) conditions at various stages on stem elongation and flower yield was investigated. `Bristol Fairy' required more LD cycles (>56) than `Bridal Veil' for maximum stem elongation and flower yield. Terminating LD conditions before the start of inflorescence expansion resulted in lower yields and shorter plants in both cultivars.
Winter greenhouse production of perennial baby's breath (Gypsophila paniculata L.) is hampered by short daylength, low PPF and low temperatures. Flowering of the popular cultivar `Bristol Fairy'(BF) can be improved by supplemental assimilation lighting, but the costs are rarely justifiable. `Bridal Veil' (BV) is a new cultivar with similar flower morphology to BF. BF and BV were grown under long day (LD) conditions at 8, 12, 16 and 20C night (20C day) and either 450 or 710 μmol s-1 m-2 in controlled environments. Most BF plants failed to lower at 8C in both PPF. Nearly all BV plants flowered irrespective of growth conditions. Flower yield decreased with night temperature in BF but was greatest at 8 or 12C in BV. BF required more LD cycles (>56) than BV for maximum stem elongation and flower yield. Termination of LD conditions before the start of inflorescence expansion resulted in reduced yields in all plants.
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).