Deferring flowering of greenhouse-grown Phalaenopsis orchids by alternating dark and light.

摘要

Most Phalaenopsis species and hybrids start to produce flowering shoots in the autumn, flower in January or February, and become limited in supply by April when market demand is strong. Delaying the onset of flowering in potted plants was investigated. On 15 September 1994, seedlings of 2-year-old hybrid Phalaenopsis cv. TAM Butterfly were exposed to repeated cycles of 1 day darkness/1 day light (natural photoperiod, 1D/1L); 4 days of darkness/3 days of light (4D/3L); 7 days of darkness/7 days of light (7D/7L); and the natural photoperiod control (0D/7L). The dark treatments were achieved by covering plants with black fabric or by placing them in a dark cage. Treatments were terminated on 16 December, and all plants were exposed to the natural photoperiod. The control plants flowered on 20 January 1995, whereas the 4D/3L plants did not reach anthesis until 14 April, nearly 3 months later. Flowering of the 1D/1L and 7D/7L plants was also delayed until early April. Regardless of treatments, flowercount and size were unaffected. In another experiment, beginning on 15 September 1995, 3-year-old plants were exposed to repeated weekly cycles of 2D/5L, 3D/4L, 4D/3L or 5D/2L until 22 January 1996. The untreated control plants flowered on 8 February 1996, whereas the 5D/2L plants did not reach anthesis until 6 May. The 4D/3L treatment was not as effective as it was in 1994, and resulted in anthesis 4 weeks after the control. In another investigation which began on 22 January 1996, plants were removed at 2-week intervals from a 5D/2L treatment, which was initiated on 15 September 1995, and were exposed to the natural photoperiod. Staggered anthesis was achieved. Plants that flowered in May and June had fewer flowers, although flower size was unaffected.