Red firespike (Odontonema strictum) is a tropical flowering plant that has a potential as a new flowering potted plants for its attractive red inflorescence. Flowering and morphology of red firespike were evaluated in response to photoperiod. In Expt. 1, morphology and growth characteristics of firespike were evaluated in response to photoperiod. Plants were propagated from semi-softwood cuttings and grown under long days (LD). Plants were exposed to short days (SD) of 9 h for 0, 4, 8, 12, 16, 20, 24, 28 or 32 days. Plant height and growth index increased as the number of SD increased. Plants that received 16 or more SD reached anthesis earlier than plants grown under fewer SD. The number of plants that flowered was higher in 32 SD than in lower SD. In Expt. 2, plants were placed in SD for 0, 8, 16, 24 or 32 days and then apical meristems were examined histologically to determine the pattern of flowering in firespike during the time prior to anthesis. Plants that received only 8 SD showed early floral initiation and after 16 SD, meristems continued reproductive differentiation even when returned to LD. Under the experimental conditions tested, the most rapid, uniformed, and complete flowering of firespike occurred when plants received 24-32 days of inductive signal (SD). | Floral initiation in red firespike (Odontonema strictum): Effects of photoperiod and duration of short day exposure
