Effect of photoperiod and temperature on flowering of Rhodanthe floribunda and Pycnosorus thompsonianus

The flowering responses of two Australian native Asteraceae species, Rhodanthe floribunda and Pycnosorus thompsonianus , to photoperiod and temperature were investigated to facilitate the manipulation of floral initiation and development. Plants were grown at 20/10 °C or 30/20 °C (day/night) under short day (SD: 11 h light) or long day (LD: 16 h light) in environment-controlled greenhouse bays in 2009 and 2010. LD advanced flowering by about 15 days and anthesis by 13 days in R. floribunda , and by 12 days and 15 days, respectively, in P. thompsonianus . Rhodanthe floribunda grown under cool temperatures (20/10 °C) produced 30% more inflorescences than the plants grown under warm temperatures (30/20 °C). Pycnosorus thompsonianus under LD produced more than double the number of inflorescences per plant than under SD (79.8 vs 33.7) regardless of temperature regimes. Both species are facultative LD plants. This knowledge is useful to regulate flowering of these ornamental plant species for potential commercialisation.