Effects of different photoperiods on flowering time of facultative short day ornamental annuals

Abstract: An experiment was carried out to study flowering response of six facultative short day plants (zinnia cv. Lilliput, sunflower cv. Elf, French marigold cv. Orange Gate, African marigold cv. Crush, cockscomb cv. Bombay and cosmos cv. Sonata Pink) under four distinct controlled photoperiods (8, 11, 14 and 17 h d^-1). A curvilinear facultative response was observed in almost all cultivars studied. zinnia, sunflower, French marigold, African marigold, cockscomb and cosmos took minimum time to flower when grown under 8 h d^-1 photoperiods however it was significantly (P<0.05) increased when photoperiod was increased to 17 h d^-1. These findings revealed plant scheduling prospect that is, the flowering time of facultative SDPs grown under long day photoperiod can be extended in order to continue supply of these plants in the market