Initiation of Floral Primordia in Cestrum diurnum and Cestrum nocturnum in Response to Various Photoperiodic Patterns

Information concerning the photoperi.odic response of Cestrutm nocturnum L. was initially reported by Sarhs (4). From his investigation he found it was a long-short day (LSD) plant and, under experimental conditions he used, did not produce flioral primordia in response to other light patterns. More recent work with C. nocturnum confirmed the previously reported LSD response 'but added that this species also produced floral primordia when grown continuously under an 18-hour photoperiod (2). Previous work on C. diurnum L. indicated that it also responded to a LSD stimulus in floral primordia initiation (2). Further investigation over a wider range of photoperiods and time periods, giving a more concise picture of floral primordia initiation patterns of these 2 species is herein reported.