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

Information concerning the plhotoperio(lic response of Cestrum isocturnums L. was initially reported by Sachs (4). From his investigation he found it was a long-short day (LSD) plant and, under experimental conditions he used, did not produce floral primordia in response to other light patterns. More recent work with C. niocturnunti 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. diurnumt L. indicated that it also responded to a LSD stimulus in floral primordia initiation (2). Further investigation over a wider range of photoperiodls and time periods, giving a more concise picture of floral primordia initiation patterns of these 2 species is herein reported.