Co-Authors:
Wai.I.Rrstr1n, I., Department of Ornamental Horticulture, Agricultural Research Organization, The Volcani Center, P.O. Box 6, BetDagan, 50250, Israel
Abstract:
Leucospermum patersonii was found to be an obligatory long-short day plant under a moderate temperature regime (22/17°C, day/night). The short-day (SD) requirement could be compensated by a low temperature (17/12°C) regime under long-day (LD) conditions. Long days had an inductive effect, whereas floral differentiation occurred under short days or a low temperature regime. The LD effect resembles that of the release from apical dominance following the production of a terminal bud. The morphological differentiation of the inflorescence was inhibited under LD and promoted under SD conditions. The effect of the low temperature regime or of short days on the initial stages of floral differentiation was similar; however, further inflorescence differentiation and development were faster under SD conditions and a moderate temperature regime. The correlative inhibition caused by the primary inflorescence under SD conditions could be overcome by treatment with cytokinin (benzyl adenine). All the inflorescences released from inhibition by cytokinin developed simultaneously, but aborted later during the growth season. In April, as natural days grew longer, the aborted inflorescences were replaced by vegetative axillary shoots. The nature of the LD effect and its disappearance under SD conditions are discussed. © 1989 Taylor & Francis Group, LLC.