title: Bolting induction in Oenothera erythrosepala Borbás in relation to rosette size, vernalization, and photoperiod.
abstract: The relationships between rosette size, vernalization, and photoperiod in bolting induction of Oenothera erythrosepala (a facultative biennial) were examined. A natural population of O. erythrosepala in a sand dune system at Azigaura, Japan, behaves as a monocarpic perennial, while a population treated with fertilizer showed the life cycle of a winter annual. In both natural and fertilized populations, bolting was restricted to size classes with rosette diameter greater than 9 cm, regardless of the chronological age and the amount of food reserves accumulated in the tap root. Pot culture experiments showed that the species requires both vernalization and long-day photoperiod for bolting induction, and has a critical leaf area for receiving photoperiodic stimuli. The amount of food reserves in the plant per se does not contribute to the size-dependent flowering of the species.
authors.affiliation: Division of Environmental Biology, National Institute for Environmental Studies, Yatabe, 305, Tsukuba, Ibaraki, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kachi
authors.affiliation: Department of Botany, Faculty of Science, University of Tokyo, Hongo, 113, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hirose