Photocontrol of flowering and stem extension of the intermediate-day plant Echinacea purpurea.
Physiol Plant
; 112(3): 433-441, 2001 Jul.
Article
em En
| MEDLINE
| ID: mdl-11473702
ABSTRACT
Intermediate-day plants (IDP) flower most rapidly and completely under intermediate photoperiods (e.g., 12-14 h of light), but few species have been identified and their flowering responses are not well understood. We identified Echinacea purpurea Moench as an IDP and, based on our results, propose a novel mechanism for flowering of IDP. Two genotypes of E. purpurea ('Bravado' and 'Magnus') flowered most completely (>/=79%) and rapidly and at the youngest physiological age under intermediate photoperiods of 13-15 h. Few (=14%) plants flowered under 10- or 24-h photoperiods, indicating E. purpurea is a strongly quantitative IDP. Plants were also induced to flower when 15-h dark periods were interrupted with as few as 7.5 min of low-intensity lighting (night interruption, NI). Flowering was progressively earlier as the NI increased to 1 h, but was delayed when the NI was extended to 4 h. Stem length increased by >/=230% as the photoperiod or NI duration increased, until plants received a saturating duration (at 14 or 1 h, respectively). Flowering was inhibited when 16-h photoperiods were deficient in red (R, 600-700 nm) light, and was promoted when photoperiods were deficient in far-red (FR, 700-800 nm) light. Because of our results, we propose the flowering behavior of IDP such as E. purpurea is composed of two mechanisms a light-dependent response operating through light-labile (type I) phytochrome in which flowering is inhibited by an LD, and a light-stable (type II) phytochrome (i.e., phyB, D and E) response in which flowering is promoted by a short-night.
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01-internacional
Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2001
Tipo de documento:
Article