Photoperiodic Control of Flowering and Anthocyanin Formation in Fuchsia

Abstract

MEASUREMENTS of the rates at which phytochrome P₇₃₀ reverts to P₆₆₀ in the dark have not been made for green plants because of the low concentrations of phytochrome and high chlorophyll content. Estimates based on physiological experiments have indicated that the time taken for reversion varies in different species from less than 3 h^1,2 to more than 72 h³. In vivo spectrophotometric measurements on tissues containing no chlorophyll have indicated that there may be a fast and a slow component of P₇₃₀ reversion: although a considerable amount had disappeared after 2 h of darkness, some still persisted after 12 h⁴. Results from physiological studies on flowering and anthocyanin formation in the long-day plant Fuchsia reported here are consistent with this.