ABSTRACT
The China aster (Callistephus chinensis Nees.) is an erect, branching annual, with ovate or triangular ovate leaves with dentate margins forming a basal rosette in the young plant, but spirally arranged on the flowering stems. The China aster has been subjected to intensive breeding and selection with the principal objective of producing “double-flowered” forms with large numbers of ray florets in each inflorescence. Long-days (LD) promote inflorescence initiation, and the terminal apical meristem of the main shoot forms fewer leaves prior to the inflorescence in LD, with the result that inflorescence buds appear earlier, and often reach anthesis earlier than in short-day (SD). Daylength extensions using different wavebands and given both after dusk and before dawn have given variable results, though the R waveband was always effective in advancing anthesis. Flowering seems relatively unaffected by nutrition, but is promoted by application of Gibberellic acid which induces earlier inflorescence initiation in SD, but not LD, and promotes inflo-rescence development.
