Flowering control of recently introduced F₁-hybrid cultivars of Godetia

Clarkia amoena, commonly known as Godetia, is a well-known garden plant. The recent introduction of F₁-hybrid cultivars of this plant have greatly increased its value as a source of cut flowers. The plant was found to be sensitive to high temperatures. At 24°C and higher the plants died after a few weeks of growth, before flower bud formation. At 20-24°C Godetia behaved as a neutral-day plant, initiating flowers under both long-day (LD) and short-day (SD) conditions. At lower temperatures, however, it behaved as an absolute LD plant. Both flower initiation and development were enhanced under LD conditions. Plants grown under LD conditions (natural winter SD plus supplementary photoperiodic light) produced flowering stems of superior quality: the stems were much longer and the flowers were concentrated at the top of the stems, not along the shoot as in SD plants.