Effect of Supplementary Lighting and Soil Warming on Flowering of Three Gerbera Cultivars

Abstract

Abstract Cut flower Gerbera ( Gerbera jamesonii Bolus) plants were grown in pots or ground benches under various photoperiods, levels of irradiance, and soil temperatures. Photoperiodic flowering response varied with the 3 cultivars; ‘Appelbloesem’ was not sensitive to photoperiod; ‘Oranje Nasau’ and ‘Fabiola’ were promoted by short day (SD). In pot-grown Gerbera , SD increased the number of flowers (inflorescences) per plant of ‘Oranje Nassau’ and ‘Fabiola’ in the summer-fall and fall-winter. Supplementary lighting with high-pressure sodium (HPS) lamps increased the fall-winter production of all 3 cultivars. Plants grown under 16 hr photoperiod by extending natural day length with incandescent light (INC) produced the least flowers per plant in both summer-fall and fall-winter. In bench-grown Gerbera , supplementary HPS increased the number of flowers during the fall-winter as compared to natural daylight (ND). Soil warming from 16°−20° to 23°C had no effect on productivity, but increased the peduncle length.