617 Day and Night Temperatures, Daily Light Integral, and CO2 Enrichment Affect Growth and Flower Development of Campanula carpatica `Blue Clips'
Campanula carpatica Jacq. `Blue Clips' plants were grown in a greenhouse under ambient (400 μmol·mol-1) and enriched (600 μmol·mol-1) CO2 concentrations, three daily light integrals (DLI; 4.2, 10.8, and 15.8 mol/m per day), and nine combinations of day and night temperatures created by moving plants every 12 h among three temperatures (15, 20, and 25 °C). Time to flower decreased as plant average daily temperature (ADT) increased. Flower diameter decreased linearly as ADT increased in the 15 to 25 °C range and was not related to the difference between day and night temperatures (DIF). Increasing DLI from 4.2 to 10.8 mol/m per day also increased flower diameter by 3 to 4 mm regardless of temperature, but no difference was observed between 10.8 and 15.8 mol/m per day. Carbon dioxide enrichment increased flower diameter by 2 to 3 mm. Number of flower buds and dry mass at high and medium DLI decreased as plant ADT increased. Plant height increased as DIF increased from ñ6 to 12 °C. Number of flower buds and dry mass were correlated closely with the ratio of DLI to daily thermal time using a base temperature of 0 °C.