The Interaction of Temperature on Flowering of Alstroemeria ‘Regina’1

Abstract

Abstract When Alstroemeria ‘Regina’ plants were programmed to flower after 6 or 8 weeks at 5°C treatments, flowering was hastened by forcing plants at 18° vs. 13° greenhouse night air temperature. However, the 18° forcing temperature reduced flower production, flowers per shoot and shoot grade when compared to 13° forcing temperatures. Due to the decrease in flower production observed at 18° forcing temperature, a 13° temperature is recommended. When plants were grown for 16 weeks at 13°, an inductive temperature, or for 16 weeks at 21°, a non-inductive temperature, prior to the 5° inductive treatments, the 13° pretreatment without a 5° treatment was as effective as 8 weeks at 5° following the initial 21° pretreatment when forced at 18°. Thus, the cold requirement can be fulfilled either at 5° for a short period of time (6 to 8 weeks) or at 13° over an extended time span (16 weeks). Total shoot production during the flowering span decreased as the duration of the 5° treatment increased.