COLD REQUIREMENTS FOR FLOWERING OF FORGET-ME-NOT

Flowering of Myosotis ‘Victoria’, ‘Indigo’ and the Bobo series was determined at 16 ± 1°C, 8.6 mol·d^-1·m^-2 and 16-hour photoperiod following exposure to comparative periods of 6 ± 0.5°C. Polynomial analysis showed the flowering time at 16°C to decrease linearly with increasing exposure to 6°C from 3 to 12 weeks.
Flower time was observed at 52 days for ‘Victoria’, 50 days for ‘Indigo’ and 44 days for the Bobo series following 3 weeks of 6°C. After 84 days (12 weeks) at 6°C, flowering took place after 21 days at 16°C independent of cultivar.
Plants grown at 16°C without any chilling failed to flower within the 7 months of the study.
The cultivars Compindi, Indigo, Musik and Snowsylva produced 4 to 6 additional flowering branches in response to removal (pinch) of the apical 1 cm portion of the main stem either at the beginning or end of the cold period.
The greatest number of branches was 16 for the Bobo series following pinching after 6 weeks at 6°C. For ‘Bluesylva’ and ‘Rosylva’, pinching had no effect on branching.
Plants of the Bobo series, ‘Indigo’, ‘Miro’ and ‘Musik’ pinched at initiation of 6°C flowered 7 to 12 days earlier and those pinched after 6 weeks at 6°C flowered at the same time as the non-pinched control plants.
The only cultivar to flower faster when pinched at either stage was ‘Compindi’. The rate of flowering was not affected by pinching in ‘Bluesylva’, ‘Rosylva’ and ‘Snowsylva’.