PREPARATION TREATMENT OF HYACINTH FOR FLOWERING BEFORE CHRISTMAS
The results thus far led to a change in the recommended preparation treatment for the forcers:
'10 days 23°C + 2 weeks 30°C + 3 weeks 25°C + 23°C until stage A2+ of the latest developed flower + 4 weeks 13°C + x weeks 9°C (planted)'
was changed into:
'10 days 23°C + 2 weeks 30°C + 3 weeks 25°C + 23°C until stage G + 4 weeks 17°C + (x + 1) weeks 9°C (the cold period of x weeks depends on the cultivar)'.
A longer period at 23°C improved flower quality and reduced losses in the greenhouse. After stage G, 17°C reduced rooting and attack by Penicillium during storage and improved flower quality as well. A longer cold period was necessary to prevent top flowering. Research was started to shorten the 4-weeks period of 17°C or to replace this period with a longer period at 23°C and a longer cold period at 9°C.
In this paper the reasons for the different temperatures of the preparation treatment will be given as well as results of research that led to the change of the recommended treatment.