FROST INJURY TO FLOWERBULB CROPS
Frost injury can be caused either directly by low temperatures or by processes accompanying the formation and the presence of ice in the soil. As a first approach the effect of low temperatures on several cultivars of tulip, narcissus, hyacinth, iris and crocus was tested in sand-filled containers at various temperatures below 0°C. This was done at different stages of plant development, with different lengths of freezing period.
The effects of continuous freezing and a repeated alternation of freezing and thawing were also compared.
The negative effects of low temperatures increased from tulip, crocus, hyacinth, narcissus, to iris, but temperatures below -1°C seemed to have a harmful effect on shoot formation in all crops. Only the degree of freezing and the total duration were of influence.