Two experiments were carried out to investigate the influence of low temperatures in winter on the subsequent growth of two cultivated strawberry varieties, Royal Sovereign and Auchincruive Climax.
In the first experiment chilling treatment was given in a cold store at 35-40 F. Plants subjected to no chilling, 36 days and 72 days of cold storage, were grown independently in a constant environment cubicle. In the second experiment plants were exposed to low winter temperatures outdoors. Batches of plants were grown in the growth rooms both in November (having had little or no chilling) and in March (after chilling).
The results show that low temperatures in winter have a marked effect on the subsequent growth of the plants. Plants placed in November under the controlled conditions of an eleven-hour photoperiod at 60-62 F. continued flower initiation, produced no stolons, had short petioles, small leaves, and increased root and crown dry weight. After subjection to low temperatures, similar plants under a similar environment made vigorous vegetative growth with strong runner production, long petioles and large leaves, while flower initiation was delayed for several weeks.
Modification of the carbohydrate status by shading in autumn and by low light intensity treatments in spring had a small effect on the expression of post-chilling vegetative vigour.