It was investigated whether successful forcing of strawberries could start before 15 January. To study flower initiation the influences of daylength and temperature were traced for early, mid season and late cultivars, particularly the early Deutsch Evern. After leaf area bad reached a minimum 14-18 short-day cycles of 8h of light and 16h of darkness at 18°C initiated flowering of this cv. Probably a short cold period (e.g. 5°C) removed the light inhibition, and a longer period caused accumulation of a substance stimulating elongation and inhibiting flower initiation. After short-day treatment of parent plants the floral stimulus was not transported to daughter plants.No absolute dormancy was observed. The term relative dormancy was preferred. Fairly prolonged chilling promoted truss elongation, but in autumn fairly brief cold could do this if supplemented with long-day treatment and spraying with gibberellic acid (GA 3 ).The rate of plant development was mainly influenced by cv., later forcing and warmth. Prolongation of chilling and of day length, and spraying with GA 3 caused no acceleration. Yield was influenced by cv. and the time when forcing commenced. The prospects for early forcing were determined by all measures promoting the efficient use of assimilatory light.
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