DOUBLE-CROP SYSTEM IN OUT-OF-SEASON STRAWBERRY PRODUCTION
There are few greenhouse strawberry (Fragaria x ananassa Duch.) producers in Finland. They grow Junebearing strawberry cultivars and obtain a maximum of two crops per year, in the spring and in the fall. The aim of this study was to develop a new plant production technique to increase productivity in greenhouse strawberry production. Plants of cultivar Korona were exposed to two successive short day (SD) treatments followed by cold storage in order to obtain two successive crops during forcing. The effects of the following daylength treatments on vegetative and generative growth were studied: treatment 1: 3 weeks SD + 2 weeks LD (long day) + 3 weeks SD; treatment 2: 3 weeks SD + 4 weeks LD + 3 weeks SD; and treatment 3: 10 weeks SD. No treatment effects on vegetative growth were observed during forcing. Two distinct flower truss formation and cropping periods were observed in treatment 2 plants, but not in treatment 1 or 3. Probably the first SD treatment started crown branching and induced flowering in a main-crown and in the oldest branch-crown(s), whereas younger branch-crowns were induced during the second SD treatment, when they had reached adequate size. There were only minor differences in the numbers of flowers and berries between treatments although the number of inflorescences in treatments 2 and 3 was almost two-fold greater than in treatment 1. Total yield was highest in treatment 3 followed by treatments 2 and 1, respectively. However, the advantage of two successive SD treatments was a longer cropping period that increased berry size.
Hytönen, T. and Palonen, P. (2003). DOUBLE-CROP SYSTEM IN OUT-OF-SEASON STRAWBERRY PRODUCTION. Acta Hortic. 626, 213-218
cold storage, crown, flowering, Fragaria x ananassa, inflorescence, short day treatment, yield