Effect of photoperiod and the duration of short day treatment on vegetative and generative growth of strawberry 'Korona'.

摘要

Short days induce both flowering and dormancy in Junebearing strawberry (Fragaria x ananassa Duch.) cultivars grown for winter production in greenhouses. If not removed by a cold treatment, dormancy reduces vegetative growth of the plants and lowersthe yield. The aim of this study was to examine the possibility of inducing flowering without reduction in vegetative growth. The effects of photoperiod (12, 13.5 or 15 h) and the duration of short day treatment (21, 35 or 49 days) on vegetative and generative growth of 'Korona' strawberry were studied. Half of the plants flowered after the treatment in a 15 h photoperiod regardless of the duration of the treatment. In the shorter photoperiods all plants flowered and the number of flowers was greatly increased by lengthening the duration of the treatment. Plants from 12 and 13.5 h photoperiods flowered equally, but the vegetative growth was inhibited more in a 12 h photoperiod than in a 13.5 h photoperiod. The reduction in the vegetative growth was not permanent; one month after the end of treatments differences between the treatments had disappeared. In conclusion, dormancy and flowering in strawberry are separate phenomena. Dormancy in 'Korona' is probably induced by photoperiods shorter than 12 h,but flower induction occurs also in longer photoperiods. As shorter photoperiods reduce vegetative growth, it may be beneficial for the yield to induce flowering with longer photoperiods than 12 h.