Abstract
Four everbearing strawberry (Fragaria × ananassa Duch.) cultivars, ‘Kaho’, ‘Ohishi-shikinari’, ‘Miyoshi’ and ‘Yamato-shikinari’, which were overwintered, were grown at day (6:00–18:00)/night (18:00–6:00) temperatures of 30/25°C under 12-, 13-, 14- and 15-h photoperiods for 16 weeks. ‘Yamato-shikinari’ was also grown under a 16-h photoperiod. Under such a high temperature condition, these cultivars were found to be qualitative long-day plants. Flower bud initiation was inhibited under 14-h or shorter photoperiod in ‘Kaho’, under 13-h or shorter in ‘Ohishi-shikinari’, under 12-h in ‘Miyoshi’ and 15-h or shorter in ‘Yamato-Shikinari’. Non-chilled ‘Kaho’ and ‘Ohishi-shikinari’ plants were also tested. The photoperiods under which their flower bud initiation was inhibited were the same as those of overwintered plants. The critical photoperiod for flower bud initiation in everbearing strawberry plants grown under high temperature varied among cultivars.
