ASSESSMENT OF TIMING OF BUD DIFFERENTIATION AND DEVELOPMENT STAGES OF FLOWER INFLORESCENCE IN BLACKBERRY (Rubus spp.) CULTIVARS IN NORTHERN TURKEY

Blackberry (Rubus spp.) production is attracting interest in Turkey’s northern part, but information on timing of bud differentiation and developmental stages of flower inflorescence on next season is limited. The objective of this study was to determine the timing of bud differentiation and development stages of flower inflorescence in 4 biennial fruiting blackberry (Rubus spp.) cultivars (‘Chester’, ‘Dirksen Thornless’, ‘Jumbo’, ‘Bursa 1’) grown in northern Turkey. Axillary bud samples were collected from the middle parts of the one year of lateral branches every 7–15 days from September 2008 to May 2010. Ten development stages were identified from the flower bud differentiation to post-bloom period. The transition from the vegetative to reproductive stage occurred during September to October, with the differentiation of the terminal flower occurring on September 18 in ‘Bursa 1’, October 4–9 in ‘Dirksen Thornless’, October 16–20 in ‘Jumbo’, and October 20–22 in ‘Chester’. In all the examined cultivars, flower development occurred between September and June and lasted for 193–215 days.