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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #205281
Title: Flowering and Fruiting Morphology of Primocane-Fruiting Blackberries

Author
item THOMPSON, E - OREGON STATE UNIVERSITY
item STRIK, B - OREGON STATE UNIVERSITY
item CLARK, J - UNIVERSITY OF ARKANSAS
item Finn, Chad

Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: 3/2/2007
Publication Date: 8/1/2007
Citation: Thompson, J.R., Strik, B.C., Clark, J.R., Finn, C.E. 2007. Flowering and fruiting morphology of primocane-fruiting blackberries. Acta Horticulturae.777:281-288.

Interpretive Summary: Blackberry cultivars such as Prime-JanTM and Prime-JimTM that fruit in the fall in new growth are a totally new type of blackberry. While there have been fall fruiting or "everbearing" raspberries for some time, this is new in blackberry. Although the flowering and fruiting of these blackberries has many similarities, there are differences as well. This study looked at the order of flowering lateral development and flower opening in response to some tipping treatments designed to increase yield.

Technical Abstract: The flowering morphology of the erect, thorny primocane-fruiting blackberry (Rubus L. subgenus Rubus) cultivars Prime-JanTM and Prime-JimTM were studied in 2005 in Aurora, Oregon. Primocanes that were "soft-tipped" in early summer to 1 m were compared to un-tipped primocanes and floricanes. On average, soft-tipped primocanes developed five lateral branches, whereas un-tipped primocanes developed just two. Tipped canes developed almost twice the number of flowers as un-tipped canes. 'Prime-Jan' and 'Prime-Jim' began blooming on the branches of tipped canes in mid-July. Un-tipped primocanes began to bloom in late July. Apical branches on tipped canes bloomed earlier than branches on the mid and basal portions of the primocanes. Within a primocane inflorescence, the terminal or distal flower was always the first to open, followed by terminal flowers from axes located on the basal portion of the inflorescence. Flowers then opened acropetally within the inflorescence. In contrast to primocanes, floricanes developed two types of floral structures: 1) short axial floral structures: over-wintered, unopened primocane-developed floral buds that generally lacked compound leaves; and 2) long axial floral structures: floricane-developed structures borne from a secondary bud that always developed compound leaves. Both types of floral structures developed below the spent primocane-fruiting apex of the un-tipped cane. Flowers on short floral structures began to open in early April while those on long floral structures began to open in mid-May. Days from anthesis to black fruit for soft-tipped and un-tipped primocanes averaged 46 to 52 d, and 57 d on floricanes. The blooming pattern within an inflorescence was the same for soft-tipped and un-tipped primocanes and floral structures on floricanes.