The successful transfer of primocane fruiting expression from raspberry toRubus hybrid berry

This paper describes the successful transfer of the primocane fruiting (PF) character from raspberry (Rubus idaeus) to Rubus hybrid berries following crosses between raspberry and blackberry. The transfer was achieved by doub ling the chromosome complement of PF raspberry selections in culture using colchicine, and using regenerant tetraploid PF plants as the female parents in crosses with tetraploid or octoploid blackberries, or with hexaploid hy brid berries (all summer fruiting). The results show that the PF character is expressed more readily in hybrid plants where at least 50% of the chromo somes in the hybrid genome are derived from raspberry. In vitro germination of cut seeds overcame the poor germination often encountered in Rubus and ensured the rapid recovery of hybrid seedlings.