Propagation of Thornless Blackberries Utilizing Adventitious Shoots from Root Cuttings

Studies were conducted in early 2003 to determine the effect of root source and length on yield of adventitious shoots and plant yield from root cuttings of Arkansas-developed thornless blackberries. In the first study, roots from ‘Arapaho’ and ‘Apache’ plants grown in an aboveground bed containing commercial potting soil were compared to field-grown roots. Bed-grown roots averaged 6.9 shoots per 15 cm root cutting while field-grown roots averaged 3.4 shoots per root. ‘Apache’ produced more shoots/root cutting compared to ‘Arapaho’, (5.9 vs. 4.4 shoots/root cutting, respectively). In a comparison of 15and 30-cm-long root cuttings of ‘Apache’, ‘Arapaho’, and ‘Ouachita’, shoot yield of 30-cm roots was higher than that of 15 cm roots, but total yield of shoots per unit root was not increased by the longer root cuttings. Rooting of adventitious shoots neared 100% in both studies, and resulting quality of plants from these shoots was very good. This minor modification to the traditional method of using root pieces to yield individual plants could lead to a more efficient and productive yield of propagules. The use of adventitious shoots from root cuttings for blackberry plant propagation appears to be a viable method for growers to consider.