Effect of diameter and length on root cuttings of thorny & thornless blackberries cultivars

The present experiment was performed to optimization of blackberry propagation via factorial in a CRD, by the first factor included cultivar (Everthornless, Thornless evergreen, thornly Marion and SariIzadyar) from blackberry collection, the second factor root cutting's diameter (2-3 and 3-5 mm) and the third factor involves the root cuttings length (6, 8, 10 and 12 cm), with seven replications in March 2016. After three months rooting performed under shade and humid condition then the rooting and its related traits measured. Results of rooting in all cultivars showed root cuttings with 2-3 mm diameter and 12cm length produced longest root in proximal end of Marion cultivar with 123.43 mm. In chimera (Thornless evergreen) and Everthornless cultivars the most rooting percent observed in the 12 cm length in all of diameters with average of 71.42 percent, which was significantly different from other cultivars. Thornless cultivars significantly, showed better survival percent (77.33), inside of shorter roots length (51.8cm) and shoot (46.07cm), in compare to thorny cultivars. The highest percent of survival (77.33%) observed in normal thornless, among thornless cultivars, and early thorny (64.58 percent) in thorny cultivars. Results showed significant effect of root cutting with 3-5mm diameter and 10-12cm length on increase of blackberry root cutting rooting. The genetic difference of cultivars and amount of reserved material in cuttings must be considered in propagation of blackberries by root cutting.