Influence of Plant Growth Regulators and Dark Pretreatment on Shoot Proliferation, Rooting and Acclimatization of Thorny Blackberry

Document Type : Original Article


1 Horticulture department, faculty of Agriculture, Suez Canal University, Ismailia, Egypt

2 Horticulture Department, Faculty of Agriculture, Suez Canal University, Ismailia, Egypt


This study aimed to establish an efficient micropropagation protocol for blackberry. For shoot multiplication, shoots tips-derived plantlets were cultured on MS medium supplemented with 0.5 or 1.5 mg l-1 BA individual or in combined with 0.5 mg l-1GA3. The highest number of shoots/cluster, shoot height, shoot fresh weight and number of leaves were observed on MS+1.5 mg l-1 BA+0.5 mg l-1 GA3. In a second proliferation experiment, explants were subjected to in vitro auxin pretreatments (0.5 and 1.0 mg l-1 IBA or NAA) for two weeks with presence of 1.5 mg l-1 BA. Results indicated significant increase in shoot fresh weight, shoots cluster height (9.75) of explants pretreated with 0.5 mg l-1 IBA under dark incubation condition but the roots number significantly increased (4 roots/cluster) under light incubation and MS+1.0 mg l-1 NAA. Rooting and growth were examined under dark versus light pretreatments, followed by further growth for four weeks on MS medium supplemented with different concentrations (0.5 and 1.0 mg l-1) of auxin types (IBA and NAA). All auxins concentrations maximized the root length under light incubation condition with no significant difference among all values under light condition. Anyway, the highest root length ( was obtained on MS +0.5 mg l-1 IBA. While, the highest roots number (7.2 roots/plantlet) was recorded on MS+1.0 mg l-1 NAA, under light condition. On MS medium without auxin under dark pretreatment, plantlets possessed the highest shoot/root ratio. The effects of in vitro auxin treatments on subsequent ex vitro growth were studied. Plantlets previously grown on MS medium+1.0 mg l-1 NAA or IBA recorded the highest root fresh and dry weight and root number.