The micropropagation of blackberry can generate virus-free plants in short time. In order to improve micropropagation techniques of blackberry cv. Tupy (Rubus spp.), nodal segments with 2 cm length and 2 axillary buds originating from plants in vitro were excised and inoculated in MS culture medium, supplemented with different concentrations of sodium phosphate (0, 125, 250, 500 and 1000 mg L-1) and potassium chloride (0, 125, 250, 500 and 1000 mg L-1). The pH was adjusted to 5.8 before the addition of 6 g L-1 agar and sterilization at 121ºC and 1 atm for 20 minutes. After the inoculation, the explants were transferred to growth room at 25 ± 1ºC, 35 mmol m-2 s-1 irradiance and photoperiod of 16 hours, where they stayed for 60 days. The experiment was arranged in a completely randomized design, using four repetitions with 12 plants each. Number of sprouts and length of the aerial part of plants were smaller, due to larger concentrations of potassium chloride. Better results were obtained in the absence of KCl, and in the presence of sodium phosphate, mainly for length and fresh weight of the aerial part.
Rubus spp.; micropropagation; macronutrients