The experiment was conducted at the Tissue Culture Laboratory of Tuber Crops Research Centre (TCRC), Bangladesh Agricultural Research Institute (BARI), Gazipur, Bangladesh in 2012. The explants of internodes were placed in MS media supplemented with 16 different concentration of 2,4-D and NAA such as, T1=Control, T2=1 mg L-1 2,4-D, T3=2 mg L-1 2,4-D, T4=3 mg L-1 2,4-D, T5=1 mg L-1 NAA, T6=2 mg L-1 NAA, T7=3 mg L-1 NAA, T8=1 mg L-1 2,4-D + 1 mg L-1 NAA , T9=1 mg L-1 2,4-D + 2 mg L-1 NAA, T10=1 mg L-1 2,4-D + 3 mg L-1 NAA, T11=2 mg L-1 2,4-D + 1 mg L-1 NAA, T12=2 mg L-1 2,4-D + 2 mg L-1 NAA, T13=2 mg L-1 2,4-D + 3 mg L-1 NAA, T14=3 mg L-1 2,4-D + 1 mg L-1 NAA, T15=3 mg L-1 2,4-D + 2 mg L-1 NAA and T16=3 mg L-1 2,4-D + 3 mg L-1 NAA to find out suitable combination for callus formation. For regeneration from callus, 4-5 mm sized callus were placed at MS media (1.0 mg L-1 NAA were used for root formation) supplemented with different concentration of BA (0.0 mg L-1, 1.0 mg L-1, 2.0 mg L- 1, 3.0 mg L-1, 4.0 mg L-1 and 5.0 mg L-1) to find out suitable concentration of BA for the regeneration of plants from the callus. Preparation of explants In vitro plantlet of 25-30 days old at solid medium was considered for the explants collection. For explants, only the first 5-6 internodes from the top of the plantlet excluding shoot apex of the each plantlet were excised and divided into 0.5- 1.0 cm long segments. For regeneration from callus, the produced callus (5 mm to 7 mm size) were used in aseptic condition at the cabinet of laminar flow. All the explants were placed in test tube and fuel paper were used and kept in a growth room at 25±2 °C. Only the first five internodes from the top of the plantlets were excised. Using alcohol, the laminar air flow chamber was thoroughly cleaned to maintain the aseptic condition. Under aseptic conditions, young and tender plantlets were taken out on a sterile glass plate using sterile forceps. The plantlets were not surface sterilized as those were already maintained under in vitro aseptic conditions. The roots of these plantlets were excised using a sterile scalpel and the leaves were removed. Preparation of media, inoculation of explants and incubation The composition of MS ( Murashige and skoog ) media were supplemented with 16 different concentration of 2,4-D and NAA such as T1=Control, T2=1 mg L-1 2,4-D, T3=2 mg L-1 2,4-D, T4=3 mg L-1 2,4-D, T5=1 mg L-1 NAA, T6=2 mg L-1 NAA, T7=3 mg L-1 NAA, T8=1 mg L-1 2,4-D + 1 mg L-1 NAA , T9=1 mg L-1 2,4-D + 2 mg L-1 NAA, T10=1 mg L-1 2,4- D + 3 mg L-1 NAA, T11=2 mg L-1 2,4-D + 1 mg L-1 NAA, T12=2 mg L-1 2,4-D + 2 mg L-1 NAA, T13=2 mg L-1 2,4-D + 3 mg L-1 NAA, T14=3 mg L-1 2,4-D + 1 mg L-1 NAA, T15=3 mg L-1 2,4-D + 2 mg L-1 NAA and T16=3 mg L-1 2,4-D + 3 mg L-1 NAA to find out suitable concentration and combination of 2,4-D and NAA for rapid callus formation; and different concentration (0.0 mg L-1, 1.0 mg L-1, 2.0 mg L-1, 3.0 mg L-1, 4.0 mg L-1 and 5.0 mg L-1) of BA were supplemented with MS media to find out suitable concentration of BA for regeneration from callus. Fine agar powder of Loba, India brand was used. After pH adjustment 8 g L-1 agar was added to the solution to solidify the media. An amount of 10 ml media were dispensed into each test tubes. The test tubes were autoclaved at l2l0 C for 20 minutes at 1.2 kg/m2 and thereafter stored at 250 C. After 2-3 days, the media was checked for any type of contamination and the explants were inoculated after performing several sequential steps. The explants were placed in each plate for each treatment horizontally in contact of media. The treatment was replicated for three times under CRD design. Every ten test tubes were used for one replication. The plates were sealed, labeled carefully and were finally kept in the culture room under constant temperature (250C) and light (16 hrs. light, 8hrs. dark), and the growth of the inoculated explants was monitored regularly. Only plantlets with well developed roots were used for multiplication in net house. Data on callus initiation was recorded after one week, percent explant establishment after two weeks and buds per explant after five weeks. The data were analyzed statistically and means were separated by Least Significance Difference method.