Tissue culture technique for rapid propagation of cassava improved variety GR891.

[Objective]The aim of this experiment was to find out a suitable method and optimal conditions for rapid micropropagation of cassava plants. [Method]The axillary or apical buds of stems derived from over wintered cassava plants and its new plants were used as explants for induction, multiplication and rooting of adventitious buds under different conditions, viz., different sterilization times and concentrations of 6-BA and NAA. [Result]As compared to the over wintered stem of cassava, the young stem derived from new plant was more suitable for the induction of adventitious buds of cassava. When the explants were sterilized with HgCl2 (0.1%) solution for 10-15 min before inoculation to the medium, the adventitious bud and callus showed the highest induction rate (57.1 and 61.9%, respectively). The best medium for induction of axillary buds was MS medium containing 0.5 mg/L 6-BA, which attained 72.2% induction rate of adventitious buds. The suitable medium for multiplication of cluster buds was MS + 0.5-1.0 mg/L 6-BA, 2-3 times multiplication in this medium made the cluster buds more stronger. The MS medium containing 0.3-1.5 mg/L NAA was recorded as best medium for rooting of adventitious buds and resulted in 90.0% rooting rate. The survival rate of rooted plantlets was recorded as 95.0% when plantlets were transferred in pots containing 60.0% pond mud and 40.0% river sand. [Conclusion]Adding low concentration of 6-BA in MS medium was beneficial to the induction and multiplication of adventitious buds of cassava, while the induction and growth of adventitious buds did not require NAA. The combination of 6-BA and NAA was not found beneficial for induction and multiplication of adventitious buds. Addition of 0.9 mg/L NAA in MS medium showed better effects on rooting of adventitious buds, while adding 6-BA in medium played an inhibitory role in rooting.