Stimulation of in vitro shoot proliferation from nodal explants of cassava by thidiazuron, benzyladenine and gibberellic acid

Multiple shoots were produced from nodal explants of cassava (Manihot esculenta Crantz.) by a two-step procedure: a 6- to 8-day exposure to 0.11-0.22 mu M thidiazuron (TDZ) in liquid Murashige and Skooge (MS) medium followed by culture on agar-solidified MS medium supplemented with 2.2 mu M 6-benzyladenine (BA) and 1.6 mu M gibberellic acid (GA(3)). TDZ caused the nodal explants to expand and this expansion (growth) continued during culture with BA and GA(3). From this expanded explant, clusters of buds and fasciated stems developed continuously and these gave rise to shoots. The shoot proliferation process was open-ended, yielding an average of 31.5 shoots per nodal explant after 10 weeks of culture with genotype CG 1-56. A positive response was also obtained from seven other genotypes evaluated with this protocol.