Direct somatic embryogenesis was successfully obtained from young leaves of
cassava cultured on induction medium. The addition of 2,4-0 and picloram at 4 or 6
mg/l to induction medium was significantly effective in induction of somatic
embryogenesis and in increasing number of embryogenic explants. The presence of
cytokinins in induction medium, except kinetin, significantly reduced frequency of
embryogenesis and number of embryogenic explants. Increasing carbon source from
20 g/l to 40 g/l was associated with a significant reduction in number of embryogenic
explants and in frequency of embryogenesis. Maltose at 20g/l was the most effective
carbon source for the induction of somatic embryogenesis and for increasing number
of embryogenic explants. Supplementing somatic embryo induction medium with
amino acids did not improve frequency of embryogenesis or number of embryogenic
explants. As for the extended effect of auxins, cytokinins, carbon sources and amino
acids on plantlet regeneration from somatic cotyledons, results pointed out that 2,4-0
and picloram at 4 mg/l, SA at 1 mg/l and zeatin at 0.5 mg/l and maltose at 20 gil had a
positive extended effect, which led to significant increase in frequency of regeneration
and number of regenerated plantlets lexplant. However, amino acids had no positive
effect on frequency of regeneration or number of regenerants lexplant. Adding silver
nitrate at 4 mg/l to plantlet regeneration medium was very effective in increasing
percentage-regenerating explant, but did not affect number of regenerated plantlets
per explant. Field experiments, during summer seasons of 2002103 and 2003/04
proved that both tissue culture propagated cassava or those propagated by stem
cuttings did not significantly differ in average root length, diameter and weight, number
of tuber roots/plant and tuber root yield/ plant.