Abstract

The potential of cassava starch as an alternative and cheap gelling agent for potatoin vitro culture micro-propagation media was investigated. A two-factor experiment in randomized complete block design was conducted. Four levels of gelling agents; 10% (w/v) cassava starch, 8% cassava starch mixed with 0.25% agar, 0.8% agar and a liquid medium, were evaluated using three selected Kenyan potato cultivars (Tigoni, Asante and Kenya Sifa). Cassava starch at 10% gave adequate support of explants, though it had low viscosity and softened at 42 days after explant inoculation. Cassava starch mixed with 0.25% agar provided the same firmness as 0.8% agar and maintained gel integrity throughout the culturing period of 84 days. Survival in- and ex vitro was lowest in liquid medium culture. Potato transplants from the liquid medium and cassava starch gelled medium had similar (p > 0.05) mean number of nodes and biomass. These mean values were significantly higher compared to the transplants from the agar gelled medium. The use of 10% cassava starch reduced cost by 42.5% in comparison with use of agar.

Key words: Cassava starch, gelling agents, micro-propagation, transplants, potato.