Abstract

Cassava starch from nine varieties, namely, NR 8082, TMS 97/2205, TMS 97/0162, TMS 92/0057, TMS 98/0505, TMS 92/0326, TMS 30572, TMS 82/0058, and TME 419 were evaluated for their suitability as gelling substitute to conventional gelling agents (gellan gum and agar) in medium using cassava shoot tips and nodal segments as explants. Explants were seeded singly into a 15 ml cassava multiplication medium gelled either in 0.2% gellan gum, 0.7% agar or 7% starch from the nine cassava varieties. Cultures were maintained at 28 ± 2°C, 16 h photoperiod and 30 to 40 μEm^-2 s^-1 flux intensity supplied by white fluorescent tubes on shelves for four weeks. Percentage survival of explants irrespective of type ranged from 61.5 to 100 with NR 8082 and TMS 97/2205 cassava starch-gelled medium recording the highest score while the mean number of nodes produced per explant ranged between 3.6 ± 1.43 and 5.33 ± 0.87 for shoot tips and 2.73 ± 0.96 and 4.79 ± 0.97 for nodal segments. The nodal segments from TME 419 starch-gelled medium had the highest mean number of nodes though not significantly different (p>0.05) from those from gellan gum and agar media. TME 419 was the most consistent in influencing regeneration of cassava plantlets.

Key words: TME 419, cassava starch, explants, gelling agent, micropropagation.