Colchicine-sensitivity Test in Cassava Leaf Lobes and its Effect on Callus and Somatic Embryo Formation

Colchicine acts as a polyploidy inducer but at high concentrations, it causes high cell mortality. To improve the efficiency of colchicine polyploidization in cassava, leaf lobes colchicine-sensitivity tests were carried out and LD₅₀ determined at 0.00, 0.05, 0.10, 0.20 and 0.25 g/l colchicine concentrations in the varieties Ankrah, Dagati, Tomfa and Tuaka.

Colchicine treated leaf lobes were regenerated into callus on either 8 mg/l 2, 4-D or Picloram. The calli were subsequently regenerated into somatic embryos by NAA. LD₅₀ of 0.09, 0.11, 0.13 and 0.09 mg/L colchicine concentration were determined for Ankrah, Dagati, Tomfa and Tuaka respectively in 2, 4-D. Similarly, LD₅₀ of 0.12, 0.10, 0.14 and 0.10 mg/L were respectively obtained in Picloram.

In 2, 4-D, Ankrah and Tuaka were more sensitive to colchicine than Dagati and Tomfa whereas in picloram, Dagati and Tuaka showed more sensitivity. Callus proliferation differed significantly among varieties and influenced by the concentration of colchicine.