Micro-tuber Induction of Elephant Yam (Amorphophallus oncophyllus)

Abstract

Micro-tuber induction of elephant yam (Amorphophallus oncophyllus Prain ex Hook.f.) was carried out for rapid propagation. In vitro shoots with two-to-three leaves were individually cultured for 8 weeks on modified Murashige and Skoog (MS) medium solidified with 5.5 g/l agar and supplemented with 2.69 or 5.37 µM  1-naphthalene acetic acid (NAA) alone or in combination with 2.22 or 4.44 µM N6-benzyladenine (BA). High concentration of NAA at 10.74, 16.11, 21.48, and 26.85 µM in combination with 8.88 µM BA were also tested for micro-tuber induction. It was found that at the low concentrations of NAA and BA, 2.69 µM NAA in combination with 4.44 µM BA provided the highest shoot fresh weight (0.32 g), micro-tuber fresh weight (0.28 g) and micro-tuber diameter (0.85 cm). For high concentrations of NAA and BA, 10.74, 16.11 or 21.48 µM NAA in combination of 8.88 µM BA showed no significant differences in shoot fresh weight and micro-tuber fresh weight but 10.74 µM NAA with 8.88 µM BA gave the highest micro-tuber diameter (0.65 cm). Then, MS medium supplemented with NAA (2.69, 5.37, 10.74, and 21.48 µM) in combination with BA (4.44, 2.22, 8.88, and 8.88 µM), respectively, were chosen to produce micro-tubers under light and dark conditions. Micro-tubers induced under dark condition from many combinations of plant growth regulators obtained more fresh weight and bigger size than those induced under light condition. However, 2.69 µM NAA and 4.44 µM BA under dark condition gave the highest micro-tuber fresh weight (0.45 g) and diameter (0.99 cm). All micro-tubers at the diameter of 0.5 cm or more were grown successfully with 100% survival rates.