Factors affecting proliferation and elongation of shoots of Phak Liang (Gnetum gnemon Linn.) through tissue culture technique

The tissue culture of Phak Liang (Gnetum gnemon Linn.) was investigated for micropropagation. The types of explant, culture media, types and concentrations of plant growth regulators, orientation of explant and section of explant were tested for their efficacy in inducing and proliferating shoot buds. The elongation of shoots and root induction was also studied. Young leaves gave the highest number of shoot buds when they were cultured in Murashige and Skoog (MS) medium supplemented with 0.25 mg/l IBA and 1.53 mg/l BA. The medium supplemented with 0.25 mg/l thidiazuron (TDZ) alone provided the best result on multiple shoot bud induction both in percentage of explant forming shoots and number of shoot buds per explant. The percentage of explant forming shoot buds and number of shoot buds obtained from leaves were 90% and 26.50 shoot buds, while those from stems were 96.25% and 23.00 shoot buds, respectively. One hundred percent friable callus was induced from stem explant in the same medium supplemented with 1.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) after 2 months of culture. Culturing whole leaf in the position of dorsal contact with medium gave the best multiple shoot bud formation of 92% and 23.00 shoot buds/explant. Cutting stem into half and culturing in horizontal position gave the best multiple shoot bud formation of 96% and 23.00 shoot buds/explant after culture for 2 months. The best elongation of shoot buds (2.54 shoots) derived from cultured leaves was induced in the liquid medium. While stem-derived shoot buds (3.45 shoots) was induced in the solid medium of the same medium components. However, root could not be induced from elongated shoots.