The role of GA, IAA and BAP in the regulation of in vitro shoot growth and microtuberization in potato

The effect of auxin, GA and BAP on potato shoot growth and tuberization was investigated under in vitro condition. The shoot length of potato explants increased with the increasing of concentrations (0.5 - 10 mgdm⁻³) of IAA treatment especially with the addition of GA3 (0.5 mgdm⁻³), but was inhibited by BAP (5 mgdm⁻³). The root number and root fresh weight of potato explants increased with the increasing of IAA levels either in the presence of GA3 (treatment IAA+GA) or not (IAA alone). However, no root was observed in the treatment IAA+BAP, inttead there were brown swolten calli formed around the basal cut surface of the explants. The addition of GA3 remarkably increased the fresh weight and diameter of calli. Micro tubers were formed in the treatments of IAA + BAP and IAA + GA + BAP but not observed in the treatments of IAA alone or IAA + GA. IAA of higher concentrations (2.5 - 10 mgdm⁻³) was helpful to form sessile tubers. With the increastng of IAA levels, the fresh weight and diameter of micro tubers increased progressively. At 10 mg/L IAA, the fresh weight and diameter of microtubers in the treatment of IAA + GA + BAP were 409.6 % and 184.4 % of that in the treatment of IAA + BAP respectively, indicating the interaction effect of GA and IAA in potato microtuberization.