Use of microtubers for slow-growth in vitro conservation of potato germplasm

Use of microtubers for in vitro conservation of potato germplasm was studied by culturing them on MS medium with 40 gl⁻¹ sucrose and 20 gl⁻¹ mannitol at 6±1°C under a 16-h photoperiod (from cool white fluorescent lamps, approx. 20 μmol m⁻² s⁻¹ light intensity). The results showed that microplants from freshly harvested microtubers could be maintained satisfactorily without sub-culturing for 15 months, whereas those raised from 9-month-old microtubers required sub-culturing after 3 months. Microplants from microtubers produced in the absence of ABA had better condition. Sucrose level in the microtuber induction medium had no effect both on microplant survival and microplant condition. After 18 months of incubation, surviving microplants from freshly harvested microtubers produced new microtubers indicating the possibility of microtuber to microtuber cycle for conservation of potato germplasm.