Conservation of medicinal yam in vitro: Effect of ionic strength, sucrose, mannitol, ABA and low temperature

The effects of ionic strength, sucrose, ABA, mannitol and low temperature was investigated on the development of slow growth cultures for in vitro conservation of medicinal yam germplasm. Though higher concentration of mannitol (5%), lower concentration of ionic strength (1/4 MS+ 0.5% sucrose) and sucrose (0.5% and 1%) induced significantly high growth reduction in the plantlets, however, these treatments except sucrose not only negatively affected survival of the cultures but also abnormal leaf morphology and multiple shoot formation was observed with increase in concentration of mannitol. Sucrose (0.5% and 1%) not only induced slow growth but also reduced the shoot production and showed no effect on survival of cultures even maintained up to 180 days without subculturing. Storage of culture in normal MS media at low temperature (18±1°C) maintained upto 150 days not only reduced the growth parameters but also induced development of both basal and aerial microtubers. Use of low temperature could be the best option for monocrop repositories of yam in vitro. However, reduced dose of sucrose can be a suitable and economically sustainable method for in vitro conservation of D. floribunda at 25±2°C.