Potential substitutes for agar in tissue culture media

Three different plant sources viz., isabgol, arrowroot and sago were evaluated to explore the possibility of using them as gelling agents instead of agar to reduce the cost of tissue culture media. The shoot explants of in vitro grown plantlets of gerbera were cultured on Murashige and Skoog s media supplemented with 3 per cent sucrose, 2.5 mg l⁻¹ BAP and 0.1 mg l⁻¹ NAA. The medium was solidified with sago (50-80 g l⁻¹), isabgol (30-50 g l⁻¹) and arrowroot (80−120 g l⁻¹) at different concentrations and compared with agar (8 g l⁻¹). As the concentration of gelling agents increased the shoot proliferation decreased due to increased gel consistency. The highest number of multiple shoots was produced in media gelled with sago at 50 g l⁻¹ along with agar (1.0 g l⁻¹). Vigorous shoots in terms of length, girth and weight were observed in medium gelled with arrowroot at 120 g l⁻¹, while the number of shoots produced per explant was less in this medium. The number of shoots produced per explant and vigour of the shoots were poor in isabgol gelled media at all concentrations used. More number of vigorous shoots were produced in sago (50 g l⁻¹) gelled medium in combination with agar (1.0 g l⁻¹). The media gelled with sago produced more number of shoots than agar (8.0 g l⁻¹), but quality wise agar and sago were almost equal. The cost of the plantlets was reduced by 4-5 times in sago gelled media when compared with agar (8.0 g⁻¹). Considering all aspects of multiple shoot production, quality of shoots and cost, sago at 50 g l⁻¹ + 1.0 g l⁻¹ agar was found to be a suitable replacement for agar.