Abstract:
The present study was undertaken to evaluate various blends of three alternative gelling agents, viz., guar gum, isubgol or xanthan gum, with agar for their rheological properties and suitability for plant tissue culture as substitute of agar, an expensive component of culture media. In past, many attempts have been made to replace this with cheaper alternatives. Guar gum, isubgol and xanthan gum, three of the suggested alternatives, do not provide culture media capability of forming stable slants. Moreover, such media are difficult to dispense. To overcome these problems, 55 blends of agar and one of the alternative gelling agents, were compared for their capability of forming stable slants and ease of dispensing. Eighteen of these provided culture medium capability of forming stable slants. Among these, only xanthan gum+agar blends possessed ease of dispensing comparable to agar. As guar gum+xanthan gum, isubgol+guar gum and isubgol+xanthan gum blends spurted during autoclaving, only the blends of guar gum, xanthan gum or isubgol with agar, were compared for their rheological properties (viscosity and texture) and their capability of supporting morphogenic response. Although, blending of guar gum, xanthan gum or isubgol with agar increased viscosity and firmness, none had rheological properties equivalent to agar medium. However, in vitro seed germination, shoot differentiation and rooting of Albizzia lebbeck on media gelled with any one of these gelling mixes, except one having isubgol (2.6%)+agar (0.4%), were comparable to or better than the controls. Thus, because of their suitability comparable to agar and a distinct cost advantage, xanthagar [xanthan gum+agar (6:4)] gelling mix is recommended as a possible alternative to agar.
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