Ancymidol and liquid media improve micropropagation of Hemerocallis hybrid cv. ‘Todd Monroe’ on a thin-film “rocker” bioreactor

Abstract

SummaryShoots of the Hemerocallis hybrid cv. ‘Todd Monroe’ were micropropagated on semi-solid agar and in a thin-film “rocker” bioreactor for three repeated cycles of sub-culture, in the presence or absence of the gibberellin-antagonist, ancymidol. Ancymidol increased the numbers of plants multiplied, decreased residual sugar levels in the media, and reduced the size of individual plants. Liquid culture increased the availability of sugar and the biomass of plant tissue. There was an indirect linear relationship between residual sugar levels in the media following culture (°Brix) and plant biomass (g fresh weight). It was likely that 5% (w/v) sugar was inadequate for optimal growth in ancymidol-containing liquid media. Smaller plants, using ancymidol, and larger numbers of plants from larger bioreactor (e.g., “rocker”) vessels were more rapidly cut and transferred in the hood. Larger plants from ancymidol-free media, agar or liquid, were well-conditioned for greenhouse culture. However, the smaller plants from ancymidol-containing cultures on agar were not as fit for greenhouse culture. Liquid media increased the efficiency of micropropagation, but this required a greater quantity of available sugar than with conventional, agar-gelled media.