Characterization and comparison of agars and other gelling agents for plant tissue culture use

A range of gelling agents, including commercial agars, was characterized with respect to pH and conductivity of rinse water, absorbance, calcium and ash content. The growth response of Seseli gummifera callus, and nodes of Helianthus, Dianthus and Fuchsia, genotypes prone to hyperhydration, was evaluated on media containing the respective gelling agents. The parameters assessed included signs of hyperhydration, microplant height, node number, multi-stemming, dry matter content, root fresh weight and percentage microplant establishment. Duplicated parameters were excluded in the ranking of gelling agents. The physico-chemical ranking of the gelling agents was not related to the biological performance of the gelling agents. While the ranking of gelling agents was related to the respective model genotype, a `tissue culture tested commercial agar performed best overall.