Influence of carbon source on shoot multiplication and adventitious bud regeneration in in vitro beech cultures

Experiments were performed to determine the effects of carbon source and concentration on shoot multiplication in shoot cultures of Fagus sylvatica (one clone) and F. orientalis (two clones) and on the induction of adventitious shoot buds from leaf and internode explants of F. orientalis. In general, glucose was the best carbon source for both axillary branching and adventitious shoot regeneration. Shoot-tip explants grown on 3-4% glucose medium produced more shoots than those on sucrose or fructose. For maximum shoot length, glucose medium was best for two of the three clones, and 4% sucrose for the other. The number of shoots was the parameter most influenced by glucose concentration in the adventitious shoot regeneration experiments, the number increasing with sugar concentration. The lowest hyperhydricity rate occurred in the presence of sucrose in both species. Shoot growth and quality was negatively affected by fructose supplied media. The use of filter-sterilized rather than autoclaved fructose neither stimulated shoot growth nor reduced the incidence of hyperhydricity in all three clones. The response of shoot cultures to different carbohydrate treatments appears to some extent to be genotype dependent.