Effect of sucrose on adventitious root regeneration in apple

We have examined the effect of sucrose on adventitious root formation in apple microcuttings and in 1-mm stem slices cut from apple microcuttings. The sucrose concentration influenced the number of adventitious roots, but at a broad range of sucrose concentrations (1-9%) the effect was small. In addition, there was an interaction between sucrose and auxin: increasing the sucrose concentration shifted the dose-response curve of auxin to the right. When slices were cultured on medium without sucrose for the initial period (0-48 h), rooting was reduced whereas 48-h culture without application of sucrose had hardly any effect or even a slight promotive effect in a later period (48-120 h). The results show that during adventitious root formation, applied sucrose is used as a source of energy and building blocks but they are also in accordance with a possible regulatory role of sucrose.