Production of Shoots from Dormant Species of Acer as Influenced by Length and Caliper of Stem Sections

Stem sections removed from selected, dormant species of Acer L. (maples) were forced to produce softwood shoots under greenhouse conditions. Species and clones varied widely in the percentage of stem sections forming shoots, and in the number of shoots that were generated per section. Both length and diameter of sections influenced the number of shoots that were generated. With respect to length, it was best to use stem sections of 30 to 40 cm (11.8 to 15.7 in) since longer sections failed to produce additional shoots and occupied considerably more production space. Effect of increased stem diameter varied across species. For A. rubrum, the number of shoots produced was greatest on ‘large’ diameter (5.2 to 7.6 cm; 2.0 to 3.0 in) stem sections; shoot production was greatest on ‘medium’ diameter (3.3 to 5.1 cm; 1.3 to 2.0 in) stem sections of A. palmatum. Data indicate that an optimum diameter will have to be determined for each species that is propagated when using this method.