Improvements in asexual multiplication procedures for jack pine (Pinus banksiana)

Various pre- and post-harvest factors were investigated to refine asexual propagation procedures for jack pine (Pinus banksiana) using proliferated dwarf shoot (PDS) cuttings. The factors investigated included donor plant cultural treatments (growth conditions, fertility, pruning and cold treatments) and application of auxins to cuttings to promote rooting. Production of PDS under greenhouse conditions was enhanced by pruning, fertilizer applications and a cold treatment. Cold storage of donor plants (2-6 weeks at 2 degrees C) prior to cutting harvest, increased rooting frequencies. After a 9-month seedling greenhouse growing phase between 13 and 34 PDS cuttings could be harvested from a donor plant. Three pruning treatments followed by successive harvests of the PDS developing on the most distal 2 cm of the shoots resulted in the highest PDS yields. Optimal rooting was obtained from donor plants grown in a greenhouse environment with relatively low fertilizer applications (150 ppm N; 20-8-20 monthly). Rooting of PDS cuttings ranged from 45-100%. Rooting frequencies were highest with 5.4 mM NAA application. Implications of these results with respect to operational asexual propagation of jack pine are discussed.