Factors influencingin vitro micropropagation ofPinus strobus L.

Anin vitro procedure for micropropagation ofPinus strobus L., consisting of the following four steps has been established: shoot induction, shoot growth, root induction, and root growth. Influence of certain selected factors on each of these steps was determined. Shoot induction was found to be influenced by the age of the explant as well as the concentration of 6-benzyladenine in the medium. Best shoot growth was obtained on the medium of Litvayet al. without any growth regulators. Addition of activated charcoal to shoot growth medium resulted in fewer shoots. Root induction on several media was compared. Best root induction occurred when shoots were put on a half strength Gresshoff and Doy’s medium supplemented with 0.5 to 1.0 mg r1⁻¹ α-naphthylacetic acid (NAA) for two weeks. Shorter exposure of shoots to higher concentrations of NAA or indol-3-ylbutyric acid (IBA) was not as effective. Low temperature seemed to be a requirement for root growth.