PLANTLET MULTIPLICATION FROM WHITE-PINE (PINUS-STROBUS L) EMBRYOS INVITRO - BUD INDUCTION AND ROOTING

White pine embryos were grown on 4 different media with 6 different benzyladenine (BA) concentrations. Maximum adventitious shoot initiation and growth were obtained on a modified Lepoivre medium with 20-mu-M BA. Modified Schenk and Hildebrandt, Murashige and Skoog, and Gresshoff and Doy media were also tested. Shoot elongation was achieved on half-strength basal medium lacking growth regulators. Three rooting experiments involving indole-3-butyric acid (IBA), sucrose concentration, shoot orientation, IBA pulse length, and light or dark were carried out. Treatment of shoots in an upright position with 50-mu-M IBA for eight days followed by culture in a medium with 3% sucrose in the light produced the most rooting (50% at 3 months). Rooted shoots were transplanted to the greenhouse for further growth.