Propagation from axillary buds and anatomical study of adventitious roots of Pinus taeda L

Micropropagation of Pinus taeda by axillary bud proliferation technique and anatomical study of adventitious roots were studied. Apical and basal segments were established in vitro in Murashige and Skoog (MS) culture medium. For multiple shoot induction, the explants were transferred to WV3 medium with or without 6-benzylaminopurine (BAP) (0.12, 0.25 or 0.50 mu M). The effect of the culture medium and combinations of alpha -naphthalene acetic acid (NAA) with BAP on adventitious rooting were evaluated. The basal segments exhibited higher multiplication rates (3.7 shoots per explant) than apical segments during establishment of in vitro culture. The best rooting rate (40%) was achieved by induction of roots in water-agar (WA) culture medium supplemented with 2.69 mu M NAA and 0.44 mu M BAP, for 9 days, followed by transfer into GDm/2 medium. Adventitious roots can be derived from the cambium cells, from adventitious meristem, or from a callus developed at the base of the shoots. When formed indirectly, roots can be derived from peripheral cells of the callus. In treatment resulting in the best rooting rate, 58.3% of the roots were formed directly. The callus formation at stem basis did not prevent rooting and did not impair acclimatization. The plantlets were successfully acclimatized with 90% survival.