RESPONSE OF Pinus leiophylla Schiede ex Schltdl. & Cham. IN THE PHASES OF in vitro ESTABLISHMENT AND MULTIPLICATION

Abstract

Explants of over 28 years old Pinus leiophylla trees from a sexual seed orchard obtained to establish and multiply in vitro. In the establishment phase branch bud and epicormic shoot explants (ES) tested in a MS medium, both from mature sources. In the multiplication phase, three concentrations of a cytokinin-auxin mixture in 10:1 ratio, as well ES explants from mature trees contrasting their response whit same explant type but juvenile sources (2 years old). At 30 days, the 43% in vitro establishment from ES shoots was achieved. In the multiplication phase, both explant sources (juvenile and mature) induced 20% adventitious shoots, however, the best response of explant length growth, number and length variables of adventitious shoots was from explants of juvenile explants whit 1.4 cm, 4 and 4.4 mm, respectively. Media whit PGR induced 15-35% development of adventitious shoots while the medium without PGR did not induce these structures.