VEGETATIVE PROPAGATION OF 140-YEAR-OLD LARIX-DECIDUA TREES BY DIFFERENT IN-VITRO-TECHNIQUES

Adventitious shoot regeneration, shoot tip tissue culture and microgra fting were used to investigate the vegetative propagation potential of 140-year-old Larix decidua trees. Multiple shoot regeneration from do rmant buds was high when explants were hormone-free precultivated prio r to an auxin/cytokinin treatment; however, elongation of the newly fo rmed shoots was low. Grafts made by micrografting of excised buds onto seedling rootstocks survived up to 29% and resulted in long shoot dev elopment during the following growing seasons. For the first time in m icropropagation of adult larch trees, a sustainable clone could be est ablished by shoot tip tissue culture that shows a juvenile status. Aft er several subcultures the propagation rate via axillary buds was appr oximately exponential and the capacity to form adventitious roots was high. The growth of rooted plantlets acclimatized to greenhouse condit ions is comparable to plants derived from juvenile clones propagated i n vitro.