THE INFLUENCE OF MICROGRAFTING IN-VITRO ON TISSUE-CULTURE BEHAVIOR AND VEGETATIVE PROPAGATION OF OLD EUROPEAN LARCH TREES

The influence of a new micrografting method in vitro was tested by usi ng long shoot meristems of adult 140 year old European larch trees gra fted onto larch seedling rootstocks in sterile peat pellets. Five mont hs after grafting and transfer of grafts to ex vitro conditions, new s hoots from sprouting scions were re-established into tissue culture. T he propagation behavior of shoots derived from these explants was comp ared with shoots established via bud culture from the same donor trees . Shoot explants from micrografts multiplied more rapidly than shoots explants from the original adult donor trees. Rooting experiments with cuttings from six micrografted clones resulted in 49.9 +/- 11.9% root ing. Cuttings from donor trees invariably showed no root formation. Th e results confirm a rejuvenating influence of micrografting in larch.