SELECTION OF THE BEST METHOD FOR VEGETATIVE PROPAGATION OF MATURE ALNUS GLUTINOSA (L.) GAERTN. TREES RESISTANT TO PHYTOPHTHORA ALNI

Although alder is readily propagated by seeds our objective was to examine the feasibility of propagating mature Alnus glutinosa (L.) trees by vegetative means that could be used to propagate trees resistant to Phytophthora alni. Both so wood and hardwood cuttings were taken. In the case of hardwood cuttings, two diff erent treatments, based on diff erences in temperature, two growth stimulators (NAA, IBA) and rooting conditions, were tested. Rooting success rate was low, with only 1.3 to 5 % of treated cuttings rooting, in comparison with 0 to 1.3 % of the untreated control cuttings. In the case of so wood cuttings, two treatments were used which diff ered in their use of growth stimulators (NAA, IBA) and the dates when material was collected. In contrast to the hardwood cuttings, the so wood cuttings rooted better in both treatments. The cuttings collected at the later date rooted better; 30 to 42.5 % of the treated cuttings rooted when compared to 15 % in the control treatment. So wood cuttings collected in the middle of July and then treated with 1% IBA rooted the best of all, with 42.5 % of cuttings rooting successfully.