PROPAGATION OF LILAC BY GREEN CUTTINGS DUE TO THE BIOLOGICAL CHARACTERISTICS OF THE VARIETIES

One of the main sources of the production of root-related lilac planting material is propagation by softwood cuttings. Different breeds and cultivars do not have the same rooting capacity of softwood cuttings. Research on the vegetative propagation of rare lilac cultivars by softwood cuttings was carried out at the Department of Fruit and Vegetable Growing and Ornamental Horticulture of St. Petersburg Agrarian University. The ability to reproduce by softwood cuttings of various lilac cultivars was studied for two years. The variants of the experiment were lilac cultivars. The cuttings were planted in a greenhouse with a fog-forming unit. The cuttings wer harvested during flowering and shoot growth. All the studied cultivars are suitable for reproduction by this method. A comparative assessment of the ability of six lilac cultivars to propagate by softwood cuttings was carried out. It was revealed that the regenerative capacity of the studied cultivars varied from 15 to 50 %. The studied lilac cultivars are divided into two groups according to their ability to reproduce by softwood cuttings. The following cultivars are classified as difficult to take root: ‘Baikal’, ‘Pamyatnik zhertvam fashizma’, ‘Nadezhda Krupskaya’, ‘Cosmos’, ‘Lady Lindsay’ – the rooting ability was 15–35 %. In the second group with an average rooting degree, the cultivar ‘Charles X’ was allocated, the rooting ability was 50 %. The length and number of roots on the cuttings of the studied cultivars by the end of the growing season was not significant, the difference between the cultivars according to these indicators was not found. The influence of methods of preparing softwood cuttings before planting in the ground was studied on the ‘Nadezhda Krupskaya’ cultivar. Treatment of cuttings with a growth stimulant based on indolylbutyric acid (IBA) increased the rooting ability of softwood cuttings of the above-mentioned cultivar by 19 % compared with the control. The best results were obtained when preparing softwood cuttings using IBA in conjunction with additional furrowing of the cuttings base, which allowed for a 35 % increase in the yield of rooted cuttings compared with the IBA use.