Вплив системи догляду за кроною на декоративність і довговічність рослин сортів Syringa vulgaris L.

The plants of Syringa vulgaris L. within the culture are proved to require annual pruning of the crown. It is caused by dichotomous (not real) branching, according to which each annual branch produces two shoots in the spring from the apical pair of buds and a few more from the buds located below the axis of this branch. Therefore, their total number at least triples every year. The root system will not be able to increase its mass and physiological activity in such volumes during this time, which correlatively causes a significant reduction in the size of shoots and inflorescences. If care was irregular or absent, there would be a need for intensive thinning or radical rejuvenation of the crown. These measures are found to able to improve the decorativeness of plants, but they will negatively affect longevity. There are two reasons for this. The first is the appearance of various sections on the trunk or on skeletal branches after removal of the branches on the ring. We have defined that even among these sections, even 1.5-2.0 cm ones will never heal, but in 10-15 years, their wood will turn into dust. The wood of large wounds is destroyed faster, which causes the formation of hollows and the slow death of the whole plant. The second reason for the shortening of longevity is a sudden distortion of the functional correlative root-leaf connection, which is a consequence of a sharp decrease in the rejuvenated plant aboveground part. Firstly, this leads to a rapid attenuation of photosynthesis (the crown is almost absent), and then, consequently, to slowing of root synthesis due to the scant supply of assimilates to the roots. As a result, the mass of the physiologically active part of the root system will be significantly reduced, which will negatively affect the longevity of the plant as a whole. It has also been established that thickened planting of lilacs also forces intensive pruning of the crown. To restore its decorativeness, all oppressed plants should be removed, and the rest should be lowered by one third to bring it closer to the root system, which will provide the plants with physical resistance and activate their root-leaf connection. This measure should be carried out as early as possible in time, because weak plants will begin to suffer from diseases. The branches should be shortened, not cut into a ring, in order not to injure the trunk. It is emphasized that with the optimal location of plants in groups, the need for intensive rejuvenation is eliminated as the annual removal of small, shaded, and low-ornamental branches will suffice. With this approach to the formation and pruning of the crown, lilacs will be decorative and in most cases – durable.