Light influence on the growth and development of genus Pyracantha Roem. representatives in conditions of Right-Bank of Forest-Steppe of Ukraine

Objective – to identify the optimal growing conditions of genus Pyracantha Roem. representatives, the light intensity influence on the above ground parts growth and anatomical structure of leaves were analysed in the conditions of the Right-Bank of Forest-Steppe of Ukraine. Material and methods. The study was conducted by traditional laboratory and field methods in the conditions of the National Dendrological Park Sofiyivka of the NAS of Ukraine. The intensity of illumination was measured by a luxmeter MS 6610. Have been used method G.H. Molotkovsky, classification of M.A. Baranova and B.R. Vasilyeva, methodical recommendations of А.Т. Grevtsova and N.A. Kazanskaya. Results. The relationship between light intensity and value of the shoots growth, bloom and fruiting was revealed. Morphological and anatomical indicators of leaf assimilation and stomatal apparatus of Pyracantha under the different lighting conditions were investigated. The most sensitive to the intensity of illumination was the spongy parenchyma. In all the samples studied, the thickness of all the components of the sheet increases in the second year. The coefficient of palisade is medium and high, the highest – in P. crenulata (61 %) and P. × ‘Orange Charmer’ (62 %) of the 2nd year of vegetation, the smallest – in P. × ‘Soleil d’Or’ (43 %). The largest number of stomata was recorded per unit surface in P. ‘Orange Charmer’ – 262 pcs. The largest number of stomata was recorded per unit surface in P. × ‘Orange Charmer’ – 262 pcs. on the il luminated site, the smallest – in P. × ‘Soleil d’Or’ – 201 pcs. on the shaded area, which indicates a xeromorphic structure of the leaf. Conclusions. During the years under investigation, we found that species and cultivars reacted equally to lighting. Pyracantha individuals who receive the maximum amount of light grow well, bloom, bear fruit, form the characteristic shape of the crown, thereby preserving the overall ornamentally of the plants. Sufficiently tolerate lateral shading, with complete shading completely lose their decorative properties. When analyzing the biometric indices and anatomical sections of leaf blades, it is established that of the genus Pyracantha representatives are facultative heliophytes. The development of multilayered, dense acacias palisade parenchyma, a large number of small stomata points to the xeromezophytality of the leaf and simultaneously indicates the illuminations of the plants. It is established that the conditions of shading reduce the number of stomata per unit surface, their sizes increase and the stomata index decreases. The stomata index is medium and high, characterizing plants as xeromesophytes. Open areas were found to be optimal for their growth and development.