Особливості розвитку крон дуба звичайного (Quercus robur L.) на клонових насінних плантаціях у Харківській області

The most important factor in the productivity of clonal seed plantations, in addition to the reproductive ability of clones, is the degree of crowns development of grafted trees. By the same fruiting intensity, the number of fruits and seeds obtained from trees with large crowns will be higher. The difference in the crowns projections diameter, respectively, between the rows and in rows was on average 2.1 m. Therefore, when selecting and evaluating the breeding value of plus trees, the indicators of the crown sizes of their clones are important. The results of studies of English oak (Quercus robur L.) clones crowns development from Kharkiv and Sumy regions on three clonal seed orchards (CSO) at the age of 35 and 40 years with the placement of seats 5 × 5 m and 10 х 5 m in the Kharkiv region are presented in the papaer. When studying the development of crowns on English oak CSO for not less than 3 ramets of each clone determined the height of the tree, the diameter of the crown projection and calculated the volume of the productive part of the crown. The calculation of the optimal number of trees on the CSO, which is based on the average diameter of the projection of the crown of grafts on the CSO, is proposed. The low and average individual variability between the clones in height of the trees, the average - in the diameter of the crown projection, high and elevated – in volume of the productive part of the crown. Clones that significantly exceed the averages for CSO at the same time in indexes of height and diameter of the crown projection (Danilovka-3 and Pechenegi-8). The most developed crowns on different CSO have clones Danilovka-3, Kochetok-36, Merchik-4, Pechenegi-8, 18, 20, 24, Sumy-27, Taranovka-18 and Sharovka-6. Correlation analysis did not reveal the relationship between the size of crowns of grafted clones and the intensity of their reproduction. The advantages of tree height at the age of 35 were fixed at 5 × 5 m, while the highest indices of the crown diameters and the volume of the crown productive part were noted on the 40-year CSO with the placement of seats 10 x 5 m. It was revealed that before the closure of the crowns between the rows, there is a more intensive development of the crown in width, and after closure - in height. The clones’ placement of on CSO 5 × 5 m is undesirable, since it inhibits the crowns development in width and causes the loss of half of the productive part of the crowns. When it placing grafts of 10 × 5 m, forming a wide spreading crown, which contributes to more intensive reproduction.  In order to improve the lighting and nutrition conditions of the trees and the productive part of the crown preservation, it is expedient to selective cutting from 15 to 20 years with the removal of trees. The optimal number of trees should be calculated based on the average diameter of the crown projection.  The long-term exploitation of English oak CSO is advisable when carrying out timely thinning and preservation of the maximum size of the productive part of the crown.