Dimensions of crowns and their level of productivity of apple trees of the Jonaweld variety depending on the method and term of crown pruning

Abstract

In this experiment, different methods and terms of crown pruning of Jonaveld apple trees and their influence on the change in crown habitus were investigated. The experiments were conducted at the educational and production department of the Uman National University of Horticulture in the city of Uman, Cherkasy region, for three years from 2014 to 2016. The studied trees were grown on the rootstock M.9 T337 and were formed with a spindle-shaped crown. They were planted according to the 4x1 m scheme in 1995. The experimental plot is represented by podzolized black soil. The research scheme included the study of the effect of three pruning methods: the traditional method of manual pruning, the contour method of forming a fruit wall of the crown 80 cm wide in the lower part and 50 cm wide in the upper part from the row spacing with annual contour pruning of growths on the periphery of the crown and the contour method with manual modification, which consisted in removing fattening shoots, too thick branches and hanging branches in the stem zone. Crown pruning was performed at five different times: in winter (during winter dormancy), during the pink bud phase, during flowering, in early summer (with 10 leaves on the growth), and after harvest. In the orchard plantations with the formation of trees by the type of slender spindle by hand, a more spreading crown was formed, which significantly exceeded the other variants of the study in terms of its diameter. A significant impact on the change in the values of the indicator was caused by the factor "method of pruning" ‒ with the predominance of manual pruning. Also, the influence of postponing the term of pruning to a later date, regardless of the method of pruning the crown, on reducing the value of their diameter was revealed. As a result of contour pruning, in particular contour pruning with manual refinement, a decrease in crown volume was observed. The introduction of contour pruning with manual refinement contributed to the formation of 25 % less crown volume. Regardless of the method of tree pruning, a clear tendency to reduce crown volume with the delay of pruning was revealed. The level of specific productivity per crown volume as a result of manual pruning of the studied trees was 14 % lower than the contour pruning method and 30% lower than the contour pruning method with manual refinement. The gradual increase in the level of specific productivity per crown volume was facilitated by the delay in the cutting period.