Parameters of apple tree crowns depending on the crown shape and pruning time

Abstract

The apple tree is a leading fruit crop in Ukraine in terms of production volumes and planting areas and is a valuable food product with a high content of vitamins. In new modern plantings, fruit producers prefer intensive cultivation technologies that ensure the maximum amount of high-quality fruit yield per unit area. The main criterion for solving this problem is the design of plantings: a narrow-row scheme for planting trees and a low-volume crown shape. The purpose of the study was to establish the influence of the pruning period of different types of crown formations on the growth and productivity of apple trees of two varieties: Fuji and Honey Crisp. The study was conducted in the conditions of the central Forest-Steppe of Ukraine (Uman National University of Horticulture). The scheme of planting was 4x1 m, M.9 rootstock, chernozem sod-podzolic soil, drip irrigation. Field, statistical, and computational-analytical methods were used in the course of the study. It was identified that the growth pattern of the examined varieties differed substantially, and crown volume, projection area, and development of the feeding area prevailed in Honey Crisp trees. However, in terms of productivity, the plantings of the Fuji variety substantially exceeded the values of the Honey Crisp variety. Forming a ballerina crown with the removal of overgrown wood in a 25 cm zone on the central trunk above the lower tier of semi-cellular branches provided an increase in the growth activity of the examined trees by 3-5%. A substantial decrease in the values of crown parameters was provided by the formation of the French axis crown – there was a decrease in the crown diameter by 44%, the crown volume – by 67%, and the crown projection area and the development of the feeding area – by 69%. Performing additional summer pruning of trees also helped to reduce growth activity by 6-11%. However, the specific productivity of plantings doubled in plantings with the formation of the French axis and by 45-50% with the introduction of double pruning of trees. It is recommended that agricultural producers investigate the terms of pruning low-volume crown forms, considering varietal characteristics, to create compacted apple stands and increase the intensification of production