Peculiarities of growth and development of apple tree varieties depending on the formation of the crown under aid conditions of the northern Pre-Caspian region

In the conditions of the sharply continental climate of the Northern Pre-Caspian region, various methods of forming the crowns of apple trees are being studied to create highly productive intensive plantations in the arid zone. The article presents the results of a study on the influence of various methods of crown formation on the main economic and biological indicators of apple tree varieties in the semi-desert zone of the Northern Pre-Caspian region. The purpose of the research is to determine optimal crown designs that maximally take into account the biological characteristics of varieties in intensive plantings when grown in arid zone conditions. The work was carried out in the Astrakhan region in 2018–2022 at the Pre-Caspian Agrarian Federal Scientific Center on the territory of the experimental fruit garden. The region is characterized as very arid with hot summers and moderately cold winters. The experimental design involved the study of the following options: variety (factor A) - Galakub, Rossoshanskoye Bagryanoye, Talida; crown type (factor B) – sparsely tiered, cup-shaped and modified slender spindle. The trees formed according to the “sparsely-tiered” crown type grew the most powerfully in height (2.9…3.2 m); the restrained growth of trees of the varieties was ensured by the “cup-shaped” and “modified slender spindle” crowns (2.5…2.7 m). The minimum crown projection area relative to the control was recorded in varieties with a “cup-shaped” crown (1.5...2.6 m2); trees with a “sparsely tiered” crown formation had a powerful crown (1.6...4.5 m2). The early fruiting of apple tree varieties was largely influenced by the “cup-shaped” form of pruning. An increase in tree productivity in the fourth year of planting was recorded in varieties with a “cup-shaped” crown – 1,5…2,6 kg/tree while in the control it was 0,9…1,6 kg/tree.