Impact of crown shapes, irrigation and fertilizer methods on the biochemical composition of apple fruit

Abstract

The research was performed in 2021-2022 in an orchard planted in 2015 and located on the laboratory plot of Federal Horticultural Center for Breeding, Agrotechnology and Nursery (Moscow region). Objects of study included Spartan and Common Antonovka apple varieties, on a semi-dwarf clone rootstock 54-118. The research was aimed at studying the impact of crown shapes, irrigation and fertilizer methods on the biochemical composition of apple fruit. The impact of the studied factors on the biochemical composition of apple fruit when grown on sod-podzolic soil was established to depend on the biological characteristics of the variety and to manifest itself in different ways. The Spartan variety, when the spindle-shaped crown was formed, revealed the decrease in the vitamin C content by 7.1-11.2 % compared to the other two forms of crowns. Drip irrigation increased this rate by 9.5 % compared to the control, and the fertilizer methods had no significant differences. The spindle-shaped crown of the Common Antonovka variety, on the contrary, increased the content of ascorbic acid, as did the combination of drip irrigation with N120K150 in the form of solid fertilizers. The studied factors and their interaction had no significant impact on the total amount of sugars and the content of soluble dry substances in the fruits of the Spartan apple variety. The titratable acidity largely depended on the biological characteristics of the variety. The Common Antonovka variety had much higher titratable acidity than the Spartan variety. The highest indicators were specific for the combinations of drip irrigation with N 120K150 in the form of solid fertilizers with a spindle-shaped crown (0.7%) and drip irrigation with N120K150 fertigation with a semi-flat crown and cutting of the central extension shoot in the Common Antonovka variety (1.63%). The sugar-acid ratio was influenced by both the crown shape and drip irrigation in combination with fertilizer methods. The highest values of the sugar-acid ratio in the Spartan variety were revealed during the formation of a column-type crown (20.1), and in the Common Antonovka variety – with a spindle-shaped crown (7.7). The content of nitrates in apple fruit in all variants of the experiment was significantly lower than the MAC.