Cultivation of the feeding area of Jonaveld apple trees depending on the method and timing of crown trimming

Goal. To study the influence of different methods and periods of trimming apple tree crowns on their habit for the development of the area of plant nutrition. Methods. Field (data acquisition), statistical, and correlational (data processing and analysis). The experiment was conducted in the garden of the educational and production department of the Uman National University of Horticulture for 3 years (2014–2016) with apple trees of the Jonaveld variety (First Red®), planted according to the scheme of 4x1 m using rootstock M.9 T337. Trimming was carried out in 5 periods: in winter (BBCH 0), in the phase of a pink bud (BBCH 57), flowering (BBCH 65), in the early summer period (when there were 10 leaves per growth) (BBCH 74) and after harvesting (BBCH 93). Crown trimming methods were as follows: manual, contour with the formation of a fruit wall 80 cm wide in the lower and 50 cm in the upper parts and annual shortening of growths on the periphery of the crown from the side of the row, and contour with manual finishing, during which suckers, thickening in the upper part of the crown and hanging branches in the trunk area were trimmed. Results. The studied trees had the largest crown projection area and development of the feeding area under traditional manual trimming. With contour trimming, the value of these indicators decreased by 13%, with contour trimming by hand, by 23% compared to the control. The highest value of the studied indicators was during the winter trimming of apple trees. A clear tendency to decrease the projection area of the crown and development of the feeding area with a postponement of the trimming period was noted. The most compact crowns, corresponding to the smaller crown projection area and the level of development of the feeding area, were obtained by trimming apple trees after harvesting. The specific productivity per unit area of crown projection was greater than contour trimming with manual finishing. The value of the indicator was 13% lower for contour trimming and 30% lower for manual trimming. Conclusions. With contour trimming with manual finishing, the dimensions of the crowns were more compact, which contributed to a decrease in the value of the crown projection area and their development of the feeding area by 13% and 23%, respectively, compared to the control. There was a clear tendency to decrease the size of the projection area of the crown and the development of the feeding area with the postponement of the trimming period.