The Growth Activity and Productivity of Apple Trees Depending on the Form of the Crown and the Time of Pruning

Abstract

Abstract The apple tree is the most common fruit crop in the temperate climate zone. Modern intensive fruit cultivation involves the use of new, highly productive cultivars and cultivation technologies, thanks to the creation of small crown shapes with an increased number of trees per hectare. Reducing planting patterns and creating more dense plantation systems can significantly improve their yields. However, the limiting factor that can reduce tree productivity and deteriorate fruit quality is the degree of crown illumination. Ensuring even access of sunlight to all parts of the crown is the main task in the formation and pruning trees. The study aimed to determine the effect of crown pruning at BBCH 0 (winter) and BBCH 74 (early summer) and various types of crown formation on the growth activity and productivity of ‘Fuji’ and ‘Honeycrisp’ apple trees. A significant decrease (20%) in the number of newly formed shoots in the form of the French axis crown compared to the ballerina and slender spindle crowns was found. However, their length and total growth were significantly higher. The formation of the ballerina crown (with the removal of overgrown wood in the 25 cm zone on the central conductor above the lower tier of semi-cross-branched branches) contributed to a decrease in shoot length and total growth. The introduction of crown pruning in the summer also improved crown illumination – shoot length decreased by 17% and total growth by 12%. Specific productivity per bole cross-section and total shoot length was the highest in ballerina crown trees, followed by trees with a slender spindle crown, and trees pruned in winter and summer.