Cultivar and rootstock effect on sweet cherry fruit density and fruit drop

Abstract The yield formation of sweet cherries occurs in a relatively short time and has been influenced by various factors. Shortly after blooming, the incompletely fructified fruits drop off the trees. Later, the second fruit drop is mostly is related to resource availability and sink-source relations in the trees. The aim of the study was to evaluate the initial fruit density, fruit drop and final fruit density for eleven sweet cherry cultivars and the impact of rootstocks, year-to-year differences and growing systems. Fruit density on a sample branches was detected in 2022 – 2024 after the initial fruit drop and the second fruit drop. Generally, the number of fruits reduced by 24 – 86% during their development and it was affected by growing season, cultivar and rootstock. The lowest level of fruit drop was shown by the cultivars ‘Paula’ in growing system with VOEN cover and drip irrigation. Fruit drop was significantly less for the trees grown on the rootstock ‘Latvijas Zemais’ ( Prunus cerasus L. ) comparing to the trees on the rootstocks P7 and Mahaleb cherry ( Prunus mahaleb L.).