Wood age, rootstocks and cultivars drive the formation of productivity and fruit size in sweet cherry

To maintain the high yields and fruit quality necessary for profitability of sweet cherry production, it is important to consider precision crop load and canopy management techniques during limb renewal. The effects of branch section age, rootstock, and cultivar on spur and flower density and fruit quality have been discussed in previous studies, but most of them focus on a limited range of fruiting wood ages and scion-rootstock combinations. This study aims to analyse the processes of sweet cherry productivity and fruit size formation on a wide range of wood age to determine the limit after which branch preservation is not sustainable, and to evaluate the influence of rootstocks and cultivars on these parameters. The results indicate that wood age is one of the main drivers of productivity formation in cherry. The highest flower density was observed on 3-year-old branch sections - 324 flowers per linear m, due to high spur density, number of reproductive buds per spur and flowers per bud. Productivity on 2-year-old wood was also good (256 flowers per linear m), while a sharp decline in flower density was noted on 4-and 5-year-old wood. The largest fruits were formed on young branch sections, with a significant decline in fruit weight and diameter on 4-and 5-year-old sections. Rootstock vigour had a bigger effect on floral organ induction on 1-year-old shoots, than on spurs. Based on the results, it is advisable to regularly renew lateral branches older than 3 years to maintain high yield efficiency and fruit quality.