Abstract

High density sweet cherry (Prunus avium) orchards using highly productive cultivars and dwarfing rootstocks usually require crop load regulation to achieve high quality fruit. Among the strategies used to reduce crop load in highly productive combinations, fruiting spur thinning (FST, spur extinction) before budbreak has been suggested to be an effective way to improve fruit size. Currently, there is little information about the effect of spur thinning on sweet cherry orchards using self-fertile cultivars grafted on vigorous rootstocks. For this reason, the objective of the present study was to evaluate the effects of manual FST on fruit quality and vegetative growth of the cultivar ́Lapins̀ grafted on the rootstock ́Mazzard F-12/1̀ with 0, 50 and 75% spur removal. Spur removal was carried out 28 days before full bloom (August 23). FST had no beneficial effects on fruit size, total soluble solids or fruit weight. However, there were significant differences in the foliar development of current season growth and fruiting and non- fruiting spurs. Although the leaf area to fruit ratio was high in all treatments, this parameter increased with the removal of 50 and 75% of fruiting spurs. Fruit quality did not increase, suggesting a possible sink limitation of Lapins̀ grafted on ́Mazzard F-12/1̀ or the presence of an alternative vegetative sink that is stronger than the fruit. However, further research is needed to clarify this point.