Thinning Methods to Regulate Sweet Cherry Crops—A Review

Abstract

In perennial fruit crops, bearing can be influenced by various factors, including environmental conditions, germplasm, rootstocks, and cultivation methods. Cherries, one of the most important and popular fruit species from the temperate climate zone, achieve high prices on the market. New agricultural technologies and environmental factors force a change in the approach to cherry cultivation. Old-type cherry orchards, with their high demand for water, nutrients, and manual work, are replaced by orchards of self-pollinating cherry cultivars grown on dwarf rootstocks. These changes make it necessary to search for ways to regulate fruiting, in particular to thin buds, flower, and fruit. In light of environmental regulations and consumer pressure, thinning methods are being sought that either do not involve the use of chemicals or that use eco-friendly chemical agents. This review examines recent progress in understanding the effect of thinning methods on the physiology, tree growth, and fruit quality of cherries; discusses horticultural practices aimed to ensure regular cropping and their influence on fruit quality; and provides suggestions for future research.

Fruit Development in Sweet Cherry

“…However, cherry trees often do not drop flowers, and thus require additional resources and mechanical and hormonal thinning to protect the yield and quality. In the past, the requirement for thinning during cherry production was rare; however, due to the introduction of dwarfing rootstock (see Section 7.4), thinning has become necessary to avoid excessive flowering [173]. Thinning can be carried out via large-scale pruning, mechanical hand removal of flowers or chemical thinning.…”

“…Thinning can be carried out via large-scale pruning, mechanical hand removal of flowers or chemical thinning. These different methods have recently been reviewed by Rutkowski and Lysiak [173]. Thinning, however, comes with inherent risks.…”

“…To overcome this, flower thinning (see Section 7.3) is undertaken to prevent over-yielding and to increase the quality of the fruit [176]. For a review, see Ruthowski and Lysiak [173] and Kurlus et al [177]. Different rootstocks also provide advantages in different regions, (i.e., adapted for soil moisture content, soil types and soil temperatures), allowing the selection of rootstocks for the growing conditions.…”

Ranunculus sceleratus as a Model Species to Decrypt the Role of Ethylene in Plant Adaptation to Salinity

“…Ethylene released from CEPA inside the cultivation container was used in the present study, and it seems that at 100 μL L –1 ethylene, side effects of CEPA breakdown products appeared, as petiole elongation was not further stimulated and leaf petiole water content decreased independently on ethylene binding to the receptors, as MCP did not reverse this response ( Figure 6 B). CEPA-containing products have indeed been used in agricultural practice, both as defoliants and desiccants [ 63 , 64 ]. Upon breakdown, CEPA also releases phosphoric acid and Cl – [ 65 ], which could have an additional effect at a high concentration of CEPA.…”

Performance of Sweet Cherry Cultivars and Advanced Selections on Gisela 5 Rootstock in Young Orchards

“…The lowest SSC in our study was found in the year of the most abundant yield. High crop loads may have certain negative effects on fruit SSCs [ 47 ], and reducing the crop load results in an increase in SSC [ 48 ].…”