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Influence of several methods of flower and fruitlet thinning on the yield and quality of Gala Must apples

DOI: https://doi.org/10.24326/asphc.2025.5489
Submitted: January 21, 2025
Published: 11.06.2025

Abstract

Apple trees of the Gala Must, grafted onto the dwarfing M.9 rootstock, planted in 2014 at a spacing of 3.5×1.8 m, were subjected to flower and fruitlet thinning in 2022–2024. Seven thinning combinations were used: 1 – (M) Mechanical thinning of flowers at the stage when the petals had emerged in 2 or 3 flowers in the inflorescence, using the German BAUM device; 2 – (C) Chemical thinning of fruitlets with Globaryll 100 SL containing cytokinin; 3 – (H) Hand thinning of fruitlets after June drop; 4 – (M+C) Mechanical thinning of flowers with the BAUM device supplemented by chemical thinning of fruitlets as in pt. 2; 5 – (M+H) Mechanical thinning of flowers with the BAUM device supplemented by hand thinning of fruitlets after June drop; 6 – (C+H) Chemical thinning of fruitlets with Globaryll 100 SL supplemented by hand thinning after June drop; 7 – (Control) Trees in which neither flowers nor fruitlets were thinned out.
In most treatments, the thinning of flowers or fruitlets caused a significant decrease in fruit yield but improved fruit quality, compared with the control. The thinning treatments increased the weight and size of apples, as well as their soluble solids content. Most apples were of a favourable marketable size in the range of 7.0–7.5 cm. The combined thinning treatments (M+H, M+C, C+H) resulted in the production of too many overgrown apples, which are known to be more susceptible to bitter pit, which in turn may reduce their storage life. Most of the thinning treatments resulted in a higher soluble solids content in the fruit without a significant effect on their firmness.

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