Porównanie efektywności mechanicznego przerzedzania kwiatów do chemicznego i ręcznego przerzedzania zawiązków owocowych jabłoni odmian ‘Gala Must’ i ‘Red Jonaprince’

Eight-year-old abundantly blooming apple trees ‘Gala Must’ and ‘Red Jonaprince’ grafted on a dwarf rootstock M.9, spaced 3.5 × 1.5 m and 3.5 × 1.8 m, were subjected to bloom and fruit thinning. This included 7 types of treatments: 1. (M) mechanical flower thinning in the full bloom stage with the German produced BAUM appliance; 2. (C) chemical thinning of fruitlets with cytokinins (Globaryll product); 3. (R) hand fruit thinning in June; 4. (M+C) mechanical thinning of flowersin full bloom, followed by chemical thinning of fruitlets in June as in point 3; 5. (M+R) mechanical thinning of flowers in full bloom stage, followed by hand fruit thinning in June; 6. (C+R) chemical thinning of fruitlets, followed by hand fruit thinning in June; 7. (K) control – no thinning. All thinning treatments decreased yield but increased the size of the fruit, the mean fruit weight, and the growth of the shoots. Among the treatments applied to ‘Gala Must’ trees, the best results were obtained with the M and M+R treatments. Most of the fruit had a favorable marketing size, in the range of 7.5–8.5 cm. The M+C and C+R treatments resulted in too many overgrown apples, which are prone to physiological disorders during storage. Among the treatments applied to ‘Red Jonaprince’, the best results were obtained with M and M+R. The other treatments resulted in an excessively large drop in yield and a very high share of overgrown fruit over 9.0 cm in diameter, unacceptable on the market. The thinning treatments increased the solubility of the solids in the fruit of both cultivars with no clear effect on their firmness.