Abstract
Apple (Malus domestica Borkh.) is the most important fruit in the EU. The total yield is more than 11 million tons.year-1, 15% of which is that of the early apple varieties. Several papers have already been published on the efficacy of crown and fruit thinning in the 20th century. Nowadays, hybrid varieties and intensive crown types are used in modernized systems. Our research was carried out in a Hungarian orchard during two cultivation periods. We studied two early apple varieties (Idaho, Gala Must) to determine how fruit thinning affected the quantity and quality of fruits. We found that the effectiveness of non-thinned technology is similar or slightly better compared to fruit thinning, after the second harvest. The average yield of Idaho apples per tree per harvest was 35.9 vs. 24.8 kg, while that of Gala Must was 50.8 vs. 59.2 kg (with thinning vs. without thinning). To assess quality, we measured water-soluble sugars, NO3-, NO2 and vitamin C content. Immediately, after the harvest, a surprisingly high vitamin C content was found in the fruits (4.4 mg.100 g-1 on average), which, however, decomposed after 3 months of storage. We also determined the pathway of the decomposition of vitamin C.