Results from testing of yellow-green apple cultivars

The present study was carried out during 2015-2019 at the Institute of Agriculture – Kyustendil, with yellow-green apple cultivars not commonly used in the production. The purpose was to offer the most suitable cultivars for wider use in Bulgaria.The trees were grafted on MM 106 rootstock and planted in spring 2002 at distances of 4.5×2.5 m. Control cultivar was ‘Golden Delicious’. The blooming and ripening time, growth, productivity and chemical characteristics of the fruit were evaluated. First flowering occurred on 15 April (‘Rosana’, ‘Ginger Gold’, ‘Arkcharm’) and the latest on 19 April (‘Golden Delicious’). Fruit of ‘Arkcharm’ and ‘Ginger Gold’ ripened the earliest – between 11 and 23 August, while ‘Charden’ and ‘New Jonagold’ the latest – from 28 September to 4 October. Average yield per tree ranged from 17.0 kg (‘Belgolden’) to 37.6 kg (‘Rosana’), the fruit weight ranged from 128 g (‘Belgolden’) to 253 g (‘Charden’), fruit flesh firmness - from 7.1 kg cm^-2 (‘Arkcharm’) to 11.3 kg cm^-2 (‘Rosana’). The fruits of ‘Golden Delicious’ and ‘New Jonagold’ are characterized with the highest content of soluble solids (18.0 and 16.6%) and total sugars (9.1 and 8.5%). The results showed that the cultivars studied are suitable for the agro-climatic conditions of the Kyustendil region and deserve a wider spread in apple production.