‘RubyS’ (Malus domestica Borkh.) apple cultivar was developed from Korean Apple Breeding Program, at Apple Research Institute, National Institute of Horticultural & Herbal Science (NIHHS), Rural Development Administration (RDA), Republic of Korea and then commercially released as a new apple cultivar in 2014. ‘RubyS’ was selected from a hybrid between ‘Alpsotome’ and ‘Sansa’ cultivars. Fruit maturity is reached in the middle of August. Fruit are high quality small dessert apples with excellent storability and marketability. In addition, fruit are very attractive and flavorful. ‘RubyS’ cultivar is higher in fruit weight and yield than ‘Alpsotome’. Fruit shape and overall peel color coverage of ‘RubyS’ are ‘conic’ and ‘red’, respectively. Moreover, there was no preharvest fruit drop in ‘RubyS’ even though fruit drop was high in ‘Alpsotome’, the mother parent. The fruit flesh is cream-colored, aromatic, crispy, and juicy. Flesh firmness of ‘RubyS’ is 78.2 N at harvest, similar to that of ‘Alpsotome’. The soluble solids content is higher in ‘RubyS’, compared with ‘Alpsotome’. Suitable pollinizers for ‘RubyS’ cultivar are ‘Golden Delicious’, ‘Gala’, and ‘Fuji’. The fruit quality, in terms of firmness, juiciness, and flavor, was retained fairly well during long-term cold storage. ‘RubyS’ showed strong resistance to the most serious apple pests and diseases as does ‘Alpsotome’ cultivar and is self-thinning as well. Overall, the results indicated that tree characteristics and fruit quality of ‘RubyS’ apples are highly desirable in terms of fruitlet self-thinning ability, fruit sweetness, storability and low preharvest fruit drop, compared with those of ‘Alpsotome’ cultivar. In summary, ‘RubyS’ is a promising small apple cultivar.
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