Malus domestica Borkh.

국표에는 이명으로

재배식물

이명

Malus domestica Borkh.

사과나무

2003/11/30

‘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.

Origin

The RubyS cultivar was selected among 320 seedlings that were originated from a cross between Alpsotome and Sansa cultivars. Parental forms were crossed in 2004. The seedling resulting in ‘RubyS’ plants was selected in 2014 and then registered in 2016 in the Republic of Korea. The selections were propagated by grafting on apple rootstock M.9. The selections were evaluated for 5 consecutive years (5 to 9 years of tree age) in Gunwi (36°16′ N, 128°27′ E, elevation 71 m), Republic of Korea. The soil of the experimental orchard at a depth of 0 to 50 cm was a clay loam, slightly acidic (pH 6.5), with low (2.21%) organic matter content. Maximum day air temperature is 36.6 °C in August, and minimum day air temperature is –16.7 °C in January at the experimental orchard.

Trees, flowers, and leaves.

The proposed cultivar RubyS was described per the UPOV standard protocol (UPOV, 1994). ‘RubyS’ tree grows well in fertile, acidic, well-drained sandy soils and loams, which are typical for apple cultivation (Barden and Neilsen, 2003). Grafted on M.9 rootstocks, ‘RubyS’ trees show low vigor and a tree height of ≈2 m . Because the tree shape is a slender spindle, semidwarf rootstocks are recommended, such as M.7 at conventional apple orchards. ‘RubyS’ scions grafted with M.7, MM.106, and MM.111 rootstocks were normally responded without any symptoms of incompatability, such as swelling at the union. First fruiting occurred when trees were in their second year. In the southern region of South Korea, ‘RubyS’ starts flowering ≈1 to 3 d after ‘Alpsotome’, depending on the orchard locations and weather conditions. Full bloom of ‘RubyS’ occurs between 20 and 22 Apr. (data from 3 years) and 10 and 20 Apr. for ‘Alpsotome’ and ‘Sansa’, respectively. A predominant color at balloon stage is light pink; petal diameter pressed into a horizontal position is 38.6 mm in ‘RubyS but 42.7 mm and 51.8 mm in ‘Alpsotome’ and ‘Sansa’, respectively; arrangement of petals is overlapping in ‘RubyS’ but intermediate in ‘Alpsotome’ and ‘Sansa’ apples . The self-incompatible genotype of ‘RubyS’ is S5S9. Therefore, it is possible to use pollen for pollination with ‘Gala’ (S2S5), ‘Golden Delicious’ (S2S3), and ‘Fuji’ . On average, leaf size is 75.7 mm in length and 48.1 mm in width

 Soon-Il Kwon1, Jeong-Hee Kim1, Sun-Ae Kim1, Young-Soon Kwon1, and Jinwook Lee2