Ornamental crabapples are a general term for a group of plants in the genus Malus (Rosaceae) with small fruit sizes (usually fruit diameter ≤ 5 cm), and mostly small trees (Zhou et al. 2018). Since the Han Dynasty, ornamental crabapples have been cultivated and used in landscape and gardens in China. They were widely eulogized by literatus and were once referred to as “the fairy of flowers” (Zhou et al. 2018). Chinese ornamental crabapples were introduced to North America in the second half of the 18th century and then to Europe in the 19th century (Wang 2014). During more than 200 years, a large number of excellent new cultivars of ornamental crabapples have been cultivated through complicated hybridization and selection work (Zhou et al. 2018). Ornamental crabapples breeding in China started relatively late, and the main ornamental crabapple cultivars were introduced from North America and Europe, but with the rapid development of ornamental horticulture cultivation research in China in recent years more and more new cultivars of excellent ornamental crabapples are being introduced to the market, including ‘Yangzhi Yu’ (Jiang et al. 2020), ‘Er Qiao’ (Yang et al. 2022), ‘Yi Honglian’ (Zeng et al. 2022), and ‘Fenghong Nichang’ (Fan et al. 2019). Although there is no shortage of semiheavy petal types, double flowers are still extremely uncommon. It is of great significance to vigorously cultivate new crabapple species with a high degree of double petals, novel flower shape, and good stability and ornamental properties. The elite cultivars also enrich the diversity of crabapples and make up better flowering plant combinations in garden designs.
Yun Xiangrong [Note: from 《Qingping Tune》made by Li Bai, a poet of the Tang Dynasty, mostly describing the richness of posture, rich and luxurious] (Ke 2017) is a new cultivar selected and released by Nanjing Forestry University. It is an excellent light-colored double-flowered crabapple cultivar with large flower buds (1.5–1.9 cm in diameter larger than ‘Van Eseltine’ 1.2–1.4 cm in diameter).
Origin
In Fall 2011, ≈1500 seeds of ‘Donald Wyman’ were collected from Jiangsu, Henan, Shandong, and Beijing, China. We processed the seeds before sowing according to the third (Soaking) and fourth sections (Seed germination) in the second section (Preparation before sowing) of the sixth chapter in Forest Breeding Technology (p. 73–77) (Sun 2013). We sowed these emerged seeds on raised beds in the field (width, 1.5 m; length, 50 m; depth 8.0–10.0 cm) in Spring 2012 at the National Crabapple Germplasm Genetic Center (Yangzhou, Jiangsu, China) and watered every 3 d. After germination, seedlings were transplanted into the field with a 10.0 cm × 10.0 cm spacing.
From 1317 seedlings, an individual plant with huge buds, which opened with double, light-pink flowers, was observed in 2014 and selected for further evaluation. From 2015 to 2017, the plant consistently exhibited 14 to 22 petals per flower and large flower buds. We named this individual plant ‘Yun Xiangrong’. From 2014 to 2018, we budded it into the popular rootstock Malus hupehensis seedlings, on a yearly basis. A total of 50 seedlings were grafted and survived in 4 years, and all showed the same flowering characteristics, demonstrating the phenotypic stability of ‘Yun Xiangrong’. It is worth noting that all the bud-grafted seedlings grew vigorously and exhibited good adaptation to high temperatures of 37 to 40 °C in Jiangsu.
Description
The distinguishing characteristics of ‘Yun Xiangrong’ are large flower buds and light-pink flowers with double petals (Fig. 1-1). Among existing double-flowered crabapple germplasms, ‘Yun Xiangrong’ most resembles ‘Van Eseltine’. The fruit of ‘Van Eseltine’ is globose with the predominant fruit color of orange, and the fruit of ‘Yun Xiangrong’ is flat obloid with the predominant fruit color of yellow. In addition, the petal marginal zone of the inner side of the two cultivars is light pink (‘Van Eseltine’) and white (‘Yun Xiangrong’, Table 1).
Characteristics of flowers, fruit, and foliage of Malus ‘Yun Xiangrong’ crabapple. (1) Full-bloom branches. (2) The blooming stage of inflorescence in Malus ‘Yun Xiangrong’: (A) small bud stage; (B) large bud stage; (C) initial blossoming stage; (D) full blossoming stage; and (E) final flowering stage. (3) Annual branches and leaves. (4) Mature fruit: (F) side view of a fruit sequence; (G) view of a fruit sequence; (H) bottom view of the fruit; and (I) cross-sectional view of fruits.
Citation: HortScience 58, 5; 10.21273/HORTSCI17080-23
Characteristics of flowers, fruit, and foliage of Malus ‘Yun Xiangrong’ crabapple. (1) Full-bloom branches. (2) The blooming stage of inflorescence in Malus ‘Yun Xiangrong’: (A) small bud stage; (B) large bud stage; (C) initial blossoming stage; (D) full blossoming stage; and (E) final flowering stage. (3) Annual branches and leaves. (4) Mature fruit: (F) side view of a fruit sequence; (G) view of a fruit sequence; (H) bottom view of the fruit; and (I) cross-sectional view of fruits.
Citation: HortScience 58, 5; 10.21273/HORTSCI17080-23
Characteristics of flowers, fruit, and foliage of Malus ‘Yun Xiangrong’ crabapple. (1) Full-bloom branches. (2) The blooming stage of inflorescence in Malus ‘Yun Xiangrong’: (A) small bud stage; (B) large bud stage; (C) initial blossoming stage; (D) full blossoming stage; and (E) final flowering stage. (3) Annual branches and leaves. (4) Mature fruit: (F) side view of a fruit sequence; (G) view of a fruit sequence; (H) bottom view of the fruit; and (I) cross-sectional view of fruits.
Citation: HortScience 58, 5; 10.21273/HORTSCI17080-23
Phenotypic attributes of ‘Van Eseltine’ and ‘Yun Xiangrong’.
Habit.
This cultivar has red brown branches and an upright crown, reaching 3.5 m in height and 1.58 m in width in 7 years.
Foliage.
The leaves are leathery and elliptic, 7.6 to 8.8 cm in length and 3.8 to 4.1 cm in width; with crenate margins, petioles measure 1.5 to 2.5 cm, if the margins are crenate, they are not lobed (Fig. 1-3). The leaf blades have a medium green color with medium glossiness on the upper side at maturation.
Flower.
The flowering time (10% open flowers) of ‘Yun Xiangrong’ is early spring (≈29 Mar in Jiangsu, China). It has an umbellate inflorescence, plump buds (Fig. 1-2B), and large flowers in diameter of 4.5 to 5.5 cm. Each flower has 15 to 25 petals with a shallow cup shape, usually five pistils and numerous stamens (≈55). Petals are elliptic, overlapping, and have prominent veins. Flower buds are medium pink (RHS-RED-PURPLE 58B) (Royal Horticultural Society 2007). At anthesis, the marginal area of the inner side of the petal is white (RHS-WHITE NN155C), the middle zone of the inner side is white (RHS-WHITE NN155C), the basal zone of the inner side of the petal is white (RHS-WHITE NN155D), and the color of the outer side is light pink (RHS-RED-PURPLE 70D) (Fig. 1-2). Sepals are sparsely tomentose, nonrevolute, and reddish green.
Fruit.
The fruit is yellow (RHS-GREYED-YELLOW 160D), flat obloid, and relatively small in size (1.7–2.2 cm in diameter, considering fruit as a sphere) (Fig. 1-4). The fruiting calyx is deciduous and the fruit pedicel is brownish yellow, 3.5 to 4.5 cm long.
Cultivation and Pest Management
‘Yun Xiangrong’ prefers full sun, flat land, and a good depth of loose, rich, sandy soil with good drainage, but can also grow and blossom normally in ordinary soil environment. It is suitable for planting between the Yellow River and the Yangtze River Basins, China (USDA Hardiness Zones 5–9) (Agricultural Research Service, US Department of Agriculture 2012).
‘Yun Xiangrong’ is regenerated mainly by bud grafting during the fall season (August to September in Jiangsu, China) using T-Budding and Malus hupehensis crabapple seedlings as rootstocks (0.5 cm whip diameter at ground level). Scion buds should be greater than 0.5 cm in diameter from current year. Buds need to be wrapped in plastic film to prevent water loss. If the grafting buds are light green after 7 d, the grafting should be successful. Usually, the plastic cover should be removed in Mar of the following year if the buds are healthy. Attention should be directed to removing undesirable rootstock sprouts constantly.
In the spring, ‘Yun Xiangrong’ may be affected by aphid-transmitted diseases that damage its leaf extension. To control aphids, the surface of the leaves can be sprayed with mixed pesticides that consist of 70% imidacloprid (water-dispersible granules) (Aimeile, Hangzhou, Zhejiang, China) at 2000× dilution and 5% cyhalothrin (water emulsion) (Leduoxi, Kaifeng, Henan, China) at 1000× dilution. Trunk borers have not been observed.
Availability
‘Yun Xiangrong’ can be purchased through Nanjing Forestry University and Yangzhou Crabapple Horticulture Limited Company (Contact person: Wangxiang Zhang; E-mail: malus2011@163.com).
Literature Cited
Agricultural Research Service, US Department of Agriculture 2012 USDA plant hardiness zone map Agricultural Research Service, US Department of Agriculture USA
Fan JJ, Zhang WX, Zhang DL, Zhou T, Jiang H, Wang GB & Cao FL. 2019 ‘Fenghong Nichang’ flowering crabapple HortScience. 54 7 1260 1262 https://doi.org/10.21273/HORTSCI13897-19
Fiala JL. 1994 Flowering crabapples: The genus Malus Timber Press Portland, OR, USA
Jiang H, Zhou T, Fan JJ, Zhang DL, Zhang L, Sun YY & Zhang WX. 2020 ‘Yangzhi Yu’: A double-flowered ornamental crabapple HortScience. 55 4 589 590 https://doi.org/10.21273/HORTSCI14677-19
Ke LG. 2017 A study of music morphology in Qingping Tune Explor. Music. 01 51 58 https://doi.org/10.15929/j.cnki.1004-2172.2017.01.009
Royal Horticultural Society 2007 RHS colour chart 5th ed. Royal Horticultural Society London, UK
Sun SX. 2013 Forest seedling technology Jindun Publishing Company Beijing, China
Wang DM. 2014 Construction concept and layout of Taizhou urban forest Linye Gongcheng Xuebao. 28 04 136 140 https://doi.org/10.13360/j.issn.1000-8101.2014.04.036
Yang LM, Peng Y, Yang F, Zhang DL & Zhang WX. 2022 ‘Er Qiao’ flowering crabapple HortScience. 57 5 613 614 https://doi.org/10.21273/HORTSCI16494-22
Zeng J, Zhou T, Zhang DL & Zhang WX. 2022 ‘Yi Honglian’ flowering crabapple HortScience. 57 3 374 375 https://doi.org/10.21273/HORTSCI16386-21
Zhou T, Sheng XC, Zhou DJ, Fan JJ, Zhao MM, Zhang WX & Cao FL. 2018 Advances in the classification of crabapple cultivars Yuan Yi Xue Bao. 45 02 380 396 https://doi.org/10.16420/j.issn.0513-353x.2017-0140
