Genus Hemerocallis (daylilies) is composed of 14 species with yellow, orange, and red flower colors (Cui et al., 2019). Daylilies are among the most popular ornamental herbaceous perennials (Griesbach, 2004) and are widely cultivated all over the world because of their attractive appearance, excellent drought tolerance, pest and disease resistance, and survival in a wide range of soils under full sun or slight shade conditions (Blythe et al., 2015; Li et al., 2021; Podwyszyńska et al., 2015). More than 90,000 Hemerocallis cultivars have been registered in the American Daylily Society database. These cultivars have various blooming times (from early May to late October), colors (near-white, yellow, orange, pink, green, purple, and many color blends and multicolored patterns), inflorescence heights (from <30 cm to >120 cm), and flower sizes (from <5 cm to >20 cm) (American Daylily Society, 2021; Keene et al., 2020).
Flower size is an important indicator of the economic and ornamental values of ornamental plants. Large-flowered plants are often more attractive to consumers; therefore, they are sold at higher prices than small-flowered plants. To encourage the breeding and release of large-flowered cultivars, the American Daylily Society established the Extra Large Diameter Award in 2005 to recognize outstanding and charming cultivars with flowers larger than 7 inches (≈17.78 cm) in diameter. So far, the winners have included ‘Megatron’, ‘Linda Bell’, ‘Jordan’, and ‘Jazz’ (American Daylily Society, 2021).
Although China is the distribution center of Hemerocallis and has cultivated daylilies for more than 2000 years (Li et al., 2021), the breeding and release of elite daylily cultivars have progressively slowed (Jiao et al., 2016; Zhao et al., 2017). Instead, various cultivars with high ornamental values have been introduced into China, even though most of these cultivars do not grow well in China (Jiao et al., 2016; Zhao et al., 2017). Daylily cultivars with larger flowers that are suitable for local cultivation in China are much needed.
After years of selection, we bred a new cultivar named Xuan Cai Jin Huang, which has flowers larger than 18 cm in diameter and flower scapes of 101 cm in height. Its sepals and petals are golden yellow (RHS 14A). It is very suitable for growing in northern China or other areas with similar climatic conditions.
Origin
New cultivar Xuan Cai Jin Huang is a progeny of an open-pollinated population of the Hemeroallis cultivar Da Jin Bei. Dan Jin Bei has small golden flowers and was introduced from Jilin Province. It was planted in the cold perennial flower germplasm resource nursery (lat. 45.85°N, long. 126.46°E) in the modern agriculture demonstration area of the Harbin Academy of Agricultural Sciences in 2013. In 2014, open-pollinated seeds were collected from cultivar Da Jin Bei and sown in the same nursery. In 2016, one of the plants was found to be taller and stronger than the other progenies and its parent. It was 101 cm in height with large flowers 18 cm in diameter. It also had excellent cold tolerance in Harbin, China. From 2016 to 2017, the plant was propagated by ramets in the same nursery. Field trials were conducted in Harbin (lat. 45.85°N, long. 126.46°E), Wuchang (lat. 45.11°N, long. 127.17°E), Mudanjiang (lat. 44.59°N, long. 129.61°E), Yichun (lat. 46.99°N, long. 128.04°E), and other places in Heilongjiang Province in 2018 and 2019. The plant characteristics were stable and consistent in these locations. In 2019, the new cultivar was named Xuan Cai Jin Huang and registered with the American Daylily Society. In 2019–21, the second field trials to collect more data were conducted in Harbin.
Description
The female parent of ‘Da Jin Bei’ was selected as the control to evaluate the morphological characteristics of ‘Xuan Cai Jin Huang’ because it most closely resembles the new cultivar. From 2019 to 2021, 60 plants of each of ‘Xuan Cai Jin Huang’ and ‘Da Jin Bei’ were planted in the experimental field comprising ≈60 m2 in the cold perennial flower germplasm resource nursery of the Harbin Academy of Agricultural Sciences for phenotypic analysis and data collection. The experimental field was arranged in a randomized complete block design with three replications, with each containing 20 plants of each cultivar. Thirty plants of each cultivar (10 plants × 3 replications) were randomly selected to measure plant height, leaf length, leaf width, scape height, scape thickness, bud count, flower diameter, sepal length, sepal width, petal length, and petal width (Table 1). The data analysis was conducted using SPSS 22.0 software, and the significant difference was determined by performing independent sample t tests. All colors were recorded according to the Royal Horticultural Society (RHS) Color Chart.
Comparisons of plant characteristics of ‘Xuan Cai Jin Huang’ and ‘Da Jin Bei’ were collected from 30 plants (10 plants × 3 replications) planted in an area comprising ≈60 m2 in Harbin, China, from 2019 to 2021.
‘Xuan Cai Jin Huang’ flowers from July to August in Harbin, China. Each flower has three petals and three sepals, which aggregate into a trumpet shape (Fig. 1A). Its plant height and leaf length are significantly greater than those of ‘Da Jin Bei’. The most striking features of the new cultivar Xuan Cai Jin Huang are the large flower and tall scape. Flowers are 18.22 ± 0.11 cm in diameter and scapes are 101.92 ± 0.63 cm in height, which are significantly greater than those of ‘Da Jin Bei’ (13.35 ± 0.13 and 74.67 cm, respectively) (Table 1; Fig. 1B and C). The length and width of its sepals and petals are also significantly longer than those of ‘Da Jin Bei’ (Table 1). Its sepals and petals are golden yellow (RHS 14A), whereas those of ‘Da Jin Bei’ are orange-yellow (RHS N25D; Fig. 1). Additionally, the color of the ribs on the petals of ‘Xuan Cai Jin Huang’ (RHS 14D) is lighter than that of the parent (RHS 13B; Fig. 1).
The flower anatomic structure (A) and single flower (B, C) of ‘Xuan Cai Jin Huang’ and ‘Da Jin Bei’. ‘Xuan Cai Jin Huang’ has larger flowers and a different flower color. Bar = 10 cm.
Citation: HortScience 57, 4; 10.21273/HORTSCI16379-21
In summary, ‘Xuan Cai Jin Huang’ is a unique cultivar with a tall and strong scape, extra-large flowers, and bright color. These characteristics make it an attractive cultivar and a valuable resource for further breeding of large-flowered daylilies.
Cultivation Techniques
‘Xuan Cai Jin Huang’ has strong cold tolerance and is suitable for planting in northern China and other areas with similar climatic conditions because it survives in cold winters in Harbin, Wuchang, Mudanjiang, and the southern part of Yichun, which correspond to hardiness zones 3 and 4 (mean annual minimum temperature ranges are −40.0 to −34.5 °C and −34.4 to −28.9 °C) in China (Widrlechner, 1997). It is easily propagated via ramets in spring or fall. It can bloom in fall if the ramets are reproduced in spring. Each plant can produce from 3 to 10 shoots per year and should be divided every 2 to 3 years to adjust the growth density. It grows well in moist soil that is rich in humus and has good drainage. No apparent disease infestations or pest infestations have occurred with ‘Xuan Cai Jin Huang’.
Availability
Plant materials of ‘Xuan Cai Jin Huang’ are available from Zhiyang Liu (E-mail: 113559183@qq.com) at the Harbin Academy of Agricultural Science.
Literature Cited
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