Origin

Controlled crosses of R. ×pulchrum ‘Baihudie’ (female parent) × Rhododendron ‘Miyo-no-Sakae’ were made in Apr 2014, and seedlings germinated in 2015. They were potted individually in Mar 2016 at Perennial Flower Nursery in Zhejiang University and accessioned as 14-41, indicating they were seedlings resulting from the 41st cross combination in 2014. In Apr 2018, a few hybrid offspring first flowered, including ‘YuRui’. All the seedlings were then transplanted to the commercial nurseries in Haiyan County (Zhejiang Province) in Nov 2018 under partial shade. It was evaluated as 2-19-4, indicating it was planted in field 2, row 19, and plant 4. From 2019 to 2022, we propagated using semihardwood stem cuttings. During this time, commercial nurseries evaluated its propagation and production characteristics, and how well it maintained its ornamental traits. In 2023, we named it ‘YuRui’ for the appearance of pink stamens, and applied for new plant cultivar rights in China (application ID 20230932).

Description

‘YuRui’ is an evergreen shrub that grows in an upright manner. The average stature of ‘YuRui’ stands at 136.83 ± 11.65 cm, which is comparable to the average height of its male parent Rhododendron ‘Miyo-no-Sakae’ at 136.33 ± 11.37 cm, and is notably shorter than its female parent R. ×pulchrum ‘Baihudie’, which reaches up to 163.67 ± 10.01 cm (Table 1). ‘YuRui’ exhibits an annual growth increment of ∼15 to 20 cm. The leaves of ‘YuRui’ exhibit an elliptical shape, characterized by a rounded apex and a cuneate base. They possess a delicate, papery texture and are edged with a continuous, smooth margin. The leaf length ranges from 4.5 to 5.5 cm, and the width varies from 1.6 to 1.9 cm. The color of leaves and flowers was assessed using the Royal Horticultural Society (RHS) color chart (Royal Horticultural Society 2019). Young leaves emerge with a strong yellow-green coloration (RHS 142A), which is initially pubescent but becomes increasingly smooth as the leaf matures. In its fully developed state, the leaf takes on a moderate olive green (RHS 137B). The petioles, measuring 4 to 6 mm in length, are adorned with a covering of coarse hairs.

Table 1. Morphological traits of Rhododendron ×pulchrum ‘Baihudie’, Rhododendron ‘Miyo-no-Sakae’, and Rhododendron ‘YuRui’.

View Fullscreen

The mature flowers of ‘YuRui’ are funnel-shaped, mirroring the floral structure of its parent species, with a diameter of 7.1 to 7.9 cm and a length of 3.6 to 4.3 cm. The corolla lobes of ‘YuRui’ feature undulating margins, a trait it shares with ‘Miyo-no-Sakae’, whereas ‘Baihudie’ exhibits a less pronounced undulation (Fig. 1). Flower buds are characterized by a strong purplish pink color (RHS 73B) (Fig. 1B), which open to reveal a predominantly white interior (RHS NN155C), and is adorned with very light–purple margins (RHS 76B), a combination likely inherited from its parent plants (Fig. 1A). The dorsal lobes of ‘YuRui’ span a width of 2.8 to 3.3 cm, with a white base (RHS NN155C) and very light–purple margins (RHS 76B), highlighted by strong yellowish green spots (RHS N144A). This feature distinguishes it from its parents. In contrast, ‘Baihudie’ has yellowish white dorsal lobes (RHS N155D) with nearly imperceptible spots (Fig. 1C). At the same time, ‘Miyo-no-Sakae’ features white interiors (RHS NN155C) and strong purplish pink margins (RHS 68B) with strong yellowish green spots (RHS N144A) (Fig. 1D). Each flower contains 10 stamens, with anthers that are light orange (RHS 26C) and filaments that are deep purplish pink (RHS N66C). The pistil, also deep purplish pink (RHS N66C), extends beyond the corolla, featuring strong yellowish green stigmas (RHS N144A). The pedicels, which are strong yellow-green (RHS N144C), measure 7 to 9 mm in length (Fig. 1A). ‘YuRui’ flowers typically emerge in pairs or small clusters at the stem tips, blooming from early to mid-April, with individual flowers that last 4 to 5 d, similar to R. ×pulchrum (Wang et al. 2022).

View Figure

• Download as Powerpoint
• Download Figure

Cultivation

The cultivation of ‘YuRui’ takes place in Haiyan County (lat. 30.41°N, long. 120.78°E), located at the southern edge of the northern subtropical zone. This region benefits from abundant sunshine and a plentiful water supply, and is characterized by a mild and consistently humid climate throughout the year. Because of its proximity to Hangzhou Bay, this region avoids extreme heat in the summer and severe cold in the winter.

For optimal cutting propagation, high-humidity conditions (>90%) are preferred, with temperatures maintained between 30 and 35 °C and a soil moisture content ranging from 40% to 60%. Propagation uses semihardened branches from the current year’s growth of the mother plant, which are cut into sections measuring 3 to 5 cm in length, each retaining two to three halved top leaves. The propagation medium is a mix of peat and perlite in a 1:1 ratio, sterilized with a 0.5% solution of potassium permanganate. The cuttings are placed in a 72-hole tray, inserting them to a depth of about one half to two thirds of their length. After watering, the tray is covered with a film to ensure proper ventilation. A 70% to 80% shadecloth is used to protect the plants from direct sunlight. If temperatures exceed 35 °C, area is cooled by spraying it down. After a period of 3 to 4 weeks under the specified propagation conditions, ∼85% of the cuttings are expected to establish roots successfully. After the cuttings have developed 3- to 5-cm roots, they are transplanted into 10- to 12-cm pots. The plant flourishes in soil with a pH of 5.5 to 6.5 that is well drained, loose, and consistently moist. Fertilizer is applied during the spring and autumn growth periods. The plant is pruned after it has finished flowering and before the onset of the rainy season (Kierpiec-Baran et al. 2014; Liu et al. 2024).

Availability

Rhododendron ‘YuRui’ was developed jointly by Zhejiang University and Haiyan Senzhi Biotechnology Co., Ltd. It is available for research or trials. Limited quantities of unrooted cuttings are commercially available for the 2025 crop season. For more information, please contact Hong Zhou (lilyzhou@zju.edu.cn). US plant patent and European Union Community plant variety rights will be sought.