Breeding report of a new Juglans sigillata cultivar Xuanhong

Xuanhong is a new cultivar of Juglans sigillata. It was selected from a specific individual plant within a seedling cultivation population beside Xiaotong Road, Laibin Street, Xuanwei City, Yunnan Province, and cultivated through asexual reproduction. The specific mother tree was discovered in 2014 for its unique red shoots and leaves. Continuous observation starting from 2015 confirmed its stable expression of red flowers, red fruits, and red kernels. From 2018 to 2021, expanded propagation trials were conducted at multiple sites using grafting techniques, achieving success rates over 80% and 90% respectively. By 2017, after multi-year and multi-location testing, its distinct, stable and excellent traits were confirmed, and the cultivar meets all the standards for a new cultivar. It received national plant variety rights authorization (No. 20230760) in December 2023. This cultivar features an open tree shape, moderate tree vigor, and a spherical crown; its trunk is gray with deep longitudinal cracks. The annual branches are purplish red. It bears odd- pinnate compound leaves with 5- 11 leaflets, and the young leaves are purplish red. It is monoecious and protandrous, with both male and female flowers being red. The fruits are green when unripe and turn red at maturity, featuring irregular white raised spots. They are nearly round and weigh 68.46 g on average. The nuts are nearly spherical and medium-sized, averaging 14.03 g. They have a relatively smooth shell surface, a slightly convex suture, and a shell thickness of 1.16 mm. The kernels are easy to extract whole or in half; the inner seed coat of a fresh kernel is red, and turns purplish red when dried. The kernels are full and plump, with an average single ker- nel weight of 7.03 g, and a kernel percentage of 50.10%. The kernel contains 58.20 g · 100 g-1 crude fat, 15.40 g·100 g-1 crude protein, and has a high anthocyanin content of 1 752.60 μg·g-1 . The taste is excellent. In Xuanwei, this cultivar begins to germinate in mid-March. Male flowers bloom in early April, followed by female flowers 4-7 days later. Fruits mature in mid-to-late October, and leaves fall in late November. It begins to bear fruit in the 2nd year after grafting and starts large-scale fruiting in the 3rd year, exhibiting the characteristics of early fruiting and stable yield. It is cold-resistant, has few diseases and pests, exhibits strong adaptability, and features good grafting compatibility. It is suitable for planting in cold areas at altitudes between 1900 m and 2400 m in Xuanwei City, Yunnan Province, and ecologically similar areas in Southwest China. It grows better under humid and fertile conditions. This variety can bear fruits the next year after planting and has high yield potential. For orchard establishment, slightly acidic to neutral, moist, fertile, well-drained soil is preferred. Dig planting pits sized 100 cm × 100 cm × 60-80 cm in advance and amend the soil with sufficient organic fertilizer. Propagation is done by grafting scions onto Juglans sigillata rootstock. Planting is recommended in late winter, or before the rainy season ends in drier regions. Post- planting management practices include staking, providing sufficient irrigation, applying soil mulch, and carrying out timely shaping and pruning for trees that exceed 1.5 m in height; intercropping is also recommended during the juvenile growth stage. Herbicide application should be kept to a minimum in young plantations.