Breeding report of a new sour jujube cultivar Zaohong No. 1

Zaohong No. 1, a new sour jujube cultivar, was bred from a wild jujube population located in Neiqiu County, Xingtai City. This variety was selected through a comprehensive evaluation of traits such as high yield, superior quality, and stress resistance. Based on the selection criteria of strong stress resistance, high quality, and high yield performance of jujube fruit, the primary selection, re- selection and final selection processes were conducted through thorough information gathering and reporting to the masses. In October 2013, the primary- selection superior plants of the most prominent excellent types were identified. Between 2020 and 2022, adaptability tests for these varieties were conducted over three consecutive years at three locations: Xianxian County, Qingxian County, and the West Garden of Yunhe District in Cangzhou City, Hebei Province. The findings from these tests were ultimately submitted for examination in 2023. The average height of wild jujube trees is 1.58 m, with a crown width of 1.6 m × 2.3 m. The trunk is erect, and the secondary branch, which bears fruit, is curved and extended in a zigzag pattern. The bark is purple-brown, and the needles are elongated and well-developed, averaging 21.3 mm in length. The leaves are lanceolate with sharp and serrated margins. The fruit is oblate, small, and smooth, featuring a concave top and a light red peel, and the average fruit weight is 1.28 g, while the maximum weight of a single fruit could reach up to 3.20 g. Its flesh is a combination of green and white, characterized by a lower juice content, a loose texture, and a sour-sweet flavor. The edible rate of Zaohong No. 1 is 68.33% . The fruit stone is large and oblate, with a shell content of 92.40% and a kernel rate of 9.72%. The levels of the main effective components in Semen Ziziphi Spinosae were notably high, with total saponins measuring at 0.087% and spinosin at 0.097%. The fruit growth period for this variety lasts 95 days, culminating in maturation in late September in Cangzhou City, Hebei Province (longitude 116.83° E, and latitude 38.33° N). The flower buds exhibit an oblate pentagonal shape. This variety is resistant to jujube fruit-cracking (JFC) and jujube rust. The average incidence of JFC was 2.75%, and the disease index of jujube rust is 4.04. This variety is suitable for pharmaceutical use. Zaohong No. 1 is well-suited for cultivation in the Hebei plain jujube area, as well as in other regions conducive to jujube growth. It blooms and produces fruit in the same year, demonstrating high productivity. The average yield per 666.7 m2 is 978.56 kg, which represents a 14.33% increase compared to the control variety Yinji No. 5 jujube. The orchard can be established by directly planting resistant seedlings and employing high grafting and head- replacement techniques. The primary tree shapes include an open center system and a small canopy sparse layer system. Before winter, it is advisable to apply base fertilizer and irrigate before soil freezes. Water-soluble nitrogen and potassium fertilizers should be applied at the fruit setting and fruit expansion stages. It is important to promptly remove wintering disease residues and to effectively prevent and control pests such as green bugs, red spiders, jujube gall midges, and jujube turtle wax scales.