Breeding report of a new Chinese jujube cultivar Jindong 2

New cultivar Jindong 2 is a late-season, table jujube with an attractive appearance. This cultivar was discovered as a superior bud mutation in a jujube orchard located in the Dagang production area of Tianjin's Binhai New Area in 2012. The mutant shoot exhibited distinct characteristics compared to conventional winter jujube. Following leaf abscission in winter, the mutant scion was collected, stored in moisture- retaining sand, and grafted onto mature winter jujube trees during the subsequent spring sprouting period to evaluate growth and fruiting behaviors. Subsequent large-scale grafting trials and systematic observations were conducted across multiple regions, including Jinghai and Xiqing in Tianjin, as well as Huanghua City in Hebei Province. Long-term assessment confirmed the superior cultivar qualities and stable genetic performance of the mutant line. The tree is of medium size with an upright growth habit. The current-year shoots exhibit a grayish-red coloration. Leaves are oblong, measuring 4.7-6.2 cm in length and 2.4-3.9 cm in width, with sharply serrated margins. Flower buds are obtuse- pentagonal in shape, accompanied by a small disc. The flowers have an average diameter of 5.2 mm and produce yellow pollen. The fruit is oblate in shape with thin, reddish-brown skin and a smooth surface. The flesh is pale yellow, fine-textured, and rich in a honey-like aroma, offering a pleasant flavor. The average fruit weight is 21.42 g, with a maximum fruit weight of 30.32 g. The fruit shape index is 0.9. The jujube pit is elliptical and weighs 0.95 g. At the white-ripe stage, the fresh jujube is edible with a soluble solids content of 30.36%. At the full-ripe stage, the fruit becomes intensely sweet, with the soluble solids content reaching up to 36.4%. The titratable acid content is 0.20%, the firmness is 4.98 kg · cm- 2 , the edible rate is 95.5%, and the vitamin C content is 551 mg · 100 g- 1 . The fruit shows high quality. The fruit growth period is 115 days, with maturity reached in early October in the Tianjin region. Each jujube shoot bears 3 to 10 inflorescences, with 3 to 10 flowers per cluster. The flower buds are oblate pentagonal in shape. The tree exhibits a high bud germination rate but low branching ability. This variety exhibits well stress resistance, showing minimal frost damage even under extreme low winter temperatures. It has moderate resistance to pests and diseases. It is well- suited for cultivation in southern Tianjin and the Bohai Bay Rim region. In the second year after top grafting, the yield per plant can reach 12.5 kg, demonstrating excellent high-yield potential. Jindong 2 is suitable for establishing orchards in fertile sandy loam soil, with a recommended plant spacing of 1 m × 3-4 m, pruning practices include pinching, bending, and back pruning to control tree size and maintain vigor.