Abstract: Kiwifruit belongs to the family Actinidiaceae and the genus Actinidia. It is a perennial deciduous vine fruit crop. Among them, A. chinensis is currently the most widely cultivated species. However, cultivars of A. chinensis primarily harvest at late August to early September (the early-maturing type) or late October to early November (late-maturing type). The concentration of harvest periods and the short product supply window limit the effective development of A. chinensis germplasm resources. Additionally, the inflorescences are mainly panicles, which require manual thinning of flowers and fruits to promote normal fruit development, significantly increasing labor costs. Therefore, medium maturity and single-flower fruiting traits are important breeding objectives for A. chinensis. Our research team conducted a detailed survey and germplasm collection of wild kiwifruit resources in the major mountainous areas of Jiangxi Province. In Yihuang County, Fuzhou City, Jiangxi Province, at an altitude of 548 m, we discovered a single plant with medium maturity and single-flower fruiting, designated ‘YH-2’. After grafting and identification, we systematically observed and evaluated its biological characteristics, key fruit traits, and genetic stability. Results from three consecutive years of trials showed that the ‘YH-2’ exhibited stable medium maturity and single-flower fruiting traits. In Fengxin County (at an altitude of 75 m), the flowering period begins in mid-April, and the physiological maturity of the fruit is reached in late September, with the fruit development period spanning 155-160 days. The fruit is broadly elliptical, with a single-flower fruiting rate exceeding 95%. The fruit has a length of 4.30 cm, a diameter of 4.25 cm, and a fruit shape index of 1.01. The fruit has a slightly blunt, convex beak, and the pedicel length is 4.30 cm. The average fruit weight is 93.60 g, with the largest fruit reaching 127.80 g. The fruit skin is brown, covered with a moderate amount of short yellowish fuzz, while the flesh is yellow-green with distinct pith rays. The fruit is of excellent quality, with soluble solid content (SSC) reaching 19.20%, dry matter (DM) at 18.77%, titratable acid (TA) at 0.98%, and ascorbic acid (AsA) at 1.88 mg/g. The fruit has good storage potential and can be stored at room temperature for 30-45 days. The one-year-old branches are brownish-yellow, with an average internode length of 4.41 cm and a diameter of 0.95 cm. The fruit-bearing shoots are brown, with an average internode length of 2.36 cm and a diameter of 0.81 cm. Both the upper and lower surfaces of the young leaves and petioles are anthocyanin-colored, with pointed leaf tips and a gradually narrowing base. The mature leaves are broadly ovate with flat or slightly concave tips, measuring 9.86 cm in length and 12.19 cm in width, with petioles of 6.11 cm. The flowers are solitary or in cymose inflorescences, with 1-3 flowers per inflorescence. The petals are white, with 5-7 petals per flower. The fruiting rate is high (91.5%), and the plant exhibits strong continuous fruiting ability, with normal vegetative branches becoming fruiting shoots for the following year. The fruit set rate exceeds 95%, and flower and fruit drop are minimal. The first flowers bloom in mid-April, with peak bloom occurring in late April, lasting 5-8 days. The fruit matures in late September, making it a medium-maturing yellow-fleshed kiwifruit. The yield during the full fruit-bearing period is 22.56 t·hm⁻². The breed of A. chinensis is of great significance for adjusting the fruit shelf life and can effectively reduce the labor costs associated with summer pruning.
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