Breeding report of a new Juglans sigillata cultivar Wanyun

Wanyun walnut is a new late-maturing, high-yielding cultivar selected from a live population of Juglans sigillata Dode. It was initially selected in 2009 for its large fruit size, high yield, late fruit ripening period, special colour of the green skin, branch epidermis, and leaf blades. The Parental trees were grown in Dahuashan Group, Bashi Village, Bashi Town, Yunlong County, Dali Prefecture, Yunnan Province. After 14 years of comparative varietal trials and regional adaptability tests within Dali from 2009 to 2023, the new cultivar was finally selected in 2023. And in January 2025, it passed the registration of new cultivars of horticultural plants in Yunnan. This cultivar was strong and healthy, with purplegrey to dark purple-grey epidermis of branches and trunks, and strong sprouting force. The leaves were pinnately compound, number of leaflets were (7-)9-11(-13), and terminal leaves were not degraded. The leaflets were broadly lanceolate, olive green in colour, leathery, entire, apex blunt. The mixed buds were obtuse-conical, the bud scales did not open; the male buds were naked, cylindrical, scale-like, the male buds twinning rate was about 30%. It was a monoecious, androgynous species. The male inflorescences were catkins with an average of 99.8 florets and yellow anthers. The female flowers were single, two or clustered, with a light yellow-green stigma which was 2-lobed and pinnately reflexed. The green fruit was broadly ellipsoid, with an average petiole length of 40.33 mm, covered with light yellow tomentum, and with an inconspicuous papilla at the apex. There was a longitudinal groove at the correspond-ing part of the nut suture. The nut was square-rounded, the shell surface was deeply incised, the sutures more elevated, the tip bluntly pointed, both shoulders flat. The nut size was large, the mean value of three diameters was 41.82 mm, the average mass of single fruit 22.33 g, the average shell thickness 1.23 mm. inner fold wall was leathery, the whole kernel could be taken, the average kernel yield was 50.63%, the kernel was yellowish-white, full, the average weight of single kernel was 11.69 g, the taste was fragrant and sweet. The protein content was 15.6%, the fat content was 66.6%. It started flowering and fruiting 3 years after top grafting. The average number of fruits per fruiting branch was 1.9-2.2. The bud burst was in mid to late March, the male flowers opened in early to mid-April, the female flowers opened in mid to late April, and the fruits ripened in late September to mid-October in Dali area. It was resistant to barrenness, strong resistance to diseases and insects, and could avoid late frost. It would be suitable for promoting cultivation in the area with an altitude of 1800-2400 m, mean annual temperature of 10-16 ℃, annual rainfall of 800-1200 mm, and active accumulated temperature of ≥ 10 ℃ was greater than 3000 ℃. The planting spacing would be 8 m × 8 m or 7 m × 9 m (10 plants per 666.7 m2 ).