Breeding report of a new late-maturing muscat flavor grape cultivar Ruiduwanmi

Ruiduwanmi is a late-ripening table grape variety (Vitis vinifera) characterized by its yellow - green color, excellent quality, and Muscat flavor. In 2010, at the Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, it was bred by crossing Christmas Rose as the mother and Alexander as the father. Regional trials were conducted in Haidian, Pinggu and Daxing under the code name 29-14-4. After years of observation, 29-14-4 matures late with sweet Muscat flavor, has significant market potential, it was authorized with the new plant variety right (CNA20211009717) by the Ministry of Agriculture and Rural Affairs in 2025 and was later named Ruiduwanmi. The tree is moderate vigor, the shoots are semi-erect, the tips are open and the fluff is sparse. The underside of the internode is green, with intermittent tendrils that are long in length. Adult leaves pentagonal, green, main vein anthocyanin coloring on the surface of adult leaves, cross- sectional rolling, seven-lobed, deeply carved upper lobe, closed, unrestricted petiole depression, petiole depression without serration. The Ruiduwanmi cluster has a conical shape with either single or double shoulders, averaging 520.85 g in weight, 27.50 cm in length, and 16.2 cm in width. The cluster density is medium to loose. The berries are yellow green color. The length of peduncle is approximately 5.5 cm. The berry is elliptic shaped, 28.0 mm in length and 21.0 mm in diameter, the average weight is 7.5 g with the maximum of 9 g. Flesh is juicy and crisp, with sweet muscat flavor, each berry contains between 2 to 3 seeds, with soluble solids at 18.5% and titratable acidity at 0.45%. Emerging in late April, blooming in late May, and fruit maturing by late September. The shoots start to ripen in late August. The germination rate is 78.5%, the fruiting branch rate is 75.2%, the fruiting coefficient is 1.60 and the average yield per 666.7 m2 is approximately 1250 kg. There has been no severe frost damage or abnormal germination over the years, and it is resistant to black pox, highly susceptible to downy mildew, and powdery mildew. Cultivating in sheltered conditions during rain in Beijing can decrease fungal diseases, lower and enhance nutrient reserves. During production, it is important to focus on yield management by pesticide usage, leaving 1-2 flower spikes on each branch. It is advisable to plant other grape varieties at intervals along the periphery. Flower spike shaping should be performed before blooming, and the cluster size should be maintained at approximately 500 g. Cultivation without rain protection should prioritize the prevention and control of downy mildew and anthracnose, while rain- protected cultivation must address the threats of leaf hoppers, thrips, scale insects and powdery mildew.