Breeding report of a new spine grape cultivar Xiangci No. 3

Abstract: The Xiangci No. 3 (Vitis davidii) is a new extremely late-ripening spine grape cultivar selected from Tongmu Town, Zhongfang County, Huaihua City. Different from the wild V. davidii resources which are dioecious, this cultivar has perfect flowers, with high yield, and its fruits can be used as table grape or for wine making. Xiangci No. 3 was initially selected from occasional seedlings in 2012 for its hermaphrodite flower and very late ripening date. The original tree was about 20 years old, and then propagated by grafting or cutting. The field trials were carried out afterwards. It was registered as Xiangci No. 3 by The ministry of Agriculture and Rural Affairs of the P.R.C. in June, 2020. The branches and petioles are covered with prickles, and they are erect or slightly curved at the apex with a length of 2-4 m. The young leaves are bright reddish brown and shiny. Only the veins on the back of the leaves have sparse pubescence, and there are no villi between the veins. The first inflorescence is located at 3- 5 nodes. Each shoot has 1- 2 inflorescences. The mature leaves are cuneateshaped, trifid, the leaf color is green, and the leaf edge is lightly rolled downward, moderately thick. The leaf edge is serrate and projecting laterally. The petiole depressions are mostly open, and Vshaped. The clusters are mostly cylindrical, with a small number of cylindrical-winged, moderate tightness. The peel of fruit is thick and covered with thin powder, and it is easy to separate from the flesh. The flesh is pliable and difficult to separate from the seed. The average cluster weight is 163 g. The average single berry weight is 3.4 g, and the fruit shape index is 1.1 (longitudinal/transverse diameter).There are 2.8 seeds in each fruit on average, and the seeds are dark brown in color, with no transverse groove and obvious seed umbilicus. In winter, the branches are yellowish brown and oval in cross section. The annual branches bear slender prickles of medium density. The juice yield is 68%, the content of soluble solid is 15.2%, and the content of titratable acid is 0.28%. The fruit development period is about 130 days, the bud burst date is from late March to early April, and flowering date is from late April to early May, the berries ripening date is late September. The cultivar has high and stable yield, the average yield of the third year after planting is 11 250-15 000 kg · hectare-1 . The genetic specificity of the cultivar was demonstrated by the detection of nine pairs of simple repeat sequence markers. The cultivar has strong resistance to drought and extreme resistance to high temperature and humid climate. It has strong resistance to anthracnose, powdery mildew, ripe rot and gray mold, but not downy mildew, it is a valuable resource for breeding grape with dampness-heat resistance and disease resistance. This cultivar has strong insect resistance, but does not have resistance to grape phylloxera. It is suitable for planting in spring and autumn in grape producing areas of Hunan, Guizhou, Sichuan, Jiangxi, Fujian, Hubei, Yunnan, Guangdong, Guangxi and Chongqing etc. The cultivar should be cultivated by flat trellis with a planting density of 4 m×5 m, with a single trunk“H”type tree form. It also could be cultivated by“double cross V-frame”method combined with rain shelter with a spacing of 2 m× 3 m.