Breeding of a new grape rootstock variety Yunzhen 5

Grafting is beneficial for enhancing the adaptability of grapevines, improving grape yield and quality. With the continuous expansion of grape cultivation area in China, the demand for resistance rootstocks in the market is increasing. Yunzhen 5 is a late season rootstock variety bred by Chuxiong Academy of Agricultural Sciences, Insititute of Tropical Eco-agricltural Sciences of Yunnan Academy of Agricultural Sciences and so on. Its parents were derived from the cross between Yunpu 2 and Kangzhen 3. The hybrid combinations were selected in 2015, and germination and planting were accelerated in 2016, the seedlings came into flowering and fruiting sucessively from 2018. The clone LV28-3 performed well. In 2019, regional planting began in Yuanmou, Binchuan and Qujing of Yunnan province. In 2023, it was registered as a non major crop variety by the Ministry of Agriculture and Rural Affairs and named Yunzhen 5 with a registration number: GPD putao (2023) 530007. The variety is an interspecific hybrid, with female flowers, light red brown young leaves and tender canes, large mature leaves, heart-shaped mature leaves, trifid leaves, very dense creeping hairs on the back of leaves, low-lying Ushaped petioles, and slightly overlapped unfolding types. Internode length and cane hardness is good. Tendrils are well developed. The inflorescences are cylindrical, without shoulder, and with an averageinflorescence weight of about 60 g and a maximum shoulder weight of about 110 g. The spike shaft is long, with an average inflorescence length of 11.0 cm and an average inflorescence width of 8.1 cm, uniform maturation on same cane, and the berry stalk is difficult to separate. The berry powder is thick. The berry is round, blue black, with a longitudinal diameter of 1.15 cm, a transverse diameter of 1.09 cm, a shape index of 1.05, and an average weight of 0.80 g. There are 3- 4 seeds per berry. Juice yield is 50.8%, soluble solid content is 19.1%, titratable acid content is 1.8%, and soluble sugar content is 9.2%. In the dry and hot area of Yuanmou, Yunnan province, it sprouts in late February, blooms in mid April, the berry turns color in mid June and ripens in early to mid July. The internode is long and the cane hardness is good. Tendrils are well developed. The survival rate of cutting is more than 90%, and the grafting compatibility is well with Shine Muscat and Kyoho. It grows vigorously, is resistant to high temperature, drought, salt, alkali and cold, and has strong disease resistance. It is suitable for planting in Binchuan, Jianshui, Yuanmou and Qilin areas in Yunnan, and has broad growing prospects in North China and Northwest China. It is suitable for single stem hedgerow cultivation, base fertilizer should be applied in the first year, and nitrogen fertilizer and medium and trace elements are the main fertilizer for drip irrigation and topdressing in the early stage of the next year. Short-cane pruning system should be applied in winter and more attention should be paid to pest and disease prevention and control.