Breeding report of a new juice grape cultivar Yuluxiang

Yuluxiang is a mid-early ripening juice grape cultivar with a rich strawberry aroma, selected in 1995 from the hybrid progeny of grape varieties between Zizhenxiang and Ribier. Seeds were sown in the greenhouse of Shenyang Agricultural University in the spring of 1996, and the hybrid seedlings first fruited in 2000. Due to their superior botanical traits and fruit economic characteristics, an elite individual (code 19- 10) was identified as a preliminary superior line in 2007. This line exhibited high juice yield and distinct strawberry aroma, prompting grafting propagation onto Beta rootstocks for regional trials. After multi- year observation of grafted seedlings’growth and fruiting habits, the 19-10 vines demonstrated stable berry economic traits, high yield, and premium quality, leading to final selection in 2019 and official naming as Yuluxiang. This tetraploid cultivar is a perennial vine fruit crop with vigorous growth. Its new canes are semi-erect with semi-open tips, densely covered with appressed tomentum, and exhibit medium anthocyanin color intensity. Young leaves have green adaxial surfaces with medium appressed tomentum between the veins abaxially; the ventral sides at internodes are green, and the flowers are bisexual. Tendrils are 8.0 cm in length on average. Mature leaves are pentagonal and five-lobed, with an average area of 696.0 cm2 , open petiolar sinuses, closed overlapping lobes, deeply incised and open upper sinuses, open lower sinuses, and mixed straight and convex-sided serrations approximately 2.5 cm long. Mature canes are dark brown. Inflorescences are conical, lack shoulders, moderately compact without wings, averaging length of 18.48 cm and width 15.24 cm in area and 563.9 g in weight, with peduncles averaging 7.0 cm. Berries are round, with an average length of 2.5 cm and an average width of 2.5 cm, thick purple-black skins with medium astringency, soft flesh with weak anthocyanin color intensity, and contain 1-2 seeds per berry. The average berry weight is 8.2 g, soluble solids content 19.2%, and titratable acidity 0.53%. Compared to the maternal parent Zizhenxiang, it demonstrates superior juice yield, enhanced strawberry aroma, and premium overall quality. Under open-field cultivation in Shenyang, the budbreak occurs approximately on April 23 and berry ripening begins approximately on September 6. This grape cultivar exhibits strong cold resistance and is suitable for open-field or protected cultivation in northern China. It bears fruit the year after planting, yields an average of 480 kg per mu, and achieves approximately 1765 kg per 666.7 m2 during peak production, representing yield increases of 10.6% and 6.1% over the maternal parent, respectively, with significantly higher yield potential. For cultivation in northern China, vigorous-rooted Beta rootstock seedlings are recommended with spacing configurations of 0.5 m×4.0 m or 1.0 m×4.0 m, and dragon-vine training system should be adopted by retaining one-year-old canes exceeding 1.0 cm in diameter during pruning to facilitate the binding of canes in spring. In cold regions with prolific flower bud differentiation, inflorescence thinning should be performed 10-15 days before flowering to reduce nutrient depletion. Fertilizer and water management prioritizes organic and bio-bacterial fertilizers. Apply 5000 kg per 666.7 m2 of organic fertilizer supplemented with appropriate bio-bacterial fertilizer as basal dressing annually after fruit harvest or before spring budbreak. Conduct timely topdressing during the growing season. Irrigate thoroughly once before budbreak and once 7-10 days before flowering. Irrigate every 10 days during fruit enlargement, apply light irrigation every 10-15 days after veraison, cease irrigation approximately 10 days before harvest, and apply final irrigation before winter protection measures. Pest and disease control follows prevention-first and integrated management principles. After rainy season onset, apply pesticides approved for residue- free fruit production every 10- 15 days while rotating multiple agents. Discontinue applications 7-10 days before harvest to maximize pest and disease control while achieving the goal of pollution-free production.