Breeding report of a new fruit mulberry cultivar Chushen 1

Abstract: Chushen 1 is a medium-season ripening and fruit-purposed mulberry variety with excellent appearance. The seedling was derived from a cross between Zhushan3 and Yueyou78 in 1994 at the experimental field. From 1995 to 1999, we investigated the persistent biological characteristics and identified the chromosome ploidy of the hybrid progeny, and selected the superior single plant coded No. 94032. From 2000 to 2010, we investigated its stability, specificity and propagation methods, and in 2011, a comparative nursery was established for systematic observation and identification. In 2016, multi-site regional trials (situated in Wuhan, Shiyan and Xiaogan) were conducted and named Chu Fruit No. 1, and in 2022 it was approved by the Hubei Province Variety Examination and Approval Committee. Chushen 1 tree is more erect with compact crown, moderate tree vigor, long and straight branches and strong rooting ability, and it can be propagated by cuttings. The internode distance is 3.5-5.0 cm, leaf order is 2/5 or 3/8, branch bark is gray purplish red, and lenticel is elliptic, gray white and scattered symmetry. The winter buds are triangular, and red and purple flowers are adnate; the accessory buds are few and remarkable. The leaves are elliptic, 20-25 cm in length and 1.8-22.0 cm in width. They are green, with a short tail-like tip and a serrated edge, a shallow heart-shaped base, and a dense hairy vein with female flowers. The fruit of Chushen 1 is black, oval, moderate sweet and sour flavor, which had a good taste, The average fruit weight was 4.9 g, and the maximum fruit weight was 5.02 g. The content of soluble solid is 10.7%-13.4%, the content of titratable acid is 5.01-11.50 g·kg^-1 , the content of anthocyanin is 1 562.6-1 996.7 mg · kg^-1 , and it has excellent quality. The fruit ripens in late April in Wuhan area (29°58′-31 °22′ N, 113°41′-115°05′ E). The flower bud rate is 93%-97%, the fruit set rate is 91%-98% , the number of fruit per bud is 6-8, and the branch- forming ability is strong. The incidence of freezing blight and sclerotinia sclerotiorum is 2.2% and 1.41%, respectively. It has strong cold resis-tance and resistance to sclerotinia sclerotiorum. The fruit of mulberry belongs to the berry fruit, so thin and juicy skin is not resistant to storage. It is suitable for cultivation in the Yangtze River valley, this variety can bear fruits next year after planted, and in the third year it can enter the full fruit period. Orchard should be chosen on deep soil layer which is of loose texture, high content of organic matter, good drainage, moderate pH value and far away from pollution source. The spacing in the rows and spacing between rows are (1.0-2.0) m × (3.0-3.5) m. It is recommended to adhere to the principle of good spring fertilizer, re- application of summer fertilizer, multi- application of organic fertilizer, open canopy, the trunk height of 50 cm, and the lateral shoot length of 30 cm. Based on agricultural control, other procedures should be conducted, including comprehensive physical, biological and chemical control measures, scientific and rational use of chemical pesticides, and effective control of mulberry sclerotinia sclerotiorum, mulberry gall midge, mulberry longicorn and other diseases and pests.