Breeding report on a new fruit mulberry cultivar Sangzi 1

Abstract: The new fruit mulberry cultivar Sangzi 1, which was nationally approved in 2020, was bred by means of ionic beam radiation in 2009 from an introduced variety (SA1). Ten lines were initially se- lected since 2010 based on their good habits in growth, fruit yield, and resistance to cold injury andSclerotinia sclerotiorum. After regional adaptability testing, one excellent strain with more fruits and flower buds and strong stress resistance was finally selected in 2012. A 9-year-old grafted tree of this cultivar attains a height of 1.5 m. The main scaffold limb is short and thick, with numerous layers of thin and short lateral branches. The fruiting branches are strong, the nodes are slightly curved, the inter- nodes are dense, the skin is in gray brown color, and the lenticels are thick and dense. The whole leaves are small with dark green color, oval shape, petioles and stipules. It is resistant to cold injury and Sclero- tinia sclerotiorum. The budbreak of this cultivar begins in early March and the flower is unisexual. The fruits start to mature at the middle or late May with one month suitable for fruit picking. The cultivar has the habit of bearing fruit twice a year and is easy to fall to the ground. Matured fruit is seedless and tastes sour with purple brown color. The fruit length is 2-4 cm in average, fruit weight is 3-5 g, with short fruit stalk. Sangzi 1 has much higher yield in spring than the yield in summer that is about 15% of the spring yield. The total annual yield is about 3000 kg per 666.7 m2. The anthocyanin content is over 0.80 g·100 g-1, much higher than the representative variety Dashi. The juice yield is 74.8%, the soluble solid content is 6.5%, and the total sugar content is 4.0%. The contents of total acid and protein are 8.12% and 2.06%, respectively. It also has high vitamin as well as selenium and molybdenum contents. The fruit is suitable for both fresh eating and processing. The suitable cultivation areas are in Anhui, Henan and Xinjiang. One-year-old seedlings with ground diameter of more than 1cm were used as root- stocks, and full dormant buds were selected as scions for grafting. Orchards should be established on choose neutral soil with loose texture, and deep soil layer with good drainage pipes. Mature and rotten stable manure can be applied as a base fertilizer. The seedlings can be planted with 2 m×3 m spacing be- tween the plants and between the rows from December to the next March. Pruning should be strength- ened at the end of fruiting period in early June. The tree shape should be in a system of“hollow center with three-level structure of trunk, main scaffold limb and fruiting branch”. Increase of the ventilation and light transmission, timely removal of diseased fruit and ground covering can be considered to re- duce the occurrence of soil borne Sclerotinia sclerotiorum.