Breeding report of a new blueberry cultivar Baozhu

Abstract: Baozhu is a new variety of blueberry, which was bred from the natural hybrid seedlings of Legacy. 234 seedlings were obtained in autumn 2011 and planted in spring 2012, and the fruit ripened in early July 2015, from which the superior offspring was selected and numbered SMN-478. After tasting by testing, the characteristic of the strain was proven excellent, such as bigger fruit size and weight, flat round in shape, medium-blue in fruit color, rich fruit powder and uniform texture, sweet flesh, thick skin, good flavor and light fragrance, hardness, high yield, and suitability for fresh market. From July 2017 to July 2018, the characteristics of fine lines and their asexual progenies were evaluated. The results showed that the plant morphology, flowering and fruiting characteristics, fruit yield and quality were consistent, and the specific traits were quite stable. On May 13, 2022, it obtained the new variety certificate issued by the State Forestry and Grassland Administration, which was formally named Baozhu. This variety belongs to the Northern High bush Blueberry, with erect tree canopy, strong tree vigor, flower bud and corolla in red color, short cluster, altar-shaped corolla with corolla ridge, early germination of leaf bud, ellipti leaves with an average leaf area of 9.46 cm2 , leaf shape index of 1.7, and green color. The average length of new bearing branches is 16.67 cm, and the number of fruits per branch is 13.The cluster is dense, the fruit shape is oblate, sepals are flat, fruit powder is medium and uniform, fruit color is medium blue (102-C), and the scar was small and wet. The fruit has good firmness (3 kg· cm^-2 ) with average fruit size of 1.55 cm × 1.74 cm, maximum fruit weight of 2.48 g and the average fruit weight of 1.76 g. The soluble solids content of the flesh is about 10.17% and the acidity is moderate. Under the natural conditions, the initial maturity is about early July. It is suitable for growing in the north of the Yangtze River or higher altitude areas. The variety requires loose, deep and fertile soil, good drainage, wet but not waterlogged. Loam or sandy loam soil is appropriate with the soil of pH 4.0-5.5 and organic matter content above 15.0% is better. The chilling requirement of the planting area should be over 600 h. The planting land must be ploughed and leveled, and the ploughing depth is about 20-30 cm. 2-year-old or 3-year-old potted or bare-root seedlings above 40 cm in height and 0.4 cm in diameter at the base of the main stem should be selected to establish the orchard. This variety has good resistance to Botrytis cinerea and can be cultivated in southern, rainy and semi-arid areas. It is suitable for growing in north of the Yangtze River or higher altitude areas, where there are loose, deep, and fertile soil, good drainage, moist but not waterlogged land. The soil texture is preferably loamy or sandy loam. In order to manage soil, fertilizer and water well, thoroughly decomposed organic manure should be applied before planting seedlings.