Breeding report of a new blueberry cultivar Liaolan 503 with rich aroma

Aroma is one of the core indicators of the fruit quality of blueberry (Vaccinium uliginosum L.). A rich and fragrant aroma is an important factor that attracts consumers to make a purchase, greatly enhancing the eating experience. In the market, blueberry varieties with a pleasant fragrance stand out due to their unique aroma, are more likely to win the favor of consumers, and thus have stronger market competitiveness. The Liaoning Institute of Pomology has been committed to the cultivation of new blueberry varieties. It has successfully developed high-quality blueberry varieties such as Liaolan 513 and Liaolan 515 in the Liaolan series. More than 15 000 hybrid progenies have been rasied for the continuous innovation of new varieties. Aiming at the aroma traits of the fruits, the research team has combined multiple hybrid combinations. Liaolan 503 is an F1 hybrid individual bred with the northern highbush blueberry variety Spartan as the female parent and the southern highbush blueberry germplasm N5 as the male parent. The crossing was carried out in February 2008. 44 hybrid offspring were obtained in 2009. The observations on fruit traits, growth and fruiting habits were conducted from 2011 to 2014. The hybrid offspring coded as 08-48-32 was selected for its thick bloom, rich aroma, excellent taste and high yield. In 2024, the Plant Variety Right was obtained from the National Forestry and Grassland Administration of China and it was named Liaolan503 (Variety Right Number: 20240793). It had an up-right tree posture. The leaves were ovate, dark green, and covered with a silver - gray layer on the surface. One-year-old branches were red in color, with 5 to 8 flower buds on the branch top. The corolla was white, cylindrical, and had ridges, while the calyx was gray to green. The fruit stalk was long, and the fruit cluster was relatively loose. The fruit peel was blue-black with thick bloom, and a small and dry plucking scar, presenting an attractive appearance. The fruits were large, the average size of each fruit was 1.59 cm´2.09 cm, with an average single fruit weight of 3.2 g, and the maximum single fruit weight could reach 4.2 g. The soluble solid content was 14.2%, the total sugar content was 12.5%, the acid content was 0.63%, the Vc content was 11.3 mg · 100 g- 1 , and the anthocyanin content was 91.54 mg · 100 g-1 . The fruits were sweet, with a rich aroma and quality was extremely high. The productivity was high, the maturity was highly consistent. In the open field in Dalian, Liaoning Province, the bud burst began in early March. The full-bloom period was in mid to late April, and the fruit maturity period was from the end of June to early July. In greenhouse, the bud burst occurred in November, the flowering began in early December, and the maturity period was from February to April. This variety had a chilling requirement of 600 hours, and should be suitable for cultivation in greenhouses and plastic tunnel. It should be cultivated in fertile with over 3% organic matter content and 5 to 5.5 pH value. The nursery trees should be propagated by tissue culture and the spacing should be 1.2 m × 2.0 m. The autumn pruning in mid-September was recommended. The double-layer films for cold protection was suggested greenhouse cultivation in the north.