Breeding report of a new super-early maturing apricot cultivar Guojie

Abstract: Guojie, a cutting- edge super- early maturing and hard- flesh apricot cultivar, was selected from a cross between Sungold and Luotuohuang made at the Liaoning Institute of Pomology In 2008. The seeds were mixed with sand and stored in a refrigerator at a temperature range of 2-7 ℃. The seeds germinated in mid of October and the seedlings were raised in the greenhouse during the winter, and the seedlings were planted in the field in May, 2009. In 2013, Guojie was initially selected for its distinct attributes, including its short fruit development cycle and hard flesh. Comprehensive assessments of its botanical, biological characteristics, economic traits, adaptability, and resistance were conducted from 2017 to 2019 at four distinct sites. Following this evaluation, the variety was officially approved and registered by the National Forestry and Grassland Administration in 2021. The Guojie tree exhibited a medium vigor and open canopy structure. Its young branches were smooth, with a reddish-brown color. The leaves were characterized by an elliptical shape with a pointed tip and serrated edges. The petals were pure white. The fruit distribution is uniform and exhibits a regular pattern on the tree. The fruits are bright orange in color. The average fruit size was 53.5 g. The flesh was orange-yellow, featuring a moderate juice content, thin fiber, and outstanding flavor. The stone was free from the flesh, and the kernel tasted slightly bitter. The soluble solid content was 14.2% , titratable acidity 8.2% , soluble sugar 1.1%, and ascorbic acid 6.2 mg · 100 g- 1 . The firmness was 2.1 kg · cm- ². Guojie exhibited strong tolerance to storage and transportation, with a shelf-life of approximately 5 days at room temperature and upto 15 days under 4 ℃. In Xiongyue of Liaoning Province, the flowering started in early April and the blooming period lasted approximately 5 d. The fruit development phase was 55 d. The leaf falls initiated towards the end of October. The variety displayed a remarkable resistance to bacterial perforation and gum flow diseases and tolerance to cold. The variety would be ideally suitable for cultivation in the southern apricot-producing regions of Liaoning Province.