A new cold-resistant plum variety Gongzhu Hong

Abstract:  Gongzhu Hong plum is a new mid early maturing variety bred from Yuejin plum. The seeds of Yuejin plum were collected in 1982 and sown in the spring of 1983. Scions were collected from the seedlings and grafted in 1990. The fruit characters and resistance characters were investigated and eval-uated for several years. One line was found to have the advantages of high fruit quality, semidetached nucleus, high yield and strong stress resistance. It was selected as superior line in 2000. Regional experi-ments were carried out in Changchun, Panshi, and other regions in 2012. Tree shaping and yield experi-ments were carried out in Gongzhuling in 2014. The color of the annual branch is yellowish brown. The average length of annual branch is 135 cm, and the average internode length of annual branch 2.69 cm. The leaf shape is oval, the leaf tip is sharp, and the leaf base is wedge-shaped. Average length of leaf is 11 cm, average width 5.8 cm, and average petiole length is 1.1 cm. The tree is vigorous with semi-open canopy. Gongzhu Hong plum sprouts in early April and blooms from late April to early May in Gong- zhuling area. The fruit ripen in early August in Jilin area and fruit developing period is about 95 days. The variety has strong resistance to cold, to plum red spot disease and bacterial perforation disease, and medium resistance to brown rot. The fruit shape is oblate. The average weight of the fruit is 56.8 g, with a longitudinal diameter of 4.2 cm and transverse diameter of 4.4 cm. Top of the fruit is flat with shallow suture. The background color of the pericarp is yellow green and the cover color is red. The color of the pulp is yellow. The pulp is firm and juicy with little fiber. The stone is semi-detached. The average solu-ble solid content is 16.4% and the soluble sugar of the fruit is 7.93%. The fruit acidity is 0.92%. The content of flavonoids in the fruit is 67.27 mg·100 g^{- 1}; the anthocyanins 14.05 mg·100 g^{- 1} and carot-enoids 39.21 mg· 00 g^{- 1}. The fruit flavor is sweet and sour, and the fresh quality is good. Gongzhu Hong plum can be extended and planted in areas with a frost-free period above130 days and an effec-tive accumulated temperature of ≥10 ℃ above 2800 ℃.