Breeding report of a new Bingtang Orange cultivar‘Jinxiu’

Abstract: ‘Jinxiu’is a new sweet orange variety selected from bud mutation of common Bingtang Orange plants in Hongjiang county. It was initially selected in 2007 for its low acid, soft flesh and high juice in Mayang county. To further observe the propagation and characteristics of the cultivar, in 2008,the cultivars were grafted and propagated in their progeny, and using 2-year-old seedlings of Poncirus trifoliata Raf. with similar diameter as rootstock. To evaluate regional adaptability, the new variety was tested respectively at five sites, such as: Pinlin village, Changtanxi village, Tongziliang village, Xiang-yang village and Tongyoupo village, from 2009 to 2015. Through years of investigation on botanical/bi-ological characteristics and fruit quality during the citrus bearing seasons, it was showed that genetic traits of‘Jinxiu’with high grafting had good genetic stability and fruit quality. Finally, in 2015, it was selected as the common Bingtang Orange excellent bud variant variety for promotion and has applied for and obtained the protection of new plant varieties, as well as the registration of non-major crops. The‘Jinxiu’tree growth potential is strong, tree appearance opens, branch density is big. The average spring leaf length, leaf width, and leaf shape index is 69.8 mm, 34 mm and 2.1, respectively; the length and width of autumn tip leaf is 89 mm and 54 mm, the leaf shape index is 1.6. The fruit is flat and round with no mastoid process at the top, then with a smooth orange color peel. The longitudinal diame-ter and transverse diameter of the fruit are 62.99 mm and 72.33 mm respectively. The weight of single fruit is 188g and the thickness of the peel is 5.57 mm. Also, the flesh is orange, the core is full, and the  sacs are neat. According to fruit quality test, it has 0.2 seed per fruit, 76.53 % edible rate, 64.52 % juice yield, 12.0 % TSS, 0.20 % TA, and 58.08 mg·mL^-1 vitamin C. In Mayang county, the fruit ripening peri-od of‘Jinxiu’was about 210 d , and the varieties entered the germination stage in March and the flow-ering stage in April, physiological fruiting was performed twice from May to June, and ripened at the end of November. Its cold resistance, drought resistance and disease resistance are like the common, so the suitable cultivation regions of‘Jinxiu’are the same as‘Bingtang Orange’. It is suitable for cultiva-tion in loam and sandy loam, cohesive soil should be improved to increase the permeability, and should be planted in the sunny place and sparse planting, the fruit quality is reduced when there’s too much shadow. Spacing in the rows and spacing between rows are (3-4) m × 5 m. The fruit setting rate should be checked, the abnormal small fruits, deformed fruits, and thick-skinned fruits should be removed in time to improve the commercial nature of the fruits. Strengthen the comprehensive prevention and con-trol of diseases and insect pests, especially the prevention of citrus canker. Using 362 pairs of SSR prim- ers for PCR amplification, SSR analysis revealed that 2 pairs of SSR primers had significant genetic dif-ference in‘Jinxiu’and common‘Bingtang Orange’.