Breeding of a new high-quality pomelo cultivar Shuimiyou

Abstract：A new pomelo cultivar Shuimiyou originated from an individual seedling, which was found at Taoyuan County of Hunan province. It was initially selected in 2008 for its high-quality, low-acid, soft-flesh and high juice content. To further observe the propagation and characteristics of the cultivar, it was grafted and propagated in 2009. Through many years of investigation on botanical/biological characteristics and fruit quality during the citrus bearing seasons, this new cultivar showed excellent genetic stability and high fruit quality. After test of the distinctness, uniformity and stability, the new pomelo cultivar Shuimiyou was finally selected in 2018. It was registered by Changde Institute of Agriculture and Forestry and Changde Guofeng Agricultural Development Co., Ltd [GPD Citrus (2018) 430020]. The average fruit weight is 977 g. The longitudinal diameter and transverse diameter of the fruit are 14 mm and 17 mm, respectively. The shape of fruit is oblate or spherical, and the average fruit shape index is 0.81. The peel is yellow-green in color with a smooth surface. The thickness of pericarp is about 1.3 cm and the edible rate is up to 65% of the whole fruit. The juice extraction rate is as high as 79 percent. The soluble solid content (SSC) is 11.2%. The total sugar content is 3.24 g per 100 g juice. The titratable acid content is 0.08%. The ascorbic acid content is 28.2 mg per 100 g of fruit juice. The fruit of this cultivar can be stored for almost 6 months at room temperature in Changde city of Hunan province, and the annual supply can be basically realized under cold storage condition. Spring-growing shoots of Shuimiyou are sensitive to low temperature, resulting in curly leaves. There are hairs on immature fruit surface of Shuimiyou. The phenological period of Shuimiyou is slightly later than the ordinary pomelo varieties. The period of sprouting of spring bud is in March, flowering period is in mid-lateApril to early-mid May, and the full blossom period is in early May. The first physiological fruit drop period is in early-mid May, the second physiological fruit drop is in early-mid June, and the fruit ripening period is from late November to early December in Changde city of Hunan province. The tree has intermediate vigor and the main fruit-bearing shoots are sprouting in spring. The average yield with 6-10 years old trees reaches up to 2508 kg per 666.7 m² . After years of observation, it was found that the cold tolerance of Shuimiyou was poor. During the whole development stage, the lowest temperature cannot be less than -5 °C, and the lowest temperature at seedling stage cannot be less than -3 °C. In winter, chill-proof measures should be taken in northern area of Hunan. The tree vigor of Shuimiyou is moderate and it will become weak after fruiting. The cultivation should focus on promoting root growth and strengthening fertilizer and water management to ensure the balance between vegetative and reproductive growth.