Breeding report of a new low-chilling-requiring peach cultivar Nanguitao No. 1

Abstract：Low temperature is essential for the normal growth and development of deciduous fruit species like peach. To break dormancy and resume growth, adequate accumulation of low temperatures (chilling requirement, CR) is necessary. Chilling requirement is the major factor to determine the bloom date, and plays a key role in the climatic distribution of plants as well as fruit yield and quality. With the development of peach production in the southern China and forcing culture in the northern China, low chilling requirement varieties with high quality are needed urgently. Nanguitao No. 1 is a new low chilling peach cultivar with CRs about 200 h. It was derived from the cross between 97-42-40 as a female parent and Flordaglo as the pollen. The cross was made in spring of 2004, and 79 seedlings were transplanted in the experimental orchard of Jiangsu Academy of Agricultural Sciences with a spacing of four meters between rows and one meter in the rows in late April of 2005. It was initially selected in 2009 for its early blooming, nice fruit shape and good flavor, and then top grafting was applied in Lishui. After regional adaptability testing at three sites (including Nanjing, Guilin and Jingxi) over eight years from 2012 to 2019, it was finally selected in 2019. The tree is vigorous with a semi-open growth habit. Young branches are amaranth in color. The internode length is long with the average of 2.93 cm. The green leaves are long lliptic-lanceolate, 16.93 cm long and 4.50 cm wide. The petiole length is 0.97 cm, with 4-6 reniform glands. The flower is showy with five pink petals. It blooms in late-February to early-March in Nanjing (118°87′ E, 32°03′ N), mid-February in Guilin (109°45′ E, 24°18′ N), and late January in Jinxi (106°42′ E, 23°13′ N). The mature period is in early-mid July in Nanjing, mid-June in Guilin and by the end of May to early June in Jingxi. The fruit shape is oblate with concave top. The white skin is mostly covered by red blush. The flesh is white, hard melting, juicy, sweet with good quality. Haematochrome staining of pit cavities was found near the stone. The average fruit weight is 233 g and the maximum fruit weight is 454 g. The soluble solids content is 12.4% and the titratable acid content is 0.24%. The semi-free stone is small and nearly round. This cultivar is self-fruitful, and the open pollination fruit rate is very high, reaching about 60%. It has good precocity and high yield potential, and fruit thinning is needed about 25 d after full bloom for good quality. It is moderately resistant to peach gummosis, while leaf curl occurrs in warm and damp spring. Long-shoot pruning should be taken to control vigorous growth of young trees. It can be planted in Jiangsu province, Guilin and Jingxi of Guangxi Zhuang Autonomous Region as well as other areas with similar climate and geographical conditions.