Breeding report of a new seedless ponkan cultivar Huagan No. 4

Abstract：Huagan No. 4 is a new citrus cultivar selected from a bud sport of Jing’an ponkan (Citrus reticulata Blanco.) It was firstly discovered in Xiangtian township, Jing’an county, Jiangxi province in 1997. Ten grafted trees were planted in the breeding nursery of Huazhong Agricultural University and Dangyang city, Hubei province, respectively in 1999. The trees began to bear fruit in 2002. It was proved to be a true bud mutant by AFLP marker in 2006. Cytological studies in 2013 showed that the key reason for the formation of seedless fruits was embryo abortion. It was registered as non-major crop cultivar in August 2021. The tree of Huagan No. 4 is erect and vigorous. The angle of branches is small. The flower bud differentiation ability is strong, and the fruit setting rate by natural pollination is 5%-8%. The fruit shape is oblate, the fruit shape index is 0.80 and the average fruit weight is 124.81 g, the fruit peel is yellow orange. The total soluble solids of the pulp is 13.2%, the titratable acid 1.17% and vi-tamin C 30.77 mg·100 g^-1 .The fruit is almost seedless, and the average number of seeds per fruit is 0.19. The mature period is in the middle to late December in Wuhan, Hubei province. The cultivar is suitable for planting in the areas with effective annual accumulated temperature (≥10 ℃) in the range of 5500-6500 ℃. The open center tree form is required for high and stable yield.