Breeding report of a new late-ripening white flat peach cultivar Ruipan 28

Ruipan 28 is a newly released white flat peach (Prunus persica var. platycarpa Bailey) cultivar bred by the Institute of Pomology and Forestry, Beijing Academy of Agriculture and Forestry Sciences. The seedling was derived from a cross between Ruiguang 39 and Ruipan 21 in 2006 at the Haidian Ruiwangfen experimental field. Through artificial hybridization pollination, 203 hybrid seeds were obtained. In 2011, it was initially selected for its bright colors and late ripening time. From 2016 to 2018, regional adaptability testing was conducted at three sites over three years. Finally, it was selected in 2018.The tree vigor is medium, with a semi-spreading habit. The flowers of Ruipan 28 are pink, with a rose-shaped flower and five petals. The anther is orange-red and contains a large amount of yellow pollen. The fruits are large, with an average fruit weight of 317.0 g and a maximum fruit weight of 466.0 g. The fruit top is well-closed, with a medium-depth suture line, a shallow stem indentation, and the fruit does not peel after picking. When the fruit is ripe, nearly the entire surface turns red. The fruit surface is covered with fine down. The flesh is melting yet firm. The fruit juice contains 13.2% soluble solids. It is a clingstone variety, and this cultivar has the best quality. Ruipan 28 has a moderate growth vigor. The 6- year-old Y-shaped tree has a height of 4.17 m. Long, medium, and short fruiting branches are all capable of bearing fruit. According to the survey of the number of fruiting branches on the 6-year-old tree, the proportions of long, medium, and short fruiting branches were 41.11%, 30.46%, and 28.42% respectively. Young trees mainly bear fruits on long fruiting branches. There are many flower buds, mainly compound flower buds. It has good yield potential, with a yield of over 30 000 kg·hm-2 during the peak fruiting period. The fruits mature in mid-August in the Beijing area, and the fruit development period is about 128 days. For many years, it has not shown any specific susceptibility to pests or diseases. Both the tree and its flower buds exhibit strong cold resistance. The suitable cultivation area should be Beijing area, which is fertile and high - yielding. It is recommended to use the Y-shaped tree form with a spacing of 2.5-3 m × 5-6 m. Soil management suggests adopting natural grass growth between rows. The main grass species are Lagopsis supina or Bothriospermum chinense Bunge. Organic fertilizer should be applied after autumn, and the bag-controlled slow-release fertilizer hould be applied once before and after peach bud germination in spring. 500 to 700 bales per mu (95 g per bale, 20% nitrogen content, N∶ P2O5 ∶K2O=2∶1∶2). The cultivar has large fruit size and a high fruit setting rate. Fruits should be retained at a spacing of 20-25 cm. Typically, about 3 fruits are left on long fruiting branches, 1-2 on medium fruiting branches, and 1 or none on short fruiting branches. The main fruiting occurs on long fruiting branches, and the tree has strong fertility. The yield per mu should be controlled at around 2000 kg. Ruipan 28 demonstrates strong stress resistance, early fruiting, and high yield potential, along with excellent economic fruit traits, which endows it with promising prospects for promotion and application.