Breeding report of a new red pomelo cultivar Baoshi Hongyou

Abstract: Baoshi Hongyou, a new pomelo cultivar, originated from a bud mutation of Vietnam Green pomelo (Citrus grandis L.). It has strong tree vigor, dense branches and high fruit setting rate. Green pomelo was originated in Vietnam, Thailand and other Southeast Asian countries. Its fruit quality is good and has a relatively high economic value. The bud of the mutant was selected and then grafted on Sour pomelo rootstocks. The cultivar was registered in 2021 after DUS testing. This cultivar has an upright tree shape and a high branching ability, and shows strong self-incompatibility. The fruits are larger than its parent, pear- shaped with a smooth and yellow green color peel, and the average single fruit weight is about 1447 g. The length of fruit neck is longer than that of Vietnam Green pomelo. It is easier to peel than its parent, and the albedo color is pink. Its shape index is 1.1. The fruit is seedless and the eatable proportion is 59.4%. The peel is yellow-green. The flesh is red, seedless, crisp and tender. The total soluble solid, total sugar and titratable acid contents are 10%-12.5%, 6.3% and 0.44%, respectively, and the ascorbic acid content is 60.7 mg · 100 g-1 . The fruit taste is pure sweet and acid free, and there are no bitterness and numbness. It has high yield, and the tree prefers to high temperature, and it is suitable to be planted in the central and southern regions of Guangxi Zhuang Autonomous Region. The spring shoots start to grow in early February, the flower blooms in early to late February, and the fruit ripens in early October in Longan (107.92 E, 23.09 N) of Guangxi Zhuang Autonomous Region. The flower number of inflorescence is 5-13. The fruit growth period is about 160 days. The cultivar has strong cold, drought and disease resistance. It should be paid special attention to the prevention and control of canker disease and CCDaV (citrus chlorotic dwarf-associated virus) disease during production,and it has high demand for magnesium element. The picking period is short, and the phenomenon of oil cell drying and juice sac granulation will occur if the fruit is kept on the tree for a long time. This cultivar is suitable for planting on the sandy loam with pH value of 5.5-6.5, and the growth and development will be affected if the groundwater level exceeds 1.5 m. Planting density is 3 m × 4 m, and 825 plants are planted per hectare. In the fourth year, it will reach the productive period, and the yield per hectare can reach 45 tons. This variety needs to take girdling measures every year to promote flower bud differentiation, and has a large demand for magnesium. If this cultivar shows symptoms of magnesium deficiency during cultivation, it can be improved by spraying foliar fertilizers containing magnesium or calcium magnesium phosphate. Top-grafting trees should be fertilized according to the frequent thinning method to promote crown expansion. It is better to use container seedlings with developed roots to establish an orchard to achieve early yield and income.