Breeding report of a new late ripening kumquat cultivar ‘Guijingan No.2’

Abstract：‘Guijingan No.2’is a new late ripening, high-quality kumquat cultivar. The new kumquat cultivar was selected from seedlings mutation of‘Yangshuo’kumquat. The original plant was discovered inan orchard of‘Yangshuo’kumquat which was planted in 1995 in Dalingtou village, Xingping town,Yangshuo county. It was initially selected in 2005 for its late ripening time, big fruit size, high fruit quality, high and stable yield. After eight years continuous observation on the original tree and performing regional adaptability test, it was finally certificated by Guangxi Province Committee for Crop Variety Valida⁃tion in 2016. This variety has a dwarfing tree. the tree is vigorous with ramose crown and opening tree gesture. The fruit is mainly oval with orange red peel and gloss surface. The skin is smooth, waxy, shiny, norust and small oil spot. The fruit shape is ellipsoid. The fruit weight is 24.31-34.05 g, fruit horizontal di⁃ameter is 33.80-37.11 mm, fruit longitudinal diameter is 39.30-43.58 mm and fruit shape index is 1.11-1.20. The fruit edible rate is 97.81%-99.04%. Vitamin C is 31.97-54.39 mg per 100 mL fruit juice. Ti⁃tratable acid is 0.23-0.49 g. Total sugar is 12.77-15.19 g. The content of total soluble solid is 15.2%-19.9%. The number of seeds is 2.1-5.5, polyembryony, cotyledons are light green. Flavor is relativelyrich, and there is slightly pungent taste, more fruit juice, and fruit slightly slag. The fruit quality is excel⁃lent. The fruit development period is about 180-195 days. And its maturity period is from mid-Decemberto mid-January in Yangshuo county of Guilin, 15 to 20 days later than‘Yangshuo’kumquat. Its fruit setting rate is high with a light physiological drop. The fruit has very long storage-life, on-tree storage life is3 months and shelf life is over 20-40 days. Suitable cultivation region of‘Guijingan No.2’kumquat in⁃cludes the Guilin and Liuzhou where are suitable for the planting of kumquat. This variety can bear fruitsin the third year after planted, has high yield potential. In‘Guijingan No.2’orchard，there is no seriouscanker, anthracnose spreading in leaves, and the Huanglongbing is also not serious because of less newshoots. But they are susceptible to citrus red mite harm, and the black spot disease may be serious whenthe fruits ripening. Orchards should be built on acid soil which has ability of moisture and fertilizer retention. Virus-free seedlings should be selected to plant. The best field planting density is 833 to 1 666 per hm² in planting spacing 2-3 m×3-4 m. Main stem of tree is 0.4-0.5 m high with 2-3 main branches, andthe trees should be trained in natural roundhead shape. Young trees are inclined to sprout axillary flowerbuds. The excess axillary flower buds should be ticked off to avoid looting nutrients. Meanwhile, for adulttrees, strict blossom and fruit thinning should be done. After harvest, a certain amount of organic fertilizershould be given. In the fruit expansion period, the nutrition should be replenished in time, and some atten⁃tion should be paid to prevent fruit cracking. Prevention of disease and insects should be taken seriously.