Breeding of a new cold-resistant and high quality white pulp loquat cultivar ‘Dongyu'

Abstract:‘Dongyu'is an mid-season loquat cultivar with excellent appearance. The seeding was derived from the seedling population, which locate at Zawan village, Dongshan town, Suzhou city, Jiangsu province. It was initially selected in 2000 for its heavy fruit, good flavor and high cold resistance. It was coded Changlv No. 9(Dongshan No. 3 by Dongshan town) after test at 2008—2010. After regional adaptability testing at four sites(including Wuzhong district, Xiangcheng district of Suzhou city, Shanghai and Zhejiang province) over five years from 2009 to 2014, it was finally selected in 2015. This species is a tall tree, attaining a height of about 6 m; The tree is vigorous with ramose crown and upright tree gesture. The length of the central branch is 10.7 cm,and the diameter is 1.06 cm; the lateral branch length is 29 cm, diameter is 0.88 cm. Young branches are densely pubescent, yellow- green in color. Leaves of summer branch is elliptic, 22.8 cm long, 7.6 cm wide, sharply serrated. The length of the inflorescence with 9.7branches is 11.8 cm, the diameter is 0.93 cm. The colour of flowers is pale yellow, 2.76 cm across, pedicel villous. Fruit is mainly oblate, has orange peel and middle ware surface. Fruit handle end is round, fruit top is flat. Sepals are valgus, calyx pore is open. Its flesh is yellow-white, soft fleshy, rich juice and fine texture. The average fruit mass 41.3 g, maximum fruit mass 61.8 g, fruit shape index 0.88. Each fruit containing seeds 4.7, about 70% episperm is dehiscent. The edible rate is 67.1%, the content of soluble solid is 13.3%. Quality is excellent. The fruit development period is about 150 d and it matures at the end of May in Suzhou area; Every inflorescence has 70-100 single spike flowers. Branching ability is strong. It is resistant to drought, cold, anthrax and spot disease. Loquat fruit is not easy to store, the untreated fruit can be stored at room temperature for 8-12 d( keep the flavor and quality,<5% decay rate), but if refrigeration, temperature control in 4-5 ℃, relative humidity 90%-95%, it can stored more than 1 month. Suitable cultivation area is Taihu Lake and hilly ground in the southern of Jiangsu province. This variety can bear fruits 3 year after planting and it has high yield potential. Orchard should choose the slope below 30 degrees, soil deep, loose soil; Flat garden select sandy soil of high elevation, low ground water. Spacing in the rows and spacing between rows are 4 m×5 m. The best period of colonization was February to March or September to October. The annual number of fertilization is 3-4. Pruning includes pinching, cutting, thinning, bending and back spune, aiming at controlling tree size and maintaining tree vigor; flower thinning and fruit thinning must be introduced.