Breeding report of a new self-fruitful pear cultivar 'Ningsumi'(Pyrus pyrifolia)

Abstract: Pear (Pyrus pyrifolia) is a gametophytic self-incompatibility fruit tree. Almost all the pear varieties are self-incompatible. Taking rational cultivation measures such as rightly pollinated by other varieties, or artificial hybridization pollination can guarantee yield and quality. Self-incompatible has caused many difficulties in pear manufacturing management. Therefore, cultivating self-fruitful pear varieties is important in the process of simplified production.'Ningsumi'is a new self-fruitful and earlyripening table sand pear cultivar with excellent appearance. The seeding was derived from the cross between'Akiba'and'Kisui'in 2015 at experimental field of Centre of Pear Engineering Technology Research of Nanjing Agricultural University. Through artificial hybridization pollination, 237 hybrid seedlings were got. It was initially selected in 2009 for its self-fruitful characteristic and very early ripening time. After regional adaptability testing at two sites(including Nanjing and Suzhou in Jiangsu province)over four years from 2010 to 2014, it was finally selected in 2015. This species is a medium-sized tree with a large inverted conical crown, grayish-brown trunk, green-brown annual branches, smooth surface, few lenticel. There are no thorns on the branches. Shoots and young leaves are yellow-green in color. The germinating rate is high, and branching ability is moderate. Leaves are long oval, and sharply serrated. Flower is white. The fruit is oblate with yellow-brown skin color, and has obvious fruit dots.The average fruit weight is 310 g, and maximum fruit weight is up to 390 g. The fruit core is small, and the flesh is pale yellow, crisp, fine-texture, rich juice and sweet. The soluble solids content ranges from11.5% to12.5 %, accompanying with 0.12% titratable acid. The fruit quality is excellent. Flower buds germinate in early and middle March in Nanjing, Jiangsu province. Florescence lasts for 7-10 days from late March to early April. Leaf buds begin to germinate in early April. The period from anthesis to fruit ripening is about 110 d, and it matures in late July in Nanjing, Jiangsu province.It has good disease resistance, stress resistance and environmental adaptability. Suitable cultivation area is the Middle-Lower Yangtze Area. This variety can bear fruits next year after planted, and has high yield potential. The yield is up to 15 000 kg · hm-2in the fourth year after planting. In plain area with fertile soil and good irrigation conditions, spacing in the rows and spacing between rows are generally 4 m × 5 m, but in hilly areas with general soil conditions, spacing in the rows and spacing between rows are 3 m ×(4-4.5) m.When planting with“Y”type tree form, spacing in the rows and spacing between rows are generally(2-2.5) m ×(4-5) m. If planting with slender spindle tree form, the planting density could be(1.5-2.5) m ×(4-4.5) m. Rational flower and fruit thinning should be carried out in the full fruit period. Fruit bagging can result in golden color and better appearance.