Breeding report of a new small-fruit-type purple kernel variety of Juglans sigillata‘Yunxiang 1’

Yunxiang 1 is a new small-fruit-type purple kernel walnut variety selected from seedling resources of Juglans sigillata in Ludian County, Yunnan Province. The nut is spherical and uniform, and the shape is beautiful; the average diameter of the nuts is 2.84 cm. The shell features shallow grooves, the shell thickness is 0.87 mm, and the nut weight is 7.32 g. The kernel weighs 4.93 g, exhibits a light purple color, and is plump with an intact extraction rate. The kernel rate is 67.35%. The kernel has a delicate texture and rich aroma without astringency. The walnut kernel has an oil content of 65.1%, and a protein content of 18.5%. The tree vigor is strong, the tree posture is semi-open, and it is naturally open. The 1-year-old dormant branches are purple-brown, with prominent lenticels and sparse density. Mixed bud is triangle with no stalk. There are 9-13 small leaves, and the top leaves are mostly degenerated and spindle-lanceolate. It germinates in early March in Ludian, the male flower disperses in late March, the female flower blooms in early and middle April, the female flower stigma is light red, the flowering habit is protandry, the fruit matures in mid-September, and the leaves fall in late November. The green fruit (husk) is spherical, the fruit surface is covered with yellow fluff, the fruit point is obvious, and the fruit top is not prominent. The clone of this variety blossoms and bears fruit in the second year after the top-working of 4-5 years old tree (3-4 years earlier than that of Yangbi Pao walnut), which has obvious early-fruiting trait. The fruiting branches of the mother tree account for 50.3%, and the fruit branch rate is 70.2%. There are three or four more fruits, with an average of 2.6 fruits per fruiting branch. The average crown projection area produces 0.36 kg·m-2 of dried nut. This variety has the characteristics of early fruiting, high yield, round nut shape, uniform and beautiful, full and plump kernel, easiness to take out the whole kernel, light purple kernel, high kernel rate, excellent taste and so on. At the same time, it has good cold, disease and insect resistance. It is a rare new variety of small-fruit-type walnut, which can be applied to the development and utilization of walnut food for kernel, tourism and leisure snacks. It has significant potential in improving quality and efficiency and optimizing variety structure in walnut planting base in Yunnan. The popularization and application of this variety is expected to effectively improve the yield and quality of walnut fruit, enhance market competitiveness, and improve the comprehensive benefits of the industry. It is suitable for Ludian County at an altitude of 1600-2100 m, with an average annual temperature of 12-16 ℃ and an annual rainfall of 800-1100 mm, ≥10 ℃ active accumulated temperature ≥3500 ℃ area and the surrounding similar conditions of planting.