Breeding of a new late-fruiting walnut cultivar Yanxiang

Abstract：Yanxiang is an excellent new late-fruiting walnut variety selected from the seedling population of Shimen walnut. The nut is round with smooth shell surface and shallow grooves. The suture line is slightly raised and tightly combined. The green fruit is oblong and the thickness of green husk is 5.53 mm. The longitudinal diameter, the transverse diameter and the lateral diameter of nuts are 37.09 mm, 35.46 mm, and 34.78 mm, respectively. The average single fruit weight is 11.9 g. The shell thickness is 1.16 mm. The diaphragm and inner fold wall are both leathery. The whole kernel or half kernel can be taken out, and the kernel rate is 52.2%. The kernel is full, light in color, strong in flavor and no astringency. The fat content in kernel is 66.5%; the crude protein content is 21.2%; the total carbohydrate content is 7.2%; the linoleic acid content is 46.82%; and the α-linolenic acid content is 5.4%. The tree of Yanxiang grows vigorously, with branching ability of 6.0 and germination rate of 48.4%. The fruit-bearing branch rate is 55.6%, and the lateral bud fruit-bearing rate is 41.1%. The fruit-bearing branches are mainly medium and short fruit-bearing branches. The number of fruits on single branch is 1 to 3, mainly 2. The male inflorescence is catkin, 8-12 cm long, when anthers mature, the color of which is apricot yellow, the color of pollen is yellow. The female flower is terminal, with 1-3 florets clustering. The stigma is 2-lobed, reversely curled, feathery and light green. In Shijiazhuang area (38°08′48″ N, 114°28′ 57″ E), budbreak Yanxiang occurs in the end of March; the male flower blooms in the middle and late April; the female flower blooms in the late April; the male flower blooms earlier than the female one; the nut matures in the end of August; and leaves fall at the beginning of November. Yanxiang had good resistance to black spot and anthracnose. From 2019 to 2021, the average disease fruit rate in three re-gional test orchards was 2.43%, 2.36% and 2.45%, which indicates a high resistance level. The variety is suitable for cultivation in the shallow hills and piedmont plains of Taihang and Yanshan mountains in Hebei Province. The variety starts to bear fruit in the third year after top grafting, and the yield is good.