Introduction to New Jujube Cultivars Cangwu 1 and Cangwu 3

Seedling selection was carried out on jujube tree resources in Cangzhou City, Hebei Province. After 7 years of breeding, Cangwu 1 and Cangwu 3 were selected from seedless small jujube cultivars, and in February 2001 they were recognized as superior cultivars by the Hebei Provincial Forest Tree Cultivar Approval Committee.

The fruit of Cangwu 1 is oblong, with a longitudinal diameter of 2.12-3.26 cm and a transverse diameter of 1.53-2.22 cm, with an average single fruit weight of 4.51 g, and the fruit size is uniform. The fresh jujube is bright red and glossy. The skin is thin, the flesh is yellow-white, dense in texture, and extremely sweet in taste, with excellent fresh-eating quality. The soluble solids content of the fresh jujube is 36.3%, the edible rate is 100%, and the drying rate is 61.5%, making it suitable for fresh eating and drying. The fruit of Cangwu 3 is cylindrical, with a longitudinal diameter of 2.3-2.7 cm and a transverse diameter of 1.4-1.7 cm, with an average single fruit weight of 3.34 g, and the fruit size is uniform. The color is bright red and glossy. The fruit apex is concave, and the stem cavity is moderately deep. The fresh jujube has a thin skin, milky-white flesh, dense texture, and an extremely sweet taste. The soluble solids content of the fresh jujube is 36.5%, the edible rate is 100%, and the drying rate is 62.8%, with average fresh-eating quality. It is suitable for drying, and the dried red jujube has excellent quality. Both cultivars enter the fruiting stage relatively early, generally bearing fruit 3-5 years after planting, and they have strong continuous high-yield ability, with very slight alternate bearing. In full fruit period, Cangwu 1 produces 35 kg of fresh jujube per tree, and Cangwu 3 produces 45-50 kg of fresh jujube per tree.

Key points of cultivation techniques: ① Planting density. Cangwu 1 and Cangwu 3 have relatively small canopies and are suitable for close planting, generally with row spacing of 3-5 m x 2 m and 66-111 plants per mu. For jujube-grain intercropping, the row and plant spacing is 10-15 m x 3 m. ② Fertilizer and water management. Apply sprouting fertilizer in early to mid-April (1-1.5 kg urea per tree), young fruit fertilizer in early July (1 kg diammonium phosphate per tree), and base fertilizer in early October (10-15 kg farmyard manure per tree). Irrigate once each at the sprouting stage, early flowering stage, young fruit stage, rapid fruit expansion stage, and before overwintering. ③ Training and pruning. For close-planting cultivation, a natural round-headed shape can be used, with a trunk height of 70-80 cm, 5-7 main branches, and tree height controlled below 2.5 m. The pruning method of promoting in winter and controlling in summer is adopted, so that plants in the close-planting orchard overlap by 15-20 cm between trees, and a 1-1.5 m passage is kept between rows. For jujube-grain intercropping cultivation, a delayed open-center shape can be used, with 7-9 main branches on the whole tree, distributed in 2-3 layers alternately on the central leader, and the angle between the main branches and the central leader is 50-60°. Flower and fruit preservation. Cangwu 1 and Cangwu 3 have a relatively high natural fruit-setting rate, especially higher at the young fruit stage. During the flowering period, only girdling is needed, and it is not advisable to spray growth regulators to increase the fruit-setting rate, otherwise the fruit-setting rate will be too high and the jujube fruit will develop poorly. However, Cangwu 1 and Cangwu 3 show pre-harvest fruit drop, so 15-20 mg/kg naphthaleneacetic acid needs to be sprayed twice 1 month before harvest to prevent fruit drop.