The shaping of walnut trees should be determined based on the variety characteristics, site conditions, plant-row spacing, etc. When the site conditions are strong, the site conditions are good, and the supply of fertilizer and water is sufficient, the scattered layered shape can be used; when the site conditions and fertilizer and water conditions are poor, the natural open-ended shape can be used; for densely planted walnut orchards, fan-shaped pruning can be used , but auxiliary branches should be left between the rows. When the alternation between rows affects the light, they can be cut back into fruiting branch groups.

(1) Evacuated layered shape (Figure 96) This kind of tree shape is characterized by a strong central leading branch, usually 5 to 7 main branches, divided into 2 to 3 layers. On the middle stem. Generally, there are 3 main branches on the first layer; 2 on the second layer; and 1 to 2 on the third layer. This kind of tree has many branches, a large crown and high yield. It is suitable for use on the ground with good site conditions, rich soil and for varieties with strong uprightness.

Figure 96 Evacuated layered shape of walnut trees

The fixed stem height varies depending on the variety and site conditions. In walnut orchards with deep soil, good fertilizer and water conditions, fruit-grain intercropping, and upright varieties with strong dryness, the fixed stem height should be appropriately higher, preferably 1.2 to 1.5 meters; in walnut orchards with poor soil, poor fertilizer and water conditions or For tree-shaped open varieties, the fixed stem height can be appropriately lower, preferably about 1.0 meters.

After the branches germinate, select 3 to 4 branches with suitable orientation, balanced development, and suitable angles as the first layer of main branches; the remaining branches, strong upright branches, should be thinned out appropriately; those with average growth Keep; if the angle is inappropriate, adjust it to control its growth, increase the amount of branches and leaves and nutritional area, and promote the growth of saplings and early fruiting.

The main branches at the base should be selected at random intervals, and the distance within the layer should be kept at 70 to 80 centimeters to prevent neck pinching and weaken the growth of the central leading branch.

Walnuts are very light-loving, and the distance between layers should be appropriately large to avoid causing the canopy to be closed, the branchlets to be thin, and the fruiting parts to move outward, which will affect the yield. Generally, the distance between the first and second layers should be kept at about 1.5 meters, and the main branches of the second layer should be more than 1.0 meters before selecting the main branches of the third layer. The main branches of each layer should be inserted and left empty to prevent overlapping. If the seedlings are too tall and have too few branches, do not cut them short to prevent them from drying out. You can top them in late July to encourage the lower branches to germinate, and then select and cultivate them.

When selecting and cultivating main branches, you should also pay attention to selecting side branches. On each main branch in the first layer, select 3 to 4 side branches; in the second layer, select 2 to 3 side branches. Do not choose to leave the back branches as side branches. The back branches of walnuts grow particularly vigorously. If you choose to keep the back branches as side branches, it will seriously weaken the growth of the main branches. This is different from other fruit trees, so you should pay attention when pruning. The side branches also need to be evenly distributed on the main branch to avoid being opposite. The first side branch on the main branch at the base layer should be about 1.5 meters away from the main trunk. If it is too close, it will easily form a gate side and weaken the growth of the main branch. The second side branch should be left opposite the first side branch, and the two branches should be about 1.0 meters apart.

During the shaping process, attention should also be paid to adjusting the subordinate relationship and balanced growth of branches at all levels, and the growth advantages of the central leading branch and the extended branches of each main branch should be maintained. When the growth of the central leading branch becomes weak, you can choose a strong branch that grows upright and upward to replace the original branch, and at the same time control the growth of each main branch; when the central leading branch grows too strong and appears strong at the top and weak at the bottom, it can be thinned out For strong branches, replace the original branches with branches of moderate growth to moderate their growth. However, generally do not change the branches easily to prevent the adverse phenomena of strong branches becoming weak and weak branches even weaker.

(2) Natural open-ended shape (Figure 97) When it is difficult to form a strong central leading stem in plots with poor soil quality, poor site conditions and open tree varieties, the natural open-ended shape can be used . This kind of tree shape, due to the different number of main branches, can be divided into two types: natural open shape with few main branches and natural open shape with many main branches.

The few main branches are naturally open-shaped. The characteristic is that there are few main branches, usually only 2 to 3, and there is no obvious central leadership. Its composition is two main branches growing on the trunk. The main branches grow obliquely upward, and the opening angle is smaller than that of the scattered layered shape. Cultivate 2 to 3 side branches on each main branch. The first side branch is 80 to 100 cm away from the main trunk. The distance between subsequent side branches is about 50 to 60 cm and 100 cm.

A certain number of secondary side branches can be cultivated on each side branch to make full use of the space and take shape as soon as possible. This kind of tree shape is easy to form, has good ventilation and light transmission, and is easy to manage. It is a better tree shape.

Figure 97 Walnut tree is naturally open-shaped.

Multiple main branches are naturally open-shaped. The basic structure is similar to the natural open heart shape with few main branches, except that the number of main branches is slightly more. The whole plant has 4 to 5 main branches, which are evenly distributed around the main trunk. There is no obvious central leading branch. Select 1 to 2 lateral branches on each main branch, or directly cultivate large fruiting branch groups. Do not choose to leave too many main branches in this tree shape to prevent poor ventilation and light transmission, which will affect the growth of small branches, causing the fruiting parts to move outward and affect the yield. During the sapling period, the crown is mostly round-headed; after the fruiting period, the crown gradually expands and the branches gradually droop to form a natural semicircle.