(1) Evacuated layered (Figure 96) This tree is characterized by strong central main branches, generally with 5-7 main branches, which are planted on the middle trunk in 2-3 layers. Generally 1 layer has 3 main branches; 2 on the second floor; Layer 3: 1 ~ 2. This kind of tree has many branches, large crown and high yield, and is suitable for upright varieties with good site conditions and fertile soil.
Fig. 96 evacuation stratification of walnut trees
The fixed drying height varies with varieties and site conditions. Walnut orchards with deep soil layer and good fertilizer and water conditions, as well as varieties with strong uprightness, should have higher dry height, which is1.2 ~1.5m; For varieties with poor soil, poor fertilizer and water conditions or tree-shaped openings, the fixed dry height can be reduced appropriately, and it is suitable to be about 1.0 m.
After sprouting, 3 ~ 4 branches with suitable orientation, balanced development and suitable angle are selected as the main branches of 1 layer; The remaining branches, strong and upright branches, should be properly thinned; Maintain moderate growth; If the angle is not suitable, adjust and control its growth, increase the amount of branches and leaves and nutrient area, and promote the growth and early fruiting of young trees.
The main branch at the base should be selected wrongly, and the distance within the layer should be kept 70 ~ 80 cm, so as to prevent the phenomenon of pinching and weaken the growth of the main branch at the center.
Walnut has strong photophobia, and the distance between layers should be larger, so as not to cause the canopy to close, the twigs to become thinner, and the fruiting parts to move outward, which will affect the yield. Generally, the interlayer distance between 1 and the second floor should be kept at about 1.5m, and the main branches of the second floor should be kept above 1.0m, and the main branches of the third floor should be left blank to prevent overlapping. If the seedlings are too high and the branches are too few, don't cut them short to prevent drainage. The core can be picked in late July to promote the germination of the lower branches, and then selected for preservation and culture.
When selecting and cultivating main branches, we should pay attention to selecting and retaining side branches at the same time. On each main branch of 1 layer, 3 ~ 4 side branches should be selected. Choose 2 ~ 3 branches in the second layer, and don't choose the branches behind as side branches. Walnut's back branches are particularly lush. Choosing back branches as side branches will seriously weaken the growth of main branches, which is different from other fruit trees and should be paid attention to when pruning. The positions of the upper branches of the main branches should also be evenly distributed to avoid opposition. The 1 lateral branch of the main branch at the grass-roots level should be about 1.5 meters away from the main branch. If it is too close, it is easy to form a door side and weaken the growth of the main branch. The second side branch should be opposite to the 1 side branch, and the distance between the two side branches is about 1.0 meters.
In the process of plastic surgery, attention should also be paid to adjusting the subordinate relationship and balanced growth of branches at all levels to maintain the growth advantages of the central leading branch and the extended branch of the main branch. When the growth of the central main branch becomes weak, the original main branch can be replaced by a strong branch that grows upright and upward, and the growth of each main branch can be controlled at the same time; When the central leading branches grow too strong, the strong branches can be thinned and replaced with medium branches to slow their growth, but generally do not change their heads easily to prevent the strong branches from weakening and the weak branches from weakening.
(2) Natural Joy (Figure 97) When it is difficult for plots and tree-like varieties with poor soil and poor site conditions to form strong central leadership, natural joy can be adopted. Because of the different number of main branches, this tree can be divided into two types: natural joy with few main branches and natural joy with many main branches.
Less main branches are naturally happy. Its characteristic is that there are few main branches, generally only two or three, and there is no obvious central leadership. Composed of two main branches, born on the trunk. The main branches grow obliquely upward, and the opening angle is smaller than the evacuation layer. 2 ~ 3 lateral branches were cultured on each main branch, and the distance from 1 lateral branch to the main branch was 80 ~ 100 cm, and the following lateral branches were about 50 ~ 60 cm and 100 cm in turn. A certain number of secondary branches can be cultivated on each side branch to make full use of space and form as soon as possible. This tree shape is easy to shape, good ventilation and light transmission, easy to manage, and it is a better tree shape.
Fig. 97 Natural happy shape of walnut tree
Natural happy shapes have many main branches. The basic structure is similar to the natural joy with few main branches, but the number of main branches is slightly more. The whole plant has 4 ~ 5 main branches, which are evenly distributed around the trunk, and there is no obvious central main branch. Choose 1 ~ 2 side branches on each main branch, or directly cultivate a large fruiting branch group. Don't leave too many main branches in this tree, in case of poor ventilation and light transmission, which will affect the growth of branchlets, lead to the outward migration of fruiting parts and affect the yield. During the young tree period, the crown is mostly round; After the full fruit period, the crown gradually expanded and the branches gradually drooped, forming a natural semicircle.