After young trees are planted 1 ~ 2 years, full buds are selected and cut off at a certain height of the trunk, which is called fixed stem. The fixed stem height varies with site conditions and planting density. When the mountain is thin and the soil quality is poor, it is appropriate to set the drying height of 70 ~ 80 cm; The flat soil layer is thick and the soil quality is good, and the dry height is about 80 cm. Too high drying, slow molding, late fruiting and low yield; The dry setting is too low, the underground management is inconvenient, and the ventilation and light transmission are poor. In some chestnut orchards, if seedlings are planted first and then grafted with improved varieties, the seeds should be picked at a suitable height in the year when seedlings are grafted to promote secondary branching. For example, grafted seedlings grow vigorously, and 1 year can be picked many times. If coring is carried out correctly, the small crown can be formed within 1 year.
2. Select and keep the main branches and side branches.
After the young trees are fixed, according to the branching situation, three branches with uniform distribution, large angle and strong growth are selected and cultivated into the first layer of main branches. Other branches should be trimmed, put slowly or cut short in line with the principle of removing weakness and retaining strength, and removing straightness and retaining inclination. The next summer, the robust branches were cored to promote branching. The coring method is: when the main branches and extended branches at all levels are 40 ~ 50 cm long, remove 1/3 ~ 1/2, and re-core the remaining vigorous branches to promote their branching, and sparse them if there is no space. In August, some competitive branches and dense strong branches can be pulled into flat and oblique growth to prepare for next year's flowering and fruiting, and the unusable competitive branches and strong branches can be thinned out.
In the third year, before and after germination, it is best to cut short the branches extending from the trunk at the full bud to promote hair growth. Select the first side branch 70 cm away from the trunk and the second side branch about 40 cm away from the first side branch. Other branches are still sparse, cut and slow according to the above treatment principles. Generally, there are 1 ~ 2 side branches on one main branch, which are staggered. In the third to fourth years, two stout branches with good orientation 1 ~ were selected at the position above 100 cm of the main branch of the first layer, and the main branch of the second layer should be staggered from the main branch of the first layer 1 to prevent crowding. In this way, after 3 ~ 4 years of shaping and pruning, the tree skeleton is basically formed.
3. Selection and retention of extension branches of main branches.
The pruning of main branch extension mainly involves the number, orientation, direction and pruning length of extension branches. The main branches should keep a certain distance, and try to avoid the top 3 ~ 5 stout branches as the backbone branches at the same time. With the growth of the tree, the branches increase year by year, and the selection and retention of the main branches can be completed within 1 ~ 3 years. The selected main branches grow obliquely outward, do not overlap, and are scattered and bifurcated, which is beneficial to ventilation and light transmission. The selected main branch should be cut short at the full bud of the branch of 40 ~ 50 cm to promote the branch of the main branch. Due to the tip advantage, the first bud under the incision produces a strong leading branch, which extends outward to expand the crown. When the angles of several flourishing branches at the top of the main branch are too small, the strong branches in the middle can be thinned out, and the slow branches with large angles of 2 ~ 3 buds at the top can be selected to replace the extended branches of the main branch. Prune the selected extension branches on the main branch every year until the crown size required above is reached.
4. Cultivation of fruiting branches.
The common method of combining short cutting with coring is to take heavy cutting to promote the growth of strong branches in spring and heavy coring to promote the growth and branching of new branches in summer according to the planting position and space size of strong branches, thus forming a more solid fruiting branch group.
5. Pruning of long branches and auxiliary branches.
In the process of pruning young trees, because of the large amount of pruning, the hidden buds on the trunk often grow long branches. Tendrils that grow vigorously and erect, affect the main branches and disturb the tree shape should be removed in time. Tendrils growing in bare positions can be picked continuously in summer to promote branching and transform them into fruiting mother branches. The main function of auxiliary branches is to assist the growth of trees and should be transformed into fruiting branches as soon as possible. When pruning auxiliary branches, dense branches should be thinned out, and branches with room for development should be cut short.
6, in addition to Meng.
In addition to the surviving branches and leaves, the new buds on the rootstock should also be erased in time to avoid competing for nutrients and water. For the trees that do not survive after grafting, all the sprouting branches will be removed except the vigorous sprouting branches with ideal branching angles and orientations on the rootstock, which will be replanted next year.
7. Choose your heart.
Picking is mainly carried out on young trees and flourishing branches. In addition to normal winter pruning, summer pruning is an important technical link for early forming and flowering of chestnut. Generally, when the new shoot grows to 20 ~ 30 cm, the tender shoot with a tip of 3 ~ 5 cm is removed, that is, the first coring; After enucleation, 3 ~ 5 buds at the top of new shoots germinate and grow again. When the length of the second and third branches is 50 cm, the second and third coring are carried out, and the top of the new branch is 7 ~ 10 cm. According to the local climate, the third and fourth coring should be carried out, and the new shoots formed should be strong and full, and should not be peeled in winter. When the secondary branches stop growing, the tender tips at the top should be cut off, which can obviously promote the formation of fruiting mother branches. Young trees should master the principles of early topping, late topping and heavy topping, and the new shoots formed after topping are full and strong. After coring, several well-developed mixed buds can be formed at the top of the secondary or tertiary branches, which will bloom the next year. According to the survey, the proportion of mother branches bearing fruit after 2 ~ 4 times of branching is 35% ~ 56%.
8. Pull the branches.
By pulling branches, bending branches, hanging branches and other measures, the angle of young branches is changed, and the strong branches are changed from upright to oblique, which inhibits the vegetative growth of strong branches, accelerates the transformation to reproductive growth and promotes the differentiation of female flowers. Branching can be carried out in autumn, the main branch angle should be 50 ~ 60, and the strong vegetative branch angle can be extended to 70 ~ 80 or even horizontal.