At present, high-yield apple and pear trees are mainly in the form of dry and sparse layers (Figure 10), and their structural characteristics are: dry height is 60-80 cm, and tree height is about 3.5-4 meters. The whole tree has 5 ~ 7 main branches, which are arranged on the central main branch in 2 ~ 3 layers. The opening angle of the base of the main branch is 50 ~ 60. The first layer has 3 ~ 4 main branches (usually 3), and the distance between layers is about 40cm；; 2 main branches on the second floor; The third layer has 1 ~ 2 main branches. The spacing between the first and second layers of main branches is 100 ~ 120cm, and the spacing between the second and third layers is about 80cm. 2 ~ 3 lateral branches can be left in the main branch of the first layer, and the first lateral branch is 50 ~ 60 cm away from the central trunk, and the first lateral branch on each main branch should keep the same direction. The second lateral branch is 30-40 cm away from the first lateral branch, and the third lateral branch is 50-60 cm away from the second lateral branch; The main branches of the second and third floors can leave 1 ~ 2 side branches.

Figure 10 sparse tree structure of trunk layer

(2) Pruning techniques for young trees and first-bearing trees.

According to the characteristics of growth and fruiting, local climate, soil, topography and plant growth conditions, pruning methods such as light pruning and appropriate slow-release wattarum branches are generally adopted for young trees to achieve the purpose of early formation and early fruiting (figure 1 1).

Figure 1 1 shaping process of sparse form 8776① selection and retention of central trunk: for young trees with fixed trunk, the upright and strong branches at the top of the tree should be selected as the central leading branches in winter pruning every year, and 50 ~ 60cm should be reserved in winter pruning in 1 ~ 2 years and 40 ~ 50cm in winter pruning in 3 ~ 4 years. If the branches are weak in the current year, they should be cut again appropriately, and then moderately shortened in the next winter. Generally speaking, the length (the sum of two years' length) should be cut to meet the requirements of interlayer spacing. When the top advantage is too strong, the weak branches can be replaced and retracted appropriately to control the advantage of the central trunk. Young trees are usually pruned for 5 to 7 years. When the whole tree has 5 ~ 7 main branches and the height of the tree is about 3.5 meters, the central trunk should be capped or reduced in time.

(2) Selection, preservation and cultivation of main lateral branches: When cutting in winter in the same year after planting, select three branches with good directions and angles under the central main branch as the first layer of main branches, and leave 40-50 cm for cutting. For plants that can't choose three main branches in the year after planting, the central main stem can be shortened by about 40 cm, but the second to third buds should be left in the direction where the main branches are missing, so that the branches issued in the next year are suitable for the main branches. When cutting in the winter of the following year, the extension branches of the main branches still have short branches of 40 ~ 50 cm. When cutting in the winter of the third year, pay attention to the first lateral branch of the second layer main branch and the first layer main branch, and the direction of lateral branch selection is the same. The first layer of main branch shear 40 ~ 50 cm, lateral branch shear 40 cm. In the 4th to 6th year of winter pruning, the pruning of main branches and extended branches of lateral branches is basically the same as that of last year. Pay attention to selecting and retaining the third layer of main branches. If the opening angle of the main branch and the lateral branch is small, it is necessary to open the angle by pulling, bracing and bracing as soon as possible, which is beneficial to the opening of the crown, and at the same time, it is necessary to maintain a good subordinate relationship between the main branch and the lateral branch.

(3) Utilization and control of auxiliary branches: Young trees should appropriately keep more auxiliary branches to enhance tree vigor and bear fruit early. When auxiliary branches affect the growth of main branches and side branches, they should be controlled in time. Generally, methods such as removing straight branches to keep the slope flat, changing the head, removing strong branches and leaving weak branches, slowly releasing annual medium branches, increasing the angle, coring and girdling during the growing period are adopted to weaken its growth ability and promote its early fruiting. When the auxiliary branches seriously affect the growth of the main branches and side branches and the light in the crown, they should be shrunk and drained again in time until the whole branch is drained.

④ Cultivation of fruiting branches: Young trees and early fruiting trees should be cultivated as soon as possible. The cultivation method of fruiting branches of apple pear is basically the same as that of apple, which adopts cutting before putting or cutting before putting, generally cutting before putting. For small branch group and long branch group, branches with moderate growth are generally selected, and short branches with more germination are kept for several years or lightly cut, and then retracted at appropriate branches after flowering and fruiting. For medium and large branches, healthy long branches are generally selected, and the method of cutting first, then releasing, and then retracting in the appropriate position is adopted for culture. In the first two years, proper cutting will promote their branching, and in the third year, most of the branches above them will be slowly released, with a small amount of cutting. When there are many branches or vigorous growth, the strong branches should be removed and the weak branches should be kept to facilitate flowering and fruiting. The middle branchlets on both sides of the main branch and the big branches under the back should be cultivated in the first fruit tree. When the tree is bigger, reduce and control the big branches appropriately and increase the oblique branches. The distribution of fruiting branches on the main branches is generally dominated by the middle branchlets on the back; Medium, small and large branches are combined on both sides, forming a reasonable layout in which large branches occupy space and middle branches make up for vacancies; Behind and below are mainly large and medium branches. Branchlets are the main branches in the front, middle and lower branches are the main branches, and branchlets are the supplement. Results If the branches grow weak after continuous fruiting, they should be retracted in time to facilitate regeneration and rejuvenation. For some whorled, crossed and crowded branches in the crown, methods such as retraction or drainage should also be adopted to facilitate the growth of main and lateral branches and ventilation and light transmission in the crown. (3) Pruning of trees in full fruit period.

The main tasks of pruning in this period are to adjust the balance between growth and fruiting, improve the light conditions inside the crown, maintain the moderate growth of the peripheral new shoots, and promote the formation of robust fruiting branches and flower buds, thus improving the fruiting ability. At the same time, adjust the number of branches of the whole tree and the proportion of flowers and leaf buds to reduce the fruiting range in different years. Therefore, the pruning principles of trees in the full fruit period are: generally, strong trees and strong branches are lightly pruned, weak trees and weak branches are appropriately re-pruned, the whole tree with many flower buds is lightly pruned, and the whole tree with few flower buds is carefully pruned. The pruning method of all branches of the whole tree is as follows.

(1) Annual branches: annual development branches, which are generally not short-cut or light-short-cut, except for the extended branches of main and lateral branches and moderately short-cut branches with growth space. When the main branches and lateral branches grow too vigorously or erect, they should be picked. Annual branches that grow too densely should be properly thinned. Annual branches should generally be thinned, but if there is space, they should be slowly released and leveled, and then the branches should be shrunk after flowering, or the branches should be cut short first, and then they should be cultivated into fruiting branches in shear center the next year to increase the fruit yield. The annual branches of annual trees should be cut gently and put slowly to promote more short and medium branches to form flower buds. How short the annual branches of young trees should be to promote growth and reduce the formation of flower buds.

(2) Perennial branches: The pruning method of "row upon row, row upon row, row upon row, row upon row" should be adopted. When the main branches and lateral branches are weak or drooping, they should be retracted to the branches that are strong and upward. When the main branches and lateral branches grow strongly or moderately, only the annual extension branches need to be shortened moderately. When the perennial branches in and around the crown are too dense or overlapping, they should be properly thinned to make the whole trimmed crown sparse outside and dense inside, which is beneficial to ventilation and light transmission in the crown.

③ fruiting branch group: the pruning methods of fruiting branch group in full fruit stage are mainly retraction, renewal and rejuvenation. Therefore, the bearing branches with weak growth should be retracted by turns in batches every year, generally 65,438+0/3 ~ 65,438+0/4 per year. When retracting, it should be retracted to the branches with upward angle and proper direction, and the rest branches should be trimmed moderately, especially those with more flower buds. For the strong branches before and weak after, some strong branches or annual branches in front can be properly thinned, and the branches in the middle and lower parts can be moderately shortened or retracted to promote the strong branches and buds behind. Short branches on short fruit branches can be pruned by removing weakness and staying strong, and removing far and staying near. Strong or erect branches planted on the back of the main and lateral branches should be gradually retracted in years. For annual branches on retracted branches, vigorous growth should be released slowly, and moderate or weak growth should be shortened. For some branches with weak growth, long elongation and bare base in the middle and lower parts of the main and lateral branches, they can be retracted directly before obvious latent buds, or girdled at the early stage of growth to promote the emergence of latent buds. When the fruiting branches of pears are too dense or overlapping, it is generally not appropriate to thin them. Pruning can be used, that is, some branches are re-pruned, while others are lightly pruned or not, so that each branch group occupies a certain space and increases the fruit volume.

In the New Year's tree, the bearing branches with many flowers and the flower buds on them should be pruned again, and the bearing branches with few flowers and no flowers should be pruned lightly or not, and as many leaves and buds as possible should be left. The top flowers and axillary flower buds on medium-long fruit branches should be cut off, and the redundant flower buds on short fruit branches can be cut off to reduce the number of flower buds. After pruning, the flower bud reserve of the whole tree should be 30% ~ 40% of the total number of terminal buds of annual branches (long, medium and short branches) of the whole tree. The annual development of branches in a branch group should generally be postponed unless it can be shortened moderately by increasing the number of branches. The flower buds of the peripheral branches of the main branches and side branches should be sparse.

The fruiting branches of young trees generally have fewer flower buds and more leaf buds. When pruning, leave as many flower buds as possible, generally cut or shrink before the flower buds or on their branches to improve the fruit setting rate. The robust branches without flower buds or with few flower buds should be retracted, and the annual branches on the branches should be cut short and released slowly to strengthen vegetative growth and reduce the formation of flower buds. (4) Pruning of apple and pear trees during senescence.

During this period, the new shoots on the periphery of the trees are short or not, and most of the fruiting branches grow weak or die, and the flower buds are thin, and the fruiting parts obviously move outward and the inner cavities are exposed. Some apple pear trees have incomplete main branches and lateral branches, and a certain number of long branches germinate in the crown. The pruning methods of these trees are mainly to renew and rejuvenate and cultivate new fruiting branches.

(1) trunk branches: the main branches and side branches with weak growth, drooping or dry tips should be largely retracted. Generally, the branches that grow well and incline upward should be retracted in the middle and lower parts, and the retracted top branches should be carefully trimmed to gradually cultivate new main branches and side branches. The main and lateral branches will shrink in batches in several years. Generally, it will shrink by 1 ~ 2 backbone branches every year.

② fruiting branch group: the weak fruiting branch group on the main branch should also be properly retracted to promote robust growth and good fruiting, but the branch group retracted again on the main branch and side branch should shrink less and lightly. The sprouting branches on the crown should be moderately shortened or slowly released to gradually become new fruiting branches. The long branches or middle branchlets in the parts with missing branches and large gaps should be moderately shortened every year to promote more branches and gradually cultivate them into larger branches. For the main branches and lateral branches with long bald belts, subcutaneous grafting can be used to repair the exposed branches to make up for the space and enhance the fruit volume.

The regeneration and rejuvenation of aged pear trees must be carried out on the basis of strengthening the management of underground soil, fertilizer and water, and the regeneration effect can be obvious.