There are obvious differences in biological characteristics between different tree species, such as apple and pear: the top advantage of pear tree is stronger than that of apple, and the branches are more upright when they are young, and the angle of main branches is wider than that of apple tree after entering the full fruit stage. Pear has higher germination ability than apple, but weak branching ability, which makes it easier to blossom and bear fruit early, but it is easier to bear fruit in different years than apple. The life span of hidden buds of pear trees is longer than that of apples, and it is more convenient to shrink, update and prune than apples. Because of these differences in biological characteristics between apples and pears, attention should be paid to the pruning of young pear trees, and the pruning degree of main branches is lighter than that of apples, that is to say, more emphasis should be placed on light pruning and more seeds. The height of the top of the main branch should be close to the height of the central main branch to prevent the phenomenon of being strong on the top and weak on the bottom; In order to prevent the main branches of pear trees from bending and drooping after entering the full fruit stage, the opening angle of the main branches of the first layer can be relatively small, generally kept at about 40 degrees, instead of being rounded to a bottom angle of about 80 degrees at the beginning like apple trees; Pear trees have high germination ability and are easy to bloom, so attention should be paid to controlling flowers after entering the fruiting period; The stable bud period of pear trees is also longer than that of apple trees. Therefore, the main branches and crown can be updated by using the perennial hidden buds at the base. However, when pruning the branches of apple trees over 4 years old, it is difficult to get the ideal effect of renewal and rejuvenation, and sometimes the pruned branches may accelerate aging or dry up and die.
Among different grape varieties, longan with high branching meristems should be shaped by trellis and pruned by long branches, while varieties with weak growth potential and low branching meristems, such as Rose Fragrance, should be shaped by hedge and pruned by short branches.
(2) Potential fruit trees with different ages have different growth and fruiting conditions, so the methods used in pruning should be different. Apple, pear and other fruit trees generally grow vigorously. From young branches to early fruiting, there are few branches and leaves, many long branches, few short branches, many erect branches, few open angles and few flowers and fruits. After entering the full fruit stage, the length of the tree gradually tends to be stable, from vigorous to moderate to weak, the number of branches and leaves increases obviously, the number of long branches decreases, the proportion of medium and short branches increases, the angle gradually opens, and the number of flowers and fruits increases. Therefore, in the process of shaping and pruning, different pruning methods should be adopted according to the growth and fruiting characteristics of different ages: young trees should be lightly pruned from early fruiting stage, the total number and order of branches should be increased, the crown of trees should be enlarged, and early fruiting and high yield should be achieved; For the big trees that have entered the full fruit period, it is necessary to increase the pruning efforts appropriately, pay attention to adjusting the number of flowers and fruits, and do a good job of renewing and rejuvenating pruning to prevent the trees from aging and prolong the full fruit period. For trees that grow too vigorously, no matter what age stage they are in, the pruning amount should be light to facilitate flowering and fruiting; For trees with weak growth, we should first take measures to strengthen the comprehensive management of soil, fertilizer and water, enhance the tree vigor and increase the number of branches, and then take corresponding pruning measures.
(3) Tree species and varieties with different planting densities and planting methods have different pruning methods. Generally, in orchards with high planting density, we should pay attention to cultivating trees with low branch order, small skeleton and small crown when shaping, and pay attention to the angle of branches when pruning, control their vegetative growth, inhibit the crown from being too large, promote the formation of flower buds, and give full play to their potential of early fruiting and high yield; For orchards with low planting density, the number of branches and the total number of branches should be appropriately increased in order to quickly expand the crown and bear fruit; Different pruning methods should be adopted for planned dense planting and temporary encryption of fruit trees, permanent plants and temporary plants. For permanent plants, routine pruning measures should be taken, and attention should be paid to tree shape and early fruit. For temporary plants, pruning measures should be taken as far as possible to promote flowering and fruiting, compress crown, control vegetative growth, promote early fruiting and more fruiting, and not emphasize tree shape. When temporary plants affect the crown expansion of permanent plants, they should be retracted, trimmed, transplanted, thinned or cut off according to the specific situation.
(4) Different tree species or varieties have different responses to pruning. That is, when the branches of different parts of the same variety are treated by the same pruning method, the degree and range of their reactions are also very different. Therefore, pruning reaction can not only test the severity of pruning, but also be an important symbol to test whether pruning is reasonable. Only by being familiar with and mastering the law of pruning reaction can we do a good job of plastic pruning.
Pruning reaction depends on local performance, that is, the growth, flowering and fruiting of branches under cutting or sawing, and the growth of the whole tree.
Taking apple as an example, when the flower branches of Guoguang and Hongxing are cut to the same degree at the initial fruit stage, the pruning reaction is different: after cutting the flower branches of Guoguang, the reaction is stable growth and high fruit setting rate; After pruning flowers, especially when pruning trees in the first fruit stage, the response of Marshal variety is often to promote the growth of new shoots and reduce the fruit setting rate. Therefore, when pruning the flower branches of Marshal varieties, according to the different growth potential of trees, it is appropriate to cut them at the ring mark at the junction of spring and autumn branches or the bud at the base of new branches to reduce the pruning reaction and improve the fruit setting rate. Under the same thinning degree, when thinning the branches on both sides of the main branch and the branches on the back of the main branch, the pruning reaction is often different because of the different number of branches on the back of the main branch: when the number of branches on the back of the main branch is large, the reaction of the branches on the back is relatively mild after thinning, but when the number of branches on both sides of the main branch is small, the reaction of the branches on the back is very strong after thinning, which often leads to vigorous growth. Therefore, only after fully mastering the pruning reaction of different tree species and varieties can pruning play a better role in increasing production.
(5) The site conditions and cultivation management level of orchards are different. Different cultivation management levels will lead to different growth, development and fruiting conditions, and different responses to pruning. In hilly orchards with thin soil layer, poor soil quality and drought, the trees are generally weak, short in stature and small in crown, but they bloom quickly and bear fruit early. For this orchard, in addition to paying attention to close planting, when pruning, the trunk should be short, the crown shape should be small, the backbone branches should be short, and the branches should be as short as possible. Pay attention to rejuvenation and pruning to maintain the robust growth of the tree and maintain more fruitful parts; Orchards with deep soil layer, fertile soil, abundant fertilizer and water, and high management level generally have lush trees and leaves, and it is difficult to blossom and bear fruit in the later stage. In this orchard, we should not only pay attention to increasing the row spacing of trees when building the garden, but also pay attention to choosing large and medium-sized crown trees when shaping and pruning. The trunk should also be appropriately high, lightly trimmed, with more branches to slow down the growth, fewer main branches and appropriately increased interlayer spacing. In summer, we should also pay attention to pruning to slow down the growth of trees, increase the order of branches and promote flowering and fruiting.
The planting density and planting mode of fruit trees are different, and the methods of shaping and pruning are also different: close planting gardens should pay attention to the light, so when pruning, the trunk should be short, the crown should be small, the main branches should be few, and the results should be early.
When planting grapes in places with low temperature in winter, it is necessary to take the grapes off the shelf and bury them in the soil to prevent cold in winter, so the pruning method should meet the needs of taking off the shelf and burying them in the soil, the trunk should be low, and the amount of bud holes should be appropriately increased; In winter, in areas where it is not necessary to bury soil under the frame for cold protection, the pruning amount can be relatively large and the amount of bud holes can be appropriately reduced. Similarly, the management level of fertilizer and water also has obvious influence on the growth and development of fruit trees. When pruning, corresponding management measures should be taken according to the strength of tree potential and the sensitivity to pruning reaction.
In addition, the tree shape, the number of flower buds and the harm of pests and diseases are also factors to be considered in plastic pruning.