The bud at the top of the branch has stronger germination ability and branching ability than the bud at the bottom, and it decreases downwards, which is called apical dominance. According to this feature, different pruning purposes can be achieved when pruning large cherries. For example, in order to make the tree grow vigorously, we can leave more vigorous branches, or cut them off at strong branches and strong buds to promote vigorous branches, or raise the angle of weak branches to enhance the branch potential and promote vigorous branches. In order to make the tree relax and bear fruit early, we can leave more horizontally drooping branches or open the flourishing branches at an angle to weaken its advantages and promote the short branches to bear fruit. The growth polarity of young cherry trees is strong, which is highlighted by the fact that no matter whether the peripheral development branches are short or not, several development branches can easily lead out from the top, forming two, three or four branches, or even more long branches, with short lower branches and few middle branches. If this branch is allowed to grow, it will have obvious apical advantage. Because a large number of long branches are produced at the top, a lot of nutrients are consumed, so that the branches below gradually die and become bare. Therefore, it is one of the most important tasks in cherry pruning to weaken the top advantage of young cherry trees and promote the development of fruiting branches.
(2) The precocity of buds and the characteristics of pruning.
Under the condition of natural growth, the buds on the new shoots of that year can produce secondary buds, which is early maturity. Big cherry has this precocious characteristic. In the growing season of young trees, summer pruning methods such as pinching and twisting the tips can promote the secondary branches to enter the fruiting stage as soon as possible, and achieve the goal of early fruit and high yield.
(3) Sprouting power, branching power and pruning characteristics
The germination ability of buds on 1 annual branches is called germination ability. The ability to germinate and grow branches on 1 annual branches is called branching ability. The strength of germination power and branching power is one of the important basis for determining different pruning methods. Young cherry trees have strong ability of sprouting and branching, large growth, rapid crown expansion, early fruiting and fast entry into full fruit stage. Therefore, we should make full use of this feature in shaping and pruning, adopt light pruning and long pruning, give priority to summer pruning, advocate the combination of controlled pruning, expand crown shape, promote flower bud formation and bear fruit early. However, varieties with high germination ability and weak branching ability need to adopt short pruning method to expand the crown and increase the fruiting area.
(4) Branch angle and pruning characteristics
Branches that grow vertically, with small angles and strong top advantages, often grow too vigorously and are not easy to become flowers. By using the methods of pulling branches and holding tips, the angle of branches can be opened to make them grow horizontally and relax the potential of branches, which is beneficial to the formation of short and medium branches and easy to bloom.
Young cherry trees are easy to form sandwiched branches because of the small angle of long branches. This kind of branch with skin should be opened or thinned early, otherwise, with the growth of branch age, the fruit will easily crack and the branch with skin will easily flow when there are too many fruits. Therefore, it is not appropriate to choose branches with skin as the backbone of culture.
(5) Variety group and pruning characteristics
Different types of cherry varieties have different growth and fruiting habits and different requirements for shaping and pruning. The big cherry is slightly dry, and the tree shape should be naturally happy, sparse or dry; However, sour cherries are weak in dryness, and the trees are clustered; China cherry is somewhere in between.
Big cherry mainly bears short fruit branches and long fruit branches. Only the axillary buds of the short and slow internodes at the base of long fruit branches are transformed into flower buds, and the rest of the upper buds are leaf buds. In addition, the flower buds on long fruit branches are not as full as those on short fruit branches, so efforts should be made to form more short branches when pruning. The fruit branches of sour cherry and China cherry are divided into short fruit branches, middle fruit branches and long fruit branches, and all kinds of fruit branches have flower buds above and below.
Cherry is a light-loving tree species. Big cherry has the strongest photophobia, followed by sour cherry and hairy cherry, and China cherry is more tolerant to shade. Good lighting conditions are easy to blossom and bear fruit early, which is beneficial to high yield, stable yield and high quality. Therefore, corresponding shaping and pruning methods should be adopted. Big cherries need highlights. In the case of dense branches in the crown, many peripheral branches and poor ventilation and light transmission conditions, the internal branches and branches are easy to die. Therefore, reducing the number of peripheral branches, relaxing the top growth potential and improving the ventilation and light transmission conditions are the two main ways to improve the quality of crown branches of big cherry and prolong its fruiting life. Happy pruning should be adopted in the production of medium and large cherry. China cherry has relatively low light requirement, and the planting density can be higher.
(6) Tree age, tree potential and pruning characteristics
The growth and fruiting habits of big cherries with different ages are different, and the pruning methods and purposes are also different. The young tree stage is mainly plastic, and the purpose of pruning is to increase the amount of branches and leaves, rapidly expand the crown and promote its early flowering and fruiting; Fruiting is the main stage, and the purpose of pruning is to relax tree vigor, cultivate fruiting branches, increase fruiting area, and promote the transformation from vegetative growth to reproductive growth. For trees with vigorous growth, we should cut them gently and put them slowly to ease the tree potential and promote the formation of fruiting branches; For trees with weak growth potential, it is necessary to strengthen short cutting, promote their local growth potential and promote the rejuvenation of trees.
(7) Cultivation conditions and characteristics of pruning
Different site conditions and cultivation methods have different pruning characteristics. In orchards with poor site conditions, the growth of trees is weak, so it is advisable to use low-stem and small-crown pruning, and pay attention to rejuvenation pruning; In orchards with good site conditions, the growth potential of trees is relatively strong, so it is advisable to use large and medium crowns for pruning, light pruning and slow pruning to promote early flowering and early fruiting. In orchards with high planting density, small crown pruning should be adopted to promote crown formation at an early stage, and measures should be taken to promote flowering and pruning at any time. Temporary plants and permanent plants tend to adopt different pruning characteristics for orchards with planned close planting. The purpose of pruning is to promote the early fruiting of temporary plants and the rapid formation of permanent plants. After permanent plants bear fruit, temporary plants are diluted.