Because the branches of fruit trees have the advantage of the top, the top of 1 annual branches can grow branches every year, while the middle branches grow short branches, and the lower buds do not grow branches, which are mostly in a latent state. This is repeated once a year, so that the crown develops branches and is distributed in layers. When fruit trees are reshaped, according to the stratification of branch growth, the crown backbone branches are reasonably arranged, and the light energy is fully utilized to obtain high quality and high yield (Figure 6).

(1) dryness refers to the ability of a fruit tree to form a dry and maintain its growth potential. Self-forming dry ability is strong, but the growth advantage of dry is easy to maintain, which is called strong dry; On the contrary, the dryness is weak. The intensity of drought is not only different from varieties, but also related to natural conditions and fertilizer and water management level. Among different tree species, apple tree and pear tree are relatively dry; Peach and apricot trees are weak in dryness. Among different apple varieties, Jinguan and Guoguang have stronger dryness, while green bananas and red Fuji have weaker dryness. The dryness of red Fuji grafted with dwarf rootstock M9 is the weakest. For varieties with strong dryness, a tree in the middle of the trunk should be used for plastic surgery; When pruning, the central leadership should adopt the method of bending to control the growth potential of the upper part of the crown and prevent the phenomenon of strong upper part and weak lower part. For trees with strong top and weak bottom, the method of increasing the number of branches at the base can be used to balance the tree potential; For varieties with weak dryness, it is advisable to use heart-shaped or tree with three main branches at the base to prevent strong bottom and weak top; Pay attention to prevent premature aging of the upper part when pruning.

Fig. 6 Branch Stratification

(2) Stratification. Refers to the ability of branches to naturally stratify in the crown. Because the branches of fruit trees have obvious apical advantages, there is obvious stratification on the trunk of central leadership. The obvious stratification is called strong stratification; The stratification is not obvious, which is called weak stratification. Generally, tree species and varieties with strong branching ability are weak in stratiform, such as Zhuguang, Celosia cristata and Ruby. Varieties with weak branching ability have a strong sense of hierarchy, such as green bananas and green lights. Trees and fruit trees have a strong sense of hierarchy when they are young, and gradually weaken after entering the full fruit stage. For varieties with strong layering, trunk drainage should be adopted to prevent the distance between layers from being too large; For varieties with weak bedding, it is advisable to adopt heart-shaped openings, keep a large distance between leaf curtains, control the thickness of leaf curtains, and do not make them too thick to facilitate ventilation and light transmission.