(1) Growth potential and flowering: The growth potential of trees is directly related to the amount of pruning. Generally speaking, young trees have strong growth potential and it is difficult to blossom and bear fruit. The method of light cutting and slow growing should be adopted to promote its flowering and fruiting. Although the tree is too weak and easy to blossom, it is difficult to bear fruit, with high quality and high yield. It can be pruned properly to promote the development of new branches, increase the number of vegetative organs and improve the quality of trees. Therefore, it is very important to maintain normal tree potential by pruning. The basis for determining the growth potential is mainly the growth amount of extended branches of main branches and the percentage of long branches. The suitable extension branch length of young trees in flat orchard is 80 ~ 100 cm and that of adult trees is 30 ~ 60 cm. Short branches and short trees can be pruned according to the lower limit, and long branches and short trees can be pruned according to the upper limit. Judging from the number of long branches, the number of long branches of general fruit trees should account for about 20% of the total number of branches in the whole tree. When there are too many long branches, it means that the tree is too strong to blossom and bear fruit. In pruning, the method of cutting less and putting more can be adopted to slow down short and medium branches and increase flower bud differentiation. When the long branches are insufficient, it means that the tree is too weak, often with more flowers and less fruits, poor fruit development, small fruit and poor quality. When pruning, the method of cutting more and putting less should be adopted to increase the amount of long branches.
(2) Light-loving and openness: Most fruit trees are light-loving, and maintaining good light conditions in the crown through pruning technology is the guarantee for normal flowering and fruiting of trees. However, different tree species and varieties have different degrees of light preference. Peach, apricot, jujube, etc. Like light, apples, pears, plums and grapes like light. Walnut, hawthorn and kiwifruit also like light, but they are also more tolerant to shade. Different photophobic fruit trees should take different forms in crown modeling. Generally speaking, fruit trees with strong light preference should adopt a happy tree shape without a central stem, those with strong light preference should adopt a layered conical tree shape with a central stem, and those with strong shade tolerance can adopt a natural multi-stem round-headed tree shape without layering. The opening of the crown is closely related to the light condition of the crown. Open varieties, with good canopy illumination, are easy to blossom and bear fruit, but attention should be paid to hanging branches at the top of fruits to prevent premature senescence of trees. Varieties with relatively upright branches have poor crown illumination, which is not conducive to flowering and fruiting. When pruning, we should always pay attention to the angle of branch opening, improve the light conditions in the crown cavity, prevent the fruit parts from moving out, and strive for three-dimensional fruit and high quality and high yield.
(3) Drying and stratification: Trees and fruit trees have certain drying and stratification, but different tree species and varieties are different, so more attention should be paid to pruning. Generally speaking, the varieties with strong dryness and obvious stratification are mostly stratified trees with the main trunk in the middle, and the main branches in the same layer can be arranged adjacent to each other. Varieties with weak dryness and no obvious stratification often adopt a heart shape without a central trunk, or have a central trunk without stratification, and the distribution of main branches on the central trunk mostly adopts adjacent distant rows.