1, two parts. That is, above ground and underground, that is, crown and root system. These two parts are closely related. In the annual growth cycle of fruit trees, these two parts are in dynamic balance. To a certain extent, the crown is trimmed, and the more it is cut off, the stronger the power to promote crown restoration. What is cut is the branch, not the root, and the root system is destroyed, which will inevitably affect the growth of the crown.
2. Two roads. Namely, two paths of water and organic nutrition transportation. Water and inorganic salts absorbed by roots are transported to the crown through xylem ducts; Organic nutrients produced by leaves are transported to the root system through sieve tubes in the cortex. Measures such as girdling were taken to improve the fruit setting rate and promote the formation of flower buds. The vigorous part of the tree was weakened and slowed down because the normal functions of the two branches were destroyed, which achieved the expected purpose.
3. Two centers. For the aboveground part, there are two centers in the distribution process of organic nutrients produced by fruit tree leaves during the growth period: one is to transport them to the top of the most active new shoots for growth; The second is to transport it to the fruiting part for fruit growth. The transfer of nutrition to the growth center will cause the tree to be too strong; Nutrition is easy to transfer to the core of the fruit (too many fruits are set), which will make the tree too weak. One of the main tasks of pruning is to adjust the distribution center of organic nutrition, so that its growth and fruit are coordinated and appropriate.
4. Two growth stages. The growth of new shoots in the annual cycle is generally divided into two stages: spring shoots and autumn shoots. Spring shoots, also known as shoots in buds, play a decisive role in the nutritional level of fruit trees in the early stage and belong to accumulated branches; Autumn shoots grow after the rainy season, which is not conducive to fruit growth and flower bud differentiation, and belong to consumption branches. For young flourishing trees, autumn shoots can be fully used to achieve the purpose of light cutting and long retention to expand the crown; For the fruit tree, how to control and weaken the growth of autumn shoots is one of the tasks of plastic pruning.
4. Two technologies. That is, short cutting and dewatering, that is, cutting branches from the base or dewatering. These are two basic techniques of fruit tree pruning. Short shears are divided into light shears, medium shears, heavy shears and extremely heavy shears, which are helpful for pruning local branches. For the same branch, the heavier the short cut, the stronger the local potential pressure increase, and the smaller the growth of the cut branch. The lighter the short cutting, the weaker the local promotion and the greater the growth of cutting branches. Thinning can reduce the potential of the upper part of the incision, but can promote the potential of the lower part of the incision. Only when these two techniques are combined properly can the ideal pruning effect be achieved.
6. Combination of winter and summer. That is, combining winter pruning with summer pruning. For young trees and early-bearing trees, pruning only once in winter is often too heavy, and the next year, there are too many clockwork, and the results are late; The combination of light cutting in winter and wiping, picking, peeling, twisting, pulling and carving in summer will accelerate the formation of crown and make it blossom and bear fruit early. The greater the pruning amount after germination, the more serious the damage to the "vitality" of the tree. Therefore, plastic pruning in summer should try to reduce the loss of leaves, so as to achieve the purpose of prosperous management, slowing down the trend and early flowering and early fruiting.
7. lifelong contradictions. That is, the contradiction between growth and fruit throughout the whole life cycle of fruit trees is manifested in the strength of trees and the number of fruits. Genetic law determines that all measures to make young trees grow in vain and fruitless are to achieve their goals by weakening the tree potential.
8. Two motives. That is, light and water, light is energy, which determines the nutrition and accumulation level of fruit trees; Water is the lifeblood and determines the growth of fruit trees. As the saying goes, "it is good to plant trees by water, and it is good to say that the light path is good." This is a fact. Soil and fertilizer conditions and scenery conditions should be considered first in fruit tree shaping and pruning. The individual and group structure of fruit trees can achieve the best effect only if it is consistent with ecological conditions.
9. Two advantages. That is to say, vertical advantage and apical advantage are upward characteristics in the growth process of fruit trees, and they are the principle that all fruit trees can grow tall and grow up. In the process of fruit tree pruning, adjusting the balance between the upper and lower crowns, the external and internal growth results are essentially adjusting the relationship between these two advantages.
10, two angles. Namely that angle of the main branch and the angle of the branch group on the main branch. Angle is the "key" to adjust the light path and waterway, adjust the two advantages, and realize the coordination of growth and results. From a small angle to a large angle, the tree potential turns from strong to stable to weak; On the contrary, the angle changes from big to small, and the tree potential changes from weak to strong. The most effective measures for young trees to bear fruit early are light cutting, long putting and oblique opening. Old trees are updated with backs and corners.
Second, the principle of standard plastic trimming:
1. plastic pruning technology should be conducive to the formation of crown. Dwarf close planting also needs a certain number of growing branches in a short time to ensure high-yield fruit in the early stage.
2. The shaping and pruning technology should promote the transformation and accumulation of nutrients, be conducive to the formation of flower buds, and achieve the purpose of early fruiting and stable yield.
3. The shaping and pruning technology should be beneficial to illumination. Dense planting garden is easy to be closed, so it needs to be trimmed to make dense planting trees ventilated and transparent. Therefore, different planting densities should adopt different shaping methods and achieve the purpose of dense branches and good illumination through shaping and pruning.
4. Close-planted trees should be pruned, the size of trees should be controlled, and the height of trees should be reduced. Pear trees are very polar. Because of the small row spacing, trees tend to grow upward. Trees should be shortened by pruning.
5. Plastic pruning depends on the response of fruit tree types and varieties to pruning. Pomegranate, for example, should not be cut short, otherwise it is easy to agglomerate. Red banana type of apple Some varieties are only suitable for thinning branches but not for pruning.
6. Pruning depends on the nutritional status of trees and the growth characteristics of fruit trees. Peach trees have thick branches and can be cut again properly.