brief history
The initial stage of fruit tree cultivation is laissez-faire. /kloc-in the mid-7th century, in France, in order to match the garden fruit trees with the landscape and pursue the graceful posture of the fruit trees, the crown of the fruit trees was forcibly trimmed to form a solid geometric shape (Figure 1). At the end of 19, fruit tree cultivation expanded from courtyard to suburb, which put forward new requirements for reducing investment, saving labor and making full use of space. The tedious manual forced shaping was replaced by natural pruning. At the beginning of the 20th century, in view of the shortcomings of natural crown, the position moved outward and the hole was easy to be empty, and it was gradually improved from natural shape to artificial natural shape pruning. In 1930s, Britain cultivated dwarf apple rootstocks, and in 1950s, the United States began to popularize apple short-branch varieties in production. With the development of dwarf and close planting cultivation, it is required to reduce crown height, crown volume, backbone branch order and increase the proportion of branches and fruiting branches. The fruit tree shaping technology has changed again, and hedge-shaped and spindle-shaped trees have appeared (Figure 2).
Figure 1
Fig.2 The plastic technology of ancient fruit trees in China is relatively simple. Generally, it is allowed to grow naturally, and most of them are natural. /kloc-In the late 20th century, apple, pear, cherry and other fruit trees were introduced from Europe, America and Japan, and plastic technology was also introduced. It began to emphasize artificial forced shaping, which affected the fruit trees' age-appropriate results. Since 1930s, it has gradually turned to artificial natural shape, and deciduous fruit trees in the north have created sparse trunk shape, natural happy shape, three-legged shape and cluster happy shape. Evergreen fruit trees in South China are mainly round-headed, happy and dry. Since 1970s, with the development of dwarfing and close planting cultivation, a tree shape with a middle stem, a small crown shape and a heart shape with two openings has been put forward (see tree shape).
Plastic foundation
The modeling of fruit trees should not only consider the reasonable tree shape of individual trees, but also pay attention to the changing process of orchard group structure, so as to maximize the yield and economic benefits of fruit trees throughout their lives. Young trees have great individual independence, sufficient space and good lighting conditions. The tree structure of a single tree can be slightly dense, the central trunk can be left high (see backbone branches), and the tree shape can be slightly higher. With the increase of tree age, the crown began to hand over, the light in the crown cavity and the lower part gradually deteriorated, and the tree shape also changed, such as thinning the central trunk, gradually lowering the head to be happy or increasing the interlayer spacing, and retracting the main branches. The shape of fruit trees depends on the growth potential, branching habits and fruiting habits of different tree species and varieties. Apple, pear, jujube, persimmon, olive and other fruit trees are relatively dry, so trees with central trunk should be used; Fruit trees such as stone fruit and pomegranate are weak in dryness, so it is advisable to adopt a tree without center; Citrus, chestnut, walnut, litchi, etc. Between the two, it can adopt natural round head shape or natural drying shape; Grapes, kiwifruit and other trailing fruit trees should be in the form of scaffolding or walls. Fruit tree modeling should also be based on the environmental conditions of the planting area, such as fertile soil, rainy and long growth period, etc., and it is appropriate to adopt a big crown with sparse bones and noon branches, otherwise it should adopt a small crown modeling. The low temperature in winter determines whether the fruit trees should be buried for cold protection. For example, where grapes don't need to be buried in winter, they can be vertical in height, width and width, while where they need to be buried in winter, it is more appropriate to form a single trunk with a shed, while apples need to lie prone.
tree structure
The tree consists of two branches, one is called backbone, which includes trunk, central trunk, main branch and lateral branch, forming the skeleton of the tree; A branch group consisting of various vegetative branches, fruiting branches and auxiliary branches, which has the function of vegetative trees and fruiting. The shaping process is mainly to determine the height of the trunk, whether there is a central trunk, the number of main branches, the position and opening angle of branches on the central trunk, the number of side branches and the planting position. Trunk height is related to planting density, orchard location and final tree height. Generally, the crown height cannot exceed 3/4 of the row spacing. Dwarf fruit trees in arid, cold, windy and barren mountainous areas should have short trunks, such as 20 ~ 30 cm; Tall trees and fruit trees planted sparsely on high temperature, humid and fertile flat land should have high trunks, such as 40 ~ 60 cm. In Gao Qian, trees grow slowly, have strong top advantages and form late; Short and dry, trees grow fast, form early and bear fruit early. Trees with central trunk are easy to maintain tree vigor, long life and large fruit bearing area, but it is easy to have the problem of strong crown and empty cavity: the crown cavity without central trunk has good illumination and high fruit quality, but the tree vigor is not easy to maintain for a long time. In production, trunk trees often adopt the central trunk in the early stage, and gradually retract the central trunk after maturity or crown handover, which makes the head happy; For trees without a central trunk, a false "central trunk" that grows obliquely inward is often selected on the main branch in the late growth stage to maintain the tree potential. The number of main side branches should generally be less than more, or more first and then less. For trees with a central trunk, the main branches should be selected by layers, and the branch angle of the first layer should be larger (50 ~ 70), and the second layer should be slightly reduced in the direction of the main branches of each layer, staggered to make full use of space, and the growth potential between the main branches should be balanced, so that the lower layer is stronger than the upper layer, and the main branches are stronger than the side branches. Small opening angle, long-term retention of branches, the branch trend is booming; On the contrary, it will weaken. Therefore, it can be adjusted by changing the opening angle of the main and lateral branches and the number of nutrient branches on each branch.
Plastic principle
Fruit tree shaping is the main task of pruning young fruit trees. First, the tree shape should be determined according to the growth and fruiting habits of different tree species, cultivation management system and soil climate conditions. When using artificial natural shaping, the following principles should be followed:
Because trees are pruned, they follow the branches.
In the process of fruit tree growth, bud germination and branching are different, especially in the case of inconsistent seedling quality and different rootstocks. In practice, it is almost impossible to find two small trees with identical buds and branches. If they are shaped strictly according to the predetermined tree structure, all the unqualified branches will be cut off and new branches will grow, which will inevitably delay the formation and fruiting period. Therefore, we can only use branches to shape and cultivate the backbone branch structure similar to the standard tree. Take the shape of sparse layer of trunk as an example. For the three main branches of the first floor, they can be adjacent or adjacent. 1 or 2 years can be selected, and even four of them can be selected occasionally. As long as they are scattered in each other's direction, the opening angle can also be cultivated year by year, which is called "tangible and intangible". This is easy to form and bear fruit early.
Overall consideration, light and heavy combination
Reasonable tree shape is for long-term high yield and requires strong skeleton. When pruning, we should ensure the growth advantage of backbone branches, but in order to bear fruit as soon as possible, we must leave as many branches as possible to promote the flowering of branches, so we should consider the initial stage of plastic surgery. Fruit trees grow developing branches every year. With the growth of tree age, when the number of developing branches increases sharply, in addition to the backbone branches, a certain number of auxiliary branches must be reserved or used as reserve branches for future backbone branches. This requires a comprehensive planning of the tree shape with the center of the trunk, natural round head and happy nature. Therefore, in the young stage, we should give priority to light pruning, leave more branches and leaves and expand the nutritional area. At the same time, it is necessary to prune the backbone branches again and slow down the auxiliary branches to create conditions for early flowering and early fruiting. In the future, with the increase of branches, the tree will relax and the pruning amount will increase gradually to maintain the growth advantage of backbone branches.
Balanced tree potential and clear subordination
Growth is always unbalanced between different plants, or between different branches of the same plant. When shaping, it is necessary to restrain the strong and help the weak, correct thinning, make the growth of orchard trees close to the same, maintain the growth balance and subordinate relationship between the main branches of a tree and between the upper and lower backbone branches, and achieve balanced fruit trees with high yield and high quality.
Plastic stage design method
It is mainly accomplished by pruning during dormancy, supplemented by supporting and binding when necessary, so that the backbone branches are formed according to the planned orientation and angle. In the case of vigorous growth, long or short dense planting, in order to accelerate the molding, methods such as coring, short cutting, thinning and pulling branches in the growing period are often supplemented, and the effect is more ideal (see summer pruning). The first step of shaping is to trim the trunk according to the height of the trunk and the shaping zone (branches of main branches are required to be extracted), which is called fixed stem. In the late stage of the first growing season, the main branch and the central trunk are selected from the branches appearing in the main plastic belt. If the growth is vigorous, and the main branch or central trunk in the first growth period has reached the predetermined length, full buds can be selected at appropriate positions for coring, so that they can extend outward in the predetermined direction, maintain the tree potential and accelerate the formation, and the rest branches are treated according to their growth potential. Generally, measures such as light cutting, long planting and leveling are taken to increase the amount of branches and leaves, but it does not hinder the growth of the central trunk or main branch. In the second year, in addition to continuing to cultivate the main branch or central trunk, the lateral branches are selected and retained according to the above method, and the main branch and the branch group are distinguished by different pruning methods (see pruning). For tree species or varieties with strong dryness, in order to prevent them from being strong on the top and weak on the bottom, the central trunk can bend them up, while those with weak dryness should stay for a long time to maintain their advantages. Generally, the plastic surgery process can be completed in 5 ~ 7 years.