/kloc-After the middle of the 0/7th century, due to the aesthetic requirements of a few ruling classes, such as feudal nobles, landlords and church owners, they began to manually trim the crown of trees and control the size of trees with dwarfing anvil. This indicates that the purpose of fruit tree cultivation has changed from green ornamental to higher-level ornamental at that time, and gradually improved and developed into later garden ornamental gardening. Judging from the planting area and scale, due to poor traffic conditions and backward storage and processing technology, the demand for fruits in society was not too great. Fruit trees are mainly planted as the ornamental demand of noble gardens, landlord manors, city parks and courtyards. For example, the famous Palace of Versailles in Paris, France, has a garden-style orchard built for Emperor Louis XIV. Apple, pear, peach, apricot, plum, cherry, grape, strawberry, fig and other fruit trees are planted in the park, among which peach, apricot, grape and pear are forced to cultivate because they are not suitable for the local climate and ecological conditions. Especially in the cold climate of Paris, in order to cultivate fruit trees with high heat requirements, it is necessary to build walls to reflect sunlight to raise the temperature. The tree forms are mostly diversified fence wall shapes such as double U-shaped fans, nested U-shaped fans, oblique branch fans, flat branch fans, folding fans, lyre shapes, double arms shapes, and artificial mechanical shapes such as high cups and feather cones.
/kloc-artificial mechanical modeling of ornamental fruit trees in Europe in the 0 th and 7 th centuries
The pruning of branches often adopts the method of leaving three buds to cut short, so that the result part is as close as possible to the backbone branches. /kloc-in the 0/8th century, this artificial mechanical pruning technology developed rapidly, but it did not seek high yield, but only sought beautiful tree shape, large fruit, good color and good quality, which was very attractive to watch. This pruning method is not practical for large-scale economic production, because it requires a lot of support, walls and skilled labor, and the management cost is too high.
/kloc-from the end of 0/9 to the beginning of the 20th century, with the rise of the industrial revolution, the progress of science and technology and the development of capitalism, the conditions of transportation, storage and processing have been greatly improved, and the social demand for fruits has also increased greatly, which objectively requires that the purpose of fruit tree cultivation must be changed to the direction of large-scale commodity economic production. Since then, fruit trees have gone out of the garden and been cultivated in the field, and a few excellent varieties have been concentrated for large-scale economic production. From the management goal, we should strive to increase the yield per plant, reduce the production cost, and obtain better economic benefits under the condition of sparse planting at that time. Therefore, the delicate and complicated pure manual pruning technology originally applied to ornamental fruit trees has been replaced by a flexible and simple pruning method which is close to nature because of too much labor. According to the dryness and photophobia of trees, trees mainly adopt two categories: dry shape and happy shape.
In the pruning of branches, it also conforms to the characteristics of fruit trees, and improves the pruning system from short cutting to pruning. The crown created by this shaping and pruning method is tall and firm, which is convenient for mechanical operation and reduces manual labor. From the results, the yield of young trees increased slowly in the early stage, while the yield of big trees was higher, more stable and longer in the middle and late stage. The disadvantages are too high crown, slow formation of backbone branches in the early stage, low yield, serious shading of branches and leaves in the later stage, poor fruit quality, many pests and diseases and inconvenient management.
Since 1950s, with the intensification of the contradiction among population, grain, land, energy and labor, new changes have taken place in the social, economic and market situation. Fruit tree producers pay more and more attention to early yield and benefit, and consumers demand more and more fruit quantity and quality, so the fruit tree cultivation system begins to develop in the direction of dwarf and close planting. At the same time, a large number of dwarf rootstocks and short-branch varieties were selected, and the pruning methods were changed accordingly. The shape of the tree changes from big to small, and from high to short. The main branches change from long to short, from changeable to less. Pruning changes from complexity to simplicity, and from heavy to light. In countries with large population, small labor force and backward industrial economy, replacing scissors with ropes, wooden sticks, clay balls, stones and bricks, pruning small trees with more hands, using less scissors, bending more and cutting less is a major feature. In countries with small population, insufficient labor force and developed industrial economy, the aim is to improve pruning efficiency. On the one hand, scaffolding and self-made appliances are used for facility shaping pruning, on the other hand, mechanical pruning and chemical pruning techniques that try to replace manual pruning are popularized. In the 1960s, Britain, France and other countries also made bold attempts and successfully planted an ultra-high density "grassland orchard" with 1,000 mu of fully mechanized management. However, due to the high cost of establishing the orchard, it could not be promoted continuously. The United States, the Soviet Union and other countries have developed various pruning machines to prune the crown into regular geometric shapes such as trapezoid, triangle and cube, and the operation efficiency is very high. Of course, mechanical pruning is rough and often needs manual pruning to supplement it. At the same time, many countries try and popularize chemical pruning technology, and use various synthetic growth regulators to regulate the growth rhythm of different organs of fruit trees. In addition to Europe and America, Japan, New Zealand and other countries have also followed this trend, studied and popularized simplified pruning methods and techniques suitable for dwarf and close planting.
Judging from the actual effect of fruit tree pruning in recent 20 years, the tree structure and pruning methods of intensive cultivation of fruit trees abroad will mainly develop in two directions in the future. One is a hedge tree centered on European and American countries, and the other is a flat shed tree centered on Japan and New Zealand, which is suitable for high light efficiency and high quality production. In fact, in order to further improve the production quality and economic benefits of fruits, the United States and other countries are also experimenting with flat shed trees. From this point of view, in the future, the research and development of flat shed trees in fruit-producing countries in the world is likely to continue to heat up, and supporting facilities such as pruning, keeping fruits at a distance, bagging and cleaning, picking leaves and turning fruits will be paid more attention. As for the "grassland orchard" with ultra-high density and fully mechanized management, the long-term management methods, technologies and benefits need to be further tested.