1. Requirements for shaping dwarfing trees: The shaping of dwarfing and densely planted fruit trees should make full use of the characteristics of vigorous growth in their infancy, and select, retain and cultivate backbone branches at all levels from the early stage. In other words, it is better to cultivate the backbone branches of dwarf fruit trees sooner rather than later, and there should be no wrong idea of "bearing fruit first, then shaping". Because dwarf trees grow weaker and faster after fruiting, it is actually difficult to cultivate ideal backbone branches. The principle of plastic surgery should be "small crown, few backbone branches, many branches and firm structure". For varieties with strong dryness, the central trunk can be bent and elongated, and the main branches can be arranged adjacent to each other. It should be noted that the angle of the lower main branch should not be too large or too flat, and the fruit should not be left near the elongated head. The upper branches should not be selected too early or too fast, but should be cultivated after the lower branches have developed to a certain extent. At the same time, the height and width of the crown should be strictly controlled according to the row spacing of planting plants to ensure the necessary lighting conditions and working channels. For the specific target tree, we should comprehensively consider the characteristics, planting density, site conditions and technical level of the rootstock, and we can flexibly choose the small three-dimensional shape or hedge wall shape suitable for close planting from the "high-yield tree shape" introduced in the first section of chapter 2 of the second part.
Second, the pruning points of dwarf trees: (1) Young trees should handle the relationship between shaping and results at the same time. The principle is to make full use of the achievements of auxiliary branches while ensuring the growth advantages of main branches. Therefore, when pruning, except the extension head of the main branch must be cut off from the middle, other non-main branches should be kept as much as possible, and light cutting and slow release can alleviate the tree potential and increase the bearing parts. For branches with upright posture and vigorous growth, first control them by methods such as softness, bending and injury, and then release them slowly.
(2) The fruit tree should be carefully pruned. Moderate flower bud branches should bear some fruits and cut some, and the bearing branches should be constantly updated and rotated by cultivating "three sets of branches" For long and weak branches that have been drooping for many years, they should be retracted and raised in time to ensure the necessary growth of branches and prevent them from continuing to age and weaken.
(3) Weakening trees should pay great attention to thinning flowers and fruits, so as to reduce ineffective consumption and improve the nutritional conditions of trees, thus preventing "big and small years" from prolonging the fruiting life.
Branches should not blossom and bear fruit within three years before the extension of main branches. Results Proper leaf-fruit ratio should be maintained in pruning branches. To achieve "fixed yield by trees, care for leaves and flowers, reasonable load, and no fruit pressure", so that trees can "bear more fruits without affecting the growth of branches and leaves, and do not lose storage nutrition in high-yield years".
(4) For varieties with few branches, it is necessary to pay attention to short-node supporting branches, increase the number of branches, cultivate compact multi-axis bearing branches and expand the bearing area in the young tree stage.
Branches should not blossom and bear fruit within three years before the extension of main branches. Results Proper leaf-fruit ratio should be maintained in pruning branches. To achieve "fixed yield by trees, care for leaves and flowers, reasonable load, and no fruit pressure", so that trees can "bear more fruits without affecting the growth of branches and leaves, and do not lose storage nutrition in high-yield years".
(5) Pay attention to the supplement and adjustment of summer pruning, balance the tree potential in time, and control the free and standardized development of crown width and crown width.
For extra-wide branches, the head should be changed from high to low, and the long head should be changed to short head. For the bias phenomenon of upper strength and lower weakness, we should suppress the upper strength, promote the lower strength, replace the upper strong head with a weak head and raise the lower strong head. At the same time, pay attention to the treatment of cross branches, overlapping branches, sparse branches and disorderly branches to improve canopy illumination. It is necessary to achieve "the trees are balanced, not weak or prosperous, the branches are not vacant, and the branches do not affect the light transmission." (six) pruning dwarf trees should fully consider the combination of rootstock and spike, site conditions and comprehensive nutrition management level.
Generally speaking, strong orchards are lightly cut and weak orchards are heavily cut. Soil, fertilizer and water management is the foundation, and adequate nutrition is the guarantee.