Figure 13 Opening angle
1. Opening angle of supporting branch 2. Branch opening angle
Increasing the opening angle of the main branch can inhibit the tip advantage of the upright branch, which is beneficial to the germination and branching of the middle and lower buds and prevent the base from being exposed. After the branch angle is opened, the carbohydrate content increases, the nutritional growth slows down, and the effect of promoting flower bud formation is obvious. After leveling the upright branches, the crown of the tree is enlarged, the ventilation and light transmission conditions are improved, and the space and light and heat resources are fully utilized, which is conducive to flowering and fruiting.
Changing the opening angle and extension direction of branches can also adjust the distribution of photosynthetic products, promote flowering and fruiting, adjust the balance of endogenous hormones in branches, and adjust the appropriate ratio of fruiting branches to vegetative branches. However, the opening angle depends on the actual situation: in the flat orchard, arbor stock fruit tree and dwarf stock fruit tree, the opening angle of branches can be appropriately larger; For trees and rootstocks in orchards in mountainous, hilly and arid areas, the opening angle of branches can be appropriately smaller.
After the branch angle is opened, the growth of nutrients slows down and it is easy to blossom and bear fruit. However, in order to balance the relationship between growth and fruiting, and achieve the goal of high quality and high yield, we must use it flexibly according to different tree species, varieties, tree age, tree potential and site conditions. The opening angle of the first main branch of the tree rootstock apple tree should be 60 ~ 70 degrees, and that of the dwarf rootstock apple tree should be 70 ~ 80 degrees. If the angle is too large, it is difficult to maintain the normal growth of the tree, and it is easy to grow branches on the back, forming trees on the tree and affecting the growth of the main branches; If the angle is too small, the growth is easy to be too vigorous, which affects ventilation and light transmission and is not conducive to flowering and fruiting.
The opening angle of the main branch is suitable, which not only opens the crown, but also has good ventilation and light transmission, early fruiting and good quality; Fruiting branches are easy to shape and cultivate, which is beneficial to overall fruiting and has long economic life. The basic requirements for the three main branches at the base of the mother tree are: the base angle is about 60 degrees, the waist angle is 60-80 degrees, and the sharp angle is about 50 degrees. The opening angle of main branches is related to cultivation management techniques. When pruning, we should not only pay attention to the angle of big branches, but also pay attention to their opening angle and extension direction in the process of cultivating branches.
Branch angle refers to the angle between the branch and the parent branch. The branching angle is directly related to the firmness of the branch. The smaller the branch angle is, the weaker the bearing capacity of the branch point is, and it is easy to split. Therefore, attention should be paid to the angle of main branches and branches when shaping and pruning.
Different tree species and varieties have different branching angles. Green bananas and golden crowns in apple trees have larger natural branching angles, while Marshal, Fuji, Guoguang, Zhuguang and Huang Kui have smaller branching angles.